Horizon Episode Rating Graph

To celebrate the 30th anniversary of its launch, this film tells the remarkable story of how Hubble revealed the awe and wonder of our universe and how a team of daring astronauts risked their lives to keep it working.

The inside story of the James Webb Space Telescope, following the Nasa team building the £8 billion device and the scientists taking its first image of distant stars and galaxies.

Professor Brian Cox takes a global journey in search of the energy source of the future. Called nuclear fusion, it is the process that fuels the sun and every other star in the universe. Yet despite over five decades of effort, scientists have been unable to get even a single watt of fusion electricity onto the grid. Brian returns to Horizon to find out why. Granted extraordinary access to the biggest and most ambitious fusion experiments on the planet, Brian travels to the USA to see a high security fusion bomb testing facility in action and is given a tour of the world's most powerful laser. In South Korea, he clambers inside the reaction chamber of K-Star, the world's first super-cooled, super-conducting fusion reactor where the fate of future fusion research will be decided.

In the mid-1990s, a team of American science students took on the might of the Las Vegas casinos, and came home with millions of dollars. Hard working engineering students during the week, they became high-rolling gamblers by the weekend and proved that, in one game at least, the house doesn't always win. The game was blackjack, and the students were from the world-renowned Massachusetts Institute of Technology (MIT). Their audacious winnings marked the climax of an arms race between casino and player that began 40 years earlier with maths professor Edward Thorp. He realised that the one feature of blackjack that made it different from other casino games also made it possible to beat. In most gambling games - roulette, dice, slot machines, the lottery - events in the past do not determine the future. The odds are the same on every roll of the dice or spin of the wheel. Winning streaks or losing streaks may occur, but they are only one possible result from the set of all possible outcomes. A fair coin that has shown heads ten times, still only has a 50% chance of showing heads on the next flip. Casinos and bookmakers make certain that the odds are always stacked slightly in their favour. In other words, over time, the house will always win.

Looks at Ian Waterman, who at 19 caught a virus that destroyed half of his nervous system and who, in spite of medical assertions that he would never walk, feed or move again, managed by sheer will-power to get back some mobility. Examines the question of how far the brain can over-ride disease or physical problems.

Michael Mosley has set himself a truly ambitious goal: he wants to live longer, stay younger and lose weight in the bargain. And he wants to make as few changes to his life as possible along the way. He discovers the powerful new science behind the ancient idea of fasting, and he thinks he's found a way of doing it that still allows him to enjoy his food. Michael tests out the science of fasting on himself - with life-changing results.

Only 4% of our universe is made from stuff we understand. Horizon explores the 96% that is made up of the elusive substance 'Dark Matter'.

A&E doctor Kevin Fong finds out how doctors can avoid making mistakes in the high-pressure, high-stakes world of the operating theatre. He sets out to learn how other professionals make life and death decisions under pressure, from airline pilots facing emergencies, to the Fire Service dealing with lethal blazes, to the world of Formula One pit crews. Kevin discovers how all these fields are helping to make surgery safer.

There is a strange and mysterious world that surrounds us, a world largely hidden from our senses. The quest to explain the true nature of reality is one of the great scientific detective stories. Clues have been pieced together from deep within the atom, from the event horizon of black holes, and from the far reaches of the cosmos. It may be that that we are part of a cosmic hologram, projected from the edge of the universe. Or that we exist in an infinity of parallel worlds. Your reality may never look quite the same again.

Horizon plunges down the biggest rabbit-hole in history in search of the smallest thing in the Universe. It is a journey where things don't just become smaller but also a whole lot weirder. Scientists hope to catch a glimpse of miniature black holes, multiple dimensions and even parallel Universes. As they start to explore this wonderland, where nothing is quite what it seems, they may have to rewrite the fundamental laws of time and space.

Comedian and impressionist Rory Bremner is on a personal mission to uncover the science of ADHD (attention deficit hyperactivity disorder), a condition which he has suspected he has. In this film, Rory learns about the science of ADHD, goes for a diagnosis and tries the drug methylphenidate (also known as Ritalin) for the first time - just before walking on stage.

When she's diagnosed with cervical cancer at the age of 36, Hannah Fry explores the problematic issues surrounding how we screen for and treat cancer, asking if we could be overmedicalising it.

There's something very odd going on in space - something that shouldn't be possible. It is as though vast swathes of the universe are being hoovered up by a vast and unseen celestial vacuum cleaner. Sasha Kaslinsky, the scientist who discovered the phenomenon, is understandably nervous: 'It left us quite unsettled and jittery' he says, 'because this is not something we planned to find'. The accidental discovery of what is ominously being called 'dark flow' not only has implications for the destinies of large numbers of galaxies - it also means that large numbers of scientists might have to find a new way of understanding the universe. Dark flow is the latest in a long line of phenomena that have threatened to rewrite the textbooks. Does it herald a new era of understanding, or does it simply mean that everything we know about the universe is wrong?

For centuries we have dreamt of reaching the centre of the Earth. Now scientists are uncovering a bizarre and alien world that lies 4,000 miles beneath our feet, unlike anything we know on the surface. It is a planet buried within the planet we know, where storms rage within a sea of white-hot metal and a giant forest of crystals make up a metal core the size of the Moon. Horizon follows scientists who are conducting experiments to recreate this core within their own laboratories, with surprising results.

A billion miles from home, running low on fuel, and almost out of time. After 13 years traversing the Saturn system, the spacecraft Cassini is plunging to a fiery death, becoming part of the very planet it has been exploring. As it embarks on its final assignment - a one-way trip into the heart of Saturn - Horizon celebrates the incredible achievements and discoveries of a mission that has changed the way we see the solar system. Strange new worlds with gigantic ice geysers, hidden underground oceans that could harbour life and a brand new moon coalescing in Saturn's magnificent rings. As the world says goodbye to the great explorer Cassini, Horizon will be there for with a ringside seat for its final moments.

Horizon explores the findings of physicists at Brookhaven, Long Island, New York. Who, after two years and thousands of photographs, have identified a predicted new particle which has a unique characteristic: 'strangeness minus three'.

Like many, Michael Mosley want to get fitter and healthier but can't face hours on the treadmill or trips to the gym. Help may be at hand. He uncovers the surprising new research which suggests many of us could benefit from just three minutes of high intensity exercise a week. He discovers the hidden power of simple activities like walking and fidgeting, and finds out why some of us don't respond to exercise at all Using himself as a guinea pig, Michael uncovers the surprising new research about exercise, that has the power to make us all live longer and healthier lives.

Surgeon Gabriel Weston discovers the surprising truth about why so many people are piling on the pounds, and how to fight the fat epidemic. She discovers the hidden battles of hormones that control people's appetites, and sees the latest surgery that fundamentally changes what a patient wants to eat by altering how their brains work. Gabriel is shocked to find out that when it comes to being overweight, it is not always your fault you are fat.

Over a person's lifetime they are likely to be prescribed more than 14,000 pills. Antibiotics, cholesterol lowering tablets, anti-depressants, painkillers, even tablets to extend youth and improve performance in bed. These drugs perform minor miracles day after day, but how much is really known about them? Drug discovery often owes as much to serendipity as to science, and that means much is learnt about how medicines work, or even what they do, when they're taken. By investigating some of the most popular pills people pop, Horizon asks, how much can they be trusted to do what they are supposed to?

This summer, the black hole at the centre of the Milky Way is getting ready to feast. A gas cloud three times the size of our planet has strayed within the gravitational reach of our nearest supermassive black hole. And across the globe, telescopes are being trained on the heart of our Milky Way galaxy, some 27,000 light years from Earth, in the expectation of observing this unique cosmic spectacle. For cosmic detectives across the Earth, it is a unique opportunity. For the first time in the history of science, they hope to observe in action the awesome spectacle of a feeding supermassive black hole.

The acerbically witty and severely facially disfigured broadcaster Adam Pearson presents a personal film about genetics. He and his twin brother Neil are genetically identical and both share the same genetic disease, Neurofibromatosis 1 (Nf1) - yet they are completely different. Adam's face is covered with growths, whereas Neil has none. Neil has short term memory loss, whereas Adam is razor sharp. How can the same genetic disease affect identical twins so differently? Adam is on the cusp of a successful film and television career, but the disease has left tumours on his face that are growing out of control and he could lose his sight. For years, everyone thought Adam's brother Neil had escaped symptoms, but today his life is governed by epilepsy and a mysterious memory loss that suddenly came on during his teens. Determined to save their future, Adam tries to find out why the disease affects the twins so differently and see if there is anything he can do to stop it from tearing their lives apart.

Why are you more likely to have a heart attack at eight o'clock in the morning or crash your car on the motorway at two o'clock in the afternoon? Can taking your medication at the right time of day really save your life? And have you ever wondered why teenagers will not get out of bed in the morning? The answers to these questions lie in the secret world of the biological clock.

Exploring the murky and fast-paced world of the hackers out to steal money and identities and wreak havoc with people's online lives, and the scientists who are joining forces to help defeat them. Horizon meets the two men who uncovered the world's first cyber weapon, the pioneers of what is called ultra paranoid computing, and the computer expert who worked out how to hack into cash machines.

Cosmologists talk about their project to create a map of everything in existence, and also reveal that their research has some highly unexpected results, creating a picture stranger than anything they had ever imagined.

Comedian Ben Miller returns to his roots as a physicist to try to answer a deceptively simple question: what is one degree of temperature? His quest takes him to the frontiers of current science as he meets researchers working on the hottest and coldest temperatures in the universe, and to a lab where he experiences some of the strangest effects of quantum physics - a place where super-cooled liquids simply pass through solid glass. Plus, Ben installs his very own Met office weather station at home. Ben's investigations in this personal and passionate film highlight the importance of measurement and accuracy in the 21st century.

Dr Michael Mosley seeks to establish the truth about meat. Every year, humans raise and eat 65 billion animals - nine animals for every person on the globe. In this eye-opening documentary, Michael examines the impact that this is having on the planet and finds out what meat eco-friendly carnivores should be buying. Is it better to buy free-range organic or factory-farmed meat? The answers are far from obvious.

BBC News special correspondent Fergal Keane has covered conflict and brutality for more than 30 years and is known for reporting with humanity and extraordinary empathy, but in 2020 revealed he had been diagnosed with an acute form of post-traumatic stress disorder. In this Horizon documentary, he reveals the impact of PTSD on his life, exploring how it led him to consider withdrawing from reporting on conflicts, as well as investigating the latest scientific thinking behind its treatment.

At a pivotal moment in the history of one of the world’s oldest drugs, Dr Javid Abdelmoneim investigates the latest medical and scientific research into the effects of cannabis on the brain and body.

Following the NHS as they start to implement proton beam therapy, an advanced but expensive cancer treatment, as well as following as the first children awaiting the lifesaving treatment.

Horizon uncovers the truth about how you really make decisions. Every day you make thousands of decisions, big and small, and behind all them is a powerful battle in your mind, pitting intuition against logic. This conflict affects every aspect of your life - from what you eat to what you believe, and especially to how you spend your money. And it turns out that the intuitive part of your mind is a lot more powerful than you may realise.

Over the past year, Horizon has been behind the scenes at one of Britain's leading cancer hospitals, the Royal Marsden in London. The film follows Rosemary, Phil and Ray as they undergo remarkable new treatments - from a billion pound genetically targeted drug designed to fight a type of skin cancer, to advanced robotic surgery. We witness the breakthroughs in surgery and in scientific research that are offering new hope and helping to defeat a disease that more than one in three of us will develop at some stage of our lives.

Something weird seems to be happening to our weather - it appears to be getting more extreme. In the past few years we have shivered through two record-breaking cold winters and parts of the country have experienced intense droughts and torrential floods. It is a pattern that appears to be playing out across the globe. Hurricane chasers are recording bigger storms and in Texas, record-breaking rain has been followed by record-breaking drought. Horizon follows the scientists who are trying to understand what's been happening to our weather and investigates if these extremes are a taste of whats to come.

Black holes are one of the most destructive forces in the universe, capable of tearing a planet apart and swallowing an entire star. Yet scientists now believe they could hold the key to answering the ultimate question - what was there before the Big Bang? The trouble is that researching them is next to impossible. Black holes are by definition invisible and there's no scientific theory able to explain them. Despite these obvious obstacles, Horizon meets the astronomers attempting to image a black hole for the very first time and the theoretical physicists getting ever closer to unlocking their mysteries. It's a story that takes us into the heart of a black hole and to the very edge of what we think we know about the universe.

Horizon follows the emotional journey of three young people with currently untreatable conditions to see if, within their lifetime, they can be cured. Sophie Morgan is determined not to spend the rest of her life in a wheelchair. She is tempted by the online claims of unregulated private clinics promising a cure using stem cells. Anthony Bath was just 20 when his right leg was amputated after a botched pinning procedure. In Finland, Anthony witnesses one of the world's first operations in which stem cells are used to replace bone. Dean Third was diagnosed with dilated cardiomyopathy, a condition in which his damaged heart could cause his death at any moment. Desperate for a cure, he visits Dr Anthony Mathur from University College London to witness the world's first trial using stem cells taken from bone marrow.

Ever since he was at school, actor and comedian Alan Davies has hated maths. And like many people, he is not much good at it either. But Alan has always had a sneaking suspicion that he was missing out. So, with the help of top mathematician Professor Marcus du Sautoy, Alan is going to embark on a maths odyssey. Together they visit the fourth dimension, cross the universe and explore the concept of infinity. Along the way, Alan does battle with some of the toughest maths questions of our age. But did his abilities peak 25 years ago when he got his grade C O-Level? Or will Alan be able to master the most complex maths concept there is?

Dr Brian Cox wants to know why the Universe is built the way it is. Particle physicist and ex D:Ream keyboard player Dr Brian Cox wants to know why the Universe is built the way it is. He believes the answers lie in the force of gravity. But Newton thought gravity was powered by God, and even Einstein failed to completely solve it. Heading out with his film crew on a road trip across the USA, Brian fires lasers at the moon in Texas, goes mad in the desert in Arizona, encounters the bending of space and time at a maximum security military base, tries to detect ripples in our reality in the swamps of Louisiana and searches for hidden dimensions just outside Chicago.

The coastline that protects the city of New Orleans is sinking into the ocean. Horizon explores what can be done to save the city if it is worth saving at all.

Rudi Affolter and Gwen Tighe have both experienced strong religious visions. He is an atheist; she a Christian. He thought he had died; she thought she had given birth to Jesus. Both have temporal lobe epilepsy. Like other forms of epilepsy, the condition causes fitting but it is also associated with religious hallucinations. Research into why people like Rudi and Gwen saw what they did has opened up a whole field of brain science: neurotheology. The connection between the temporal lobes of the brain and religious feeling has led one Canadian scientist to try stimulating them. (They are near your ears.) 80% of Dr Michael Persinger's experimental subjects report that an artificial magnetic field focused on those brain areas gives them a feeling of 'not being alone'. Some of them describe it as a religious sensation. His work raises the prospect that we are programmed to believe in god, that faith is a mental ability humans have developed or been given. And temporal lobe epilepsy (TLE) could help unlock the mystery.

In the summer of 2000, one of the great frontier cities of the Roman Empire, the city of Zeugma, all but disappeared from the face of the Earth under the flood waters of a dam. In a bid to modernise, the Turkish government has embarked on one of the most ambitious engineering projects in the world, building a series of dams on the Euphrates over the past twenty years. Almost every dam threatens ancient remains that lie below in one of the most archaeologically rich regions of the world. The completion of the Birecik dam, featured in this film, has flooded the valley where Zeugma is buried. The city on the flat plain has entirely disappeared and the waters have now risen to cover 30% of the city on the hillside. Horizon tells the story of the archaeologists' fifth and final visit, struggling to save what they could before the dam waters rose. It witnesses the uncovering of some of the most beautiful examples of Roman art ever found. The team’s discoveries at Zeugma caused an international outcry and further excavations were hurriedly put together. Since 1995, French archaeologists Pierre Leriche and Catherine Abadie-Reynal have taken up the challenge to save what they can from the city before the dam is finished. The archaeologists have two main tasks - to uncover the history of this desperately under-excavated region of Turkey and to remove what treasures they could from the site before they were lost forever. On this, their final excavation, they had to work against the clock: they only had a permit to dig for six weeks Zeugma was founded by one of Alexander the Great’s generals, Seleucia Nicator, and prospered under later Roman rule. It became one of the major cities of the Roman eastern frontier with a garrison of over 6,000 soldiers. The city’s bridge across the Euphrates made it one of the most critical trading cities in the region, on the silk routes to the East. The archaeologists know that the city contains vital clues to the history of the region. Previously looted exquisite mosaics have hinted at the treasures of its past that must be buried somewhere in the vast site. The part of the old city on the Euphrates flood plain, Apamea, was the first to go. But the archaeologists didn’t stand a chance of excavating it in such a short amount of time. So using a technology originally developed for finding oil and mineral deposits, they instead generated a picture of the buried city just as it lies below ground. They discovered a preserved ancient Greek city, laid out in a perfect grid. Meanwhile, in the remains of a Roman villa across the river, the archaeologists had an extraordinary stroke of luck. With only five days left on the excavation permit, Catherine Abadie-Reynal unearthed a masterpiece: a beautiful Roman mosaic floor. The discovery caused an international outcry and hit the headlines across the world. The archaeologists were granted more days to excavate, but they could not stem the tide of the dam project. With time running out, they uncovered more stunning mosaics in the villa. They were dug out from the site and sent to a local museum at Gaziantep - just in time. By mid June 2000, the newly uncovered fourteen room villa disappeared underwater. By October, the level of the water finally settled to form a vast, still lake in the valley. All excavations at the site ceased. There's recently been a move by the Turkish government to declare Zeugma a site of special archaeological interest. The remainder of the ancient city on the hillside could, in theory, still be explored. The dam will not only erase much of Zeugma from history. It will also displace 30,000 people, mostly Kurds, from the villages they have lived in for generations. For many, the loss of Zeugma is a tragedy.

Horizon investigates the use of psychological techniques in job recruitment and career development.

In this episode, Horizon investigates the nuclear accident which took place in the United States at the Three Mile Island nuclear power plant during March 1979.

Horizon examines some of the effects that moderate amounts of alcohol can have on the body.

Horizon presents a report on zero gravity and the effects of weightlessness in spacecraft on humans.

Horizon presents a study of Thomas Alva Edison and his achievements as an inventor.

This story by Horizon is about American research into techniques for controlling bodily functions with the mind.

In this episode, Horizon investigates the study of science by african americans.

Prof. Arthur C. Clarke, Derek Price and Nigel Balchin discuss the past and future of science.

Horizon goes behind the scenes at Nasa to discover how it is preparing for its most ambitious and daring mission: to land men - and possibly women - on the surface of Mars. It's over 40 years since Neil Armstrong made the first human footprint on the moon. But getting to the red planet would involve a journey of at least three years. Horizon meets the scientists and engineers who are designing new rockets, new space suits and finding ways to help astronauts survive the perils of this long voyage. And it turns out that having the 'right stuff' for a mission to mars might not be quite what you expect.

50 cats were fitted with GPS collars to track their every movement, and cat-cams to record their unique view of the world. In this groundbreaking experiment, a few cats stood out. They include the intruder cat, an unneutered tomcat, who comes into the village and seems to have no owner; the hunter, who prefers food that he can catch and kill to anything his owners might buy him; and the deserter cat who has abandoned his home in favour of a new set of owners. This film reveals that the relationship between cats and their owners isn't quite what we imagine.

Michael Mosley investigates the alleged danger in eating red and processed meat, and does a one month test on himself, doubling his meat intake.

Liz Bonnin presents a controversial and provocative episode of Horizon, investigating how new scientific research is raising hard questions about zoos - the film explores how and why zoos keep animals, and whether they need to change to keep up with modern science or ultimately be consigned to history. Should zoos cull their animals to manage populations? Liz travels to Copenhagen Zoo, who killed a giraffe and fed it to the lions, to witness their culling process first hand. They think it is a natural part of zoo keeping that is often swept under the carpet. Should some animals never be kept in captivity? In a world exclusive, Liz visits SeaWorld in Florida and asks if captivity drove one of their orcas to kill his trainer. But could zoos be the answer to conserving endangered species? Liz examines their record, from helping breed pandas for the wild to efforts to save the rhinos. She meets one of the last surviving northern white rhinos and discovers the future of this species now lies in a multimillion-dollar programme to engineer them from stem cells. Veteran conservation scientist Dr Sarah Bexell tells Liz the science of captive breeding is giving humanity false hope.

Dr Xand Van Tulleken is single and looking for love. Mathematician Dr Hannah Fry wants to use him as her guinea pig to test whether the algorithms that dating sites use to match people actually work. While Hannah builds a dating site, Xand meets the scientists investigating online dating - and learns what pictures to use and what to write in his profile. He tries out a 'bot' that has automated a swiping app and has an MRI scan to find out whether his brain is equipped for love. 50 members of the public take part in some mini experiments at a date night - and Xand goes on various dates to test whether the algorithm is better than him choosing randomly.

Michael Mosley puts himself through a battery of health tests available to people who feel perfectly well. From an expensive heart scan to a new national screening procedure to detect the earliest signs of bowel cancer, Mosley sets out to discover which if any of the tests are worth doing.

What makes us good or evil? It's a simple but deeply unsettling question. One that scientists are now starting to answer. Horizon meets the researchers who have studied some of the most terrifying people behind bars - psychopathic killers. But there was a shock in store for one of these scientists, Professor Jim Fallon, when he discovered that he had the profile of a psychopath. And the reason he didn't turn out to be a killer holds important lessons for all of us. We meet the scientist who believes he has found the moral molecule and the man who is using this new understanding to rewrite our ideas of crime and punishment.

Documentary exploring the impact of colours on people's lives, and how perceptions of them can be influenced by age, gender and mood. The programme examines scientists' claims that different hues have hidden powers, from the winning properties of red to how blue seemingly makes time speed up.

Horizon reveals the untold story of the 87-day battle to kill the Deepwater Horizon oil blowout a mile beneath the waves - a crisis that became America's worst environmental disaster. Engineers and oil men at the heart of the operation talk for the first time about the colossal engineering challenges they faced and how they had to improvise under extreme pressure. They tell of how they used household junk, discarded steel boxes and giant underwater cutting shears to stop the oil. It's an operation that one insider likens to the rescue of Apollo 13.

Iain Stewart investigates a new and controversial energy rush for the natural gas found deep underground. Sometimes, this is right under the places people live in. Getting it out of the ground involves hydraulic fracturing - or fracking. Iain travels to America to find to find out what it is, why it is a potential game changer and what we can learn from the US experience. He meets some of the people who have become rich from fracking as well as the communities worried about the risks.

Tells the story of mathematician Andrew Wiles who has made it his life's work to solve the puzzle of Fermat's last theorem that has baffled minds for three centuries.

Professor Alice Roberts is making a new human being - she is pregnant with her second child. But before he is born, she wants to find out what makes a human, human? What is that separates us from our closest living relatives - the chimpanzees? We share 99% of our DNA with chimpanzees and yet from the moment of birth, our lives are completely different. So are we just another animal, or is there something special about being human? Before her new baby emerges into the world, Professor Roberts sets out to explore what it is about our bodies, our genes and ultimately our brains that set us apart from our furry cousins - what is it that truly makes us human?

We have an extraordinary relationship with dogs - closer than with any other animal on the planet. But what makes the bond between us so special? Research into dogs is gaining momentum, and scientists are investigating them like never before. From the latest fossil evidence, to the sequencing of the canine genome, to cognitive experiments, dogs are fast turning into the new chimps as a window into understanding ourselves. Where does this relationship come from? In Siberia, a unique breeding experiment reveals the astonishing secret of how dogs evolved from wolves. Swedish scientists demonstrate how the human/dog bond is controlled by a powerful hormone also responsible for bonding mothers to their babies. Why are dogs so good at reading our emotions? Horizon meets Betsy, the world's most intelligent dog, and compares her incredible abilities to those of children. Man's best friend has recently gone one step further - helping us identify genes responsible for causing human diseases.

They are the biggest questions that science can possibly ask: where did everything in our universe come from? How did it all begin? For nearly a hundred years, we thought we had the answer: a big bang some 14 billion years ago. But now some scientists believe that was not really the beginning. Our universe may have had a life before this violent moment of creation. Horizon takes the ultimate trip into the unknown, to explore a dizzying world of cosmic bounces, rips and multiple universes, and finds out what happened before the big bang.

In Los Angeles, a remarkable experiment is underway; the police are trying to predict crime, before it even happens. At the heart of the city of London, one trader believes that he has found the secret of making billions with math. In South Africa, astronomers are attempting to catalogue the entire cosmos. These very different worlds are united by one thing - an extraordinary explosion in data. Horizon meets the people at the forefront of the data revolution, and reveals the possibilities and the promise of the age of big data

Scientists genuinely don't know what most of our universe is made of. The atoms we're made from only make up four per cent. The rest is dark matter and dark energy (for 'dark', read 'don't know'). The Large Hadron Collider at CERN has been upgraded. When it's switched on in March 2015, its collisions will have twice the energy they did before. The hope is that scientists will discover the identity of dark matter in the debris.

Horizon explores the strange and wonderful world of illusions - and reveals the tricks they play on our senses and why they fool us. We show how easy it is to trick your sense of taste by changing the colours of food and drink, explain how what you see can change what you hear, and see just how unreliable our sense of colour can be. But all this trickery has a serious purpose. It's helping scientists to create a new understanding of how our senses work - not as individual senses, but connected together.

As they contain no active ingredient, placebo medicines and pills should not really work, but they are now being shown to be effective in helping treat pain and depression and even alleviating some of the symptoms of Parkinson's disease. This programme explores why they work and how everyone could benefit from them.

Changes to the bacteria that live inside all of us are responsible for increasing the number of people with allergies, suggests new research. The show investigates this claim by conducting a unique experiment with two allergic families in order to find out just what it is in the modern world that is to blame. With a raft of mini cameras, GPS units and the very latest gene sequencing technology, the show discovers how the western lifestyle is impacting their bacteria. Why are these changes making people allergic? And what can be done to put a stop to the allergy epidemic?

Twenty-five years after the world wide web was created, it is now caught in the greatest controversy of its existence: surveillance. With many concerned that governments and corporations can monitor our every move, Horizon meets the hackers and scientists whose technology is fighting back. It is a controversial technology, and some law enforcement officers believe it is leading to 'risk-free crime' on the 'dark web' - a place where almost anything can be bought, from guns and drugs to credit card details.

How bad can our drinking pattern be for our health? Doctors and genetically identical twins Chris and Xand van Tulleken want to find out. With the current drinking guidelines under review, the twins embark on self-experimentation to see the effects of different drinking patterns on their health. With Chris drinking 21 units spread evenly across the week and Xand having his 21 in single weekly binges, how will their bodies differ after a month? Catching up with the latest research into alcohol drinking patterns, we ask if moderate drinking is genuinely good for us - and whether binge drinking is really that bad.

Will the Large Hadron Collider finally reveal the elusive God particle? In the coming months the most complex scientific instrument ever built will be switched on. The Large Hadron Collider promises to recreate the conditions right after the Big Bang. By revisiting the beginning of time, scientists hope to unravel some of the deepest secrets of our Universe. Within these first few moments the building blocks of the Universe were created. The search for these fundamental particles has occupied scientists for decades but there remains one particle that has stubbornly refused to appear in any experiment. The Higgs Boson is so crucial to our understanding of the Universe that it has been dubbed the God particle. It explains how fundamental particles acquire mass, or as one scientist plainly states: "It is what makes stuff stuff..."

Top quality diamonds at knock down prices? The only catch is: these rocks don't come out of the ground, but are made in a lab. This is the promise offered by a series of recent scientific breakthroughs. For most of us, it seems we may soon be able to bejewel ourselves like movie stars. But for De Beers, the world's largest diamond trader, could this, one day, be a serious threat? Following a dodgy meeting in Moscow, retired US Army General Carter Clarke acquired some experimental diamond growing machines, originally destined for the Russian military. He created the world's first gem diamond production line, to mass produce highly prized coloured diamonds. In a secret location south of Boston, a father and son team developed a different technique. Robert Linares and son Bryant have made colourless diamonds, allegedly higher quality than those found in nature. De Beers, at vast cost, set up a new scientific division called the Gem Defensive Programme. Its goal: to find ways to tell apart their natural diamonds from these new synthetic gems. But will the new synthetics slip through De Beers detection net? And could anyone really tell the difference? Horizon tells the story of the Diamond Labs.

It was the simplest idea but one with enormous potential. If a gene is defective in the human body, just replace it with one that works properly. Gene therapy would mean that genetic disorders would become a thing of the past. Cancer would be cured, as would cystic fibrosis and hundreds of other genetic illnesses. Scientists were justifiably excited about the idea but, this enthusiasm that would end up costing one young man his life. Jesse Gelsinger was born with a liver disorder, a rare condition called ornithine transcarbamylase (OTC) deficiency that stops the liver metabolising ammonia. People with the disease can suffer from brain damage or coma. At its most extreme the illness is fatal. Jesse was lucky, able to lead a fairly normal life although he had a daily cocktail of drugs to control his condition. Jesse wanted to help others. When he was offered a chance to take part in a medical trial to test the safety of using gene therapy for OTC deficiency, he was keen to participate. He knew this was not a cure for his condition but that, by volunteering he might be able to help others in the future. Although the concept of gene therapy is simple, the practice of administering the treatment is much more difficult. In order to replace defective genes, doctors must get working ones into the body and to the place where they are needed.

This is the first part of a two-part Horizon series presenting a portrait of Richard Feynman, the American Nobel Prize winning physicist.

Michael Mosley investigates the dramatic rise in e-cigarettes. They're everywhere these days, but what does the latest scientific research on them reveal? Michael reveals what e-cigarettes are really doing to your health. Are they really better for you than cigarettes? What is actually in them? Is passive vapour harmful? And can they really stop you from smoking? Michael meets some of the scientists around the world studying them, asks a group of volunteers to try to give up smoking regular cigarettes using them, and even takes up 'vaping' himself, smoking an e-cigarette every day for a month to see the effects on his own health - no easy task for such a committed non-smoker.

What's worse for us: sugar or fat? To answer the hottest question in nutrition, twin doctors Chris and Xand Van Tulleken go on month long high-fat and high-sugar diets. The effects on their bodies are shocking and surprising. But they also discover that in the debate about fat and sugar, the real enemy might have been hiding in plain sight.

Scientists are expecting a fit of violent activity on the sun which will propel billions of tonnes of superheated gas and pulses of energy towards our planet. They have the power to close down our modern technological civilization. Horizon meets the space weathermen who are trying to predict what's coming our way, and organistions like the National Grid which are preparing for the impending solar storms.

Horizon follows an international team of volcanologists in Iceland as they draw fascinating parallels with the volcanoes on Earth and those elsewhere in the solar system. Through the team's research, we discover that the largest volcano of the solar system - Olympus Mons on Mars - has been formed in a similar way to those of Iceland, how a small moon of Jupiter - Io - has the most violent eruptions anywhere, and find out that a moon of Saturn called Enceladus erupts icy geysers from a hidden ocean. Computer graphics combined with original NASA material reveal the spectacular sights of these amazing volcanoes. Along the way, we learn how volcanoes are not just a destructive force, but have been essential to the formation of atmospheres and even life. And through these volcanoes of the solar system, scientists have discovered far more about our own planet, Earth- hat it was like when Earth first formed, and even what will happen to our planet in the future.

By our third year, most of us will have learned to count. Once we know how, it seems as if there would be nothing to stop us counting forever. But, while infinity might seem like an perfectly innocent idea, keep counting and you enter a paradoxical world where nothing is as it seems. Mathematicians have discovered there are infinitely many infinities, each one infinitely bigger than the last. And if the universe goes on forever, the consequences are even more bizarre. In an infinite universe, there are infinitely many copies of the Earth and infinitely many copies of you. Older than time, bigger than the universe and stranger than fiction. This is the story of infinity.

The oceans define the earth. They are crucial to life and we used to think that they were unique to our blue planet. But we were wrong. It has recently been discovered that there are oceans all over our solar system and they are very similar to our own. And now scientists are going on an epic journey in search of new life in places that never seemed possible. Nasa is even planning to dive to the depths of a strange, distant ocean in a remarkable submarine. Horizon discovers that the hunt for oceans in space is marking the dawn of a new era in the search for alien life.

Horizon investigates a new era of Alzheimer's research, which is bringing hope to millions of sufferers across the world. New scanning and gene technology is allowing scientists to identify the disease at its earliest stages, often 15 years before symptoms appear and the brain cells are destroyed. A series of new drugs trials in Colombia, the USA and Europe are showing startling success in reducing beta amyloid, the protein which is a hallmark of the disease. It is also becoming clear that changes in lifestyle can prevent the development of the disease. A new system inside the brain has been discovered which clears amyloid when we are in deep sleep, but allows it to accumulate if we don't sleep well. The programme reveals that for sufferers in the early stages of the disease, brain connections, or synapses, can be strengthened and even replaced by absorbing enough of the right nutrients. A UK-wide trail helps sufferers in the early stages to concentrate on improving everyday tasks, and in the process not only make their lives easier, but helps to reactivate the planning and organisational parts of the brain. In an aging world, where the biggest risk of developing Alzheimer's is old age, the scientific breakthroughs in Alzheimer's disease are bringing hope where once there was despair.

Could a machine replace your doctor? Dr Hannah Fry explores the incredible ways AI is revolutionising healthcare - and what this means for all of us. This film chronicles the inside story of the AI health revolution, as one company, Babylon Health, prepare for a man vs machine showdown. Can Babylon succeed in their quest to prove their AI can outperform human doctors at safe triage and accurate diagnosis? Artificial intelligence is starting to transform healthcare beyond recognition - and tech companies large and small see almost limitless commercial opportunity. The ultimate vision is for accessible, affordable, better healthcare for almost everyone with a phone. In Britain this is already radically changing how some of us see our GPs. And in a world with a chronic shortage of doctors, but where even the very poor own mobile phones, it could be truly revolutionary. To witness this revolution from the inside, this film has privileged, behind-the-scenes access to ambitious British tech start-up Babylon Health, whose CEO Dr Ali Parsa declares with complete conviction 'we're going to do with healthcare what Google did with information.' Babylon launched its GP at Hand app in London in late 2017 and has already persuaded 30,000 Londoners to quit their old GPs to register instead for this NHS 'digital first' service, where patients discuss symptoms with an AI chatbot and see a doctor in minutes 24/7 via their phone. But GP at Hand's arrival has proved controversial - with many traditional GPs worried about the disruptive consequences for them and their patients, and others seeking to thwart its expansion nationwide. As this film reveals, there is a fundamental culture clash at play - between the 'move fast and break things' world of tech, and the cautious, diligent, often slow-moving world of medical science. So how will both camps respond when Babylon's AI attempts to pass the diagnostic sections of the Royal College of GPs exam? Amazingly, the NHS is today the largest purchaser of fax machines in the world - and the British government are eagerly embracing AI as the remedy for our public health system's antiquated inefficiencies. British health secretary Matt Hancock is an unabashed evangelist for tech - boasting Babylon's GP at Hand as his GP. Yet some scientists are increasingly alarmed, questioning the current hype and asking where is the proof that AI health apps, now in widespread use, are effective and safe. How should they be evaluated and regulated? And what needs to happen before we all trust our health to AI? As well as following a tumultuous year inside Babylon, both in the UK and Rwanda, the film also explores how another British AI Health start-up, Kheiron Medical, has successfully used deep learning to train its AI to detect breast cancer and now outperforms human radiologists at spotting the tell-tale signs of cancer in mammograms.

Filmmaker Natalie Hewit follows the everyday people battling in the most extreme environment on Earth to move Halley VI, a vital polar research station. Britain's state-of-the-art Antarctic research base Halley VI is in trouble. Built on the Brunt Ice Shelf, it sits atop a massive slab of ice that extends far beyond the Antarctic shoreline. But the ice is breaking apart and just 6km from the station is a ginormous crevasse, which threatens to separate Halley from the rest of the continent, setting the £28 million base adrift on a massive iceberg. So Halley needs to move. But this is probably the toughest moving job on Earth, and the team of 90 who have been tasked with the mission aren't just architectural or engineering experts. They are plumbers, mechanics and farmers from across the UK and beyond - ordinary men and women on an extraordinary adventure. Their practical skills will be what makes or breaks this move.

Horizon explores the secrets of what makes a long, healthy and happy life. It turns out that a time you can't remember - the nine months you spend in the womb - could have more lasting effects on you today than your lifestyle or genes. It is one of the most powerful and provocative new ideas in human science, and it was pioneered by a British scientist, Professor David Barker. His theory has inspired a field of study that is revealing how our time in the womb could affect your health, personality, and even the lives of your children.

Dr Kevin Fong finds out how close scientists are to being able to mend your heart if it stops working. He meets some of the people who have undergone pioneering heart operations and the scientists who are pushing the limits of cardiac treatment. We meet a man who has had his heart replaced with an artificial one powered by a mechanical pump he carries around in a rucksack, and witness a scientist bring a dead animal heart back to life on a workbench. Plus, the work of an American scientist who is using stem cells to turn what she calls a 'ghost heart' - the scaffold of a heart - into a replacement heart for humans.

At the heart of the AIDS epidemic in Africa, there is a deadly mystery that has puzzled scientists for years. There are groups of people who are four times less likely to get HIV than other people, sometimes living just yards away, across a single valley - people with apparently similar behaviour and lifestyle. Scientists realised that if they could understand why these people are so much less vulnerable to the HIV virus, it might lead to an answer that could save millions of lives. And after 15 years of detective work it turns out there may be a remarkably simple answer: the high risk areas for HIV coincide with tribes who are uncircumcised. In Africa, it seems a man is much more likely to get HIV if he is uncircumcised. In Kaoma, Western Zambia, a young boy is on his way to the sacred Mukondaa - the tribal circumcision ground. Around him the tribal elders are gathered, dressed in their ceremonial garb, and vivid masks. But the young boy himself is an outsider, not from this tribe, and none of his relatives or ancestors have ever been circumcised. In fact, his parents are only prepared to break the taboo of their own tribe because they believe that circumcision could save his life by protecting him from AIDS. At first sight this belief seems like the kind of superstition to which desperate people often turn in times of plague. But now there is scientific evidence that suggests these people could well be right. There have now been twenty seven statistical studies that show a big difference in HIV infection between circumcised and uncircumcised men. For example, among the uncircumcised people of Kisumu in Western Kenya, a man is three times as likely to get AIDS than his circumcised neighbours. Among truck drivers in Mombasa the difference is four-fold. Horizon travels across Africa, tracing the work of scientists who have unearthed the statistical data behind this correlation. At the same time microbiologists have been battling to understand the complex and insidious virus, and their work indicates that the foreskin may be a key entry point for HIV. The logical conclusion for these scientists is that if you remove the foreskin, you begin to protect the man. No-one believes that circumcision can protect completely - the evidence so far only indicates that it reduces the risk of infection by HIV, and then only during heterosexual sex. Unquestionably, condoms are still the best protection. But in the many countries where the use of condoms is minimal, it seems that circumcision might help to reduce the spread of AIDS. In the absence of a vaccine for AIDS, and the lack of condom use in the developing world, should governments think the unthinkable and encourage the circumcision of young boys in non-circumcising tribes as a public policy? Opposing this idea are the voices of tribal elders who are loath to change tribal traditions that have existed for generations, and a fierce Western anti-circumcision lobby which believes that circumcision is a form of mutilation and violates basic human rights.

This is the second part of a two-part Horizon series presenting a portrait of Richard Feynman, the American Nobel Prize winning physicist.

Imagine if the food you eat could 'clean' your body and make you feel well. Dr Giles Yeo investigates the latest diet craze and social media sensation - clean eating. In a television first, Giles cooks with Ella Mills, the Instagram entrepreneur behind Deliciously Ella, one of the most popular brands associated with clean eating, and examines how far her plant-based cooking is based on science. She tells him clean has lost its way: "Clean now implies dirty and that's negative. I haven't used it, but as far as I understood it when I first read the term, it meant natural, kind of unprocessed, and now it doesn't mean that at all. It means diet, it means fad". Giles sifts through the claims of the Hemsley sisters, who advocate not just gluten-free but grain-free cooking, and Natasha Corrett, who popularises alkaline eating through her Honestly Healthy brand. In America, Giles reveals the key alternative health figures whose food philosophies are influencing the new gurus of clean. He discovers that when it comes to their promises about food and our health, all is not always what it appears to be. Inside a Californian ranch where cancer patients have been treated with alkaline food, Giles sees for himself what can happen when pseudoscience is taken to a shocking extreme.

The video game industry is a global phenomenon. There are over 1.2 billion gamers across the planet, with sales projected soon to pass $100 billion per year. But their very popularity fuels the controversy that surrounds them. They frequently stand accused of corrupting the young - of causing violence and addiction. But is this true? Horizon reveals a scientific community deeply divided. Some are convinced that video games incite aggression. Others insist they have no effect whatsoever on real-world violence. But away from the controversy, there is a growing body of evidence that suggests video games may help keep the brain sharp, and could soon revolutionize how we combat mental decline as we age.

Michael Portillo looks at the science behind executions. Former Conservative MP, Michael Portillo pushes his body to the brink of death in an investigation into the science of execution. As the American Supreme Court examines whether the lethal injection is causing prisoners to die in unnecessary pain Michael sets out to find a solution which is fundamentally humane. To do so he examines the key methods of execution available today: he discovers why convicts can catch on fire in the electric chair, learns how easy it is to botch a hanging and inhales a noxious gas to experience first hand the terror of the gas chamber. Armed with some startling evidence Michael considers a completely new approach. Will it be the answer? There is only one way of finding out - to experience it himself.

Alan Davies attempts to answer the proverbial question: how long is a piece of string? But what appears to be a simple task soon turns into a mind-bending voyage of discovery where nothing is as it seems.

In 2014, the International Space Station had to move three times to avoid lethal chunks of space debris and there is an increasing problem of satellites mysteriously breaking down. With first-hand accounts from astronauts and experts, Horizon reveals the scale of the problem of space junk. Our planet is surrounded by hundreds of millions of pieces of junk moving at 17,000 miles per hour. Now the US government is investing a billion dollars to track them, and companies around the world are developing ways to clear up their mess - from robot arms to nets and harpoons. Horizon investigates the science behind the hit film Gravity and discovers the reality is far more worrying than the Hollywood fiction.

The hunt for life within the long-dead bones of dinosaurs may sound like the stuff of Hollywood fantasy - but one woman has found traces of life within the fossilised bones of a T Rex. Dr Mary Schweitzer has seen the remains of red blood cells and touched the soft tissue of an animal that died 68 million years ago. Most excitingly of all, she believes she may just have found signs of DNA. Her work is revolutionising our understanding of these iconic beasts.

20 robotic cars, with no drivers and no remote controls, race across the Nevada desert. Horizon follows 3 teams and their cars as they develop their vehicles.

Most of us think that Obsessive Compulsive Disorder (OCD) is just over fussy tidying. But it's actually much more serious. Sophie has to check that she hasn't killed people, looking for dead bodies wherever she goes, Richard is terrified of touching the bin, and Nanda is about to have pioneering brain surgery to stop her worrying about components on her body - that her eyebrow might not be aligned or that she has bad breath. Professor Uta Frith meets the people living with OCD, looks at the therapy available and asks what neuroscience can offer by way of a cure.

Antarctica is the last great wilderness. It's the coldest, windiest, driest and most isolated place on Earth. And every winter, for over three months of the year, the sun never rises. But it's also home to the British Antarctic Survey's Halley Research Station. A veteran of living and working at Halley in the early eighties, BBC weatherman Peter Gibbs makes an emotional return to the place he once called home. A place that, during his time, was key to the discovery of the ozone hole. The journey starts with an arduous 12-day, 3000-mile voyage onboard the RRS Ernest Shackleton. Once on the ice shelf, Peter is delighted to finally arrive at the futuristic research station and marvels at the cutting edge science being done at Halley today. From vital discoveries about how our lives are vulnerable to the sun's activities, to studying interplanetary travel and the threat of man-made climate change. But Peter's journey is also something of a rescue mission. The research station's home is a floating ice shelf that constantly moves and cracks, and the ice shelf has developed a chasm that could cast Halley adrift on a massive iceberg.

In February 2013, a hole opened up beneath a home in Florida, and swallowed a man. Jeff Bush was asleep when a sinkhole opened up beneath his bedroom. Despite the efforts of his brother to rescue him, Jeff was never seen again and his body was never recovered. Professor Iain Stewart travels to Florida to try and understand what killed Jeff, and why the geology of this state makes it the sinkhole capital of the world.

Adam Rutherford meets a new creature created by American scientists, the spider-goat. It is part goat, part spider, and its milk can be used to create artificial spider's web. It is part of a new field of research, synthetic biology, with a radical aim: to break down nature into spare parts so that we can rebuild it however we please. This technology is already being used to make bio-diesel to power cars. Other researchers are looking at how we might, one day, control human emotions by sending 'biological machines' into our brains.

The science series explores varying attitudes to smoking around the world. Filmed in a single day, the documentary meets the people whose lives are defined by the cigarette. Contributors include Allen Carr, who claims he may get viewers to quit by the end of the programme, the inventor of the nicotine patch Dr Jed Rose and Dr Chris Proctor, the chief scientist at British American Tobacco who has the tricky task of making a safer cigarette.

New planets are now being discovered outside our solar system on a regular basis, and these strange new worlds are forcing scientists to rewrite the history of our own solar system. Far from a simple story of stable orbits, the creation of our solar system is a tale of hellfire, chaos and planetary pinball.

Horizon discovers what your cat really gets up to when it leaves the cat flap. In a groundbreaking experiment, 50 cats from a village in Surrey are tagged with GPS collars and their every movement is recorded, day and night, as they hunt in our backyards and patrol the garden fences and hedgerows. Cats are fitted with specially developed cat-cams which reveal their unique view of our world. You may think you understand your pet, but their secret life is more surprising than we thought.

Documentary exploring science's long-standing obsession with the idea of gravity control, including recent breakthroughs in the search for loopholes in conventional physics. The programme examines how the groundwork carried out by Project Greenglow in the mid-1990s by UK defence manufacturer BAE Systems (based on the work of Eugene Podkletnov[82]) has changed the understanding of the universe, making the dream of flying cars and journeys to the stars no longer quite so distant.

The car has shrunk the world, increased personal freedom and in so many ways expanded our horizons, but there is a flipside. Fumes from car exhausts have helped to destroy our environment, poisoned the air we breathe and killed us in far more straightforward ways. But all that is going to change. This episode of Horizon enters a world where cars can drive themselves, a world where we are simply passengers, ferried about by wholesome green compassionate technology which will never ever go wrong. And it is almost here. Horizon explores the artificial intelligence required to replace human drivers for cars themselves, peers into the future driverless world and discovers that, despite the glossy driverless PR (and assuming that they really can be made to work reliably), the reality is that it might not be all good news. From the ethics of driverless car crashes to the impact on jobs, it might be that cars are about to rise up against us in ways that none of us are expecting.

The Ebola virus. No-one knows exactly where it comes from but one thing is certain - it's one of the most virulent infections known to science. This special episode of Horizon meets the scientists and doctors from all around the world looking for the cure and hears first-hand accounts of what it's actually like to catch - and survive - this terrible disease.

Just months ago, the world stood in fear of an emerging new disease that threatened to kill millions. A new flu variant H1N1 had arrived. In the UK alone, 65,000 deaths were predicted. Yet to date, these dire warnings have not materialised. If this latest pandemic has taught anything, it is just how little is understood about the invisible world of viruses. But that has not stopped scientists trying. Horizon follows the leading researchers from across the world, who are attempting to unravel the many secrets of viruses to understand when and why they kill.

Horizon tells the inside story of the search for Malaysia Airlines flight MH370. With access to the key players on the frontline in the southern Indian Ocean and the British satellite engineers who tracked the plane's final hours, Horizon breaks open the biggest mystery in aviation history. The film reveals how MH370 disappeared in a radar blind spot; what investigators believe happened to the aircraft in its last minutes; and how the area in which it could be found is still to be searched. Plus Horizon examines the new technologies, like black box streaming and enhanced air traffic surveillance, that mean an airliner should never vanish without trace again.

We love talking about the weather - is it too hot or too cold, too wet or too windy? It's a national obsession. Now scientists have started looking to the heavens and wondering what the weather might be like on other planets. Today, we are witnessing the birth of extra-terrestrial meteorology, as technology is allowing astronomers to study other planets like never before. They began with our solar system, sending spacecraft to explore its furthest reaches, and now the latest telescopes are enabling astronomers to study planets beyond our solar system. Our exploration of the universe is revealing alien worlds with weather stranger than anyone could ever have imagined - we've discovered gigantic storm systems that can encircle entire planets, supersonic winds, extreme temperatures and bizarre forms of rain. On some planets, the temperatures are so hot that the clouds and rain are believed to be made of liquid lava droplets, and on other planets it is thought to rain precious stones like diamonds and rubies. We thought we had extreme weather on Earth, but it turns out that it is nothing compared to what's out there. The search for the weirdest weather in the universe is only just beginning.

We all like to think we are in control of our lives - of what we feel and what we think. But scientists are now discovering this is often simply an illusion. Surprising experiments are revealing that what you think you do and what you actually do can be very different. Your unconscious mind is often calling the shots, influencing the decisions you make, from what you eat to who you fall in love with. If you think you are really in control of your life, you may have to think again.

Horizon explores a new theory of evolution.

Is a space tourism revolution just around the corner?

Every year we spend £300 million on vitamin supplements, but do they actually do us any good? Some believe they offer the promise of preventing or even curing some of the world's biggest killers, such as heart disease and cancer. Others claim that taking large doses of some vitamins may in certain cases be harmful. So what are the facts? Nearly 40 years ago, one of the greatest scientists of the 20th century and double Nobel Prize winner, Linus Pauling, revolutionised the way people thought about vitamins. He claimed that by taking huge doses of vitamin C you could prevent or even cure the common cold. He predicted that if everybody followed his advice, the common cold could even be eradicated. Many scientists dismissed his theory as quackery, but the public loved it and it helped launch a huge industry. But the latest evidence shows the great man was mistaken. Vitamin C can help you once have got a cold, but for most people it does nothing to prevent you from catching one in the first place. Even if large doses of vitamin C do not prevent the common cold, some claim that it can still offer a more profound benefit. It is one of a group of vitamins called anti-oxidants that some believe can prevent illnesses such as cancer, Alzheimer's and heart disease. In 2004, scientists in the United States claimed that people could be missing any of the potential benefits of taking one of the world's most popular anti-oxidant vitamin supplements, vitamin E, because their bodies might not be absorbing it. But our own investigation suggested that the American scientists' conclusion could be mistaken. While most safety experts believe that vitamins C and E can be taken safely even in quite large doses, there is worrying evidence that one form of another common vitamin, vitamin A, could be linked to osteoporosis, a debilitating bone disease. If the theory is right it means that a person's diet, or some supplements that they take every day to improve their health, could actually be slowly and silently weakening their bones.

On August 2nd 1947, a British civilian version of the wartime Lancaster bomber took off from Buenos Aires airport on a scheduled flight to Santiago. There were 5 crew and 6 passengers on board the plane - named "Stardust". But Stardust never made it to Santiago. Instead it vanished when it was apparently just a few minutes from touchdown. One final strange Morse code radio message - "STENDEC" - was sent, but after that nothing more was heard from the plane. Despite a massive search of the Andes mountains no trace of the plane was ever found. For 53 years the families of those who disappeared have not known what happened to their loved ones. But earlier this year the plane suddenly reappeared on a glacier high up in the Andes, more than 50 km’s from the area where the plane was last reported.

In this report, Horizon looks at the spread of the AIDS virus in the United States and their search for the cause and cure of the deadly disease.

Develops the theory that four and a half thousand million years ago the earth was formed thanks to the explosion of a huge star which provided the rocks, the minerals and the radioactivity from which life developed. These theories are based partly on analysis of a meteorite which dropped near a village in Mexico at the beginning of the seventies.

This is the story of how our solar system will be transformed by the aging sun before coming to a spectacular end in about eight billion years. Astronomers can peer into the far future to predict how it will happen by analysing distant galaxies, stars and even planets in their final moments. In this film, Horizon brings these predictions to life in a peaceful midwestern town that has a giant scale model of the solar system spread out all over the city. As it ages, the sun will bloat into a red giant star, swallowing planets... as well as half the town. The fate of the Earth itself hangs in the balance. How will the solar system end?

Michael Mosley explores the latest science about how our personalities are created - and whether they can be changed. Despite appearances, Mosley is a pessimist who constantly frets about the future. He wants to worry less and become more of an optimist. He tries out two techniques to change this aspect of his personality - with surprising results. And he travels to the frontiers of genetics and neuroscience to find out about the forces that shape all our personalities.

Forget the big bang. The real moment of creation was the Cosmic Dawn - the moment of first light. This is the scientific version of the story of Genesis. The big bang gets all the credit for creating our universe. But in fact, the universe it gave was dark and boring. There were no stars, no galaxies, just a vast, black fog of gas - the cosmic dark ages. But, after a hundred million years of nothing, came a dramatic moment of transformation - the Cosmic Dawn. It's the moment the first stars were born, the moment that lit up the Universe, and made the first structure and the first ingredients of life. This was the real moment of creation. Astronomers are now trying to witness the cosmic dawn. For the first time they have the tools to explore the very first stars of the universe and to tell the scientific story of our creation.

A few weeks ago, the National Health Service was hit by a widespread and devastating cyber attack - Horizon tells the inside story of one of the most challenging days in the history of the NHS. On the morning of 12 May the attack started. Appointment systems, pathology labs, x-rays and even CT scanners were infected - putting not just data but patients lives at risk, and on every screen a simple - some may even say polite - message appeared. 'Ooops, your files have been encrypted!' But what followed was far from civilised. It was very clear that all the data on an infected machine was now scrambled and only the hackers could unscramble it. For a price - and with an extra twist - after a few days the ransom money doubled, and if nothing was paid within a week, the hackers threatened to destroy all the data - forever

Use the Drake equation to calculate the number of civilisations in our galaxy. For fifty years, the Search for Extra Terrestrial Intelligence has been scanning the galaxy for a message from an alien civilisation. So far to no avail, but a recent breakthrough suggests they may one day succeed. Horizon joins the planet hunters who've discovered a new world called Gliese 581 c. It is the most Earth-like planet yet found around another star and may have habitats capable of supporting life. NASA too hopes to find fifty more Earth-like planets by the end of the decade, all of which dramatically increases the chance that alien life has begun elsewhere in the galaxy.

Last century, earthquakes killed over one million, and it is predicted that this century might see ten times as many deaths. Yet when an earthquake strikes, it always takes people by surprise. So why hasn't science worked out how to predict when and where the next big quake is going to happen? This is the story of the men and women who chase earthquakes and try to understand this mysterious force of nature. Journeying to China's Sichuan Province, which still lies devastated by the earthquake that struck in May 2008, as well as the notorious San Andreas Fault in California, Horizon asks why science has so far fallen short of answering this fundamental question.

Examining Dark Energy, the mysterious force that is unexpectedly causing the universe's expansion to speed up. Its effects were discovered in 1998, but physicists still do not know what it is, and its very existence calls into question Albert Einstein's General Theory of Relativity; the cornerstone of modern physics. The hunt for the identity of Dark Energy is on, and although experiments conducted on earth and in space generate data that might provide a clue, physics is hoping another Einstein might emerge and write a new theory that explains the mystery.

Taste is our most indulgent sense but it is only in recent years that we have started to understand why we really love the foods we do - and it is a lot more surprising than you might think. There may a way to make food taste sweeter without adding any extra sugar and it is all down to a trick that happens in your brain. Horizon meets the scientist who has grown the perfect tomato, that is sweeter and juicier than anything you are likely to find on a shelf, as well as the men and women hoping to become elite, professional tasters.

Mixing powerful and deeply moving footage with telling forensic analysis, Horizon reveals what really went wrong on the Space Shuttle Columbia. The film's final revelation is telling. If NASA had acted differently, all seven astronauts could have been brought back to Earth alive. The film begins with the astronauts' final moments and shows the haunting scenes at Mission Control at the moment the disaster struck. What then follows is a disturbing detective story as the investigators gradually realise that the tragedy was caused by the failure of a small panel on the shuttle's left wing that had been built to be indestructible. No one had ever thought such an accident was possible. It has led to the shuttle being grounded for the foreseeable future. But that wasn't all. The film also shows that NASA had a number of options to bring the crew back safely - if only it had commandeered a spy telescope to visually inspect the damage. It could even have launched a rescue mission. But instead, NASA chose to rely on a computer programme for damage assessment. The programme got it wrong; as a result, there was no hope for those seven crew members.

Remember that long, hot summer? You might never see its like again. And all that talk of global warming? Forget it. This season's first Horizon reveals that a growing number of experts fear Britain could be heading for a climate like Alaska. Our ports could be frozen over. Ice storms could ravage the country, and London could see snow lying for weeks on end. It would be the biggest change in the British way of life since the last Ice Age. The first signs that such a disaster could happen came from deep within the ice sheet of Greenland. Scientists discovered that the Earth's past was littered with sudden, drastic drops in temperature. The big question was: could it ever happen again? Clues came from tiny shells at the bottom of the Atlantic; a huge glacier on the move in Arctic and some alarming discoveries in the far north of Russia. In the end there came the terrifying revelation: the Gulf Stream, that vast current of water that keeps us warm, could be cut off. According to one scientist, there is a one in two chance it will happen in the next century. Others say a climatic catastrophe could be heading our way in just twenty years time.

This Horizon episode is all about Uranium; its history, the use of uranium for nuclear energy, the dangers of uranium, and the scarcity of the mineral.

Horizon presents evidence that links the drought cycle with the number of magnetically-hyperactive sunspots.

Dr Kevin Fong explores a medical revolution that promises to help us live longer, healthier lives. Inspired by the boom in health-related apps and gadgets, it's all about novel ways we can monitor ourselves around the clock. How we exercise, how we sleep, even how we sit.

Alice Roberts explores the latest discoveries in the study of human origins, revealing the transformation that has been brought about in this field by genetics.

Over 62% of adults in the UK are currently overweight or obese and this figure is set to rise. A common attitude is that obese people should be ashamed - it is their fault, they have no will power and if they could just 'eat less and exercise more', the problem would soon be solved. Yet, despite millions of pounds being spent on this simple message, the UK is getting fatter every year. Cambridge geneticist Dr Giles Yeo believes that for many obese people, simply eating less is a lot harder than you might think - and he is taking a road trip around the UK and America to uncover why. He meets the real people behind some of the more shocking newspaper headlines and, through their stories, reveals surprising truths which dispel commonly held myths about obesity. He gains access to scientists and doctors trialling cutting-edge techniques to tackle the crisis - from a 'miracle' hormone injection to a transfusion of faecal matter, and even learns a thing or two about his own size and relationship with food.

Around the world, a new generation of astronomers are hunting for the most mysterious objects in the universe. Young stars, black holes, even other forms of life. They have created a dazzling new set of super-telescopes that promise to rewrite the story of the heavens. This film follows the men and women who are pushing the limits of science and engineering in some of the most extreme environments on earth. But most striking of all, no-one really knows what they will find out there.

It has been predicted that by 2029 computers will be powerful enough to rival that of the human brain. Will be able to download ourselves into a computer and live forever? Or will a race of super intelligent destructive machines rise. The only thing we know for sure is the moment is coming and whatever it brings is inevitable.

How the biggest international forensic operation in history identified the victims of the most devastating natural disaster of recent times.

This is the extraordinary story of how a small metal disc is rewriting the epic saga of how civilisation first came to Europe, 3600 years ago. When grave robbers ransacked a Bronze Age tomb in Germany, they had no idea that they had unearthed the find of a lifetime. But they knew that it was worth selling. It was a small bronze disc of exquisite design. So they contacted the archaeologist Harald Meller, offering to sell it to him for €300,000. Meller went deep into the criminal underworld and, after a police sting, he got his disc. It depicted the sun, the moon and the stars. This suggested an understanding of the heavens greater than that of the first great civilisations, like Egypt. Could it possibly be real? After exhaustive tests, the disc was declared genuine. Then a team of crack scientists pieced together what it meant. What emerged is a true marvel. This disc, it seems, is a Bronze Age Bible, combining an advanced understanding of the stars with some of the most sophisticated religious imagery of the age. In intellectual achievement and also age, it surpasses anything yet found in Egypt or Greece. It seems that civilisation had already dawned in Europe.

In 2001, scientists announced an amazing discovery: the oldest skull of a human ancestor ever found. The 3 million year old fossil was remarkably complete, and unlike any previous fossil find. Its discovery - by a team led by Meave Leakey of the famous Leakey fossil-hunting family - has revolutionised our understanding of how humans evolved. The great mystery of our evolution is how an ape could have evolved into the extraordinary creature that is a human being. There has never been another animal like us on the planet. And yet ten million years ago there was no sign that humans would take over the world. Instead the Earth was dominated by the apes. More than 50 different species of ape roamed the world - ten million years ago Earth really was the planet of the apes. Three million years later, most had vanished. In their place came something clearly related to the apes, but also completely different: human beings! For years scientists searched for the first key characteristic which had allowed us to make the huge leap from ape to amazing human. At first they thought the development of our big brains was decisive. They even found the fossil that seemed to prove it, until along came the famous three million year old fossilised skeleton Lucy. This quashed the big brain theory, because here was a human ancestor which clearly walked on two legs, just as we do, but had the tiny brain of an ape. It seemed that the development of walking on two legs (bipedalism) was the first key human characteristic, the thing that set us on the road to becoming human. Lucy soon became even more important. She seemed to defy the laws of evolution. Normally a major evolutionary adaptation like walking on two legs is followed by what scientists call an adaptive radiation. Many related species quickly evolve from an initial evolutionary innovation. It gives a very bushy evolutionary family tree, with many different but related species. Scientists knew that the human branch of the family tree had begun about six or seven million years ago, when the planet of the apes ended. And yet there was no sign of an adaptive radiation. The family tree showed just a straight line leading from the planet of the apes through to Lucy. All that has changed with Meave Leakey's spectacular new discovery, named Kenyanthropus platyops or, less formally, Flat-faced Man. Her find is the same age as Lucy's species, but also completely different. It's proof that there were two different bipedal human ancestors living at the same time, more than three million years ago. And it's the first sign of the adaptive radiation that the theory of evolution says should have followed the planet of the apes.

A tropical seaweed that escaped from an aquarium is endangering sea life in the Mediterranean and has gone on to infect the California coast.

When and how did space and time begin? The birth of the Universe is one of the biggest mysteries in astronomy. It has perplexed the best scientific minds for centuries. Decades before space travel was possible, astronomers dreamed of putting a telescope into orbit to try and answer these fundamental questions. It wasn't until the 1970s, when space flight had become a reality, that NASA resolved to build just such a space telescope. They named it Hubble. This was one of the most ambitious missions ever conceived. The technical challenges were enormous and it took 12 years to design and build. Travelling at seventeen thousand miles an hour, the Hubble Telescope would take pictures of the furthest reaches of space, transmitting them 400 miles back to Earth. In April 1990 the Hubble Space Telescope was launched. But just weeks later, disaster struck - the $2 billion telescope had a fatal flaw in its main mirror. This was not just a disaster for NASA; it was a national scandal. Hubble had to be saved; scientists and engineers began to search desperately for a solution to the problem. Plans for an adventurous repair mission began to take shape but it was two years before work could be carried out. It took astronauts five gruelling space-walks to carefully replace the instruments and patch up the telescope. But nobody knew if Hubble would be able to deliver on any of its original promises. Finally, the miracle happened. An unexpected avalanche of data from Hubble confirmed that the telescope was fixed. At last it began to solve the most fundamental puzzles of the Universe. Hubble has given us breathtaking images of the birth of stars; it has found black holes swallowing matter at the centre of galaxies; and last year the Hubble Telescope resolved the most fundamental question in astronomy - the age of the Universe. At last, half a century of scientific endeavour was rewarded. Horizon marks the 10th anniversary of the launch of the Hubble Space Telescope by tracing the extraordinary tale of triumph, disaster and eventual success of this unique window into the Universe.

Horizon shows how American scientists struggled to fulfil the dreams which challenged fundamental scientific laws.

Documentary looking at the scientific facts about the growing cult of Astrology. In this report, Horizon looks at the way astrology has evolved and examines statistical evidence to evaluate its credibility.

Documentary about smoking and about the secondary effects of it. Britain leads the world in smoking deaths at 200 per day. The film looks at prognosis of deat h and at the chances of those who give up smoking of dying of the effects.

Explains, within a historical context, how Israel and Jordan are trying to make use of the Dead Sea. Its mineral-rich waters are being harnessed by scientists and engineers to produce such diverse products as protein, potash and cheap energy .

The new perspectives which can be gained on the natural world through time-lapse and high-speed photography. Includes footage of droplets of water merging in mid-air, a bullet spiralling up its barrel toward you, a wet dog shaking its fur, flowers bursting open, starfish scurrying on the sea floor, and spark plugs spreading their fire.

Astronomers are seen at work in the UK, Arizona, Hawaii, New Mexico and Australia, describing their discoveries about the galaxies beyond the Milky Way.

For decades some have suspected that there might be others out there, intelligent beings capable of communicating with us, even visiting our world. It might sound like science fiction, but today scientists from across the globe are scouring the universe for signals from extraterrestrials.

Dr Michael Mosley and Professor Alice Roberts investigate if male and female brains really are wired differently.

Six months after the explosions at the Fukushima nuclear plant and the release of radiation there, Professor Jim Al-Khalili sets out to discover whether nuclear power is safe. He begins in Japan, where he meets some of the tens of thousands of people who have been evacuated from the exclusion zone. He travels to an abandoned village just outside the zone to witness a nuclear clean-up operation. Jim draws on the latest scientific findings from Japan and from the previous explosion at Chernobyl to understand how dangerous the release of radiation is likely to be and what that means for our trust in nuclear power.

Horizon examines the evidence that our ancestors' changing diet and mastery of fire prompted anatomical and neurological changes that took us out of the trees and into the kitchen.

Time travel is not forbidden by the laws of nature, but to build a time machine, we would need to understand more about those laws and how to subvert them than we do now. And every day, science does learn more. In this film Horizon meets the scientists working on the cutting edge of discovery - men and women who may discover how to build wormholes, manipulate entangled photons or build fully functioning time crystals. In short, these scientists may enable an engineer of the future to do what we have so far been only able to imagine - to build a machine that allows us travel back and forward in time at the touch of a button. It could be you! Science fiction? Watch this space.

Over the last few years, our weather in Britain has become more extreme. Last winter was the wettest ever recorded, as deadly storms battered the country for weeks on end. But previous winters have seen bitter lows of -22, as Britain was plunged into a deep freeze. What everyone wants to know now is: why is our weather getting more extreme, can we expect to see more of it in the future, and has it got anything to do with climate change? In this episode of Horizon, physicist Dr Helen Czerski and meteorologist John Hammond make sense of Britain's recent extreme weather and discover that there is one thing that connects all our recent extreme winters - the jet stream, an invisible river of air that powers along 10 km above us. What's worrying is that recently it has been behaving rather strangely. Scientists are now trying to understand what is behind these changes in the jet stream. Helen and John find out if extreme winters are something we may all have to get used to in the future.

Sir David Attenborough reveals the findings of one of the most ambitious scientific studies of our time - an investigation into what is happening to our oceans. He looks at whether it is too late to save their remarkable biodiversity. Horizon travels from the cold waters of the North Atlantic to the tropical waters of the Great Barrier Reef to meet the scientists who are transforming our understanding of this unique habitat. Attenborough explores some of the ways in which we are affecting marine life - from over-fishing to the acidification of sea water. The film also uncovers the disturbing story of how shipping noise is deafening whales and dolphins, affecting their survival in the future.

Thalidomide was one of the biggest medical tragedies of modern times. The images of children born with shrunken limbs still haunt anyone who sees them. And the tragedy is not over. Those children are adults today, still coping with their disability. For many, thalidomide is a drug that should be consigned to the dustbin of history - an awful cautionary tale of the errors that science can make. But now it is making a comeback - as a radical treatment for incurable blood cancers. But can it possibly be safe to use such a dangerous drug again? In a powerful and deeply moving film, Horizon tells the tale of thalidomide and how this drug that has become so infamous may now be giving hope to people who otherwise face death. It also explores the mystery at the heart of thalidomide. It seems that the reason why it works for cancer may at least partly explain something that has long baffled scientists - why thalidomide caused such terrible damage to babies in the womb all those years ago.

Builders in Miami, Florida unearth a ring of holes. The State then pays $27million to preserve either a Native American village or remnants of a 1950s sewerage system.

Looks at different ways of teaching a foreign language and contrasts them with the way babies and young children pick up their native language, without formal teaching.

Horizon looks at the life of whales and dolphins, and how they interact with man.

Horizon travels to the South Pole to tell the inside story of the greatest scientific quest of our time. In March 2014, a team of astronomers stunned the scientific world when they announced that their BICEP2 telescope at the South Pole had possibly detected a signal of “gravitational waves” from the early universe. This is the inside story of the hunt for gravitational waves from the beginning of time. How the BICEP2 team came close to making one of the greatest discoveries of the century – and what happened when it all began to unravel...

Investigating the story of how a Russian internet millionaire, Dmitry Itskov, is turning to cutting edge science to try to unlock the secret of living forever. The programme investigates the real science inspiring his bold plan to upload the human mind to a computer, and examines whether his goal of bringing about immortality for humans within thirty years is attainable.

When pioneering developmental psychologist Professor Uta Frith started her training back in the 1960s, she met a group of beautiful, bright-eyed young children who seemed completely detached from the rest of the world. It turned out they had just been given the then-new diagnosis of autism. Uta passionately wanted to know more about these children, and they inspired her to dedicate the rest of her career to studying the autistic mind. On the eve of National Autism Day, Horizon reveals how Uta's lifetime study of people with autism has transformed our understanding of this mysterious condition. In this film Uta shows how people with autism perceive and interact with the world and how, for them, another kind of reality exists. She meets people with autism who have extraordinary talents, and explains why they often fail to understand jokes. She also explores whether many of us could be just a little bit autistic.

Cannabis is the world's favourite drug, but also one of the least understood. Can cannabis cause schizophrenia? Is it addictive? Can it lead you on to harder drugs? Or is it simply a herb, an undervalued medicine? Addiction specialist Dr John Marsden discovers that modern science is finally beginning to find answers to these questions. John traces the cannabis plants' birthplace in Kazakhstan; finds the origins of our sensitivity to cannabis in the simple sea squirt; and finds out just what it does to our brains. He meets people who have been changed by this drug in drastically different ways - from those whose lives have been shattered to those who lives have been revived.

The controversial science of epigenetics suggests you may inherit a lot more than you imagine from your forebears. The scientists who believe your genes are shaped in part by your ancestors' life experiences.

265 people died when an Airbus operated by American Airlines crashed into the New York suburb of Queens in November 2001. The twin-engined jet took off from John F Kennedy Airport in fine conditions but hit trouble after just 67 seconds. In the following 38 seconds the plane started to disintegrate before nose-diving into the residential Rockaway area of the city. Everyone aboard was killed (along with five people on the ground) so the crash investigators had to rely on eyewitnesses, recovered parts of the plane and information from both air traffic control and the flight data recorders. The discovery of the Airbus' vertical tailfin hundreds of metres from the fuselage immediately focussed attention on whether the pilots lost the ability to control the plane. Why the tailfin detached was at the heart of the investigation by the National Transportation Safety Board. The airline and the manufacturer blame each other for creating a situation in which the stress on the rudder and tailfin exceeded the so-called ultimate load, the worst-case scenario set by the Federal Aviation Administration (FAA). A number of American Airlines pilots have taken matters into their own hands though: requesting transfers to other aircraft because of their safety concerns.

Imagine a world where dinosaurs still walk the earth. A world where the Germans won World War II and you are President of the United States. Imagine a world where the laws of physics no longer apply and where infinite copies of you are playing out every storyline of your life. It sounds like a plot stolen straight from Hollywood, but far from it. This is the multiverse Until very recently the whole idea of the multiverse was dismissed as a fantasy, but now this strangest of ideas is at the cutting edge of science.And for a growing number of scientists, the multiverse is the only way we will ever truly make sense of the world we are in. Horizon asks the question: Do multiple universes exist? And if so, which one are we actually in?

This episode of Horizon looks at the issues that will change the way we live our lives in the future. Rather than relying on the minds of science fiction writers, mathematician Hannah Fry delves into the data we have today to provide an evidence-based vision of tomorrow. With the help of the BBC's science experts - and a few surprise guests - Hannah investigates the questions the British public want answered about the future.

With exclusive behind-the-scenes access, Horizon follows the highs and lows of an extraordinary story in particle physics. In June 2015, teams at CERN started running the large hadron collider at the highest energy ever. Rumours quickly emerged that they were on the brink of a huge discovery. A mysterious bump in some data suggested a first glimpse of a brand new particle that could change our understanding of how the universe works. A new particle could hint at extra dimensions and help us understand the very beginning of the universe - but first the team has to find it. Horizon follows the scientists as they hunt for the elusive signals that would prove if there is a new particle or if it is just noise from their machine.

It is a feeling we all know - the moment when a light goes on in your head. In a sudden flash of inspiration, a new idea is born. Today, scientists are using some unusual techniques to try to work out how these moments of creativity - whether big, small or life-changing - come about. They have devised a series of puzzles and brainteasers to draw out our creative behaviour, while the very latest neuroimaging technology means researchers can actually peer inside our brains and witness the creative spark as it happens. What they are discovering could have the power to make every one of us more creative.

Dr Xand van Tulleken investigates the world of performance-enhancing drugs - from the athletes seeking the rewards of fame, glory and lucrative sponsorship deals to the hundreds of thousands of people in the UK now regularly taking anabolic steroids to look good and buff up. What are these drugs? What do they do to the body? And is it worth it? Xand's investigation reveals the extraordinary gamble dopers take with their health. Long-term effects include kidney failure, cognitive impairment and testicular shrinkage, and Xand witnesses how users are self-experimenting with drugs that have not yet been approved for human use. Horizon uncovers the new frontier of doping, from new molecules to gene therapy - where the genes that control muscle growth are altered. These new methods could be completely undetectable by the doping authorities. Finally, with the help of his twin brother Chris, Xand discovers the legal ways some athletes try to gain the edge.

In medical science, there’s been no longer harder fight than against malaria. This is the inside story of a historic new vaccine - from the Oxford lab behind the Covid jab. Part of the Horizon strand

As more people than ever report struggling with their sleep, Michael Mosley uses the latest science to explore how this impacts our health and what can be done to improve our sleep.

The story of the scientists who created Dolly, the sheep that changed the world in this documentary, part of the Horizon series. This Horizon branded documentary tells the full story for the first time with never-before-seen archive, revealing how on a small Scottish farm, a handful of the world’s best genetic scientists worked in secret to crack the holy grail of life: cloning.

The incredible story of how Pluto has been propelled from an unremarkable ball of ice on the edge of the solar system to a world of unimaginable complexity - where some form of alien life might exist.

The unknown story of the worst child-poisoning case since thalidomide, featuring a landmark legal battle by a group of mothers determined to uncover the truth.

Dr Michael Mosley immerses himself on the frontline of our prescription painkiller habit. In America, it is an epidemic. Now, new evidence raises concern about the UK's use of prescription opioids.

We spend 190 billion pounds a year on groceries, but can we trust our supermarkets to tell us the truth about what we’re buying? Dr Hannah Fry and Priya Tew investigate the food we eat.

In the wake of the Gatwick drone crisis, high-risk specialist Aldo Kane investigates the threat drones pose to UK skies and tests the new technology we can use to keep ourselves safe.

Dr Kevin Fong makes a personal journey through the moral questions about death that face not just the medical profession, but each and every one of us.

Can we predict avalanches? How can we save more lives? A team of scientists led by Prof Danielle George create a massive avalanche to find out.

Dr. Michael Mosley cures real pain with fake pills in Britain's largest ever placebo trial.

Deception is an integral part of human nature and it is estimated we all lie up to nine times a day. But what if we created a world in which we couldn't lie? In a radical experiment, pioneering scientists from across Europe have come together to make this happen. Brand new technology is allowing them to rig three British people to make it impossible for them to lie undetected. Then they will be challenged to live for a whole week without telling a single lie. It is a bold social experiment to discover the role of deception in our lives - to investigate the impact lying has on our mental state and the consequences of it for our relationships, and to ask whether the world would be a better or worse place if we couldn't lie.

'To send a spacecraft there is a little bit insane,' says Scott Bolton when talking about Jupiter, the largest planet in the solar system. But that is exactly what he has done, because Scott is head of Juno, the Nasa mission designed to peer through Jupiter's swirling clouds and reveal the wonders within. But this is no ordinary world. This documentary, narrated by Toby Jones, journeys with the scientists into the heart of a giant. Professor Kaitlin Kratter shows us how extreme Jupiter is. She has come to a quarry to measure out each planet's mass with rocks, starting with the smallest. Mercury is a single kilogram, and the Earth is 17. But Jupiter is on another scale entirely. It is seven tonnes - that is two and a half times the mass of all the other planets combined. On Kaitlin's scale it is not a pile of rocks, it is the truck delivering them. With extreme size comes extreme radiation. Juno is in the most extreme environment Nasa has visited. By projecting a 70-foot-wide, life-size Juno on a Houston rooftop, Scott shows us how its fragile electronics are encased in 200kg of titanium. As Scott puts it, 'we had to build an armoured tank to go there.' The team's efforts have been worthwhile. Professor Andrew Ingersoll, Juno's space weatherman, reveals they have seen lightning inside Jupiter, perhaps a thousand times more powerful than Earth's lightning. This might be evidence for huge quantities of water inside Jupiter. Prof Ingersoll also tells us that the Great Red Spot, a vast hurricane-like storm that could swallow the Earth whole, goes down as far as they can see - 'it could go down 1,000s of kilometres'. Deeper into the planet and things get stranger still. At the National Ignition facility in northern California, Dr Marius Millot is using powerful lasers normally used for nuclear fusion for an astonishing experiment. He uses '500 times the power that is used for the entire United States at a given moment' to crush hydrogen to the pressures inside Jupiter. Under these extreme conditions, hydrogen becomes a liquid metal. Juno is finding out how much liquid metallic hydrogen is inside Jupiter, and scientists hope to better understand how this flowing metal produces the most powerful aurora in the Solar System. But what is at Jupiter's heart? In Nice, Prof Tristan Guillot explains how Juno uses gravity to map the planet's centre. This can take scientists back to the earliest days of the solar system, because Jupiter is the oldest planet and it should contain clues to its own creation. By chalking out an outline of the Jupiter, Tristan reveals there is a huge rocky core - perhaps ten times the mass of Earth. It is now thought Jupiter started as a small rocky world. But there is a surprise, because Juno's findings suggest this core might be 'fuzzy'. Tristan thinks the planet was bombarded with something akin to shooting stars. As he puts it, 'Jupiter is quite unlike we thought'.

Horizon follows three people living with voices, hallucinations and paranoia, to explore what causes this kind of phenomena. Providing a rare first-hand insight into these experiences, they reveal just what it is like to live with them day-to-day. They examine the impact of social, biological and environmental influences on conditions traditionally associated with insanity, such as schizophrenia and psychosis, and within the film they look at how new ways of understanding the brain are leading to a dramatic change in treatments and approaches and examine whether targeting the root causes of psychosis can lead to recovery. Above all, they try to uncover why it happened to them - and whether it could happen to you.

Across the world we are seeing the emergence of bacteria that have gone rogue. These are the superbugs, dangerous bacteria that are becoming resistant to our only defense; antibiotics. Horizon meets the scientists who are tracking the spread of these potential killers around the globe, and discovers the new techniques researchers are developing to help defeat these superbugs.

Horizon goes behind the scenes at NASA as they countdown to the landing of a 2.5 billion-dollar rover on the surface of Mars. In six days time, the nuclear-powered vehicle - the size of a car - will be winched down onto the surface of the Red Planet from a rocket-powered crane. That's if things go according to plan: Mars has become known as the Bermuda Triangle of space because so many missions there have ended in failure. The Curiosity mission is the most audacious - and expensive - attempt to answer the question: is there life on Mars?

Across the world scientists are releasing predators, nature's ultimate killers, close to where people live. In Florida, a new population of panthers, feared as ambush predators, have been released near to the busy town of Naples. In the Italian Alps, bears have been reintroduced after they became virtually extinct, and now try to get into people's homes in the middle of the night. And in Yellowstone National Park, wolves have been brought back 70 years after they were exterminated. Horizon meets the scientist behind this radical scheme, and the people who now have to share their backyards with these predators.

Horizon reveals the latest research into one of the most mysterious and common human experiences - pain. Breakthroughs have come from studying a remarkable woman in London who has felt no pain at all in her life, a man in the US who cut off his own arm to survive, and three generations of an Italian family who don't feel extremes of temperature. We witness a new treatment that involves a pioneering computer game 'snow world' that contains the power to banish pain. And we find how powerfully our moods and emotions shape what pain we feel.

A decade ago, scientists announced that they had produced the first draft of the human genome, the 3.6 billion letters of our genetic code. It was seen as one of the greatest scientific achievements of our age, a breakthrough that would usher in a new age of medicine. A decade later, Horizon finds out how close we are to developing the life-changing treatments that were hoped for.

Dr Kevin Fong investigates a technique that is used to bring people back from the dead.

For centuries scientists have been attempting to come up with an elixir of youth. Now remarkable discoveries are suggesting that ageing is something flexible that can ultimately be manipulated. Horizon meets the scientists who are attempting to piece together why we age and more vitally for all of us, what we can do to prevent it. But which theory will prevail? Does the 95-year-old woman who smokes two packets of cigarettes a day hold the clue? Do blueberries really delay signs of ageing or is it more a question of attitude? Does the real key to controlling how we age lie with a five-year-old boy with an extraordinary ageing disease or with a self-experimenting Harvard professor? Could one of these breakthroughs really see our lives extend past 120 years?

With the help of a hammer-wielding scientist, Jennifer Aniston and a general anaesthetic, Professor Marcus du Sautoy goes in search of answers to one of science's greatest mysteries: how do we know who we are? While the thoughts that make us feel as though we know ourselves are easy to experience, they are notoriously difficult to explain. So, in order to find out where they come from, Marcus subjects himself to a series of probing experiments. He learns at what age our self-awareness emerges and whether other species share this trait. Next, he has his mind scrambled by a cutting-edge experiment in anaesthesia. Having survived that ordeal, Marcus is given an out-of-body experience in a bid to locate his true self. And in Hollywood, he learns how celebrities are helping scientists understand the microscopic activities of our brain. Finally, he takes part in a mind-reading experiment that both helps explain and radically alters his understanding of who he is.

What makes ordinary people commit extreme acts of violence? Michael Portillo investigates the dark side of human nature, and discovers what it is like to inflict pain.

David Baddiel, father of two, sets out to answer one of the greatest questions a parent can ask: how best to educate your child. Taking in the latest scientific research, David uncovers some unconventional approaches: from the parent hot-hosing his child to record-breaking feats of maths, to a school that pays hard cash for good grades. David witnesses a ground-breaking experiment that suggests a child's destiny can be predicted at four, and hears the three little words that can ruin a child's chance of success for good. He also uncovers the neurological basis for why teenagers can be stroppy and explosive and has his own brain tinkered with to experience what it is like to struggle at school. Through it all, David's quest remains true: to maximise his child's potential for success and happiness.

When disaster strikes who lives and who dies is not purely a matter of luck. In every disaster, from those people face once in a lifetime, to those they face every day, there are things that can be done to increase the chances of getting out alive. Horizon has gathered a team of leading experts to produce the ultimate guide to disaster survival. Through controversial experiments, computer simulations and analysis of hundreds of survivor testimonies from plane crashes to ferry disasters and even 9/11, they will reveal what happens in the mind in the moment of crisis and how the human brain can be programmed for survival.

Horizon uncovers the secret world of our dreams. In a series of cutting-edge experiments and personal stories, we go in search of the science behind this most enduring mystery and ask: where do dreams come from? Do they have meaning? And ultimately, why do we dream? What the film reveals is that much of what we thought we knew no longer stands true. Dreams are not simply wild imaginings but play a significant part in all our lives as they have an impact on our memories, the ability to learn, and our mental health. Most surprisingly, we find nightmares, too, are beneficial and may even explain the survival of our species.

The world is affected by an obesity epidemic, but why is it that not everyone is succumbing? Medical science has been obsessed with this subject and is coming up with some unexpected answers. As it turns out, it is not all about exercise and diet. At the centre of this programme is a controversial overeating experiment that aims to identify exactly what it is about some people that makes it hard for them to bulk up.

Danny Wallace really wants a robot. He wants it to walk like him and talk like him. It's what scientists have been promising us for generations but it's a promise so far unfulfilled. Danny circumnavigates the globe searching for robot nirvana, trying to uncover how far away his dream is. He discovers that the robotics world is as weird as it is insanely complicated. During his quest he meets a Japanese man who makes copies of himself and his daughter, an Italian who claims he's found the key to human intelligence in a video game and a Singaporean whose unpromising-looking homage to Dusty Bin might just turn out to be the robot of Danny's dreams.

We are in the grip of an allergy epidemic. Fifty years ago one in 30 were affected, but in Britain today it is closer to one in three. Why this should be is one of modern medicine's greatest puzzles. In search of answers, Horizon travels round the globe, from the remotest inhabited island to the polluted centres of California and the UK. We meet sufferers and the scientists who have dedicated their lives trying to answer the mystery of why we are becoming allergic to our world.

Particle physicist Professor Brian Cox asks, 'What time is it?' It's a simple question and it sounds like it has a simple answer. But do we really know what it is that we're asking? Brian visits the ancient Mayan pyramids in Mexico where the Maya built temples to time. He finds out that a day is never 24 hours and meets Earth's very own Director of Time. He journeys to the beginning of time, and goes beyond within the realms of string theory, and explores the very limit of time. He discovers that we not only travel through time at the speed of light, but the experience we feel as the passing of time could be an illusion.

Second part of the special documentary considering where the line between sanity and madness lies as ten volunteers come together for an extraordinary test. With five 'normal' volunteers and five who have been officially diagnosed as mentally ill, Horizon asks if you can tell who is who.

First of a two-part special. Ten volunteers have come together for an extraordinary test. Five are 'normal' and the other five have been officially diagnosed as mentally ill. Horizon asks if you can tell who is who, and considers where the line between sanity and madness lies.

Horizon asks some of the biggest names in science to have a quiet word with the new American president. The United States president is quite simply the most powerful man on earth, but past presidents have often known little about science. That is a problem when the decisions they make will affect every one of us, from nuclear proliferation to climate change. To help the new president get to grips with this intimidating responsibility, some of the world's leading scientists, from Dawkins to Watson, share some crucial words of advice.

Horizon journeys into the human memory, from how it emerges in childhood, develops through to adulthood, and fades in middle age. You might think that your memory is there to help you remember facts, such as birthdays or shopping lists. If so, you would be very wrong. The ability to travel back in time in your mind is, perhaps, your most remarkable ability, and develops over your lifespan. Horizon takes viewers on an extraordinary journey into the human memory. From the woman who is having her most traumatic memories wiped by a pill, to the man with no memory, this film reveals how these remarkable human stories are transforming our understanding of this unique human ability. The findings reveal the startling truth that everyone is little more than their own memory.

Friendly bacteria, superfoods, cholesterol busting spreads, 99% germ free, whiter than white...it's almost impossible to find a product in the supermarket today that doesn't come with impressive claims...a scientific claims, but do they actually do what they say? Are they worth the price? Are they worth a place in Prof. Regan's shopping trolly?

While scientists have been searching for the secrets of long life, a few isolated communities have stumbled across the answer. The quest to live longer has been one of humanities oldest dreams, but while scientists have been searching, a few isolated communities have stumbled across the answer. On the remote Japanese island of Okinawa, In the Californian town of Loma Linda and in the mountains of Sardinia people live longer than anywhere else on earth. In these unique communities a group of scientists have dedicated their lives to trying to uncover their secrets. Horizon takes a trip around the globe to meet the people who can show us all how to live longer, healthier lives.

Lifting the lid on the business of human choices in an exclusive guide to making better decisions. We are bad at making decisions. According to science, our decisions are based on oversimplification, laziness and prejudice. And that's assuming that we haven't already been hijacked by our surroundings or led astray by our subconscious! Featuring exclusive footage of experiments that show how our choices can be confounded by temperature, warped by post-rationalisation and even manipulated by the future, Horizon presents a guide to better decision making, and introduces you to Mathematician Garth Sundem, who is convinced that conclusions can best be reached using simple maths and a pencil!

A trip through the highs and lows of the UK’s 20 most dangerous drugs. Recent research has analysed the link between the harmful effects of drugs relative to their current classification by law with some startling conclusions. Perhaps most startling of all is that alcohol, solvents and tobacco (all unclassified drugs) are rated more dangerous than ecstasy, 4-MTA and LSD (all class A drugs). If the current ABC system is retained, alcohol would be rated a class A drug and tobacco class B. The scientists involved, including members of the government's top advisory committee on drug classification, have produced a rigorous assessment of the social and individual harm caused by 20 of the UK's most dangerous drugs and believe this should form the basis of future ranking. They think the current ABC system is arbitrary and not based on any scientific evidence. The drug policies have remained unchanged over the last 40 years so should they be reformed in the light of new research?

Psychologists subject six volunteers to a world without stimulation. For the first time in 40 years Horizon re-creates a controversial sensory deprivation experiment. Six ordinary people are taken to a nuclear bunker and left alone for 48 hours. Three subjects are left alone in dark, sound-proofed rooms, while the other three are given goggles and foam cuffs, while white noise is piped into their ears. The original experiments carried out in the 1950s and 60s by leading psychologist Prof Donald Hebb, was thought by many in the North American political and scientific establishment to be too cruel and were discontinued. Prof Ian Robbins, head of trauma psychology at St George's Hospital, Tooting, has been treating some of the British Guantanamo detainees and the victims of torture who come to the UK from across the world. Now he evaluates the volunteers as their brains undergo strange alterations.

Could Professor Jose Torero's fire protection system have saved the Twin Towers? When a fire gets out of control in a skyscraper it tests fire fighters to their limits. Predicting how a fire is behaving high up in a building is almost impossible. The fire fighters who entered the Twin Towers on 11 September 2001 could only guess at what was happening almost 1000 feet above them. That fateful day brought about the death of 343 New York fire fighters. Jose Torero believes fire fighters need not be put in such danger and that new technology could have saved many of the 343 fire fighters who died doing their duty that day. He believes he could even have saved the Twin Towers. He has spent the last ten years developing a system that could change the way fires are fought forever. It's called Firegrid. It's a revolutionary approach to fire fighting that could save thousands of lives, giving man the upper hand on one of his oldest enemies.

Seven high-flyers are put through a series of tests to measure their intelligence Can you think of 100 different uses for a sock? How would you cope with glasses that turn everything upside down? What's your emotional intelligence? Can you create a work of art in ten minutes? Horizon takes seven people who are some of the highest flyers in their field - a musical prodigy, a quantum physicist, an artist, a dramatist, an RAF fighter pilot, a chess grandmaster and a Wall Street trader. Each is put through a series of tests to discover who is the most intelligent? The principle way that we measure intelligence, the IQ test, remains popular and convenient. Yet most psychologists agree that it only tells half the story... at most. Where they disagree is how to measure intelligence, for the simple reason that the experts still don't know exactly what it is.

After 40 years, man is preparing to return to the Moon. But this time the astronauts won't just land on the Moon - they plan to stay. From his office in Nevada, Dennis Hope has spawned a multi-million dollar business selling lunar real estate. But scientists believe the real prize is trapped in the Moon's rocks. It contains large deposits of an extremely rare gas called Helium-3. Could Helium-3 be mined and used as a new source of almost inexhaustible, clean and pollution-free energy on Earth? Whoever succeeds in transporting Helium-3 back to Earth could solve the world's energy crisis. Who will win what has been dubbed the second Moon race? And should we be exploiting the Moon's valuable resources at all?

Pianist Nick van Bloss has Tourette's syndrome. Is his illness a blessing or a curse? Is there really such a thing as the mad genius? Can an illness be both a blessing and a curse? At seven years old, Nick van Bloss started shaking his head, grinding his teeth and making wild whooping noises. Nick had Tourette's syndrome. No medical intervention helped him. But one activity stopped it all... The moment Nick placed his hands on the piano keys his symptoms vanished. By the age of 20, he was an award winning international pianist. He felt sure that his illness had made him the success he was. But there is a catch. The brain state necessary for his genius can also be dangerously close to mental chaos. Nick's personal journey reveals how close he came to the edge and how determined he is to triumph.

Professor Lesley Regan is on a mission to fill her bathroom cabinet with cosmetics that actually work. Professor Lesley Regan, one of the UK's most well-respected (and glamorous) medical experts, turns her scientific eye on the world of cosmetics. She's just turned 50, and is out to create an experimentally proven beauty cabinet. Unafraid to examine the wrinkles, age spots and broken veins on her own face, Professor Regan explores just what makes us look old, and if we can slow down the ageing process. The extraordinary world of cosmetic testing is revealed, from the British hair lab which makes New York tap water, to the volunteers sun-bathing for science. Sun damage, cellulite and balding all face Professor Regan's scrutiny as she discovers which cosmetics do - and don't - have the scientific evidence to back up their claims.

How do you save an endangered species? Get the animals in the mood for love. Thomas Hildebrandt possesses one of the world's most extraordinary jobs - getting the planet's endangered animals in the mood for love. The planet's creatures are facing the biggest mass extinction since the dinosaurs were wiped out. Species are currently disappearing at up to 10,000 times the natural rate. Coming to the rescue are men like Dr Hildebrandt and his team. They are world leaders in the art of animal manipulation. The billions of pounds spent benefiting human reproduction are now being applied to save endangered species. Techniques such as artificial insemination and IVF have been crucial to the successes in breeding giant pandas, big cats and other mammals in zoos across the world. As Thomas Hildebrandt says "Man has created this annihilation of species. It's up to man to use his ingenuity to save them."

Clouds of alien life forms are sweeping through outer space and infecting planets with life – it may not be as far-fetched as it sounds. The idea that life on Earth came from another planet has been around as a modern scientific theory since the 1960s when it was proposed by Fred Hoyle and Chandra Wickramasinghe. At the time they were ridiculed for their idea – known as panspermia. But now, with growing evidence, it's back in vogue and even being studied by NASA. Horizon meets the scientists on a mission to get to the bottom of the beginnings of life on Earth - from the team in Texas who are lovingly building a robotic submarine called DEPTHX to explore a moon of Jupiter, to Southern India where they are investigating a mysterious red rain which fell for two months in 2001. According to local scientist Godfrey Louis, the rain contains biological cells unlike any he had seen before – with no DNA and the ability to replicate at 300°C. Louis has come to the conclusion that the cells are extra-terrestrial in origin.

A simple virus that started in the belly of a dead bird is set to embark on a global killing spree. H5N1 - a bird flu virus with the potential to become humanised and mutate into the next pandemic flu virus. Horizon explores what could happen if a flu pandemic hits. The last flu pandemic in 1918 killed an estimated 50 million people worldwide. A virus today can spread much easier, much faster and there are estimates that hundreds of millions could be infected and potentially die.

In 2005, Isabelle Dinoire become the first person to receive a new face. The decision made by French surgeons to perform the operation went against the findings of almost every other ethical committee in the world and has since sparked a fierce debate over the ethics of the operation. In the UK, a team led by Peter Butler struggles to get approval to perform the first full face transplant. Do the risks outweigh the benefits? Are face transplants really in the best interest of the patient? Horizon investigates.

Danny Wallace is on a mission to convince the world that chimps are people are to. If they are should they have the same rights as people?

Over 90% of plane crashes have survivors. Horizon investigate what you can do to increase your chances.

A team of scientists set out to solve the mystery of chunks of ancient glass scattered in a remote part of the Sahara Desert. Their quest takes them on a perilous journey into the Great Sand Sea, the wastes of Siberia and the test site of the world's first atomic bomb in New Mexico. What their search uncovers is a devastating new natural phenomenon.

The curious tale of an American millionaire optometrist and his dream to save humanity.

The story of three women as they attempt to overcome the odds and give birth to a baby.

On 7 July 2005 Britain experienced its first ever suicide attack. Four bombs exploded in central London, killing 52 people and injuring over 700. When Scotland Yard launched one of the biggest investigations in its history, another first was quickly uncovered: the suicide bombers were home-grown, they were young British men, attacking their own country. Horizon explores what makes someone want to blow themselves – and others - up?

Over a billion kilometres away, Saturn's largest moon, Titan, holds tantalising clues to how life began here on Earth. Horizon tells the story of the Cassini-Huygens spacecraft, the most ambitious and expensive interplanetary space mission of all time.

Time is running out for the rainforest, but a team of scientists have come up with a unique strategy to help save it: a giant inflatable raft.

Is the hobbit a new human species or nothing more than a modern human with a crippling deformity?

Has Stephen Hawking been wrong about the universe for the last 30 years? Horizon explores his latest theory.

This is the story by Horizon of an epic battle between science and nature. It's a battle to destroy a disease that is one of the biggest killers on the planet: malaria.

In this documentary, Horizon presents the largest public health issue of recent years that has attracted such heated debate as the question of whether the MMR vaccine can cause autism. The MMR jab combines three childhood vaccines, against measles, mumps and rubella, into one injection, which is first given to children at around 12-18 months. Horizon presents new, exclusive evidence about the MMR jab.

In this documentary on earthquakes, Horizon starts with the worst natural disasters of all time in December 2004. The cause of so much devastation was the most powerful kind of earthquake on the planet - a megathrust. Megathrust earthquakes only occur on a particular kind of fault. Scientists have now discovered that just such a fault could cause a huge megathrust earthquake and tsunami right off the coast of North America.

Horizon brings us back two thousand years ago when a mysterious and little known civilization ruled the northern coast of Peru. Its people were called the Moche.

Horizon investigates a strange skull that was discovered in 1848 on the military outpost of Gibraltar. It was undoubtedly human, but also had some of the heavy features of an ape... distinct brow ridges, and a forward projecting face. Just what was this ancient creature? And when had it lived? As more remains were discovered one thing became clear, this creature had once lived right across Europe. The remains were named Homo neanderthalensis (Neanderthal man) an ancient and primitive form of human.

In this documentary, Horizon investigates Attention Deficit Hyperactivity Disorder (ADHD), which is one of the most feared and misunderstood of all medical conditions. Despite over 200 scientific papers being published on this neurological condition every year, it remains stigmatised and controversial. Some doctors don't even believe it exists. Yet it is estimated that as many as 3-5 percent of the childhood population, and over one million adults in the UK are affected by ADHD. These people are often described as stupid, lazy, disorganised, wild, out of control or woozy on drugs. But the reality is altogether more complex, and deeply moving.

The story of Einstein's most famous equation E=mc² – its role in the creation of the atom bomb and our understanding of the beginnings of the Universe. Horizon brings you the second part of a two-part series on Albert Einsten. In the summer of 1939 Albert Einstein was on holiday in a small resort town on the tip of Long Island. His peaceful summer, however, was about to be shattered by a visit from an old friend and colleague from his years in Berlin. The visitor was the physicist Leo Szilard. He had come to tell Einstein that he feared the Nazis could soon be in possession of a terrible new weapon and that something had to be done.

The unpredictable results of the Theory of Relativity. Horizon brings you the second part of a two-part series on Albert Einsten. In the summer of 1939 Albert Einstein was on holiday in a small resort town on the tip of Long Island. His peaceful summer, however, was about to be shattered by a visit from an old friend and colleague from his years in Berlin. The visitor was the physicist Leo Szilard. He had come to tell Einstein that he feared the Nazis could soon be in possession of a terrible new weapon and that something had to be done.

Horizon producer David Sington on why predictions about the Earth's climate will need to be re-examined.

In 1610, Galileo used a new invention -- a simple telescope -- to look at Saturn. When he viewed the planet for the first time, he saw something strange. He thought he saw three stars together, a big one in the middle of two little stars. He knew they weren't really stars, but what were they?

Until recently most scientists thought they knew what killed off the dinosaurs. A 10km-wide meteorite had smashed into the Yucatan peninsula in Mexico, causing worldwide forest fires, tsunamis several kilometres high, and an 'impact winter' - in which dust blocked out the sun for months or years. It was thought that the dinosaurs were blasted, roasted and frozen to death, in that order. But now a small but vociferous group of scientists believes there is increasing evidence that this 'impact' theory could be wrong. That suggestion has generated one of the bitterest scientific rows of recent times.

Is Wednesday red? Take part in our experiment to test whether your senses overlap. Do melodies have a colour? Take part in our experiment to test whether you hear colours. Imagine if every time you saw someone called Derek you got a strong taste of earwax in your mouth. It happens to James Wannerton, who runs a pub. Derek is one of his regulars. Another regular's name gives him the taste of wet nappies. For some puzzling reason, James's sense of sound and taste are intermingled. Dorothy Latham sees words as colours. Whenever she reads a black and white text, she sees each letter tinged in the shade of her own multi-coloured alphabet - even though she knows the reality of the text is black and white. Spoken words have an even stranger effect. She sees them, spelled out letter by letter, on a colourful ticker tape in front of her head. Both James and Dorothy have a mysterious condition called synaesthesia, in which their senses have become linked. For years scientists dismissed it, putting it in the same category as séances and spoon-bending. But now, synaesthesia is sparking a revolution in our understanding of the human mind. Two synaesthetes seldom agree on the colours or tastes they experience. While Covent Garden may taste of crinkly chocolate to James, it's very unlikely to have the same taste for another synaesthete. And Dorothy's brother Peter, also a synaesthete, won't see M or Z in the same colour as she does. But despite these differences, scientists are now beginning to discover more and more overarching synaesthetic patterns. Dorothy doesn't only see letters and numbers in colour. Music produces a riot of colour, too. As Dorothy hears notes going from low to high, her colours change from black and purple to mid-browns and then yellows and whites. Overall, lower notes evoke darker colours and higher notes brighter colours - and this pattern is true for most synaesthetes. But surprisingly, when non-synaesthetes are asked to match colours and music, they show a similar pattern. Most of us seem to associate low notes with darker colours and high notes with brighter colours. The evidence of the synaesthete in all of us doesn't end here. Another clue comes from the way we manipulate numbers. More than half of all synaesthetes who see coloured numbers also experience their numbers arranged in space around them. Heather Birt is such a synaesthete, and she's followed by a stream of numbers wherever she goes. Recently, scientists started to investigate how non-synaesthetes deal with numbers. They found they're better at manipulating small numbers with their left hand, and their bigger numbers with our right hand. This suggests that we all somehow think of numbers as arranged in space, even if we're not aware of it. More evidence, it seems, that we're all synaesthetic to some degree. It's just that some people experience a more exaggerated version. A few scientists believe that synaesthesia might even explain how we evolved two of the traits that define our species and have transformed our world - creativity and language. Many famous artists have been synaesthetes - the jazz legend Miles Davis, for instance, and the painter Kandinsky. In fact, a number of studies suggest that synaesthesia may be more common among artists, poets and musicians. This has led some scientists to argue that synaesthesia and creativity may share a similar basis - that both may be down to brain processes that involve linking two seemingly unrelated areas. Some believe that our common synaesthetic abilities may also have been the springboard to language. Connections between our senses of hearing and vision, for example, could have been an important initial step towards the creation of words. Our earliest ancestors may have first started to talk by using sounds that actually evoked the object they wished to describe. According to this theory, language could have emerged from the multitude of synaesthetic connections within our brains.

It's one of the greatest stories ever told. The legend of Helen of Troy has enchanted audiences for the last three thousand years. In May this year a Hollywood film staring Brad Pitt and Orlando Bloom will be launched in Britain. But is there any reality to the myth? Horizon has unprecedented access to the scientist with the answers. Since 1988 Professor Manfred Korfmann has been excavating the site of Troy. He has never before spoken at this length. He has made amazing discoveries - how large the city was, how well it was defended and, crucially, that there was once a great battle there at precisely the time that experts believe the Trojan war occurred. But who had attacked the city and why? Horizon then follows a trail of clues - the ancient tablets written by a lost civilisation, the sunken ship rich in treasure, and the magnificent golden masks and bronze swords of a warrior people. The film reaches its climax in a tunnel deep beneath Troy, where Korfmann has made a discovery that may reveal, once and for all, the truth behind the myth. The story that emerges is one of great passion - but not, it seems, about love.

This is the story of two genuine scientific heroes. For forty years, John Bahcall and Ray Davis were engaged in a single extraordinary experiment - to find out why the Sun shines. In the end they would triumph. Davis would win the Nobel Prize and, thanks to their work, a whole new theory about how the universe is put together may have to be created. At the heart of this story is a tiny, utterly mysterious thing called a neutrino. Trillions of them pass through your body every second, touching nothing, leaving no trace. Yet neutrinos are one of a handful of fundamental particles in the universe, essential to every atom in existence and clues to what makes the Sun work. But their ghost-like quality made trapping and understanding them immensely difficult. What then followed was a bizarre series of experiments. They led from a vat containing 600 tons of cleaning fluid, to a vast cavern in a Japanese mountain, to a hole in the ground in Canada two kilometres deep. What they would reveal would stun the world of science. It seems that neutrinos may be our parents. They may be the reason why everything, including us, exists.

Tyrannosaurus rex - it's the scariest, meanest, most bewitching dinosaur of them all. Children are captivated by the sheer savagery of the teeth. Experts marvelled at the force of its bite - ten times more powerful than anything we know today. Movie makers made millions out of the terror it inspired. But could our picture of this monster be completely wrong? Was T. rex in fact a slow lumbering creature, with hideously bad breath, that couldn't get anywhere close to catching a Triceratops. Was it really a scavenger that lived off the scraps left by others? Was T. rex, in fact, a wimp? Featuring fabulous graphics and interviews with T. rex experts from around the world, Horizon looks at the new science that is challenging the legend of the dinosaur we love to hate.

Imagine a world where disease could be eradicated by an injection of tiny robots the size of molecules. That is the hope offered by nanotechnology - the science of microscopically small machines. But others fear nanotechnology could lead to a non-biological cancer - where swarms of tiny nanobots come together and literally devour human flesh. Sounds like science fiction? It certainly did until a brilliant young scientist called Hendrik Schön seemed to bring it a step closer. Schön's great breakthrough was to make a computer transistor out of a single organic molecule. It was an achievement of almost incalculable brilliance. Some speculated this technology could spell the end of the entire silicon chip industry. Crucially, Schön's transistor was organic. Suddenly, this seemed to be the first step towards true nanotechnology, where minute computers could grow as living cells. Scientists speculated about how these tiny machines could be used to target diseases with astonishing precision. Others wondered - could the military use them as a new weapon? Others, including Prince Charles, were terrified. If these machines can grow by themselves, how do we stop them from growing? What happened next would destroy reputations and shatter lives - because there was more to Hendrik Schön's discovery than anyone knew.

With the help of doctors and scientists in America, Germany and Britain, Horizon unpicks the mystery of the Moscow theatre siege. In October 2002, Chechen terrorists took a thousand people hostage in a Moscow theatre and threatened to kill them. The problem was how to get them out alive. A bloodbath seemed inevitable. Three days later Russian special forces stormed the theatre using a secret gas to knock everybody out. 129 hostages died - apparently killed by the very gas that was meant to save them. Horizon investigates the mystery substance, and why so many died. The Russian authorities insisted their secret weapon was not lethal. The claim provoked contempt from the victims families, and incredulity among doctors and scientists around the world. But were the Russians actually right? The Russians offered just one clue. And in Germany there was a scientist who had the means to test it: a urine sample taken from one of the survivors shortly after he was freed. Horizon follows as extremely sensitive tests are performed to find out if the Russians were telling the truth, and uncovers a deeper secret.

Horizon's Time Trip is a thrilling journey deep into the strangeness of cutting-edge physics - a place where beautiful, baffling ideas are sometimes indistinguishable from the utterly crazy. On this journey, we meet a time-travelling pizza, a brilliant mathematician in a ski mask and even God. The journey ends with a strange and dark conclusion - one which calls into question our very existence. Ever since Einstein showed it was theoretically possible, the quest to travel through time has drawn eccentric amateurs and brilliant scientists in almost equal numbers. The amateurs include Aage Nost, who demonstrates his time machine in front of the cameras. The professionals include the likes of Professor Frank Tipler of Tulane University. His time machine sounds good - but it would weigh half the mass of the galaxy. There is, however, one way that time travel to the past could be possible. And it would be much more convenient. Future civilisations could use computers to create exact replicas of the past. Unfortunately that idea has physics trembling in its socks. Because if you can generate a perfect virtual reality version of the past, who's to say we are not one of the replicas?

Could an unknown Englishman have been the first person ever to fly? To mark the hundredth anniversary of the Wright brothers inaugural flight, Horizon tells the remarkable story of Percy Pilcher. He could have been the most famous aviator of them all. Four years before the Wright brothers, he had constructed his own aeroplane. But on the day it was due to take off for the very first time, something so terrible happened that he was denied the chance of ever flying it. So Horizon has rebuilt his long lost flying machine to see if Percy Pilcher, the British amateur, could have claimed the glory and been the first person ever to fly. This film mixes dramatic reconstruction with fabulous contemporary scenes and gripping science. With a specially assembled team of historians, aviation experts and our own test pilot, Horizon painstakingly rebuilds Pilcher's flying machine and puts it to the test. The results will leave you cheering.

Horizon tells the microbiological detective story in which some of the best brains in science have been pitted against the most extraordinary bug the world has ever seen. In 1984 it was discovered that HIV was the cause of AIDS. Straight away, there were confident predictions that there would be a vaccine ready for testing in just two years. Back then, just 1,292 deaths from AIDS had been reported. Now the figure is 25 million dead. By 2010 it is predicted there will be 85 million infections and 70 million deaths. And after 20 years there is still no sign of a vaccine. Despite work of dazzling complexity, the ambition of so many brilliant scientists has been constantly thwarted. Just as a vaccine seems to be working, the AIDS virus alters itself, and ten to fifteen years of work, and millions of pounds, go down the drain. These bitter disappointments are only compounded by the desperate human urgency of the work. This is a story where the clock doesn't stop ticking.

Set against the back drop of awe inspiring geological beauty, a strange scientific adventure sets out to discover how a mineral clad cave network - the height of a 30 storey building and the length of six football fields - came to exist deep below the Guadalupe Mountains in North America. But this journey soon unravels a multitude of inexplicable phenomena and obscure geological formations, leading to the discovery of extreme rock-eating microbes - a testimony from primordial Earth and a glimpse of life elsewhere in the Solar System. Geologists believed that all limestone caves were formed by rain and underground water percolating through cracks in the rocks. Absorbing carbon dioxide from the soil, this water becomes weak carbonic acid, nibbling away at limestone, etching out networks of subterranean caves.

Are we alone in the Universe? Or are there aliens somewhere in space? New evidence suggests not only might other life-forms be out there, they may even be living on the planet right next door to us - Mars. Recent discoveries have shown that Mars has all the ingredients for life, including water. Now the Mars Odyssey probe, launched in April 2001, has detected huge frozen areas of permafrost, just like that found in the Antarctic on Earth. According to astronomers, the position of this frozen slush could hold the key to Mars' mysterious water cycle. And the surface ice may hide something even more exciting below.

Understanding of humans' earliest past often comes from studying fossils. They tell us much of what we know about the people who lived before us. There is one thing fossils cannot tell us; at what point did we stop living day-to-day and start to think symbolically, to represent ideas about our environment and how we could change it? At a dig in South Africa the discovery of a small piece of ochre pigment, 70,000 years old, has raised some very interesting questions. Anatomically modern humans (Homo sapiens) emerged in Africa roughly 100,000 years ago. We know from fossil evidence that Homo sapiens replaced other hominids around them and moved out of Africa into Asia and the Middle East, reaching Europe 40,000 years ago. Prof Richard Klein believes art is a landmark in human evolution. Unquestionable art that's widespread and common suggests you're dealing with people just like us. No other animals, after all, are able to define a painting as anything other than a collection of colours and shapes. This ability is unique to humans.

The drug Viagra revolutionised the treatment of sexual dysfunction in men on its launch five years ago. An accidental discovery, the tablet that gave impotent men the chance once more to have natural erections became the fastest selling pill in history and has earned its manufacturer, Pfizer, over $6bn. The search is now on for a similar drug that could help women. Research is revealing that female sexuality is more complex than expected. For women suffering from a loss of desire many scientists believe that drugs acting on the brain may be the way forward. A pioneering Scottish study may have identified just such a drug and begun testing it scientifically. An erection is achieved by filling the erectile tissue of the penis with blood. Blood vessels widen to allow blood in and then constrict to maintain the pressure. Male impotence was long thought to be a psychiatric effect, a result of stress, anxiety or depression. Medical advice was that there was not much to be done. Some patients refused to take this message on board.

A dirty bomb is a radiological weapon but unlike a nuclear bomb, its purpose is to contaminate rather than destroy. It uses normal explosives to disperse radioactive materials in the local environment, creating a hazard to health that could last for years unless cleaned up. The relative ease of making such a bomb means it is a potent terrorist weapon but Horizon's investigation shows that the risk to health from most such devices need not be great. It also underlines the need for governments to act to secure radioactive sources from falling into criminal hands. Horizon deliberately avoids outlining the production process in any detail. Horizon publishes the results of specially commissioned research, modelling two possible dirty bomb scenarios: attacks on either London or Washington DC. The main conclusion is that the health risks from a dirty bomb explosion are localised to people who are close to the incident or are in contact with the contamination. Although the modelled attack scenarios could have wide-ranging economic repercussions, the majority of the population of either capital city would have only a negligible increase in their risk of developing cancer.

The Earth is under constant bombardment. Each year, many fragments of debris hit our planet. Fortunately for us, most are so small that they burn up harmlessly in the atmosphere. However, there are hundreds of larger asteroids orbiting near the Earth. Many scientists now believe that one of these hit the Earth 65 million years ago, killing the dinosaurs, along with 90% of all life on the planet. What is more, it is only a matter of time before the Earth is hit again. Experts warn that nuclear weapons might not destroy an approaching asteroid. But Jay Meloch thinks he can use the power of the Sun to nudge an asteroid away from the Earth. Until recently, no one took the asteroid threat very seriously. Yet the evidence that we are in danger is on our own doorstep. We need only look at the cratered surface of the Moon to realise that it has been pounded by impacts throughout its history.

Sleeping is an essential part of everyone's life yet it remains little understood is barely understood. You might think it's a relaxing recharge but in fact your brain is working harder at times overnight than when you're conscious in the day. Fresh insight into why and how we sleep has come from studying people with sleep disorders, especially sufferers of narcolepsy. The condition means that people fall asleep many times a day, completely out of the blue. A less known symptom is paralysing attacks, that can cause narcoleptics to fall to the ground - unable to move - several times a day. If a way can be found to ease their symptoms, it could open the way to helping any of us to control our sleep patterns and perhaps even to go without rest while staying alert. Gaynor Carr has been nodding off routinely since the age of seven. Her narcolepsy has made holding down a job impossible and made her question the idea of ever having children. Gary Beattie used to work in construction, until he fell asleep 7m up a ladder. He not only loses consciousness, his body becomes paralysed in a so-called cataleptic attack. Both of them say that showing emotion sparks the paralysing attacks and that has forced them to avoid laughing and crying. Bill Baird worked in finance but describes his stockbroking days as a race. The emotion of closing a deal would bring on a fit; he had constantly to hope he could get a client's signature before his almost inevitable collapse. His sleep is restless, with vivid nightmares when he is able to hear his surroundings while seeing terrifying hallucinations.

On Easter Day 1722, Dutch explorers landed on Easter Island. A civilisation isolated by 4,000km of Pacific Ocean was about to meet the outside world for the first time in centuries. The strangers were about to find something very strange themselves - an island dotted with hundreds of huge stone statues and a society that was not as primitive as they expected. The first meeting was an immense clash of cultures. (Bloody too: the sailors killed ten natives within minutes of landing.) Where had the Islanders originally come from? Why and how had they built the figures? Modern science is piecing together the story, but it is far too late for the Easter Islanders themselves. They were virtually wiped out by a series of disasters - natural and man made - that brought a population of 12,000 down to just 111 in a few centuries. The Island's inhabitants today all have Chilean roots, making solving the mysteries even harder. There is no one to ask about the first people of Easter Island. Although fragmentary legends have been passed down, only science can hope to explain the rise and fall of this unusual civilisation.

In 1542, the Spanish Conquistador, Francisco de Orellana ventured along the Rio Negro, one of the Amazon Basin's great rivers. Hunting a hidden city of gold, his expedition found a network of farms, villages and even huge walled cities. At least that is what he told an eager audience on his return to Spain. The prospect of gold drew others to explore the region, but none could find the people of whom the first Conquistadors had spoken. The missionaries who followed a century later reported finding just isolated tribes of hunter-gatherers. Orellana's story seemed to be no more than a fanciful myth. When scientists came to weigh up the credibility of Orellana's words, they reached the same conclusion. As productive as the rainforest may appear, the soil it stands in is unsuited to farming. It is established belief that all early civilisations have agriculture at their hearts. Any major population centre will have connections with a system of intensive agriculture. If a soil cannot support crops sufficient to feed a large number of people, then that serves as an effective cap on the population in that area. Even modern chemicals and techniques have failed to generate significant food from Amazonian soil in a sustainable way . The thought that indigenous people could have survived in any number - let alone prospered - was dismissed by most scientists. Scientific consensus was sure that the original Amazonians lived in small semi-nomadic bands and that Orellana must have lied.

250 million years ago, long before dinosaurs roamed the Earth, the land and oceans teemed with life. This was the Permian, a golden era of biodiversity that was about to come to a crashing end. Within just a few thousand years, 95% of the lifeforms on the planet would be wiped out, in the biggest mass extinction Earth has ever known. What natural disaster could kill on such a massive scale? It is only in recent years that evidence has begun to emerge from rocks in Antarctica, Siberia and Greenland. The demise of the dinosaurs, 65 million years ago (at the so-called K/T boundary), was as nothing compared to the Permian mass extinction. The K/T event killed off 60% of life on Earth; the Permian event 95%. Geological data to explain the destruction have been hard to find, simply because the rocks are so old and therefore subject to all kinds of erosion processes. It seems plausible that some kind of catastrophic environmental change must have made life untenable across vast swathes of the planet. In the early 1990s, the hunt for evidence headed for a region of Siberia known as the Traps. Today it's a sub-Arctic wilderness but 250 million years ago, over 200,000km² of it was a blazing torrent of lava. The Siberian Traps were experiencing a 'flood basalt eruption', the biggest volcanic effect on Earth. Instead of isolated volcanoes spewing out lava, the crust split and curtains of lava were released. And the Siberian flood eruption lasted for millions of years. Could volcanic activity over such a long time alter the climate enough to kill off 95% of life on Earth?

Homoeopathy was pioneered over 200 years ago. Practitioners and patients are convinced it has the power to heal. Today, some of the most famous and influential people in the world, including pop stars, politicians, footballers and even Prince Charles, all use homoeopathic remedies. Yet according to traditional science, they are wasting their money. Sceptic James Randi is so convinced that homoeopathy will not work, that he has offered $1m to anyone who can provide convincing evidence of its effects. For the first time in the programme's history, Horizon conducts its own scientific experiment, to try and win his money. If they succeed, they will not only be $1m richer - they will also force scientists to rethink some of their fundamental beliefs. The basic principle of homoeopathy is that like cures like: that an ailment can be cured by small quantities of substances which produce the same symptoms. For example, it is believed that onions, which produce streaming, itchy eyes, can be used to relieve the symptoms of hay fever.

Who were the first people in North America? From where did they come? How did they arrive? The prehistory of the Americas has been widely studied. Over 70 years a consensus became so established that dissenters felt uneasy challenging it. Yet in 2001, genetics, anthropology and a few shards of flint combined to overturn the accepted facts and to push back one of the greatest technological changes that the Americas have ever seen by over five millennia. The accepted version of the first Americans starts with a flint spearhead unearthed at Clovis, New Mexico, in 1933. Dated by the mammoth skeleton it lay beside to 11,500 years ago, it was distinctive because it had two faces, where flakes had been knapped away from a core flint. The find sparked a wave of similar reports, all dating from around the same period. There seemed to be nothing human before Clovis. Whoever those incomers were around 9,500BC, they appeared to have had a clean start. And the Clovis point was their icon - across 48 states.

The world's oceans claim on average one ship a week, often in mysterious circumstances. With little evidence to go on, investigators usually point at human error or poor maintenance but an alarming series of disappearances and near-sinkings, including world-class vessels with unblemished track records, has prompted the search for a more sinister cause and renewed belief in a maritime myth: the wall of water. Waves the height of an office block. Waves twice as large as any that ships are designed to ride over. These are not tsunamis or tidal waves, but huge breaking walls of water that come out of the blue. Suspicions these were fact not fiction were roused in 1978, by the cargo ship München. She was a state-of-the-art cargo ship. The December storms predicted when she set out to cross the Atlantic did not concern her German crew. The voyage was perfectly routine until at 3am on 12 December she sent out a garbled mayday message from the mid-Atlantic. Rescue attempts began immediately with over a hundred ships combing the ocean.

The England football manager, Sven-Goran Eriksson, believes that modern soccer matches are not won on the pitch, but inside people's minds. This film examines not just how Eriksson got inside his players' brains, but how he is now starting nothing short of a revolution in English football thinking. Eriksson's plan, devised with sports psychologist Dr Willi Railo, has two critical elements. These are to banish the crippling effects of the fear of failure from the minds of the England players, and to encourage them to train mentally as well as physically to reach the highest levels of performance - dubbed playing in 'the zone'. Neurologists and psychologists from some of Britain's most prestigious universities believe anxiety and the fear of failure can make top professionals turn in performances like amateurs, and that Eriksson and Railo have a way to help the England team endure the pressure. Their view is that England's football past has been dogged by fear of failure. Piling on pressure and relying on patriotism to get people to perform doesn't work when - at heart - it's just 11 footballers taking on 11. If players accept they could lose (and that it's alright when they do) then they'll be less nervous and less prone to what's called 'choking'. When sportspeople choke, familiar instincts are overwhelmed by pressure. Monitoring shows that people use different parts of the brain to perform actions which they are learning and those which are second nature. If the brain reverts to its learning mode, motor skills are constrained and that 89th minute penalty kick goes right over the bar. Visualisation is fundamental to making sure people play to their best at all times. As far the brain is concerned, there's little difference between practising a movement and just thinking through it. By thinking in advance just how intense the pressure could be, Eriksson's players can avoid choking when critical moments arise. Eriksson has a further psychological ace to play. For all his talk and motivation, he knows he's not there on the pitch. To carry his thinking onto the field, he relies on so-called cultural architects, players whose thinking is so close to his own that they do his bidding without even realising. The captain, David Beckham, is clearly one architect; the team keeps secret just whom the others might be. Sports psychology cannot predict whether England will win the World Cup. However, it does show that - for once - England are going into a major competition with an unprecedented degree of psychological preparedness, a critical advantage that the side has never boasted before. Thirty years of hurt may soon be over.

On 4 April 1962, James Hanratty was led from the condemned cell in Bedford Prison to the gallows. On the way he protested his innocence, as he had done every day since he had been convicted of murder. At 8am, the noose was fitted round Hanratty's neck and he was hanged, launching one of the longest and most bitter appeal campaigns in the history of British justice. Hanratty's supporters believe that he was wrongfully convicted, the victim of dubious police evidence. The police maintain Hanratty was a vicious killer - and say they now have DNA evidence to prove it. After years of doubt, it appears that modern science holds the key to a 40 year old case. It all began when Michael Gregsten drove to the countryside with his lover, Valerie Storie. They had just parked in a quiet lay-by when a gunman got in the back of their car and demanded money. Several hours later Gregsten was dead and Storie had been raped and, with several bullets inside her, left for dead on the side of the A6 road. Amazingly, she survived to tell the tale. The nation was horrified by the savagery of the crime, and a massive manhunt was launched. Police began to close in on a small-time crook, 25 year old James Hanratty. Valerie Storie identified him as the killer, as did two other eye witnesses, who said they saw Hanratty driving Gregsten's car shortly before it was abandoned. Hanratty, a convicted thief, was unable to provide a credible alibi for what he was doing at the time of the murder, and in court, came across as arrogant, devious and unreliable. After a six week trial, and largely on the basis of this crucial eye witness evidence, Hanratty was found guilty and sentenced to death. As time went on, Hanratty campaigners became more and more convinced that the case against him was flawed. They claim that police withheld vital evidence from the defence, that Valerie Storie's identification of Hanratty was dubious, and the other eye witnesses may not even have seen Hanratty at all. The case against Hanratty began to look sufficiently weak that an appeal was begun, nearly 40 years after Hanratty was hanged. As part of the re-examination of the case, painstaking forensic analysis of the original police notebooks suggests that the police may even have altered the records of their interviews with Hanratty. So for Hanratty campaigners, on the evidence as presented in court in 1962, Hanratty should never have been hanged. Horizon has unique access to footage that covers a bizarre twist to this strange story. In 2001 the police exhumed Hanratty's body and took DNA samples, for comparison with crime-scene evidence still stored in police files. Using advanced techniques in DNA analysis which can analyse tiny fragments of DNA - even those from decaying, 40 year old corpses - the scientists made a conclusive match. It seemed that for all the campaign, Hanratty may well have been guilty after all. But with the judgement of the original trial possibly flawed by the suggestion of undisclosed evidence and police interference, the Court of Appeal faced a highly difficult decision. It had to decide whether the original evidence leading to Hanratty's conviction was so flawed that the guilty verdict should be overturned; or whether the case against him, including the new DNA evidence, was so compelling that the guilty verdict should remain. The A6 Murder looks at the evidence that led to two weeks of deliberation for the judges, and discusses where both sides go from here.

For years scientists have been trying to find the mysterious evolutionary master key responsible for transforming the dinosaurs into world-beaters. In the early Jurassic, 200 million years ago, they were a relatively small group of primitive creatures. By the late Jurassic, 50 million years later, they had become the magnificent array of carnivores and giant plant eaters that would dominate the planet for millions of years. In between lies the mysterious period of the middle Jurassic in which all these changes must have happened. But what were they? What was it that transformed the dinosaurs? Was there some terrible mass extinction? Had there been an amazing change in the environment? All this was speculation and theory. How and where would evidence come to light? Fossils from the middle Jurassic are incredibly rare. All anyone had to go on were a few small outcrops of rock dotted around the world. Then a treasure trove of fossils emerged from the midst of an Argentinian wilderness in the 1990s; thousands of square miles of mid-Jurassic rocks. On their first season in the field, palaeontologist Oliver Rauhut and his team unearthed two giant meat-eating dinosaurs and six huge long-necked dinosaurs. And there was much more: early mammals, crocodiles, fish and even plant life. They had uncovered a complete mid-Jurassic eco-system, a wonderful snapshot of life from this dark age of dinosaurs. "It's as if someone has unearthed a holy grail of dinosaur palaeontology," says British geologist, Dr Phil Manning. Oliver Rauhut describes the site as, "an extraordinary window on the mid-Jurassic." Above all, the hope is that this site may contain all the information they need to find the mysterious evolutionary forces that have eluded palaeontologists for so long. Already they've been able to test out many of their theories and draw some exciting conclusions. For instance, one theory about what might have happened in the mid-Jurassic clearly does not seem to be supported by the finds in Argentina: the mass extinction theory. The laws of evolution say that a major extinction event could have caused an explosion in dinosaur diversity like the one in the mid-Jurassic. Death on such a vast scale clears away the competition, allowing the survivors to evolve rapidly into new ecological niches. But there's no evidence in Argentina for an extinction event affecting the dinosaurs. A second theory was that a major climate change could have transformed the dinosaurs' environment, leading to the evolution of many new types of dinosaur. In Argentina there is indeed evidence for a dramatic change in the climate. At the time of the early, primitive dinosaurs all the continents were gathered together in one giant super-continent (Pangea). The climate of the super-continent was dominated by extremely hot and dry conditions - with rainfall concentrated in a short bursts. Scientists call this the time of the mega-monsoon. Then in the middle Jurassic Pangea began to split apart. The Argentinian site offers evidence that as the super-continent split up, the climate changed to a more moderate, less extreme climate. Many scientists believe that on its own climate change isn't enough to explain what happened to the dinosaurs in the mid-Jurassic. As Phil Manning points out, the dinosaurs could in theory simply move to find the climates they were most adapted to - unless something stopped them from moving, some major physical barrier that meant they couldn't follow the climate zones. When scientists looked into this, it became clear that as the super-continent split up, such a barrier was being formed. Today it's called the Atlantic Ocean. This major barrier would allow an evolutionary process called vicariance to operate - animals on different sides of the barrier are able to evolve separately. The problem was there was no proof of vicariance in the mid-Jurassic. Until Argentina. Fortunately the site has fossils from just before and just after the super-continent split in two, so it's ideally placed to judge whether vicariance was beginning to take effect. And the early results are lending support that this may have been a key factor in explaining what happened to the dinosaurs in the mid-Jurassic.

This is the story of a book that could have changed the history of the World. To the untrained eye, it is nothing more than a small and unassuming Byzantine prayer book, yet it sold at Christies for over $2m. For faintly visible beneath the prayers on its pages are other, unique, writings - words that have been lost for nearly two thousand years. The text is the only record of work by one of the world's greatest minds - the ancient Greek, Archimedes - a mathematical genius centuries ahead of his time. Hidden for a millennium in a middle eastern library, it has been written over, broken up, painted on, cut up and re-glued. But in the nick of time scientists have saved the precious, fragile document, and for the first time it is revealing just how revolutionary Archimedes' ideas were. If it had been available to scholars during the Renaissance, we might have reached the Moon over a hundred years ago. The trail begins in the tenth century, when a scribe made a unique copy of the most important mathematics that Archimedes ever developed. For 200 years the document survived, but the mathematics in it was so complex that no one paid it any attention. So when one day a monk was looking for some new parchment - an expensive commodity at the time - to write a new prayer book, the answer seemed obvious. He used the Archimedes manuscript. He washed the Greek text off the pages, cut them in half, rebound them, and turned the Archimedes manuscript into an everyday prayer book. As he piously wrote out his prayers, he had no idea of the genius he was obliterating. Several hundred years later, the Renaissance was under way. Scientists were beginning to grapple with new concepts, working out how mathematics could be used to explain the World around them. Little did they know that many of the problems they were just encountering Archimedes had already solved more than a thousand years before. So, tragically, they had to do that research all over again, setting back the development of science and technology immeasurably. Then in 1906, in Constantinople, the document mysteriously turned up in a monastic library. An opportunistic scholar called Johan Ludwig Heiberg identified the text as Archimedes' writings. Although the Greek text was very faint, Heiberg was able to decipher some of it. What he found astonished him, and made the front page of the New York Times. He revealed that Archimedes' manuscript contained something called 'The Method', which showed not only Archimedes' final proofs, but for the first time revealed the process of how he went about making his discoveries. But then disaster struck again. World War One broke out and in its aftermath the Archimedes manuscript disappeared. Scholars had given up any hope of seeing the manuscript again, but in the 1960s odd rumours began to surface that it was to be found in Paris. It took 30 more years, but in 1991 an expert from Christies found it in the hands of a French family. When it reached auction, it was sold to an anonymous millionaire, who has now loaned it to the Walters Art Museum in Baltimore for conservation. Although the text is incredibly difficult to read, with state-of-the-art imaging equipment, they are gradually piecing together all of the writing for the very first time. And as the team in Baltimore peel back the glue, leather and centuries of dirt, dissolve the blue-tack and unfold the lines of Greek that are buried in the spine of the book, they are building up a picture of a man who was thousands of years ahead of his time. Not only was Archimedes coming to terms with the profound subject of infinity, he had taken the first crucial steps towards calculus, a branch of mathematics that had to be reinvented after the Renaissance, and which is today used to describe every physical phenomenon from the movement of the planets to the construction of a skyscraper. Who knows what human minds could have achieved if they had only known what Archimedes already knew?

The World Trade Center was built on revolutionary design principles. It turned conventional architectural and structural techniques on their head. Built from a thin web of steel, its design was efficient, cost-effective and would inspire a new wave in modern building techniques. The result was two towers that were both lightweight and strong. When they were completed they were the tallest in the world. They were also milestones of architecture for another reason. The two towers were the first skyscrapers explicitly designed to withstand being hit by a jet plane. Although they had considered an aircraft impact, the designers of the World Trade towers had not anticipated the effect of an aeroplane's fuel load. British-born survivor Paul Neal tells how he smelt jet fuel rushing through the lift shafts close to his desk. "I recognised it because I'm a private pilot. I recall smelling it and instantly dismissed it as being illogical because it didn't have any place in the World Trade Center." Survivor, Bill Forney, recalls the instant that the 767 aircraft hit the North Tower one floor above where he was sitting. "The building started shaking. It lurched back and forth. It was the first time that I had truly thought that I might die. After a terrifying six to ten movements back and forth it was over and it was done." The World Trade Center had ultra-lightweight floors, and used the latest fireproof 'drywall' to protect the stairwells and lift shafts. Much of this internal structure seems to have been vaporized when the planes crashed, exposing the underlying steel to the intense heat of multiple fires. Brian Clark was one of the only four survivors from both towers to escape from above where the planes hit. He describess clambering over the shattered walls to break through a smoke-filled stairwell to get out. "Drywall had been blown off and was lying up against the stair railing." he says, "We had to shovel it aside." Another survivor, window cleaner Jan Demczur, found the drywall so soft that he was able to dig through it with a squeegee to break out of a lift he was trapped in. The two towers responded differently to the initial impacts, because there were crucial differences between the collisions. The South Tower, struck second, was hit lower, and the damaged zone of the tower then had to support a much greater weight of building above it . Rather than being hit head-on, the South Tower was hit at an angle. The plane wreckage scraped along the inside of the east wall and piled up in the northeast corner. Here, the fire burned intensely. At the South Tower's inner core, one escape stair was left intact - the one furthest from the plane's path. Even then, only four people, one of them Brian Clark, managed to get down it. At the northeast corner and along the east wall, the connections between the floors and the outer wall began to break as the floors sagged in the heat. The floors were an essential part of the structure, bracing both the outer walls and the inner core. Already weakened by the impact and now unbraced, the outer wall columns of the South Tower could not support the weight above them. At 9.59am Eastern Time, they snapped. The entire top third of the tower then lurched to the north and east; the floors inside the rest of the tower piled down onto those below. The downward wave of destruction - a progressive collapse - was then unstoppable. Meanwhile, the North Tower, which had been hit first, was still standing. The core of the Tower had been hit head-on, and the core had been left mostly undamaged by the impact. However, the direct hit cut off all the escape routes without exception. Meanwhile, the fire inside the North Tower was spread around the core. Again, connections between floors and columns started to fail in the heat, but here in the North Tower, it was the connections at the core that gave way first. Without the floors to brace it, the core could not stand alone. 29 minutes after the first collapse, the core in the North Tower collapsed vertically, pulling the rest of the tower down with it. The implications of the Twin Towers collapse are disturbing. Whether anything can be done to make modern lightweight skyscrapers more robust in the aftermath of 11 September is a vital question that must now be answered.

In the mid 1800s, when Charles Darwin published his theory of evolution, one species of animal remained a mystery; where did birds fit on his evolutionary tree? Several years later his friend and colleague, Thomas Henry Huxley, came up with an answer. Huxley had recently examined a new fossil from southern Germany called Archaeopteryx which was causing considerable excitement in palaeontological circles. There were clear signs of feathers and it was obvious this was the earliest fossil evidence of a bird ever found. Huxley noticed something else as well. To him it looked as though the skeleton bore a striking similarity to that of a family of meat eating dinosaurs known as therapods. In the 1860s, on the basis of this observation, he announced a new theory; birds must have evolved from dinosaurs. The theory ignited what was to become one of the biggest controversies in palaeontology. Could Huxley possibly be right; how could a large, land-bound creature like a dinosaur have ever evolved into something as light and sleek as a bird? Many questioned the accuracy of Huxley's observations and ever since there has been a search for further fossil evidence to confirm the theory; a transitional animal which would incontrovertibly show how, in one creature, birds had evolved from dinosaurs. It has become one of the big missing links in palaeontology. In Spring 1999, at the Tucson Gem and Fossil Fair in Arizona, an American collector came across a new Chinese fossil which seemed to be just this transitional animal. It had the head and upper body of a bird but the tail of a dinosaur. It was called Archaeoraptor or 'ancient hunter'. Throughout the 1990s a number of important fossils emerged from China showing an apparent relationship between dinosaurs and birds. Practically all come from a region in the north of the country called Liaoning, one of the richest fossil areas in the world. Here, 130 million years ago, volcanic eruptions buried a wetland once teeming in wildlife. Many of the fossils have been magnificently preserved in the fine silt; some even have the remains of soft tissue attached to them. It was here, in 1996, that Chinese scientists found a creature they called Sinosauropteryx, an animal which bore many similarities to a dinosaur but appeared to have been covered in a feathery like coat. Two years later a joint Chinese/American team found an even more striking creature; a dinosaur like animal with very clear feathers which they called Caudipteryx. Other similar feathered dinosaurs followed, including in 1999, an important specimen called Sinornithosurus. Yet to those who questioned the relationship between dinosaurs and birds, these fabulous finds raised as many questions as they answered. Were the feather-like markings really signs of feathers, or were they something else? And were the skeletons really those of dinosaurs or were they, in fact, the skeletons of new, as yet unidentified, birds? What was still missing was the piece of evidence which would satisfy everybody. The new Archaeoraptor fossil, also from the Liaoning region of China, seemed to be just that. Here, in one animal, was a unique range of dinosaur and bird features. It had the skull and upper body of a bird, but the teeth and hands of a dinosaur. It also had the legs of a bird but the tail of a dinosaur. It was the most complete set of transitional features ever found in one creature. In November 1999 National Geographic Magazine gave it a special mention in an article about the origins of birds, calling it, "a true missing link.". The debate, started by Thomas Huxley in the 1860s, seemed to have been resolved. Yet within months, new finds in China showed Archaeoraptor to be an extremely clever fake. The head and upper body of a hitherto unidentified bird had been glued onto the tail of a previously unknown dinosaur. It was a journalistic disaster for National Geographic Magazine. The fossil, however, was anything but a disaster for palaeontology. By an extraordinary stroke of good luck, as scientists in China and America examined the head and tail separately, they found that both were, in their own right, unique and extremely valuable specimens. Both, in their different ways, contained powerful evidence that birds had evolved from dinosaurs.

Everything you're about to read here seems impossible and insane, beyond science fiction. Yet it's all true. Scientists now believe there may really be a parallel universe - in fact, there may be an infinite number of parallel universes, and we just happen to live in one of them. These other universes contain space, time and strange forms of exotic matter. Some of them may even contain you, in a slightly different form. Astonishingly, scientists believe that these parallel universes exist less than one millimetre away from us. In fact, our gravity is just a weak signal leaking out of another universe into ours. For years parallel universes were a staple of the Twilight Zone. Science fiction writers loved to speculate on the possible other universes which might exist. In one, they said, Elvis Presley might still be alive or in another the British Empire might still be going strong. Serious scientists dismissed all this speculation as absurd. But now it seems the speculation wasn't absurd enough. Parallel universes really do exist and they are much stranger than even the science fiction writers dared to imagine. It all started when superstring theory, hyperspace and dark matter made physicists realise that the three dimensions we thought described the Universe weren't enough. There are actually 11 dimensions. By the time they had finished they'd come to the conclusion that our Universe is just one bubble among an infinite number of membranous bubbles which ripple as they wobble through the eleventh dimension. Now imagine what might happen if two such bubble universes touched. Neil Turok from Cambridge, Burt Ovrut from the University of Pennsylvania and Paul Steinhardt from Princeton believe that has happened. The result? A very big bang indeed and a new universe was born - our Universe. The idea has shocked the scientific community; it turns the conventional Big Bang theory on its head. It may well be that the Big Bang wasn't really the beginning of everything after all. Time and space all existed before it. In fact Big Bangs may happen all the time. Of course this extraordinary story about the origin of our Universe has one alarming implication. If a collision started our Universe, could it happen again? Anything is possible in this extra-dimensional cosmos. Perhaps out there in space there is another universe heading directly towards us - it may only be a matter of time before we collide.

In September 1991 two hikers made a sensational discovery - a frozen body high in the mountains, near the border between Austria and Italy. It turned out to be 5,300 years old, the oldest frozen mummy ever found. Named Ötzi the Iceman after the Ötztal area where he was found, he became a worldwide sensation. The body was taken to Austria where scientists soon got to work on him. They analysed his bone density to find out how old he was (in his 40s, an advanced age for the time) and examined his wonderfully preserved belongings. The cause of his death remained a mystery. Now archaeologists are being joined by forensic scientists to investigate this unique case and new research has revealed a shocking answer. The investigation into Ötzi's death started at the scene of discovery. By examining photos which had been taken at the site, Austrian archaeologist Konrad Spindler worked out the layout. He was particularly intrigued by the position of the Iceman's copper axe, which was found propped up against a rock. He believed that this must have been placed in that position by Ötzi himself which meant that everything at the site had been preserved in the position it was when Ötzi died. His body was slumped face down on the ground, his cap lay nearby just as if it had fallen from his head. Scientists also wanted to know when he died so they examined the ice in which he'd been found. This contained pollen that they could identify as coming from autumn-flowering plants, so they concluded that Ötzi had died in the autumn. Together, this evidence implied that the Iceman might have got caught in a storm and died of hypothermia. Then the scientists looked inside the iceman using X-rays and CAT (Computer Assisted Tomography) scans. They saw what looked like unhealed rib fractures. So Spindler came up with what he called his disaster theory. He believed Ötzi was a shepherd who, one autumn, was returning to his home village with his animals. When he got there he became involved in some kind of argument or battle. He suffered a severe injury to his chest, fracturing his ribs, but managed to escape. He fled into the mountains and made it to the top, but by then he was exhausted from his injuries. He lay down to rest in a sheltered gully where he died of hypothermia and was buried in ice. The theory seemed to make sense, but it would not go unchallenged for long. In 1998, Ötzi was transferred to Italy since the body had actually been found just inside the Italian border. There the iceman was placed on display in a specially built museum in the town of Bolzano. To put the finishing touch to their display, the museum contacted forensic pathologist Peter Vanezis to reconstruct Ötzi's face, based on the shape of the skull. Vanezis normally works from the skull itself, but in this case, of course, that was impossible. So using the 3D CAT scan data and a rapid prototyping machine, the Austrian team created a detailed life-size replica of the Iceman's skull and gave this to Vanezis. He then used a laser to scan the skull into his facial reconstruction system. This measures the proportions of the skull and shapes a generic face to match. This allowed him to recreate Ötzi's face at last. Vanezis also wanted to look again at the theory of Ötzi's death, to question assumptions that the archaeologists had made. More and more evidence was questioning the disaster theory. An examination of the contents of Ötzi's intestine found hop hornbeam pollen. This pollen was incredibly well preserved - the cell contents still intact. This could only mean that it had been consumed very soon after the flowering of the plant just before the Iceman died. And since the hop hornbeam only flowers between March and June he must have actually died in spring. Also, evidence from the body and objects showed that the site had melted at least once and so things weren't necessarily in the same position. And finally, new examinations of the ribs showed that they hadn't been fractured before death - but been bent out of shape after death. Scientists seemed to be back to square one. IIt seemed his death might be shrouded in mystery forever. Then in June 2001, his new custodians, the Italians, decided to X-ray the body again. A local hospital radiologist noticed what looked like a foreign object near the shoulder, a shadow in the shape of an arrow. When they looked at its density they found it was denser than bone, it was the same density as flint. They'd discovered a stone arrowhead embedded in Ötzi's shoulder, which had been missed despite 10 years of intensive study. Now scientists can tell a new story of the Iceman's death. Ötzi was attacked and managed to flee. As he ran he was shot in the back with an arrow. He pulled out the arrow shaft but the head remained stuck in his shoulder. He reached the top of the mountains but was now exhausted and weakened from bleeding. He could go no further, lay down and died. Although this story fits the latest results, there are still many unanswered questions. Scientists hope soon to conduct an autopsy to remove the arrowhead and only then will we be able to say for certain what killed Ötzi. The Iceman may still be hiding more secrets.

The magnificent ancient city of pyramids at Caral in Peru hit the headlines in 2001. The site is a thousand years older than the earliest known civilisation in the Americas and, at 2,627 BC, is as old as the pyramids of Egypt. Many now believe it is the fabled missing link of archaeology - a 'mother city'. If so, then these extraordinary findings could finally answer one of the great questions of archaeology: why did humans become civilised? For over a century, archaeologists have been searching for what they call a mother city. Civilisation began in only six areas of the world: Egypt, Mesopotamia, India, China, Peru and Central America. In each of these regions people moved from small family units to build cities of thousands of people. They crossed the historic divide, one of the great moments in human history. Why? To find the answer archaeologists needed to find a mother city - the first stage of city-building. They couldn't find one anywhere. Everywhere this first stage seemed destroyed or built over. And so, instead, scientists developed a number of theories. Some said it was because of the development of trade, others that it was irrigation. Some even today believe it was all because of aliens. Gradually an uneasy consensus emerged. The key force common to all civilisations was warfare. The theory was that only the fear of war could motivate people to give up the simple life and form complex societies. To prove it, archaeologists still had to find a city from that very first stage of civilisation. If it showed signs of warfare, then the theory had to be true. When archaeologist Ruth Shady discovered her 5,000 year old city of pyramids in the Peruvian desert, all eyes were on the New World. Ruth's extraordinary city, known as Caral, is so much older than anything else in South America that it is a clear candidate to be the mother city. It also is in pristine condition. Nothing has been built on it at all. Instead laid out before the world is an elaborate complex of pyramids, temples, an amphitheatre and ordinary houses. Crucially, there is not the faintest trace of warfare at Caral; no battlements, no weapons, no mutilated bodies. Instead, Ruth's findings suggest it was a gentle society, built on commerce and pleasure. In one of the pyramids they uncovered beautiful flutes made from condor and pelican bones. They have also found evidence of a culture that took drugs and perhaps aphrodisiacs. Most stunning of all, they have found the remains of a baby, lovingly wrapped and buried with a precious necklace made of stone beads.

There is a new epidemic sweeping the world. It's been silently growing over the last few decades - only now is it reaching dramatic proportions. If current trends continue, more than one quarter of British adults will have this disease by the year 2010. This new epidemic is obesity. Scientists have recently made significant discoveries, which could lead to a drug treatment for obesity. In the meantime, until the drugs are developed, what should we do to keep off the pounds? One thing is certain. Willpower alone won't stop the epidemic of obesity; however, new research suggests there may be an easier way to fight the flab than joining the gym. Meet the Padded Lilies, a troupe of obese water ballet dancers who insist it is impossible to change our natural weight. They say they are born with a slow metabolic rate that has made them fat. But scientists now know that fat people actually have a faster metabolic rate. The Padded Lilies' suspicion that there is something wrong with their biology may well be true... but not in the way they thought. In 1994, research into a fat mouse was the starting point for a revolution in the science of obesity. The obese mouse was missing a hormone called leptin, which turns off the feelings of hunger. Wall Street went mad and the patent for leptin was purchased by a biotechnology company for millions of dollars. It seemed that at last a quick fix for obesity had been found. However, researchers quickly discovered that fat people had lots of leptin. There seemed to be no connection between the fat mice and obesity in humans. Then four years ago at Cambridge University, a young researcher, examined the blood of two young children who were so obese they could hardly walk and were confined to wheelchairs. She discovered these children, just like the mouse, didn't have the genetic information to make leptin and so could not suppress their appetites. She had for the first time ever identified human beings who were obese because of a genetic error and not because they didn't have the willpower to control their desire for food. In the last few years, research into obesity has snowballed and scientists around the world have begun to explore the area of genetic human obesity. Dr John Clapham is tackling the problem of obesity from another angle, by speeding up metabolism. Based in a top secret lab he has genetically manipulated a mouse that we all want to be. It can eat huge amounts of food yet, because it has an unnaturally high metabolism, it can't put on weight. This cutting edge science could lead to another target for the battle against obesity. However, we don't yet have this miracle treatment, so what can we do in the meantime? Dr James Levine has come up with an extraordinary idea. His study suggests there may be a way to shed those pounds without taking drugs or even joining a gym. He has found that people who fidget find it very difficult to put on weight. So we don't necessarily need exercise, we simply need to up the pace of our lives; walk rather than drive, climb the stairs rather than take the lift, don't sit still: fidget. All this should help us keep the calories at bay.

It began with a ghastly tragedy. In 1985 the massive Colombian volcano Nevado del Ruiz erupted, melting a glacier and sending a vast landslide of mud down on the people asleep in the town of Armero below. Twenty thousand died. In the aftermath science was set a challenge: to make sure such a catastrophe never happened again, by finding a way of accurately predicting when a volcano will erupt. Now, at last, it seems that one scientist may have met that challenge. Anyone can tell when a volcano becomes active. You can see it and you can smell it. But a volcano can be active for years without erupting. For those living nearby, there is no way they will abandon their homes and livelihoods just because of a few rumblings. The only way to persuade them to seek safety is to predict an eruption almost to the day, leaving just enough time for an evacuation. Scientists threw themselves at the problem, but there just seemed to be no way to make sense of the violent forces at work inside a volcano. Then along came Bernard Chouet. He is different from other volcanologists. His training lay in the complex equations and theories of physics, and he believed the answer had to lie in analysing the mysterious patterns drawn by seismographs. These measure the tremors caused by active volcanoes. Previous attempts to use these tremors to predict eruptions had proved fruitless. No one could find any correlation between the squiggles on the graph paper and the timing of eruptions. So Chouet locked himself away for five years and then emerged claiming he had found the answer. The key, he said, were seismic signals called long period events. These strange shapes had baffled volcanologists for years. Chouet said they were made by molten magma resonating - that is coming under pressure - inside the volcano. The more long period events there were, then the nearer the volcano was to exploding. Chouet could use the long period events to predict an eruption to within days. But another scientist was working on a completely different method. Stanley Williams could not be more different from Chouet. Where Chouet crunched numbers and looked at graphs, Williams climbed into craters and got up close; because he believed the best clue to when a volcano would erupt was to measure how much gas it was belching out. In 1993 the two methods came head to head. A conference was held at the foot of another Colombian volcano, Galeras. The highlight was to be a trip into the crater. Williams's gas readings indicated the volcano was safe. Chouet's long period events suggested the volcano might blow. After some debate, Williams led a team of volcanologists up the mountain. Suddenly Galeras exploded, killing six scientists and three tourists. Williams himself survived but was maimed for life. Since that day on Galeras, Chouet's methods have commanded wide respect and have been increasingly used around the world. In a dramatic demonstration last year Mexican scientists used Chouet's method to predict an eruption of the mighty volcano Popocatepetl. Tens of thousands of people were safely evacuated just before the biggest eruption of the volcano for a thousand years. No one was hurt.

On a winter night in 373 BC, the classical Greek city of Helike was destroyed by a massive earthquake and tidal wave. The entire city and all its inhabitants were lost beneath the sea. What has bewitched archaeologists about Helike is that it was engulfed just when ancient Greece was reaching its height; when the philosophy and art that inspired the western world for thousands of years were invented. Its destruction was one of the most appalling tragedies of the classical world and most probably the reality behind the myth of Atlantis. But now, unlike Atlantis, a team of archaeologists may have found Helike - a lost city from the heyday of Greek civilisation. If it is as well preserved as everyone hopes, Helike could be a time capsule from this crucial time in human development. For centuries there had been just no sign of it. All archaeologists had to guide them were obscure and often contradictory ancient texts. So, despite numerous expeditions trawling the waters off the coast of Greece and vast amounts of money and technology thrown at the problem, no one could find anything except two small coins, unearthed over a hundred years ago. Then, in 1988 Dora Katsonopoulou and Steven Soter took up the challenge. Dora had grown up with the legend from childhood and was determined to find the archaeological treasure on her doorstep. Together they went back to basics and re-examined the ancient texts. These said that Helike had sunk into a poros, which everyone had taken to mean Gulf of Corinthe. But Dora thought that a poros could also be an inland lagoon. If she was right, the lost city which had inspired Atlantis might not be under the sea, as everyone thought, but somewhere inland. Studying the geology of the region, earthquake expert Iain Stewart argues that a large earthquake could well cause an inland lagoon. Small recent earthquakes in the region have caused ground liquefaction - a terrifying phenomenon where the ground literally turns to water beneath your feet. If the same had happened on a much larger scale then the whole city could have been plunged downwards, taking much of the city below sea level. But the earthquake in 373 BC could also have had a second more devastating effect. As well as liquifaction recent earthquakes have caused chunks of coastline to fall into the sea. If this happened on a large scale underwater landslides could cause a large wave, or tsunami. This would race across the Gulf of Corinthe, ricochet off the opposite bank and come charging back again, to crash over the sunken plain and fill in the lagoon. Dora's theory makes sense, except for one thing. There is no lagoon in the region today. There is, though, a trail of clues that explains what could have happened. An ancient bridge that is strangely nowhere near water shows how river sediment coming down from the mountains changes the shape of the plain - over hundreds of years the lagoon would have silted up, hiding the lost city beneath solid ground. A host of boreholes drilled into the plain and a remote cave with the legend attached to it have helped pinpoint where the now underground city might lie. Slowly Dora and Steven have pieced it all together, but there have been several false starts along the way. The first lot of ruins they found were Roman - a settlement built hundreds of years after Helike's disappearance to honour the famous lost city. Next they found ruins that turned out to be prehistoric - an early bronze age settlement built 2,500 years before Helike. It wasn't until 2001 that Dora and Steven at last got their breakthrough. Whilst Horizon was filming, the team uncovered ruins from classical Greece. Securely dated by coins and pottery, the team are convinced they have at last found the city they've been looking for. It will take years to uncover Helike's riches, but for the first time in thousands of years, we have glimpses of the lost city that inspired Atlantis.

Doctors Panayiotis Zavos and Severino Antinori claim they are ready to embark on the greatest human experiment of our age. They say they will attempt to clone a human being before the year is out. Most people think the objections to this are ethical - human cloning would create many moral dilemmas. There is another question that few ever ask: is the science actually ready yet for cloning healthy humans? Horizon follows the latest research, which has led many scientists to believe that Zavos and Antinori's plans to clone the first human could end in tragedy. The programme also meets couples like Matthew and Desiree Racquer who think cloning offers them the only way to raise a child who is truly their own. For decades, cloning remained within the realms of science fiction. The idea that instead of combining a sperm and an egg, a new human could be made from a single cell taken from an adult, seemed completely absurd. But that all changed in February 1997, when the Roslin Institute introduced the world to Dolly the sheep - the first animal cloned from an adult. Ever since Dolly, scientists have been continuing to experiment with cloning animals. So far, they have succeeded in cloning sheep, cattle, pigs, goats and mice, fuelling the belief that humans could be next. But even Dolly's creator, Professor Ian Wilmut, is concerned that beneath the veneer of success lies a disturbing reality. Most cloning attempts on animals so far have resulted in failed implantation or abnormal foetuses. Of the animals born alive, some soon die of catastrophic organ failure. Others appear to be healthy for weeks or even months, then die suddenly, sometimes from bizarre new illnesses which do not occur in nature. Years of painstaking work are only now revealing some vital clues to what is going wrong. Horizon talks to the scientists who have uncovered new evidence, suggesting that the process of cloning itself causes subtle errors in the way genes function. These random errors may be like a time bomb inside every clone, causing some of the strange - often fatal - problems. There's no reason to think cloned human babies would fare any better. According to embryologist Dr Susan Avery, death might be the best outcome for many human clones. If they survived, they would suffer from catastrophic illnesses that modern medicine is powerless to prevent or cure. Dr Zavos claims that these problems are the result of the still unsophisticated methods being used by animal researchers. Using advanced in vitro fertilisation ('test tube baby') techniques, he claims that he will strive to make human cloning safer than natural reproduction. Now though, it seems that some IVF procedures themselves are being investigated for possible harmful effects on the long term health of children. Professor Gerald Schatten of the University of Pittsburgh reveals evidence of these risks, which could be magnified in cloning. Most reproductive specialists believe that the danger to any human born by cloning is enormous. But the would-be human cloners are determined to clone a human baby. If they proceed, they may be courting tragedy.

Matthew Farrow was born with a rare and fatal blood disease, Fanconi's anaemia. His family and doctors thought he was going to die. Instead, aged just five, he became the first person in the world to be given a radical new treatment that few believed would work. It saved his life. The treatment was remarkably simple. A small quantity of blood taken from a newborn baby's umbilical cord and placenta was infused into him. Thanks to this cord blood, Matthew Farrow is now a healthy teenager and the treatment he helped to pioneer is giving hope to hundreds of critically ill children around the world. Cord blood contains a large number of blood stem cells, the mysterious factory cells that make all the red and white blood cells our body needs. Stem cells can rebuild a sick child's blood system in just a few weeks, by producing healthy new blood cells. Until Matthew's case, babies' umbilical cords and placentas were just thrown away at birth. Established medical thought said the only source of blood stem cells was the bone marrow and the only treatment for children with advanced blood cancers was a bone marrow transplant. One in three affected children cannot find a suitable bone marrow donor, and there was a desperate need for an alternative. The first doctors to suggest cord blood as an answer were dismissed as dreamers. But pioneering work over the last twenty years, mainly in America, has shown that the tiny quantity of blood contained in a newborn's umbilical cord and placenta is rich in the crucial stem cells. It is now being used to help to treat a broad range of blood cancers and serious genetic blood diseases. However, even its advocates admit that cord blood is no miracle cure. Cord blood is a significant medical breakthrough, but it cannot save everyone who is treated with it. This powerful and moving film follows patients and their doctors as they go through this arduous new treatment. Not all patients survive the transplant. However, for some patients this treatment is a lifeline when there is no option of a bone marrow transplant. Since 1990, over a thousand lives have been saved by this new treatment.

In November 2000, the international press reported an amazing find: a mummy, which was claimed to be that of an ancient Persian princess, over 2,600 years old. She was encased in a carved stone coffin, inside a wooden sarcophagus and was wearing an exquisite golden crown and mask. Her cloth-bound body was dressed with golden artefacts, with an inscription on her breastplate that read, "I am the daughter of the great King Xerxes, I am Rhodugune." All the internal organs had been taken out of her body, in the same way that the ancient Egyptians mummified their dead. It was the find of a lifetime, one of the most magnificent ancient treasures ever to be unearthed in the area. When the curator from the Karachi National Museum, Dr Asma Ibrahim, began her investigations into the mummy, a different story began to emerge. Horizon follows the story as forensic experts all over the globe analyse the mummy and her magnificent trappings and discover that she is an elaborate fake with a terrible secret. The mummy was found in a house in the desert region of Pakistan during a police raid, after a tip-off that it was to be illegally sold on the antiquities black market for $20m, and smuggled out of Pakistan. The Persian princess was immediately hailed as a major archaeological discovery. In fact, no Persian mummy had ever been found before, let alone a royal mummy. Mummification to preserve bodies had always been thought to be unique to the ancient Egyptians. However, there were some strange puzzles about this beautiful princess. The inscriptions on the mummy's breastplate had some grammatical errors. And there were peculiarities in the way she had been mummified. Several detailed operations common to Egyptian mummifications had been omitted. So it began to look like the mummy was not the princess she was supposed to be; perhaps she was a more ordinary ancient mummy dressed up to be a Persian princess by forgers trying to increase her value. As scientists investigated more closely, it became clear that this mummy had an even darker history. Computerised tomography (CT) scans and X-ray photographs of the body inside the mummy revealed that this was no ancient corpse but a woman who had died in the recent past, and that her neck was broken. An autopsy confirmed that this woman may indeed have been murdered to provide a body for the fakers to mummify - a body they intended to pass off as an ancient mummy for millions of dollars on the international art black market. And, finally there is evidence to suggest that they have done this not once but three times, raising the spectre of a mummy factory and the terrifying thought of yet more victims.

Two disruptive children are followed through a controversial treatment regime.

Tim Lawrence was an all-action stuntman until hit by Parkinson's Disease. Horizon follows his hopes of a more normal lifestyle using Ecstasy - a class A illegal drug.

A trail from Greenland to Britain via Latvia offers new evidence into how evolution could have seen aquatic life form legs and walk.

Horizon puts Graham Hancock's controversial theories about the past to the test, dissecting his evidence for a lost civilisation. Graham Hancock offers various pieces of evidence to support his theory. He claims that the mysterious lost civilisation left its mark in ancient monuments, which he calculates were built to mirror certain constellations of stars. His hugely popular ideas have attracted such a wide audience that they stand to replace the conventional view of the past, which is based on scientific evidence that the civilisations of the ancient world were developed independently, by different peoples, on different continents.

In 1965 in the Canadian town of Winnipeg, Janet Reimer gave birth to twin boys - Bruce and Brian. Six months later a bungled circumcision left Bruce without a penis. Based on a radical new theory of gender development the decision was taken to raise Bruce as a girl. In 1967 Bruce became Brenda and for the next three decades this case would be at the heart of one of the most controversial theories in the history of science. The man behind this work was world-renowned psychologist Dr John Money. In the 1950s Dr Money developed a theory that revolutionised our understanding of gender. Money believed that what he called our 'gender identity' - what makes us think, feel and behave as boys or girls - is not fully formed by the time of birth. While we may have some innate sense of being a boy or a girl, for up to two years after birth, our brains are, in effect, malleable and we can be taught to grow up as either a boy or girl by how we are raised - by the toys we are given, the guidance we receive from adults and the clothes we are given to wear. This became known as the 'theory of gender neutrality'. Dr Money had reached this conclusion by working with a rare group of individuals born with ambiguous genitals - people known as intersexuals or hermaphrodites. Dr Money studied groups of intersex children, and concluded that these children could be brought up as either boys or girls regardless of their genetic or physical sex. The legacy of Dr Money's work was a revolution in the treatment of 'intersex'. From the 1950s to the present day many intersex children born with a tiny penis are reassigned as female even if they are actually genetically male. But not everyone agreed with Dr Money's theories. Since the 1950s a small group of scientists including Dr Milton Diamond have questioned John Money's work. Diamond believed that our sex is already defined in our brains before we are born. He was convinced that the power of our genes and hormones was so strong that no amount of nurturing could override them. But John Money's theory had already become firmly accepted around the world and the most dramatic confirmation of the theory came from one particular case - the case of Bruce Reimer. Bruce was a normal boy, not an intersex child, and yet the decision was made to turn this boy who had lost his penis, into a girl. Under the guidance of Dr Money and his team at Johns Hopkins University this baby boy was surgically changed into a girl. After surgeons at Hopkins had castrated baby Bruce, he became baby Brenda. The family were instructed how to bring up Brenda as a normal little girl. According to Dr Money's theory she would grow up believing herself to be female and would go on to live a normal happy life as a woman. It seemed the ultimate test that nurture could override nature. Thirty years after Bruce became Brenda, the impact of this extraordinary story continues. After almost 14 years living as a female, Brenda Reimer reverted to her true biological sex - the case of the boy who was turned into a girl had failed. Brenda took the name David and for the last twenty years he has lived anonymously in his hometown of Winnipeg. For almost all this time no one knew the outcome of John Money's celebrated case. But now that David has gone public, the case is being widely discussed once again and its impact on John Money's theory of gender development and the treatment of intersex children is being hotly debated.

Amazing new discoveries in South America are revolutionising what we thought we knew about the dinosaur world. It now seems that South America was home to both the largest meat-eater - so new it's still without a name - and the largest herbivore - the enormous long-necked Argentinasaurus. And what's more, these dinosaurs lived at the same time in the same place. So it's possible that like in a science fiction movie, in this prehistoric world these two giants of their kind fought each other in a spectacular clash of the Titans. Horizon follows the scientists to Argentina as they unearth one of these giants - a brand new species of dinosaur; the biggest carnivore ever discovered. Not yet named, this new creature is even bigger than T. rex, the so-called 'king' of the carnivores. The new giant South American predator had a skull bigger than a man that was full of serrated, knife-like teeth and long powerful jaw muscles. They could dissect their prey with almost surgical precision. But even this formidable killing machine couldn't alone have taken on the massive long-neck, Argentinasaurus, which was the height of a five-storey building. It must have hunted in a pack. The problem is, the mega-meat-eaters have always been assumed to have been solitary creatures. The evidence shows that they lived and hunted alone. If they weren't pack hunters, then they would never have attacked Argentinasaurus. So it looked like the idea of a mighty battle between these two giants was simply science fiction. But extraordinary new clues are proving otherwise. Palaeontologist Phil Currie had long suspected that the giant carnivores might indeed have hunted in packs and he set out to find the proof. Only now after many years' work have Currie and his team unearthed the clues that are beginning to convince other palaeontologists that the huge carnivorous dinosaurs hunted in groups. With the help of his colleague Rodolfo Coria, Currie has discovered not one but two fossil bone-beds showing packs of massive carnivorous dinosaurs that have lain buried for millions of years. Each pack - one found in the badlands of Alberta, Canada and the other in Patagonia, Argentina - contains a whole range of individuals, from young through to fully mature adults indicating that they lived alongside in a herd. He's convinced that these dinosaurs were buried together because they were living together. These new finds are good evidence that these creatures really did hunt as a team. And that means a ferocious pack of enormous carnivorous dinosaurs roaming the lands of South America may indeed have taken on a huge Argentinasaurus in a fight to the death. So it may not just be science fiction - the Clash of the Titans could have happened after all.

It sometimes seems as if our planet has no secrets left - but deep beneath the great Antarctic ice sheet scientists have made an astonishing discovery. They’ve found one of the largest lakes in the world. It’s very existence defies belief. Scientists are desperate to get into the lake because its extreme environment may be home to unique flora and fauna, never seen before, and NASA are excited by what it could teach us about extraterrestrial life. But 4 kilometres of ice stand between the lake and the surface, and breaking this seal without contaminating the most pristine body of water on the planet is possibly one of the greatest challenges science faces in the 21st century.

Conjoined twins are among the rarest of human beings. There are probably fewer than a dozen adult pairs living in the world today. Only a few hundred pairs of conjoined twins are born in the whole world each year - they appear about once in every 100,000 births - but more than half of them are stillborn, and one in three live for only a few days. Of those who survive, a very small number will be selected for separation surgery. But as there are few hospitals with the skills and experience to perform this kind of surgery, separation is still a very unusual event. The harrowing decisions which surgeons have to make when faced with conjoined twins have been highlighted by the recent case in Manchester, England. Separating conjoined twins is not only technically challenging; it can involves life and death decisions about whether one twin should be sacrificed in the hope of saving the other. But "sacrifice surgery" has a poor record of success, and the Manchester case is the latest round in an international debate about the value of separation operations. The confidence of the surgeons, who believe that separation is essential, is challenged by medical historian, Dr Alice Dreger of Michigan State University. She argues that twins themselves might take a different view - if they were ever given a chance to express it. Horizon interviews two pairs of adult conjoined twins - Lori and Reba Schappell in Pennsylvania and Masha and Dasha Krivoshlyapova in Moscow. Lori and Reba are joined at the head; Masha and Dasha are joined in their lower body. They say that they prefer their conjoined lives, despite the problems and challenges, rather than face the risks of separation surgery. Lori and Reba live independent lives in their own apartment in Pennsylvania; Lori enjoys working with computers and Reba is developing a career as a country singer. Masha and Dasha had a difficult childhood; they were subjected to medical experimentation when they were very young and hidden away from the public. Since the end of the communist era they have been able to tell their story. Their autobiography is being written by a British journalist, Juliet Butler. Horizon also follows surgeons at the Red Cross Children's Hospital in Cape Town, Africa as they plan to separate eight month old twins, Stella and Esther Alphonce. The baby girls are joined at the hip, and the surgeons have little doubt that they can and should be separated, even though the operation carries risks of disability for the twins. Historically conjoined twins who were not, or could not be separated have lived successful lives, even if this involved putting themselves on public display. The original Siamese twins, Chang and Eng Bunker, were joined by a narrow strip of flesh and could easily be separated today. Like Millie and Christine McCoy, who also lived in the USA in the middle of the last century, they earned fame and fortune touring the world. But life for conjoined twins has never been easy, Millie and Christine were kidnapped and sold several times in their childhood. The British conjoined twin sisters, Violet and Daisy Hilton, provoked a scandal in the USA when one of them tried to get married. They did eventually marry, but they were never separated. The tragedy for conjoined twins who spend their lives together is that they inevitably die together too. When one twin dies, the heart of the other twin keeps pumping until he or she is drained of blood. Is this another reason why twins should be separated when they are young? There are no simple answers, because every pair of twins is unique.

Scattered across the world’s oceans are a handful of rare geological time-bombs. Once unleashed they create an extraordinary phenomenon, a gigantic tidal wave, far bigger than any normal tsunami, able to cross oceans and ravage countries on the other side of the world. Only recently have scientists realised the next episode is likely to begin at the Canary Islands, off North Africa, where a wall of water will one day be created which will race across the entire Atlantic ocean at the speed of a jet airliner to devastate the east coast of the United States. America will have been struck by a mega-tsunami. Back in 1953 two geologists travelled to a remote bay in Alaska looking for oil. They gradually realised that in the past the bay had been struck by huge waves, and wondered what could have possibly caused them. Five years later, they got their answer. In 1958 there was a landslide, in which a towering cliff collapsed into the bay, creating a wave half a kilometre high, higher than any skyscraper on Earth. The true destructive potential of landslide-generated tsunami, which scientists named "Mega-tsunami", suddenly began to be appreciated. If a modest-sized landslide in Alaska could create a wave of this size, what havoc could a really huge landslide cause? Scientists now realise that the greatest danger comes from large volcanic islands, which are particularly prone to these massive landslides. Geologists began to look for evidence of past landslides on the sea bed, and what they saw astonished them. The sea floor around Hawaii, for instance, was covered with the remains of millions of years’ worth of ancient landslides, colossal in size. But huge landslides and the mega-tsunami that they cause are extremely rare - the last one happened 4,000 years ago on the island of Réunion. The growing concern is that the ideal conditions for just such a landslide - and consequent mega-tsunami - now exist on the island of La Palma in the Canaries. In 1949 the southern volcano on the island erupted. During the eruption an enormous crack appeared across one side of the volcano, as the western half slipped a few metres towards the Atlantic before stopping in its tracks. Although the volcano presents no danger while it is quiescent, scientists believe the western flank will give way completely during some future eruption on the summit of the volcano. In other words, any time in the next few thousand years a huge section of southern La Palma, weighing 500 thousand million tonnes, will fall into the Atlantic ocean. What will happen when the volcano on La Palma collapses? Scientists predict that it will generate a wave that will be almost inconceivably destructive, far bigger than anything ever witnessed in modern times. It will surge across the entire Atlantic in a matter of hours, engulfing the whole US east coast, sweeping away everything in its path up to 20km inland. Boston would be hit first, followed by New York, then all the way down the coast to Miami and the Caribbean.

If extra-terrestrials do exist they must have a home. Horizon tells the story of the race to find out where in the Universe this might be. The answer, for scientists across the world, lies in the hunt for planets around distant stars. Stars which are trillions of miles away from our own solar system. But the history of the planet hunters is littered with failure. Centuries of searching had thrown up nothing. It was time for the new style planet hunters to step in. However, it is only in the last ten years that these scientists have had the technology to succeed. Even now looking for these distant planets is far from straightforward. The planets themselves are so faint that they cannot be seen, even by the most powerful telescopes ever built. Instead the astronomers must devise ingenious ways to search for clues to their presence. They examine stars just like our own Sun, across the galaxy, for any give-away characteristics that might indicate that they too have planets circling around them. A Swiss team finally struck gold in 1995 - convinced they'd detected a star that must have its own planet. Their discovery was the first of its kind but not the last. Other teams started to get lucky and suddenly it seemed like there were stars with planets everywhere. But the scientific community soon became restless. All they had done so far was detect the presence of alien planets - without seeing one, it was impossible to work out what the planet was like. If these planets really did exist it was time the scientists caught a glimpse of one of them. Only then would they be able to learn about the planet - its surface and its atmosphere. And only then would they know whether it could sustain life as we know it. Horizon follows the trials and tribulations of the planet hunters and shares in the triumph of the Scottish team who, just a few months ago, became the first to achieve the ultimate goal - to capture the image of an alien planet. It is orbiting another star, 55 light years away from Earth. The question is - how similar is this planet to our own and could it be home to alien life? Horizon uncovers the answers.

Some people see GM food as a ground-breaking scientific idea that could help to end world hunger and reduce global pollution. Others see it purely as 'Frankenstein foods' on 21st century menus, bringing health and environmental disasters. But what are the real scientific facts behind the newspaper headlines? Scientists can manipulate the genetic code of life to produce plants with new characteristics never seen in nature. They can isolate any one gene from any organism like an animal or bacterium, and insert it into a completely unrelated species like a plant. The possibilities are almost endless - Scientists can insert a gene from a bacterium into a grape to make it resistant to viruses. Or they can engineer maize that resists drought or potatoes that resist pests, so farmers can use less pesticides on their crops. For thousands of years we have been tampering with the genes of plants by traditional breeding. But there's a key difference here - with traditional plant breeding genes cross within the same species. But GM allows plant breeders to break the species barrier. And for critics this is fundamentally unnatural. The fear is that the proteins produced by these foreign genes might be dangerous. Either because the protein itself is poisonous or because it might alter the chemistry of the plant so that the plant becomes toxic. Detailed tests are performed on the plants to discover if they are substantially biologically and chemically the same as before modification and if they have become toxic or allergenic. Critics believe that no amount of testing can ensure that GM crops are completely safe. They believe that there is too much we don't understand about the complex genetic make-up of living organisms. And that even though there is little evidence so far, there may be a risk that genetic modification could cause effects so unexpected that they will be missed by all the tests biotech scientists carry out. In contrast genetic engineers claim their work is safer and more predictable because they are moving just one or two specific genes, and they can more easily test the effects. But those who campaign against GM have another fear: that the genes from the engineered plant will spread throughout the plant world, creating new strains of superweed and superbug we cannot control. Horizon explores the key elements of scientific facts to try to answer the ultimate question: do the dangers of GM foods outweigh their benefits?

What happens when a completely healthy person wants their leg amputated? Gregg is 55 and does not feel physically whole. This is despite the fact that he is physically healthy and able-bodied. Gregg believes he is incomplete with two legs and it has been his life-long struggle to get doctors to agree that removing one of his legs is the right thing for him. He isn't delusional. He knows what he is asking for and knows it is strange. But he cannot help his feelings. Gregg suffers from a rare but genuine psychological disorder - a form of body dysmorphia. And Gregg is not alone. Although Body Dysmorphia is rare, a worldwide network of sufferers is growing and demanding treatment. It affects both men and women and each person has a precise sense of which limb or limbs they want removed. Cases were cited a hundred years ago but still very little is known about the disorder. No one knows what causes it and very few psychiatrists have even encountered patients with the disorder. All that the patients seem to have in common is a strong memory of the first amputee they saw. They also report that the feelings started in childhood. However, the profession is now being forced to respond and devise methods of treatment. If not treated, it has been reported that suffers can go to extreme lengths to remove the unwanted limbs themselves. Some have even committed suicide. The difficulty with the condition is that the conventional methods for treating psychological problems, drugs and therapy, do not seem to be effective. The only treatment that does seem to be effective is surgery - actually removing the limb. The idea of using surgery is highly controversial and has divided the medical community. Some physicians consider it much too drastic a measure, possibly conflicting with their Hippocratic oath, not to cause harm. Others believe that it is the only way to free the patient of their obsession, 'curing' them of their psychological problem. At the present time, there is only one surgeon in Britain who has been prepared to perform such operations and who has publicly defended his decision. He has operated on two patients, both of who claim to be delighted with their new body-image and now free to get on with the rest of their lives. There are many other patients who seek similar treatment. Horizon 'Complete Obsession' follows a year in the lives of people who are body dysmorphic and are determined to have their limbs surgically removed. It follows the process they go through to try and achieve their goal.

There is something so special about diamonds, and they are so valuable, that people have always been prepared to go to the most extraordinary lengths to find them. But how would we feel about the uniqueness of diamonds if it was possible to make one in a laboratory, just like the real thing, down to the nearest atom? In the last few years there has been a scientific race to do exactly this: to manufacture the perfect gem diamond. Today the dream is close to becoming reality. Science has finally found a way to replicate in a few days something that nature has taken millions of years to produce - diamonds. These man-made diamonds are so close to the real thing, that they have the same atomic structure as natural diamonds. Even the most sophisticated machines are finding it hard to tell the difference. More importantly, these diamonds can be made and sold at a profit. Synthetic diamond press: This is the story of the race to produce man-made gem diamonds, from the first faltering steps 50 years ago, to today's 'New Alchemists' in Russia who are using the latest science and technology to produce perfect synthetic diamonds in an array of colours and sizes. And it is the story of how this leap in diamond-making technology has forced De Beers to develop ever-more sophisticated detection equipment, trying to spot the synthetics, while the physical distinction between real and man-made diamonds becomes more and more blurred. Today there are alarm bells ringing at De Beers in Johannesburg. De Beers controls the world diamond trade. By buying up most of the world's uncut diamonds, the company can regulate supply to select dealers, increasing it in good years and reducing it in bad, to keep prices high. Every year 3 billion pounds worth of rough diamonds are distributed around the world for cutting and polishing. The diamond market survives on public confidence. Already De Beers spends a fortune trying to detect synthetic gems, and teach wholesalers and graders what the molecular differences are. But imagine if these synthetics had exactly the same properties as real diamonds, each atom in place, every manufacturing flaw removed, leaving something indistinguishable from the real thing. They would be undetectable. What would a real diamond be then? To many, the difference would be purely psychological. And so what would happen to public confidence in the natural diamond market? Man made diamonds: According to the new alchemists, this is all just about to happen.

On a barren desert in South America lies one of the greatest archaeological puzzles in the world. Etched in the surface of the desert pampa sand are hundreds of straight lines, geometric shapes and pictures of animals and birds - and their patterns are only clearly visible from the air. They were built by a people called the Nasca - but why and how they created these wonders of the world has defied explanation. On the pampa, south of the Nasca Lines, archaeologists have now uncovered the lost city of the line-builders, Cahuachi. It was built nearly two thousand years ago and was mysteriously abandoned 500 years later. New discoveries at Cahuachi are at last beginning to give us insight into the Nasca people and to unravel the mystery of the Nasca Lines. Distorted heads The Lines were first spotted when commercial airlines began flying across the Peruvian desert in the 1920's. Passengers reported seeing 'primitive landing strips' on the ground below. No one knew who had built them or indeed why. Since their discovery, the Nasca Lines have inspired fantastic explanations. SpiderPerhaps most famously, the Austrian writer Erich von Danikken claimed that they were evidence that the earth had been visited by extra-terrestrials. The lines, he said, were runways for their spacecraft. Scientific study began in the 1940s with the arrival of a German mathematician and astronomer called Maria Reiche. She lived at Nazca until her death in 1998 and was known as the Lady of the Lines. Reiche believed that the lines were a sophisticated astronomical calendar. However, in 1965, astronomer Gerald Hawkins came to Nazca and used computers to check Reiche's theory. Hawkins could find no correlation between the lines and the stars. Giuseppe Orefici Italian archaeologist Giuseppe Orefici has been excavating the immense Cahuachi site for the last 17 years. Every year he brings a team of specialists to South America for three, intensive months of excavation. Horizon joined Orefici and his team in the hot, windy months of 1998 and this is a fascinating record of their extraordinary finds. Woven clothCahuachi is emerging as a treasure trove of the Nasca culture. As Orefici and his team excavate, discoveries of paintings on preserved pottery, and the ancient technique of weaving that the Nasca people developed, have given an insight into how the lines may have been made, and what they might have been used for, more than 1500 years ago. MummyMost exciting is the discovery of human remains. Stunningly preserved in the dry soil of the Peruvian desert are the mummified bodies of the Nasca themselves. Orefici's colleagues Brian Harrison and Andrea Drusini carry out modern autopsies on these remarkable finds, and reveal the strange world and rituals of the Nasca people. CahuachiOriginally believed to have been a military stronghold, Cahuachi is now reckoned to be a place of ritual and ceremony, and Orefici's stunning new evidence confirms this idea. Cahuachi is now revealed to have been abandoned after a series of natural disasters destroyed the city. But before they left it, the Nasca people covered the city in the arid pampa sand where, until recently, it has remained a barely visible mound in the desert.

In this moving film Horizon follows the Loughran family in their fight to save the life of their daughter Sheila who suffers from cystic fibrosis. They lost their youngest daughter Ann to the disease in 1974 at the age of 15, and now as the health of their third daughter Sheila deteriorates, they must face the prospect of losing a second child. The current shortage of donor organs means that Sheila's only hope of survival is a rare and controversial operation that requires her two surviving siblings to undergo an arduous and potentially fatal operation. An X-ray of Shelia's lungs Cystic fibrosis (CF) is the most common genetic disease in this country and it is incurable. The lungs of people with cystic fibrosis become covered with a sticky mucus making them extremely susceptible to bacterial infection. Over time these infections badly scar the lungs, until eventually they stop functioning. The defective CF gene is harmless when only a single copy of the gene is inherited. However, both the Loughran parents carry the gene, giving any child they may have a 25% chance of being born with cystic fibrosis. In fact two of their four children were born with the condition. Horizon joins the family at a time when Sheila's health has deteriorated to such an extent that she requires oxygen 24 hours a day and has only months to live. Although on the waiting list for a donor lung, with 50% of patients dying while waiting to receive a transplant, Sheila's chances are not good. The family has become aware of a controversial new operation, pioneered in the UK by Professor Sir Magdi Yacoub at Harefield Hospital. The technique, known as Living Donor Lung Transplantation, would involve removing Sheila's diseased lungs and, in an extraordinary three-way operation, replacing them with a lobe from one of the lungs of each her two siblings. There have been six of these groundbreaking operations carried out in this country. However, only three patients have lived longer than a month. There is a clear moral dilemma - with such a low success rate, is it ethical to put the lives of two healthy people at risk? Even if the operation is initially successful it may only give Sheila five more years to live, by which time her new lungs are likely to fail again. Damian Loughran Sheila's brother and sister, Damian and Josephine, feel compelled to do anything they can to save their dying sister. They undergo stringent tests before being certain that they are compatible donors and fit for surgery. They will have to face the risk of haemorrhaging and infection, both of which could potentially be fatal. After the operation both donors will be left with a 20-25% permanent loss of lung function. Despite these dangers, Damian and Josephine remain determined to proceed. As all three of their children are wheeled in for the 12-hour operation, Mary and Harry Loughran's emotion is apparent. A day later, Sheila is breathing with her new lungs, but it is not long before complications arise. She is unable to absorb food and develops an abscess on her lung. Sheila is kept under sedation and so is unaware of these complications. Sadly, three weeks after the operation, Sheila loses her fight for life.

The Aztecs are regarded as the most bloodthirsty of the Central American peoples, but they were also one of the most sophisticated. DrTony Spawforth discovers how, on arriving in Mexico, they created a new and brutal mythology from the relics of an earlier civilisation.

Horizon presents the extraordinary story of a beautiful mathematical formula that changed the world, the financial markets, and indeed capitalism itself. It could do the unthinkable - it took the risk out of playing the money-markets. To its inventors it brought the Nobel Prize for economics. To those who used it, it brought great wealth. But this glittering tale would end in tragedy.

Horizon reports on a February 1999 catastrophic avalanche at Galtür in Austria that claimed 31 lives. Over the next six months, Horizon followed a team of scientists as they pieced together the extraordinary chain of events that led to the disaster. The scientists' investigations into the extreme forces of nature responsible for the tragedy are making people re-evaluate their calculations about avalanches.

Could giant volcanic 'chimneys' on the ocean floor unlock the secret of how life began on Earth?

Horizon presents a documentary about Multiple Personality Disorder (MPD) where in the 1980's, it suddenly became the talk of the town. Tens of thousands of Americans were diagnosed with an illness that was previously unheard of. A trigger for this sudden was the release of a film, "Sybil". Telling the dramatic story of a woman diagnosed with Multiple Personality Disorder, the film was shown across America making Sybil a household name.

Dramatisation of biologist David Lack's struggle to reconcile scientific evidence for evolution with his belief in God.

In this report, Horizon investigates the rare disease called Fibrodysplasia Ossificans Progressiva, which causes muscles and ligaments to turn into solid bone. This disease causes severe disfigurement and suffering, and often-time death. We look at the research by scientists trying to find out the causes of the disease and how to find a cure.

Horizon presents this documentary by scientists who have calculated that the Earth will be hit by a small asteroid within 50 years. How will this effect our planet?

In this report, Horizon explores the arguments for and against the building of the Space Station Freedom and will it ever justify it's huge cost.

In this Horizon documentary, we present Alfred Steinschneider's theory on cot death where gaps in breathing could be responsible for the death of many infants.

Horizon presents a documentary looking at the United States heart specialist, Michael DeBakey, and his work and research into making miniature pumps which could help make permanent artificial hearts in the future.

In this episode, Horizon reports from Africa on the effect that rising elephant numbers are having on humans and the natural environment.

Horizon looks at the knowledge gained following the Spanish Flu Pandemic of 1918.

Horizon examines how observations of supernova in distant parts of the universe has provided evidence of the accelerating expansion of the universe. This new evidence suggests the existence of a new type energy in space which may have significant implications for the ultimate fate of the universe.

Horizon presents an investigation into how Thalidomide is being used to treat leprosy, AIDS, and cancer with encouraging results.

Horizon follows the work of various scientists attempting to turn back the biological clock.

Horizon investigates how science is fighting against the mosquito-spread disease Malaria.

Horizon tells the story of maverick scientist John Ostrom and his theory that birds are really just dinosaurs with feathers. Thirty years later, a revolution in palaeontology has proven him correct. Horizon looks at the compelling and recent evidence that shows how modern birds fine-tuned their unique design for flight. It also confirms that Velociraptor dinosaur is more closely related to the sparrow than it is to the crocodile.