Sometimes the world feels boring. All the remote islands are visited, the arctic conquered, the dense jungles discovered. Except, there is still a place to explore: A wet deadly desert where mysterious creatures live in total darkness: The deep sea. Let us dive down.

The largest things in the universe are black holes. In contrast to things like planets or stars they have no physical size limit, and can literally grow endlessly. Although in reality specific things need to happen to create different kinds of black holes, from really tiny ones to the largest single things in the universe. So how do black holes grow and how large is the largest of them all?

The human immune system is the most complex biological system we know, after the human brain, and yet, most of us never learn how it works. Or what it is. Your immune System consists of hundreds of tiny and two large organs, it has its own transport network spread throughout your body. Every day it makes hundreds of billions of fresh cells. It is not some sort of abstract entity. Your immune system is YOU. Your biology protecting you from the billions of microorganisms that want to consume you and from your own perverted cells that turn into cancer. It's so manifold that it is impossible to cover in one video, so we’ll make a series looking at different aspects of it. Today, what happens when your body is invaded and your first lines of defenses are engaged in a fight for life and death?

You are not a person, you are a planet, made of roughly 40 trillion cells. There is so much of you, that if your cells were human-sized, you would be as big as 20 Mount Everests. For your creepy-crawly inhabitants, this makes your body an ecosystem, rich in resources and warmth and space. A perfect place to move into and have a family. While some of these guests are welcome, most are not. Your immune system is the guardian of this planet, the force tasked with protecting yourself against the constant danger of invasion.

Hidden in the microverse all around you, there is a merciless war being fought by the true rulers of this planet, microorganisms. Amoebae, protists, bacteria, archaea and fungi compete for resources and space. And then there are the strange horrors that are viruses, hunting everyone else. Not even being alive, they are the tiniest, most abundant and deadliest beings on earth, killing trillions every day. Not interested in resources, only in living things to take over. Or so we thought. It turns out that there are giant viruses that blur the line between life and death – and other viruses hunting them.

For most of our history, the human population grew slowly. Until new discoveries brought us more food and made us live longer. In just a hundred years the human population quadrupled. This led to apocalyptic visions of an overcrowded earth. But the population growth rate actually peaked in the 1960s. Since then, fertility rates have crashed as countries industrialize and develop. World population is now expected to balance out at around 11 billion by the end of the century. But the big picture conceals the details.

Black hole stars may have been the largest stars to ever exist. They burned brighter than galaxies and were Larger than any star today or that could ever exist in the future. But besides their scale, what makes them special and weird is that deep inside, they were occupied by a cosmic parasite, an endlessly hungry black hole. How is that even possible?

A war has been going on for billions of years that breeds well armed monsters who struggle with other monsters for survival. Having no particular interest in us, most of them are relatively harmless, as our immune systems deal with their weapons handily. But there are exceptions. Naegleria fowleri is an amoeba that not only has developed a deadly taste for human brains but is also a match for our defenses and a guest in dramatic headlines. What happens when this monster enters your body?

Most of us love animals but also eat meat. Unfortunately, most animals we eat live in truly horrible conditions. We don’t torture them for better meat, just for cheaper meat. If we all paid just a bit more, we could avoid most animal suffering – often just for a few cents per meal. What would it truly cost us to avoid animal torture and still eat meat?

Facebook just announced 8 billion video views per day. This number is made out of lies, cheating and worst of all: theft. All of this is wildly known but the media giant Facebook is pretending everything is fine, while damaging independent creators in the process. How does this work?

For years, you have been asking us how we make our videos. So let’s finally talk about it! From research, writing the script, illustrating, to animating, narrating and composing music, a Kurzgesagt video takes roughly 1.200 hours to produce!

As you may have noticed, we like to blow stuff up on this channel. So when the International Red Cross approached us to collaborate on a video about nuclear weapons, we were more than excited. Until we did the research. It turned out we were a bit oblivious off the real impact of nuclear weapons in the real world, on a real city. And especially, how helpless even the most developed nations on earth would be if an attack occurred today. So hopefully this video demonstrates how extremely non fun a real world nuclear attack would be, without being to gruesome. This collaboration was a blast (no pun intended) and we want to say a huge thank you to the International Red Cross!

66 million years ago, maybe on a Tuesday afternoon, life was the same as it had been the day before or a thousand years before or pretty much a million years before. Things were good for our feathered dinosaur buddies. Until a tiny, tiny detail in the sky changed.

Everybody is talking about Measles – but what does the virus actually do in the body? Is it really so harmful that you need a vaccination? We go deep into the body of an infected person and see what Measles does and how the immune system reacts to it!

What are the principles behind Homeopathy and does it work?

The future of humanity seems insecure. Rapid climate change, political division, our greed and failings make it hard to look at our species with a lot of optimism and so many people think our end is in sight. But humans always thought they lived in the end times. Every generation assumes they’re important enough to witness the apocalypse and then life just goes on. This is a problem because it leads to short term thinking and prevents us from creating the best world for ourselves and our descendants. What makes this worse is that we actually may live at an extremely critical moment in human history. To understand why, let us look at the temporal window of humanity and ask: When will the last human be born and how many people will there ever be?

Kurzgesagt is lying to you, in every video, even in this one. Because our videos distill very complex subjects into flashy ten minute videos and unfortunately, reality is, well, complicated. The question of how we deal with that, is central to what we do on this channel and something we think about a lot.

Food is arguably the best thing about being alive. No other bodily pleasure is enjoyed multiple times every day and never gets old. It is an expression of culture, our parents' love and a means of celebration or comfort. That’s why it hits a special nerve when we are told we should change what and how we eat to fight rapid climate change. One of the most delicious foods, meat, gets the worst press. It doesn’t help that the topic is really hard to properly research yourself and debates get emotional quickly. But clearly science can give us an answer! The reality is, well, it’s complicated. Let’s take a look at three climate arguments against meat that are used a lot and see what happens.

What if we could stop aging forever?

Everybody feels lonely sometimes. But only few of us are aware how important this feeling was for our ancestors - and that our modern world can turn it into something that really hurts us. Why do we feel this way and what can we do about it?

We take a fair look at some of the best counter arguments for legalization and see how they hold up in review.

Alcohol kills more people each year than wars, terrorism, homicides, and car accidents combined. It destroys bodies, relationships, and lives. Yet we toast with it at weddings, sip it at parties, and unwind with it after work. Why do we cling to something so harmful?

A war has been raging for decades in the jungles of Panama, as we fight one of the most terrifying parasites on Earth. It is so relentless that our best defense is to drop 100 million radiation-blasted, flesh-eating flies from the sky – every week. It’s one of the most successful biological campaigns in history, but it’s a war we can never stop fighting… and one we can’t afford to lose.

Our home is burning. Rapid climate change is destabilizing our world. It seems our emissions will not fall quickly enough to avoid runaway warming and we may soon hit tipping points that will lead to the collapse of ecosystems and our civilization. While scientists, activists and much of the younger generation urge action, it appears most politicians are not committed to do anything meaningful while the fossil fuel industry still works actively against change. It seems humanity can’t overcome its greed and obsession with short term profit and personal gain to save itself. And so for many the future looks grim and hopeless. Young people feel particularly anxious and depressed. Instead of looking ahead to a lifetime of opportunity they wonder if they will even have a future or if they should bring kids into this world. It’s an age of doom and hopelessness and giving up seems the only sensible thing to do. But that’s not true. You are not doomed. Humanity is not doomed.

Nuclear energy creates an uneasy feeling of danger for many people: ancient and dangerous minerals are concentrated to awaken seemingly unnatural powers, creating toxic elements that, if they escape, can and have killed people in horrible ways. How many people has nuclear energy killed and how?

The desire to be free from the limits of the human experience is as old as our first stories. We exist in an endless universe, only bound by the laws of physics and yet, our consciousness is trapped in mortal machines made of meat. With the breathtaking explosion of innovation and progress, for the first time the concept of leaving our flesh piles behind and uploading our minds into a digital utopia seems possible. Even like the logical next step on our evolutionary ladder.

Since the Industrial Revolution, humans have released over 1.5 trillion tonnes of carbon dioxide or CO2 into the earth's atmosphere. In the year 2019 we were still pumping out around 37 billion more. That’s 50% more than the year 2000 and almost three times as much as 50 years ago. And it’s not just CO2. We’re also pumping out growing volumes of other greenhouse gases such as methane and nitrous oxide. Combining all of our greenhouse gases, we’re emitting 51 billion tonnes of carbon dioxide equivalents each year. And emissions keep rising – but they need to get down to 0!

Electricity is all around us, all the time. It makes our lives easier, safer, more fun and most of us never think about it. But is there such a thing as too much electricity? Electronic devices emit an electromagnetic field, which is suspected to cause cancer. We read countless sources on this topic to summarize the results of the latest research for you.

What happens if make a huge pile from all 15,000 nuclear bombs and pull the trigger? And what happens if we make an even bigger pile?

A war has been raging for billions of years, killing trillions every single day, while we don’t even notice. This war involves the single deadliest being on our planet: the bacteriophage.

What shall we do once machines become conscious? Do we need to grant them rights?

There are a group of parasites extremely disgusting and mean. Humanity declared war on them.

What causes addiction? Easy, right? Drugs cause addiction. But maybe it is not that simple.

There is this idea floating around that what doesn’t kill you, makes you stronger. That surviving a disease leaves you better off. And it seems to make sense because we have all experienced this. When you go through hardship, often you come out more resilient, more ready to face a difficult situation in the future. But it turns out that sometimes, what doesn’t kill you makes you weaker. So, what happens when you get sick?

The universe is pretty big and very strange. Hundreds of billions of galaxies with sextillions of stars and planets and in the middle of it all there is earth, with you and us. But as enormous as the universe seems looking up, it seems to get even larger when you start looking down. You are towering over worlds within worlds, within worlds – each in plain sight and yet hidden from your experience. Let’s go on a journey – we’ll start in a park, about a thousand meters long, enough for a 15 minute walk. Every time we click a magic button, we’ll become a thousand times smaller. Ready? Let’s go.

A huge thanks to the experts who helped us on short notice with the video. Especially “Our World in Data”, the online publication for research and data on the world’s largest problems – and how to make progress solving them. Check out their site. It also includes a constantly updated page on the Corona Pandemic. In December 2019 the Chinese authorities notified the world that a virus was spreading through their communities. In the following months it spread to other countries, with cases doubling within days. This virus is the “Severe acute respiratory syndrome-related coronavirus 2”, that causes the disease called COVID19, and that everyone simply calls Coronavirus. What actually happens when it infects a human and what should we all do?

Neutron stars are one of the most extreme and violent things in the universe. Giant atomic nuclei, only a few kilometers in diameter but as massive as stars. And they owe their existence to the death of something majestic.

It is time to reframe how we think about our past. We need a new year 0 for humanity. But which one should we choose and why?

The observable universe is a big place that has been around for more than 13 billion years. Up to two trillion galaxies made up of something like 20,000 billion billion stars surround our home galaxy. In the milky way alone scientists assume there are some 40 billion earth like planets in the habitable zone of their stars. When we look at these numbers it is hard to imagine that there is nobody else out there.

In nearly every corner of the Earth, ants wage war against each other. Their weapons are what nature gave them. Some have strong armour, deadly stingers or sharp mandibles. And then there is this tiny, and not very impressive ant. But it rules the biggest empire any ant has ever built. A colony spanning continents and fighting wars that leave millions of casualties. Let’s take a look at this unlikely warrioress: Linepithema humile, the Argentine ant.

Meat is a complicated issue. But also a delicious one. Let's talk about it.

Where are the limits of human technology? And can we somehow avoid them? This is where quantum computers become very interesting.

An undead city under siege, soldiers and police ruthlessly shooting down waves of zombies that flood from infected streets, trying to escape and infect more cities. This is what happens when your body fights cancer, more exciting than any movie. How does this battle for survival unfold?

In the 1970s thousands of Chickenheads rained from the sky in Europe, making foxes and other wildlife confused and very happy. Why? They were filled with a vaccine to fight the deadliest virus known to humanity – since the 1930s a rabies epidemic had been sweeping across wildlife populations in Europe and humans wanted to finally get rid of the virus once and for all. Rabies is named after Lyssa, the ancient Greek spirit of mad rage, and has been haunting us for at least 4000 years. It can turn animals into angry beasts and humans into zombies that fear water. But what makes Lyssa fascinating is not just how bizarre and deadly its infection is, but also how incredibly good it is at avoiding our defenses.

Is there a border we will never cross? Are there places we will never reach, no matter how hard we try? It turns out, there are. Even with sci-fi technology, we are trapped in a limited pocket of the Universe and the finite stuff within it. How much universe is there for us and how far can we go?

Why should you care about the well-being of people half a globe away?

The universe is magnificent and vast. Hundreds of billions of galaxies, trillions of stars, and even more planets. If even the tiniest fraction are habitable, then the Universe should be teeming with life. And yet we see nothing, only vast emptiness. Where is everyone else? The answer to this riddle could be as exciting as it is creepy: we are early, born before almost all other life – but very soon this may change. Not only might aliens appear, they could quickly surround us. An irreversible competition for the universe might be about to begin.

Look around you. Where are you? Where is this place you are occupying? Somewhere in a room, maybe in a city on a continent on a planet orbiting a star in a galaxy among billions. But… where is all of that? While this may feel like a daft question, it turns out that the concept of an absolute position is something humans made up. In a nutshell, the universe is a big bag of space that has things in it. If someone removed all these things, the stars and planets and black holes and dust, there would just be empty space left. In empty space, the concept of having a position loses all meaning. Empty space is uniform, the same everywhere.

When we think about alien civilizations we tend to look into the vastness of space, to far away planets. But there is another incredibly vast dimension that we might be giving too little thought to: time. Could it be that over the last hundreds of millions of years, other civilizations existed on earth? Indigenous technological species that rose and died out? And that they or their artifacts are buried beneath our feet? What does science have to say about this and what are the implications for us?

What would happen if we were to detonate a very very powerful nuclear weapon on the moon? Would the explosion knock its orbit towards earth, causing tidal waves and misery? Could the moon be destroyed, showering the earth in a rain of meteoric death?

In a very short amount of time the human population exploded and is still growing very fast. Will this lead to the end of our civilization?

Black holes. Lets talk about them.

Where are all the aliens? The universe is too big and too old, why have we not met aliens yet? Do they live in computers? Were they wiped out by an ancient super intelligence? Or are we just to primitive to understand their motives? Whatever the answer is, it is incredibly important for our own future.

The universe is unbelievably big – trillions of stars and even more planets. So… there just has to be life out there, right? But where is it? Why don’t we see any aliens? Where are they? And more importantly, what does this tell us about our own fate in this gigantic and scary universe?

What would happen if we were to detonate a very very powerful nuclear weapon on the moon? Would the explosion knock its orbit towards earth, causing tidal waves and misery? Could the moon be destroyed, showering the earth in a rain of meteoric death?

Fracking explained in five minutes.

Every second of your life you are under attack. Bacteria, viruses, spores and more living stuff wants to enter your body and use its resources for itself. The immune system is a powerful army of cells that fights like a T-Rex on speed and sacrifices itself for your survival. Without it you would die in no time. This sounds simple but the reality is complex, beautiful and just awesome. An animation of the immune system.

Fever feels bad. So we take medication to suppress it – but is this a good idea? It turns out fever is one of the oldest defenses against disease. What exactly is a fever, and how does it make your immune defense stronger? Should you take a pill to combat it?

Humans rule Earth without competition. But we are about to create something that may change that: our last invention, the most powerful tool, weapon, or maybe even entity: Artificial Super intelligence. This sounds like science fiction, so let’s start at the beginning.

We need to have an honest conversation about smoking: The problem with smoking is that it is way more than just a physical addiction. Smoking creates a temporary problem and offers an instant solution. Once your brain is used to nicotine, for up to 72 hours you are itchy,nervous and stressed – but one drag and instantly, you feel really good. It also helps you focus and take breaks during work, while suppressing your appetite. So why is it such a bad idea?

You are in the middle of everything in the Universe. Let us go on a fantastical journey together - to the impossibly small and the incomprehensibly large!

The universe today is happy and healthy, with exciting things going on – but at some point the night will turn dark. Everything that once was, will peacefully sleep forever. But what is the last thing that will ever happen? Let's travel to the end of the universe…

Absolutely everything you think about yourself and the universe could be an illusion. As far as you know, you are real and exist in a universe that was born 14 billion years ago and that gave rise to galaxies, stars, the Earth, and finally you. Except, maybe not.

Somewhere in your body, your immune system just quietly killed one of your own cells, stopping it from becoming cancer, and saving your life. It does that all the time. The vast majority of cancer cells you develop will be killed without you ever noticing. Which is an incredibly hard job because of what cancer cells are: parts of yourself that start to behave as individuals even if it hurts you. What is cancer and how does your body kill it all the time?

The past is a vast and mysterious land that begins at the big bang and ends in the present, expanding with each passing moment. It is the home of everything that came before, the key to understanding our present. Here we find the most amazing creatures to ever roam our planet, hundreds of millions of species so diverse that our imagination cannot do them justice. Unfortunately the past carefully guards its secrets.

Can we survive the heat death of the universe? One day, the last star will die, galaxies will dissolve, and black holes will evaporate. The universe becomes a cold, empty void where nothing happens. Forever. But there might be a loophole that lets life keep going.

Can jellyfish power Tokyo? What would happen if it rained bananas for a day? We're taking two of your most absurd (and brilliant) questions and answer them with real science.

Vaping is marketed as the “safe” alternative to smoking, but it’s far from being harmless. Unregulated ingredients, hidden toxins, and extreme nicotine levels mean we’re conducting a massive experiment on ourselves. Let’s dive into what we know – and what we don’t know, yet.

Gravastars could change how we think about the universe. These cosmic objects solve black holes’ biggest problems without breaking physics. From their ultra-thin shell to their energy-filled core, gravastars are both elegant and terrifying. But what exactly are they?

58 of you watching this video right now will not be alive next week. And it’s not because of some freak accident or rare disease. It’s because of everyday actions you probably think are harmless. Let’s save your life today by looking at what is most likely to kill you next week – so you can avoid it.

A ruthless murder was committed! Someone killed the dinosaurs and we have the murderer! Witnesses say that an Everest-sized asteroid hit Earth, devastated the planet and caused a mass extinction. A simple, fascinating and convincing explanation. Or… is it?

You’ve got trillions of viruses inside you – right now! But these aren’t the viruses you fear. Some of them are your body’s secret protectors, keeping deadly bacteria in check and even killing cancer cells. But what happens when they turn against you? Let's look at the wild world of the human virome.

Humans assume aliens look human. But why would they? Let's explore what life might actually look like in strange, distant worlds.

South Korea is heading toward a demographic collapse unlike anything the world has seen before. With the lowest fertility rate ever recorded and a rapidly aging population, the country faces a future of economic decline, shrinking cities, cultural erosion, and a vanishing workforce. By 2060, nearly half of South Koreans could be over the age of 65, and entire regions may be abandoned as the population continues to shrink. How did South Korea reach this point? Why might it no longer be possible to reverse the trend? And what does this mean for other countries on a similar path?

What happens when your time machine breaks and you end up stranded millions of years ago? You’ve landed in a world that’s nothing like today, facing deadly storms and unbearable heat, breathing toxic air. How can you survive long enough to make it back home?

Time travel is possible. In fact, you’ve been doing it since the day you were born. But what if we told you there’s a way to hack the universe and manipulate time itself? We just have to do two simple things to make it happen: 1. Make a lot of physicists grumpy. 2. Shoot one twin through space against their will, while the other chills on Earth. Let's go!

Exercising doesn’t help you lose weight. In fact, it barely changes your daily calorie burn. Welcome to the workout paradox! Let’s dive into the science of how your body actually handles calories and sabotages your best efforts to burn them.

You may think you have free will and can choose what you do, but this might be an illusion. Your body is made up of particles that blindly follow the laws of physics, with every outcome already predetermined. So, you might not have any free will at all. Is free will an illusion, or does it exist? Which philosophical camp is right?

Ten years ago, in 2014, we released a video titled "Is War Over?". Back then, the question didn’t seem so naive. It seemed violent conflict was on the decline and the world more peaceful than ever. But the last ten years weren’t what we expected. So let's see how our video has held up.

Friends make life good. They provide the scaffolding that makes it not just bearable but fun. They give us a sense of meaning and purpose and are a source of security, self esteem and happiness. Almost nothing predicts how happy you will be as how connected you feel and a lack of social connection is associated with a number of diseases and a shorter life. But maybe you have scrolled through your phone, unsure who to call to go to a movie with, to celebrate with or ask for comfort. You may realize that you don’t have enough friends and feel lonely. And it is not just you. Disconnectedness and loneliness are widespread. Many people want more close friends but don’t know how to get them.

Black holes might create infinite universes while destroying time and space. Everything in existence could be black holes, all the way down. We might live inside a black hole that is inside a black hole, that is inside a black hole. But let’s start at the beginning and build a black hole out of air.

Pregnancy is not gentle. Babies begin as invaders, growing a brand-new organ inside another human. For months, they sap energy, hack the immune system, and fight for survival. Out of this struggle emerges the most magical thing there is: new life. This is the brutal and beautiful story of how you and all of us came to be.

In 2022 nearly half of Americans expected a civil war in the next few years, one in five now believes political violence is justified. And it is not just the US but around the world. People increasingly see themselves as part of opposing teams. There are many different reasons for this, but one gets blamed a lot: social media. Social media divides us, makes us more extreme and less empathetic, it riles us up or sucks us into doom scrolling, making us stressed and depressed. It feels like we need to touch grass and escape to the real world. New research shows that we might have largely misinterpreted why this is the case. It turns out that the social media internet may uniquely undermine the way our brains work but not in the way you think.

Here in the Kurzgesagt labs we test very important ideas to see what happens when you blow things up or play with black holes. Many of you suggested that we look into an idea that sounds reasonable: Shooting nuclear waste into space. It is one of those concepts that seems like an easy fix for one of the main problems with nuclear energy. But it turns out this idea is not just bad but horribly bad and it gets worse the longer you think about it.

Mars is a disappointing hellhole lacking practically everything we need to stay alive. It looks like we’ll only ever have small crews spend a miserable time hidden underground. Except, we could terraform it into a green new world. But to solve the planet’s problems, we first need to make it worse and turn it into oceans of lava with gigantic lasers.

We often assume that advanced technology will make it easy for aliens to colonize space. But what if space exploration is always difficult, no matter how advanced you are? Let’s travel back in human history, to the colonization of Oceania over 5000 years ago, to find parallels between ancient explorers and extraterrestrial civilizations.

Cannabis is finally being decriminalized in more and more places around the world. And for very good reasons! Compared to other legal drugs such as alcohol, cannabis is pretty mild and most users enjoy it without issue. But there’s a dark side for some. So let’s take an honest look at some of the latest research together.

Mr. President! Nuclear missiles will strike our country in 14 minutes. I know it’s your first day in office so I’m going to walk you through it, but you’re the only one who can authorize our nuclear retaliation in response and you’ve only got a few minutes to make a decision!

The Egg, a story by Andy Weir, animated by Kurzgesagt. This video was more than 2 years in the making and is a little bit different than the others on this channel. We hope you like it.

What is outside of the universe? We know that the universe had a beginning 14 billion years ago and that it has been expanding ever since. But something that is expanding should also have an edge, right? What would you see if you went there?

What do you know about the Moons of Mars? Nothing? They are super cool (and strange), promise.

Climate Change is just too much. There is never any good news. Only graphs that get more and more red and angry. Almost every year breaks some horrible record, from the harshest heat waves to the most rapid Glacier melt. It’s endless and relentless. We have known for decades that rapid Climate Change is being caused by the release of Greenhouse Gases. But instead of reducing them, in 2019 the world was emitting 50% more CO2 than in the year 2000. And emissions are still rising. Why is that? Why is it so hard to just stop emitting these gases?

Let us explore the scientific mystery of what would happen to you, if Earth suddenly turned into gold! The “Midaspocalypse”, based on the ancient tale of King Midas who was cursed so everything he touched turned into gold.

Leaving earth to find new homes in space is an old dream of humanity and will sooner or later be necessary for our survival. The planet that gets the most attention is Mars, a small, toxic and energy poor planet that just about seems good enough for a colony of depressed humans huddled in underground cities. But what if we think bigger? What if we take Venus, one of the most hostile and deadly places in the solar system and turn it into a colony? Not by building lofty cloud cities, but by creating a proper second earth? It might be easier than you think.

At its height, the Roman Empire was home to about 30 % of the world’s population, and in many ways the pinnacle of human advancement. Rome became the first city in history to reach one million inhabitants and was a center of technological, legal, and economic progress. An empire impossible to topple, stable and rich and powerful. Until it wasn’t anymore. First slowly then suddenly, the most powerful civilization on earth collapsed. If this is how it has been over the ages, what about us today? Will we lose our industrial technology, and with that our greatest achievements, from one dollar pizza to smartphones or laser eye surgery? Will all this go away too?

Could aliens destroy us from light years away? Another day at Kurzgesagt Labs, where we answer the most important questions with science. Today: how might civilizations wage war across light years? What kind of devastating weapons could they use and what would they look like?

No matter how likely your death is, there will always be a version of you that survives. At least according to one of the most bizarre interpretations of quantum mechanics, known as Quantum Immortality. Can science prove that you are unkillable? And does this mean our reality is split into an endless number of copies?

So what is the difference between you and a rock? This seems like an easy, even stupid question. But even the smartest people on Earth have no idea where to draw the line between living and dead things. Which leads to mind-blowing implications. What is life after all? And is death really a thing? Let's look into it together.

The Universe is incredibly big and seems full of potential for life, with billions of habitable planets. If an advanced civilization had the technology to travel between the stars, at just 0.1% of the speed of light, It could colonize our galaxy in roughly 100 million years. Which is not that long given the billions of years the milky way has existed – so in principle any spacefaring civilization should be able to spread rapidly over huge sectors of the galaxy. And yet we see nothing, hear nothing, the universe seems empty. Devoid of others. This is the Fermi Paradox, which we have discussed in more detail in other videos. Confronted with the seemingly empty universe, humanity faces a dilemma. We desperately want to know if we are alone in the Milky Way. We want to call out and reveal ourselves to anyone watching but that could be the last thing we ever do. Because maybe the universe is not empty. Maybe it’s full of civilizations but they are hiding from each other. [...]

A breathtaking scientific revolution is taking place – biotechnology has been progressing at stunning speed, giving us the tools to eventually gain control over biology. On the one hand solving the deadliest diseases while also creating viruses more dangerous than nuclear bombs, able to devastate humanity. What is going on?

Black holes can destroy everything – but can they be destroyed? What happens if we push physics to the absolute limits, maybe even break it and the universe in the process? Let’s create a tiny black hole, about the mass of our moon, in the Kurzgesagt Labs and try to rip it apart.

Every two years one million Japanese disappear, China’s population will halve by the end of the century, the median age in Italy has reached 48. All around the world birth rates are crashing – Is humanity dying out? What is going on and how bad is it?

Is your future already written? Do your past, present, and future all exist right now? Surprisingly, the answer could be yes. Let's take a look at what time is and how it works – in our first video of the year!

Most Conspiracy Theories are stupid. By the power of the internet they spread like wildfire and often poison discussions. But there is hope – we developed a way to debunk conspiracies in just a few seconds…

What does the Ebola virus actually do in your body? Why is it so dangerous and why does it kill so many people? We take a look at the apocalyptic war that rages in the body after an infection by the Ebola virus and the soldiers fighting.

In and out, in and out. Staying alive is about doing things. This very second, your cells are combusting glucose molecules with oxygen to make energy available, which keeps you alive for another precious moment. To get the oxygen to your cells you are breathing. Breathing is an answer to a very hard problem: How do you get the resources that your cells need to survive, from the outside, to the inside of your cells? Every living thing has to solve this problem and the solution is surprisingly different depending on one of the most important regulators of life: Size.

The Moon might be much bigger than you think it is.

If Neptune didn't catch Triton we might have another Dwarf Planet in our Solar system -- maybe even another Planet or double system. We show how this could have happened.

Vaccines are one of our best tools to prevent dangerous diseases, but they come with side effects. So would it be safer not to vaccinate?

Your tattoos are inside your immune system, literally. With each very tasteful piece of art, you kick start a drama with millions of deaths, grand sacrifices and your immune system stepping in to protect you from yourself. Let us get under your skin with our newest video.

We’ve found a new planet, home to octillions of the most extreme beings living in the most absurd and deadly hellscape. In absolute darkness, crushed by the weight of mountains, starved of oxygen, cooked alive, bathed in acid, salt or radiation. And yet, they live for thousands, perhaps millions of years! It turns out, this planet is not in space – it is inside the crust of Earth! This is the deep biosphere and we basically learned that it exists yesterday. Its volume is at least twice as large as all the Earth’s oceans, home to more microbes than the rest of the entire planet.Their total biomass is more than 20 times greater than all humans, livestock, and animal wildlife. Let’s descend into this mad, deadly world where none of the rules we thought are mandatory for life apply.

Allergies are more than just overreactions – they might be an evolutionary relic from a time when worms invaded our bodies daily.

Planet Earth is this solid thing you are standing on right now. In your everyday life you don't really waste a thought about how amazing this is. A giant, ancient, hot rock. How did it come into existence and how big is it really? You will be surprised. The ground you are standing on is just a very, very small part of the big picture.

Learn about the role of the sea in global warming.

What is the Antibiotic Apocalypse? What is it all about? And how dangerous is it?

Nuclear war, cat gifs and reddit? Wait, what?

Atoms are very weird. Wrapping your head around exactly how weird, is close to impossible – how can you describe something that is SO removed from humans experience? But then again, they kind of make up everything, so let us try anyways.

What is UBI? How would free money change our lives.

Banks are a riddle wrapped up in an enigma. We all kind of know that they do stuff with money we don’t understand, while the last crisis left a feeling of deep mistrust and confusion. We try to shed a bit of light onto the banking system. Why were banks invented, why did they cause the last crisis and are there alternatives?

Nuclear energy might be a failed experiment. In over sixty years the technology has not only failed to keep its promise of cheap, clean and safe energy, it also caused major catastrophes and enabled more nuclear weapons while the nuclear waste problem is still not solved.

Out in the vast coldness of outer space, there are planets that travel alone through darkness without the boundaries of a system. Here’s how this can happen – and why these frozen deserts might secretly harbor alien life.

Inside neutron stars we can find the weirdest and most dangerous substance in the universe: Strange matter. What is strange matter, how dangerous is it and what can it tell us about the origin of the universe?

Over the last decade milk has become a bit controversial. Some people say it’s a necessary and nutritious food, vital for healthy bones, but others say it can cause cancer and lead to an early death. So who is right? And why are we drinking it anyway?

Cancer is a creepy and mysterious thing. While we tried to understand it, to get better at killing it, we discovered a biological paradox that remains unsolved to this day: large animals seem to be immune to cancer. Which doesn’t make any sense – the bigger a being, the more cancer it should have. To understand why, we first need to take a look at the nature of cancer itself.

If you are like most people, there is a gap between the person you are and the person you wish to be. There are little things you think you should do and big things you ought to achieve.

Supernovae are the most powerful explosions in the universe, unleashing enough energy to outshine galaxies. We have no real metaphor for their power – if the sun were to magically go supernova it would feel like you were being hit by the energy of a nuclear explosion, every second. For weeks. While supernovae are the engines of creation, forging the elements that enable life, they also burn sterile whole regions of galaxies. So what would happen if one hit earth?

Being a human in the 21st century often feels frustrating. We are clearly at the high point of our species, while at the same time life is incredibly hard! We are divided, unable to solve our problems while creating new ones, destroying our world in the process. In many ways the vibe is that we live in dark times. But as Terry Pratchett said, we are the storytelling ape, we think in narratives and live in a network of stories that make up our world. So without minimizing the darkness, we want to add a story that we find helpful for dealing with the world.

Reality is not real. Your world is a prediction. Every sight, sound, and touch you experience is the result of calculations your brain makes before reality even reaches you. It fills in gaps, fabricates details, and even alters time itself so you feel like you’re in control. But if everything you know is an illusion… what does that say about you? What does it mean for your choices? Is there even free will?

What happens when the immune system meant to protect you becomes your worst enemy? This is the betrayal of autoimmune diseases like Type 1 diabetes, multiple sclerosis, celiac disease, lupus, Crohn’s disease, and many others. What exactly goes on in your body and why does it happen in the first place?

From study sessions to dance floors, amphetamines can feel like a shortcut to superhuman focus and energy. Why do they work so well? What happens to your body once you take them? And what toll does it take on your health?