Getting to space is hard.


Right now it's like going up a mountain on a unicycle with a backpack full of explosives.

Right now it 's like going up a mountain on a unicycle with a backpack full of explosives .


Incredibly slow, you can't transport a lot of stuff and you might die.

Incredibly slow , you ca n't transport a lot of stuff and you might die .


A rocket needs to reach a velocity of about 40,000 km an hour to escape from Earth.

A rocket needs to reach a velocity of about 40,000 km an hour to escape from Earth .


To get to that speed, rockets are mostly containers for fuel with a tiny tip of payload.

To get to that speed , rockets are mostly containers for fuel with a tiny tip of payload .


This is bad if you want to go to other planets, because you need a lot of heavy stuff if you want to survive and maybe even come back.

This is bad if you want to go to other planets , because you need a lot of heavy stuff if you want to survive and maybe even come back .


So is there a way to get to space with less fuel and more payload?

So is there a way to get to space with less fuel and more payload ?


A nice thing that solved most of our transport problems on Earth is what you call infrastructure.

A nice thing that solved most of our transport problems on Earth is what you call infrastructure .


Whether it's roads for cars, ports for ships or rails for trains, we've made it easier to get to places.

Whether it 's roads for cars , ports for ships or rails for trains , we 've made it easier to get to places .


We can apply the same solution to space travel.

We can apply the same solution to space travel .


Space infrastructure will make getting into orbit and out to the Moon, Mars and beyond easier and cheaper.

Space infrastructure will make getting into orbit and out to the Moon , Mars and beyond easier and cheaper .


Great, but what exactly is space infrastructure?

Great , but what exactly is space infrastructure ?


there is a simple yet promising technology that does not require new science, magic materials or huge investments and that has been tested successfully in orbit already.

there is a simple yet promising technology that does not require new science , magic materials or huge investments and that has been tested successfully in orbit already .


The concept is so simple, it's surprising.

The concept is so simple , it 's surprising .


This concept is known as the skyhook.


It works even better if we make it spin.

It works even better if we make it spin .


A counterweight holds a long cable in place while it rotates around a circle.

A counterweight holds a long cable in place while it rotates around a circle .


A rotating tether slows down its tip relative to the ground at the bottom and speeds it up at the top like a catapult.

A rotating tether slows down its tip relative to the ground at the bottom and speeds it up at the top like a catapult .


This means that you can transfer energy from the tether and get a massive boost when released, more or less for free, equal to twice the tether's rotation velocity.

This means that you can transfer energy from the tether and get a massive boost when released , more or less for free , equal to twice the tether 's rotation velocity .


Specialized fibers already exist that can survive the extraordinary stresses a skyhook would be faced with.

Specialized fibers already exist that can survive the extraordinary stresses a skyhook would be faced with .


To protect against cuts and collisions from debris and meteorites, we can thread our tether into a web of redundant fibers.

To protect against cuts and collisions from debris and meteorites , we can thread our tether into a web of redundant fibers .


Since our skyhook would pass over the same spot many times a day, this would allow small, reusable shuttles to catch up with it.

Since our skyhook would pass over the same spot many times a day , this would allow small , reusable shuttles to catch up with it .


Of course, it's not that easy.


At its lowest point, the tether's tip is dashing through the atmosphere at around 12,000 kilometers per hour.

At its lowest point , the tether 's tip is dashing through the atmosphere at around 12,000 kilometers per hour .


Because of Earth's atmosphere, we can't lower the skyhook too much or it will get too hot from air friction.

Because of Earth 's atmosphere , we ca n't lower the skyhook too much or it will get too hot from air friction .


So it will dip to a height of 80 to 150 kilometers and no lower.

So it will dip to a height of 80 to 150 kilometers and no lower .


To match this, we'll need specialized spacecraft that can get to the tether.

To match this , we 'll need specialized spacecraft that can get to the tether .


While this isn't exactly easy, it's still much cheaper than getting a big tin can filled with rocket fuel to go 40,000 kilometers an hour.

While this is n't exactly easy , it 's still much cheaper than getting a big tin can filled with rocket fuel to go 40,000 kilometers an hour .


Catching the tip will be a challenge too.

Catching the tip will be a challenge too .


There's only a short time window of 60 to 90 seconds to find a tiny thing in the sky moving at Mach 12.

There 's only a short time window of 60 to 90 seconds to find a tiny thing in the sky moving at Mach 12 .


To make this easier, the tip could have a sort of fishing line, a kilometer long, with a navigation drone that helps the spacecraft connect.

To make this easier , the tip could have a sort of fishing line , a kilometer long , with a navigation drone that helps the spacecraft connect .


Another challenge is keeping our skyhook in orbit.

Another challenge is keeping our skyhook in orbit .


As more and more ships latch onto it and pull themselves up, they use up the momentum that keeps it in place.

As more and more ships latch onto it and pull themselves up , they use up the momentum that keeps it in place .


If we don't do anything, it will slow down and crash into the atmosphere.

If we do n't do anything , it will slow down and crash into the atmosphere .


And here, we can cheat the universe a bit.

And here , we can cheat the universe a bit .


The skyhook is a battery of orbital energy.

The skyhook is a battery of orbital energy .


It's possible to balance the payloads coming in and being sent off.

It 's possible to balance the payloads coming in and being sent off .


Arriving ships bringing humans and materials home to Earth add energy to the tether, which it can give to other ships departing into space.

Arriving ships bringing humans and materials home to Earth add energy to the tether , which it can give to other ships departing into space .


This way, the tether doesn't lose any energy.

This way , the tether does n't lose any energy .


The more we use it, the cheaper it gets.

The more we use it , the cheaper it gets .


If we're still losing energy with each boost, we can recover it with small electric or chemical engines that regularly correct the tether's position.

If we 're still losing energy with each boost , we can recover it with small electric or chemical engines that regularly correct the tether 's position .


A set of tethers, one around Earth and one around Mars, could make trips between the planets fast, straightforward, and low-cost compared to rockets.

A set of tethers , one around Earth and one around Mars , could make trips between the planets fast , straightforward , and low - cost compared to rockets .


The Earth tether would sit in low Earth orbit to grab people and payloads and fling them off to Mars.

The Earth tether would sit in low Earth orbit to grab people and payloads and fling them off to Mars .


The Mars tether catches them and slows them down for a landing on the surface.

The Mars tether catches them and slows them down for a landing on the surface .


In the opposite direction, the tether could pick up a vehicle traveling through Mars' thin atmosphere at only about 1,000 kilometers an hour,

In the opposite direction , the tether could pick up a vehicle traveling through Mars ' thin atmosphere at only about 1,000 kilometers an hour ,


The tethers could shorten trips between both planets from nine months down to five or even three, and reduce the scale of the rockets required by between 84 and 96%.

The tethers could shorten trips between both planets from nine months down to five or even three , and reduce the scale of the rockets required by between 84 and 96 % .


Even better, people may be able to travel in relative luxury as we could afford to invest in passenger comfort.

Even better , people may be able to travel in relative luxury as we could afford to invest in passenger comfort .


Tether travel would be first-class seats to Mars.

Tether travel would be first - class seats to Mars .


Together, tethers around Earth and Mars could provide the rapid and cost-efficient transportation backbone that would make space travel affordable.

Together , tethers around Earth and Mars could provide the rapid and cost - efficient transportation backbone that would make space travel affordable .


But let's go further.


Starting from low Mars orbit, a tether could boost ships to the asteroid belt.

Starting from low Mars orbit , a tether could boost ships to the asteroid belt .


The first craft sent to a new asteroid would need rockets to slow down at its destination.

The first craft sent to a new asteroid would need rockets to slow down at its destination .


Subsequent arrivals might find a tether waiting to catch them and send them back for free.

Subsequent arrivals might find a tether waiting to catch them and send them back for free .


Getting to asteroids cheaply is a major factor in opening up the resources of the solar system.

Getting to asteroids cheaply is a major factor in opening up the resources of the solar system .


Precious metals and valuable minerals could be delivered to Mars just weeks after they were cut out of their asteroid.

Precious metals and valuable minerals could be delivered to Mars just weeks after they were cut out of their asteroid .


They would be the perfect building blocks for our interplanetary civilization.

They would be the perfect building blocks for our interplanetary civilization .


Mars' moons are very convenient.


Phobos is so heavy that we don't need to worry about slowing it down, making it the perfect attachment point for super tethers just under 6,000 km long.

Phobos is so heavy that we do n't need to worry about slowing it down , making it the perfect attachment point for super tethers just under 6,000 km long .


The lower tip would fly just over the surface of Mars and be very easy to catch.

The lower tip would fly just over the surface of Mars and be very easy to catch .


The upper tip can fling ships all the way to Jupiter and Saturn.

The upper tip can fling ships all the way to Jupiter and Saturn .


The same super tether can also bring the inner solar system closer.

The same super tether can also bring the inner solar system closer .


Venus and Mercury are a single swing away.

Venus and Mercury are a single swing away .


Unlike Mars, they're bursting with solar energy and are rich in minerals.

Unlike Mars , they 're bursting with solar energy and are rich in minerals .


In the long term, nothing is stopping humanity from constructing a zero-propellant transport network for the terrestrial planets centered on the Martian moons.

In the long term , nothing is stopping humanity from constructing a zero - propellant transport network for the terrestrial planets centered on the Martian moons .


Tethers are a comparably cheap and sustainable solution to making space travel affordable and the rest of the solar system accessible for exploitation and exploration.

Tethers are a comparably cheap and sustainable solution to making space travel affordable and the rest of the solar system accessible for exploitation and exploration .


Considering that we have the technology to build them today, there's really no good excuse to wait any longer.

Considering that we have the technology to build them today , there 's really no good excuse to wait any longer .


Parts of the solar system are far away, but they could be very close.

Parts of the solar system are far away , but they could be very close .


Our friends from Brilliant can hook you up to a universe full of explosive ideas and fun courses.

Our friends from Brilliant can hook you up to a universe full of explosive ideas and fun courses .


Brilliant is a website that helps you tackle science in a practical way with interactive problem-solving courses and daily problems in maths, logic and engineering.

Brilliant is a website that helps you tackle science in a practical way with interactive problem - solving courses and daily problems in maths , logic and engineering .


Each problem gives you all the tools you need to crack complex topics all by yourself.

Each problem gives you all the tools you need to crack complex topics all by yourself .


It's learning by doing, but with your brain instead of your hands.

It 's learning by doing , but with your brain instead of your hands .


Use your curiosity to get to the bottom of puzzles and courses about things like classical mechanics, astronomy, gravitational physics and much more.

Use your curiosity to get to the bottom of puzzles and courses about things like classical mechanics , astronomy , gravitational physics and much more .


If you click the link in the description or visit "brilliant.org/nutshell", you can sign up for free and learn more things than you can imagine.

If you click the link in the description or visit " brilliant.org/nutshell " , you can sign up for free and learn more things than you can imagine .


And there's an extra perk for Kurzgesagt viewers.

And there 's an extra perk for Kurzgesagt viewers .


The first 688 people to use the link get 20% off their annual membership, which lets you view all the daily problems in the archives and unlock every course.

The first 688 people to use the link get 20 % off their annual membership , which lets you view all the daily problems in the archives and unlock every course .


Brilliant helps you end your day a little smarter.

Brilliant helps you end your day a little smarter .


You might get hooked on the experience.

You might get hooked on the experience .


It's unclear how precise those tests were, however.

It 's unclear how precise those tests were , however .


But how high is the risk of psychosis for the general population?

But how high is the risk of psychosis for the general population ?


The risk of marijuana-induced psychosis remains the highest

The risk of marijuana - induced psychosis remains the highest


For them, it seems more likely that marijuana speeds up the development of their condition

For them , it seems more likely that marijuana speeds up the development of their condition


So the reasoning goes, if fewer people have access to marijuana,

So the reasoning goes , if fewer people have access to marijuana ,


But actually, you could argue that precisely because marijuana is illegal,

But actually , you could argue that precisely because marijuana is illegal ,


more people will end up with psychosis.

more people will end up with psychosis .


Prohibition makes illegal drugs stronger and more potent,

Prohibition makes illegal drugs stronger and more potent ,


because this way you can ship more product in a smaller space and sell it at a greater profit.

because this way you can ship more product in a smaller space and sell it at a greater profit .


This is what happened during the prohibition of alcohol in the US,

This is what happened during the prohibition of alcohol in the US ,


And the same is happening with marijuana now.

And the same is happening with marijuana now .


Imagine a world where liquor is the only alcohol available.

Imagine a world where liquor is the only alcohol available .


You have the choice of either not drinking at all or getting much drunker than you would like to.

You have the choice of either not drinking at all or getting much drunker than you would like to .


This is the situation for many marijuana smokers today.

This is the situation for many marijuana smokers today .


People didn't stop drinking during prohibition

People did n't stop drinking during prohibition


and the numbers show that laws don't deter people from using marijuana.

and the numbers show that laws do n't deter people from using marijuana .


We can't make marijuana go away, but we can make it safer.

We ca n't make marijuana go away , but we can make it safer .


If marijuana were legal, there would be more options for consumers

If marijuana were legal , there would be more options for consumers


and regulators could, for example, insist on a high level of CBD.

and regulators could , for example , insist on a high level of CBD .


Just like most people don't drink an after-work bottle of vodka,

Just like most people do n't drink an after - work bottle of vodka ,


many people would gladly consume the after-work beer version of marijuana.

many people would gladly consume the after - work beer version of marijuana .


Argument 2. Marijuana is a gateway drug.

Argument 2 . Marijuana is a gateway drug .


If it's legalized, there will be a spike in the use of much more dangerous drugs.

If it 's legalized , there will be a spike in the use of much more dangerous drugs .


Legalizing marijuana could reinforce this trend.

Legalizing marijuana could reinforce this trend .


As more young people try legal marijuana, they might end up trying harder drugs.

As more young people try legal marijuana , they might end up trying harder drugs .


But it turns out that the real gateway to drug use comes much earlier, cigarettes.

But it turns out that the real gateway to drug use comes much earlier , cigarettes .


But if that's the case, how could making more drugs legal stop the use of hard drugs?

But if that 's the case , how could making more drugs legal stop the use of hard drugs ?


At first, it's important to acknowledge that people don't use drugs because they're legal or not.

At first , it 's important to acknowledge that people do n't use drugs because they 're legal or not .


If you want to buy any drug, you'll always find someone happy to sell.

If you want to buy any drug , you 'll always find someone happy to sell .


The real question is why do people develop an unhealthy relationship with drugs at all?

The real question is why do people develop an unhealthy relationship with drugs at all ?


Studies show that certain conditions make people especially vulnerable to drugs and addiction.

Studies show that certain conditions make people especially vulnerable to drugs and addiction .


Addicts take drugs to escape their problems,

Addicts take drugs to escape their problems ,


but drugs don't solve any of those problems and instead become a new problem.

but drugs do n't solve any of those problems and instead become a new problem .


So some argue we need to take a completely different route.

So some argue we need to take a completely different route .


In 2001, Portugal had one of the worst drug problems in Europe,

In 2001 , Portugal had one of the worst drug problems in Europe ,


so it was desperate enough to try something radical.

so it was desperate enough to try something radical .


Possession and use of all illegal drugs was decriminalized.

Possession and use of all illegal drugs was decriminalized .


You would no longer be arrested.


Instead, authorities launched a major health campaign.

Instead , authorities launched a major health campaign .


People who were found with a small amount were referred to support services


Drug use was seen as a chronic disease, not a crime.

Drug use was seen as a chronic disease , not a crime .


The results were stunning.


The number of people who tried drugs and kept using them fell from 44% to 28% by 2012.

The number of people who tried drugs and kept using them fell from 44 % to 28 % by 2012 .


The use of hard drugs decreased, as well as HIV and hepatitis infections and overdoses.

The use of hard drugs decreased , as well as HIV and hepatitis infections and overdoses .


Making drugs legal might overall help society much more than it harms it.

Making drugs legal might overall help society much more than it harms it .


Marijuana is addictive and unhealthy.


It needs to remain illegal to keep harm at a minimum.

It needs to remain illegal to keep harm at a minimum .


While marijuana addiction is more psychological than physical, it is still a real problem.

While marijuana addiction is more psychological than physical , it is still a real problem .


The demand for treatment for marijuana addiction has more than doubled in the past decade alone.

The demand for treatment for marijuana addiction has more than doubled in the past decade alone .


In total, about 10% of people who try marijuana will become addicted.

In total , about 10 % of people who try marijuana will become addicted .


This is also related to higher THC levels.

This is also related to higher THC levels .


A study released in 2017 tracked the potency of marijuana in Dutch coffee shops over a period of 16 years.

A study released in 2017 tracked the potency of marijuana in Dutch coffee shops over a period of 16 years .


For every 1% increase in THC, 60 more people entered treatment nationwide.

For every 1 % increase in THC , 60 more people entered treatment nationwide .


In terms of negative health effects, some studies linked marijuana use to increased blood pressure and lung problems,

In terms of negative health effects , some studies linked marijuana use to increased blood pressure and lung problems ,


while a 2016 study found that marijuana use was unrelated to physical health problems, except for a higher risk of gum disease.

while a 2016 study found that marijuana use was unrelated to physical health problems , except for a higher risk of gum disease .


Some studies showed that marijuana use alters teenagers' brains and decreases their intelligence,

Some studies showed that marijuana use alters teenagers ' brains and decreases their intelligence ,


but when more recent studies took drinking and smoking into account, the results were inconclusive.

but when more recent studies took drinking and smoking into account , the results were inconclusive .


Overall, research shows that taking any drugs while the brain is still in development is bad for you.

Overall , research shows that taking any drugs while the brain is still in development is bad for you .


But the truth is we don't know yet how unhealthy marijuana is.

But the truth is we do n't know yet how unhealthy marijuana is .


We need more funding for research, which is hard to get while marijuana remains illegal.

We need more funding for research , which is hard to get while marijuana remains illegal .


We can put what we know into perspective, though.

We can put what we know into perspective , though .


16% of people who consume alcohol become alcoholics, and 32% of people who try cigarettes become smokers.

16 % of people who consume alcohol become alcoholics , and 32 % of people who try cigarettes become smokers .


We know for sure alcohol affects your brain, destroys your liver and causes cancer,

We know for sure alcohol affects your brain , destroys your liver and causes cancer ,


while tobacco clogs your arteries, destroys your lungs and also causes cancer.

while tobacco clogs your arteries , destroys your lungs and also causes cancer .


3.3 million people die from alcohol abuse each year, while smoking kills more than 6 million people.

3.3 million people die from alcohol abuse each year , while smoking kills more than 6 million people .


Nobody is suggesting tobacco and alcohol are harmless just because they're legal.

Nobody is suggesting tobacco and alcohol are harmless just because they 're legal .


Also, nobody is seriously proposing to prohibit them, even though they are extremely dangerous.

Also , nobody is seriously proposing to prohibit them , even though they are extremely dangerous .


Legality is a way to exercise some control over them, especially when it comes to protecting young people.

Legality is a way to exercise some control over them , especially when it comes to protecting young people .


It's often much harder to buy legal drugs for teenagers than to buy illegal ones.

It 's often much harder to buy legal drugs for teenagers than to buy illegal ones .


Official sellers can get hefty fines and lose their license if they sell to underage kids.

Official sellers can get hefty fines and lose their license if they sell to underage kids .


Legality creates incentives here that drug dealers can't exploit.

Legality creates incentives here that drug dealers ca n't exploit .


So making marijuana legal doesn't mean endorsing it.

So making marijuana legal does n't mean endorsing it .


It means taking responsibility for the risks it poses.

It means taking responsibility for the risks it poses .


It could also open the floodgates to tons of new research that shows us how harmful it really is and to whom.

It could also open the floodgates to tons of new research that shows us how harmful it really is and to whom .


Marijuana is a drug, and just like any other drug, it has negative consequences for a sizable portion of the people who use it.

Marijuana is a drug , and just like any other drug , it has negative consequences for a sizable portion of the people who use it .


It is not harmless.


The best way to protect society from its negative consequences seems to be legalization and regulation.

The best way to protect society from its negative consequences seems to be legalization and regulation .


Kurzgesagt is lying to you in every video, even in this one,

Kurzgesagt is lying to you in every video , even in this one ,


because our videos distill very complex subjects into flashy 10-minute pieces, and unfortunately, reality is, well, complicated.

because our videos distill very complex subjects into flashy 10 - minute pieces , 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.

The question of how we deal with that is central to what we do on this channel , and something we think about a lot .


What we mean by lying is the concept of lies to children.

What we mean by lying is the concept of lies to children .


The idea that on the path to explaining something complicated, you start off with a little lie, a useful oversimplification, that makes it easier to grasp a concept.

The idea that on the path to explaining something complicated , you start off with a little lie , a useful oversimplification , that makes it easier to grasp a concept .


For example, as a kid you learn that the Earth is a sphere orbiting the Sun with planet buddies.

For example , as a kid you learn that the Earth is a sphere orbiting the Sun with planet buddies .


But it's not actually a sphere, and the buddies are super different in size, and not close to each other at all.

But it 's not actually a sphere , and the buddies are super different in size , and not close to each other at all .


By beginning at a place of oversimplification, you're building a framework, a foundation that you can then build upon and add nuance and complexity later on.

By beginning at a place of oversimplification , you 're building a framework , a foundation that you can then build upon and add nuance and complexity later on .


Step by step, you're getting towards the real gist of the complicated subject.

Step by step , you 're getting towards the real gist of the complicated subject .


Science communication has to use lies to children to some degree, or it turns into science education.

Science communication has to use lies to children to some degree , or it turns into science education .


And getting a proper education in all of the scientific fields would take years of intense study to become fluent in them.

And getting a proper education in all of the scientific fields would take years of intense study to become fluent in them .


As a species, we have a major interest in summarizing science and its advancements, and educating as many people about it as possible,

As a species , we have a major interest in summarizing science and its advancements , and educating as many people about it as possible ,


because we all benefit if more people have a fact-based scientific worldview.

because we all benefit if more people have a fact - based scientific worldview .


We will discuss what science is and how it works in different videos in more detail,

We will discuss what science is and how it works in different videos in more detail ,


but for now, let's just say it's a process to advance, organize, predict, and test our knowledge about the universe.

but for now , let 's just say it 's a process to advance , organize , predict , and test our knowledge about the universe .


If you understand the current state of scientific knowledge, then you can make better decisions based on facts and testable ideas,

If you understand the current state of scientific knowledge , then you can make better decisions based on facts and testable ideas ,


Our brains are comically ill-prepared to navigate the fast-moving world we happen to live in today, a world ironically created by science.

Our brains are comically ill - prepared to navigate the fast - moving world we happen to live in today , a world ironically created by science .


A few hundred years ago, it was possible to be knowledgeable and expert-level in pretty much every field of study.

A few hundred years ago , it was possible to be knowledgeable and expert - level in pretty much every field of study .


In the information age, this is a futile endeavor, since knowledge and data are increasing exponentially.

In the information age , this is a futile endeavor , since knowledge and data are increasing exponentially .


So to even have a chance of grasping the world we live in, we need summaries that give us, if not a true understanding of all the details, a solid overview.

So to even have a chance of grasping the world we live in , we need summaries that give us , if not a true understanding of all the details , a solid overview .


Explaining science to many people is not about enlightening the ignorant, but necessary for the progress of our species at large.

Explaining science to many people is not about enlightening the ignorant , but necessary for the progress of our species at large .


To make this possible, we need to find metaphors and stories that capture the true nature of things as much as possible, while using a language that our brains can deal with.

To make this possible , we need to find metaphors and stories that capture the true nature of things as much as possible , while using a language that our brains can deal with .


A great example here is physics.


Quarks are often depicted as blue, red, and green, with different spins.

Quarks are often depicted as blue , red , and green , with different spins .


But just saying spin and using colors forces our brain to imagine colorful spinning balls,

But just saying spin and using colors forces our brain to imagine colorful spinning balls ,


Molecules are nothing like the neat diagrams that we're taught in school, but buzzing and vibrating entities held together by something we call charge,

Molecules are nothing like the neat diagrams that we 're taught in school , but buzzing and vibrating entities held together by something we call charge ,


that describes how certain things want to be close or escape each other for some unknown reason.

that describes how certain things want to be close or escape each other for some unknown reason .


We're describing phenomena that we're pretty sure exist in some form or another,

We 're describing phenomena that we 're pretty sure exist in some form or another ,


because the maths works out, and we can do real-world experiments and predict their results before we do them.

because the maths works out , and we can do real - world experiments and predict their results before we do them .


In reality, these are models, tricks to summarize what we know, make up a coherent story, and prepare the ground for more in-depth explanations.

In reality , these are models , tricks to summarize what we know , make up a coherent story , and prepare the ground for more in - depth explanations .


Don't confuse the description of a thing for the thing itself.

Do n't confuse the description of a thing for the thing itself .


Simplifications like these are not just meant to dumb things down, they're actually useful for experts themselves.

Simplifications like these are not just meant to dumb things down , they 're actually useful for experts themselves .


But the simplification of science can also be problematic for a bunch of reasons.

But the simplification of science can also be problematic for a bunch of reasons .


Finding the true nature of reality is super hard, because our brains did not evolve for this job, and the universe doesn't care if we understand it.

Finding the true nature of reality is super hard , because our brains did not evolve for this job , and the universe does n't care if we understand it .


Science is a process to work towards gaining knowledge, and not an absolute truth generator.

Science is a process to work towards gaining knowledge , and not an absolute truth generator .


The answers it provides are multilayered and nuanced, and that complexity can get lost when it's simplified, especially when it's done so for headlines.

The answers it provides are multilayered and nuanced , and that complexity can get lost when it 's simplified , especially when it 's done so for headlines .


An interesting cancer study turns into a potential cure, a healthy food becomes the basis for a new diet.

An interesting cancer study turns into a potential cure , a healthy food becomes the basis for a new diet .


Such simplifications give a misleading definiteness to science, which goes against its process-like nature.

Such simplifications give a misleading definiteness to science , which goes against its process - like nature .


When cures don't materialize, and diets don't turn out to be magical, we lose confidence in science, and start to think of all science communication as misleading.

When cures do n't materialize , and diets do n't turn out to be magical , we lose confidence in science , and start to think of all science communication as misleading .


Then there's the opposite effect.


If a simplification is too engaging, if the story it tells is too good, it can distort the true complexity of a subject, and give you a false sense of security and an illusion of deep knowledge.

If a simplification is too engaging , if the story it tells is too good , it can distort the true complexity of a subject , and give you a false sense of security and an illusion of deep knowledge .


And this can have negative consequences for all of us, because in the worst case, overconfidence in your own understanding of science can lead to bad decisions made with confidence.

And this can have negative consequences for all of us , because in the worst case , overconfidence in your own understanding of science can lead to bad decisions made with confidence .


Just think of the surge of people that confidently disavow vaccines or climate change without truly understanding the subject matter.

Just think of the surge of people that confidently disavow vaccines or climate change without truly understanding the subject matter .


So considering all of this, and the fact that we at Kurzgesagt reach millions of people with our videos, how do we handle this?

So considering all of this , and the fact that we at Kurzgesagt reach millions of people with our videos , how do we handle this ?


Well, it has been a journey, especially the research.

Well , it has been a journey , especially the research .


When we started, we just read articles, then moved on to books, peer-reviewed papers, then to conversations with experts.

When we started , we just read articles , then moved on to books , peer - reviewed papers , then to conversations with experts .


We began to collect our sources.


With every step, we realized that we were still not doing enough.

With every step , we realized that we were still not doing enough .


Nowadays, we try to read as many primary sources as possible, talk to multiple experts and document our simplifications, and give further reading in our sources doc.

Nowadays , we try to read as many primary sources as possible , talk to multiple experts and document our simplifications , and give further reading in our sources doc .


But this doesn't make our process flawless.

But this does n't make our process flawless .


What do you do if experts disagree with each other?

What do you do if experts disagree with each other ?


What do you do if you find an amazing fact that perfectly fits a narrative, but just can't find its primary source?

What do you do if you find an amazing fact that perfectly fits a narrative , but just ca n't find its primary source ?


How do you deal with the reality that many scientific results have huge error bars or maybes attached to them?

How do you deal with the reality that many scientific results have huge error bars or maybes attached to them ?


How do you handle complex systems that defy easy answers?

How do you handle complex systems that defy easy answers ?


In the end, we make 10-minute videos, and we need to make decisions about what details and explanations can fit, which aspects need to be simplified, and which parts to cut.

In the end , we make 10 - minute videos , and we need to make decisions about what details and explanations can fit , which aspects need to be simplified , and which parts to cut .


There is no single best answer for how to do this, and so we weigh the different options every single time.

There is no single best answer for how to do this , and so we weigh the different options every single time .


It can be painful for experts to see their field simplified, some are happy with us, while others don't like it.

It can be painful for experts to see their field simplified , some are happy with us , while others do n't like it .


This is fair, but also impossible to avoid.

This is fair , but also impossible to avoid .


We're still trying to improve and want to be transparent about what we're trying to do.

We 're still trying to improve and want to be transparent about what we 're trying to do .


For example, we're taking part in the Treska project about science communication to learn more.

For example , we 're taking part in the Treska project about science communication to learn more .


All of this brings us to the purpose of our videos.

All of this brings us to the purpose of our videos .


The most important thing we want to do with this channel is to inspire you and spark your curiosity for science and the amazing universe we live in.

The most important thing we want to do with this channel is to inspire you and spark your curiosity for science and the amazing universe we live in .


Learning often doesn't feel like fun, but with the right story it is one of the best things, and we hope to provide that to you.

Learning often does n't feel like fun , but with the right story it is one of the best things , and we hope to provide that to you .


Ultimately, we hope that we light a fire in you that motivates you to read books, pay more attention at school or university, and just get interested in a scientific field or two and learn more on your own.

Ultimately , we hope that we light a fire in you that motivates you to read books , pay more attention at school or university , and just get interested in a scientific field or two and learn more on your own .


Not because you have to, but because you want to know more about how the world really works.

Not because you have to , but because you want to know more about how the world really works .


Because the universe is beautiful, and science is a way of seeing this beauty more clearly.

Because the universe is beautiful , and science is a way of seeing this beauty more clearly .


And we hope that knowing that we have to simplify a bit does not make you enjoy our videos less.

And we hope that knowing that we have to simplify a bit does not make you enjoy our videos less .


We are trying to build something with Kurzgesagt, and while we're not 100% sure yet what exactly,

We are trying to build something with Kurzgesagt , and while we 're not 100 % sure yet what exactly ,


And of course how big things are, and what happens when we blow stuff up, because it's fun.

And of course how big things are , and what happens when we blow stuff up , because it 's fun .


We really can't do this without you.


Running a science communication business is a balancing act that we take extremely seriously.

Running a science communication business is a balancing act that we take extremely seriously .


On the one hand we need to be responsible and look out for the team and be able to grow responsibly.

On the one hand we need to be responsible and look out for the team and be able to grow responsibly .


On the other hand we have to protect the integrity of our videos.

On the other hand we have to protect the integrity of our videos .


You are enabling us to stay independent, because while we do things like sponsorships or commercial work, the majority of our income comes directly from you, the birbs.

You are enabling us to stay independent , because while we do things like sponsorships or commercial work , the majority of our income comes directly from you , the birbs .


Kurzgesagt is fundamentally funded by its community, by you.

Kurzgesagt is fundamentally funded by its community , by you .


Because of you, Kurzgesagt is able to invest as much time in our videos and try to become better.

Because of you , Kurzgesagt is able to invest as much time in our videos and try to become better .


You get our calendar every year, support us on Patreon and get your personal birds, watch our videos without adblock or with YouTube premium.

You get our calendar every year , support us on Patreon and get your personal birds , watch our videos without adblock or with YouTube premium .


Our favourite way to keep the channel running are our sciency products from our shop, that hopefully add additional value to the world.

Our favourite way to keep the channel running are our sciency products from our shop , that hopefully add additional value to the world .


We love bringing little pieces of knowledge into your home or classroom, that inspire you to learn more about the universe in a little more detail.

We love bringing little pieces of knowledge into your home or classroom , that inspire you to learn more about the universe in a little more detail .


Our latest one teaches you about the night sky and showcases the stars in our night sky and their special significance for humanity.

Our latest one teaches you about the night sky and showcases the stars in our night sky and their special significance for humanity .


With every purchase you directly support what we do on this channel.

With every purchase you directly support what we do on this channel .


Please don't feel obligated to do so though.

Please do n't feel obligated to do so though .


Watching and sharing is already helping us out a lot and we are just grateful that so many of you care about what we try to do here.

Watching and sharing is already helping us out a lot and we are just grateful that so many of you care about what we try to do here .


Thank you so, so much!


Every second of your life you are under attack.

Every second of your life you are under attack .


Billions of bacteria, viruses and fungi are trying to make you their home.

Billions of bacteria , viruses and fungi are trying to make you their home .


So our bodies have developed a super complex little army with guards, soldiers, intelligence, weapons factories and communicators to protect you from, well, dying.

So our bodies have developed a super complex little army with guards , soldiers , intelligence , weapons factories and communicators to protect you from , well , dying .


For this video, let's assume the immune system has 12 different jobs.

For this video , let 's assume the immune system has 12 different jobs .


For example, kill enemies, communicate, etc.

For example , kill enemies , communicate , etc .


And it has 21 different cells and 2 protein forces.

And it has 21 different cells and 2 protein forces .


These cells have up to 4 different jobs.

These cells have up to 4 different jobs .


Let's assign them.


Here are the interactions.


Now, let's make this understandable.


First of all, let's add colors to the jobs.

First of all , let 's add colors to the jobs .


Now let's illustrate the cells.


The central color represents the main job of the cell, while the surrounding ones represent secondary duties.

The central color represents the main job of the cell , while the surrounding ones represent secondary duties .


Now the immune system looks like this.


Isn't this complexity just awesome?


For this video, we will only talk about these cells and ignore the rest.

For this video , we will only talk about these cells and ignore the rest .


So what happens in the case of an infection?

So what happens in the case of an infection ?


It's a beautiful day when suddenly a wild rusty nail appears and you cut yourself.

It 's a beautiful day when suddenly a wild rusty nail appears and you cut yourself .


The first barrier of the immune system is breached, your skin.

The first barrier of the immune system is breached , your skin .


Nearby bacteria seize on the opportunity and enter your wound.

Nearby bacteria seize on the opportunity and enter your wound .


They start using up the body's resources and double their numbers about every 20 minutes.

They start using up the body 's resources and double their numbers about every 20 minutes .


At first, they fly under the radar, but when a certain bacteria population is reached, they change their behavior and start to damage the body by changing the environment around them.

At first , they fly under the radar , but when a certain bacteria population is reached , they change their behavior and start to damage the body by changing the environment around them .


The immune system has to stop them as fast as possible.

The immune system has to stop them as fast as possible .


First of all, your guard cells, known as macrophages, intervene.

First of all , your guard cells , known as macrophages , intervene .


They are huge cells that guard every border region of the body.

They are huge cells that guard every border region of the body .


Most of the time, they alone can suffocate an attack because they can devour up to 100 intruders each.

Most of the time , they alone can suffocate an attack because they can devour up to 100 intruders each .


They swallow the intruder whole and trap it inside a membrane.

They swallow the intruder whole and trap it inside a membrane .


Then the enemy gets broken down by enzymes and is killed.

Then the enemy gets broken down by enzymes and is killed .


On top of that, they cause inflammation by ordering the blood vessels to release water into the battlefield, so fighting becomes easier.

On top of that , they cause inflammation by ordering the blood vessels to release water into the battlefield , so fighting becomes easier .


You notice this as a very mild swelling.

You notice this as a very mild swelling .


When the macrophages fight for too long, they call in heavy backup by releasing messenger proteins that communicate location and urgency.

When the macrophages fight for too long , they call in heavy backup by releasing messenger proteins that communicate location and urgency .


Neutrophiles leave their patrol routes in the blood and move to the battlefield.

Neutrophiles leave their patrol routes in the blood and move to the battlefield .


The neutrophiles fight so furiously that they kill healthy cells in the process.

The neutrophiles fight so furiously that they kill healthy cells in the process .


On top of that, they generate barriers that trap and kill the bacteria.

On top of that , they generate barriers that trap and kill the bacteria .


They are indeed so deadly that they evolved to commit suicide after 5 days to prevent them from causing too much damage.

They are indeed so deadly that they evolved to commit suicide after 5 days to prevent them from causing too much damage .


If this is not enough to stop the invasion, the brain of the immune system kicks in.

If this is not enough to stop the invasion , the brain of the immune system kicks in .


The dendritic cell gets active.


It reacts to the signals of the soldiers and starts collecting samples from the enemies.

It reacts to the signals of the soldiers and starts collecting samples from the enemies .


They rip them into pieces and present the parts on their outer layer.

They rip them into pieces and present the parts on their outer layer .


Now, the dendritic cell makes a crucial decision.

Now , the dendritic cell makes a crucial decision .


Should they call for antivirus forces that eradicate infected body cells or an army of bacteria killers?

Should they call for antivirus forces that eradicate infected body cells or an army of bacteria killers ?


In this case, antibacteria forces are necessary.

In this case , antibacteria forces are necessary .


It then travels to the closest lymph node in about a day.

It then travels to the closest lymph node in about a day .


Here, billions of helper and killer T-cells are waiting to be activated.

Here , billions of helper and killer T - cells are waiting to be activated .


When T-cells are born, they go through a difficult and complicated training process and only a quarter survives.

When T - cells are born , they go through a difficult and complicated training process and only a quarter survives .


The surviving cells are equipped with a specific setup.

The surviving cells are equipped with a specific setup .


And the dendritic cell is on its way, looking for a helper T-cell with a setup that's just right.

And the dendritic cell is on its way , looking for a helper T - cell with a setup that 's just right .


It's looking for a helper T-cell that can bind to the parts of the intruders which the dendritic cell has presented on its membrane.

It 's looking for a helper T - cell that can bind to the parts of the intruders which the dendritic cell has presented on its membrane .


When it finally finds one, a chain reaction takes place.

When it finally finds one , a chain reaction takes place .


The helper T-cell is activated.


It quickly duplicates thousands of times.

It quickly duplicates thousands of times .


Some become memory T-cells that stay in the lymph node and will make you practically immune against this enemy.

Some become memory T - cells that stay in the lymph node and will make you practically immune against this enemy .


Some travel to the field of battle to help out.

Some travel to the field of battle to help out .


And the third group goes on to travel to the center of the lymph node to activate a very powerful weapons factory.

And the third group goes on to travel to the center of the lymph node to activate a very powerful weapons factory .


Like the T-cells, they are born with a specific setup.

Like the T - cells , they are born with a specific setup .


And when a B-cell and a T-cell with the same setup meet, hell breaks loose.

And when a B - cell and a T - cell with the same setup meet , hell breaks loose .


The B-cell duplicates rapidly and starts producing millions of little weapons.

The B - cell duplicates rapidly and starts producing millions of little weapons .


They work so hard that they would literally die from exhaustion very fast.

They work so hard that they would literally die from exhaustion very fast .


Here, helper T-cells play another important role.

Here , helper T - cells play another important role .


They stimulate the hard-working factories and tell them, don't die yet, we still need you, keep going.

They stimulate the hard - working factories and tell them , do n't die yet , we still need you , keep going .


This also ensures that the factories die if the infection is over so the body doesn't waste energy or hurt itself.

This also ensures that the factories die if the infection is over so the body does n't waste energy or hurt itself .


But what is produced by the B-cells?


You've heard of them, of course.


There are even different kinds of antibodies that have slightly different jobs.

There are even different kinds of antibodies that have slightly different jobs .


The helper T-cells tell the plasma cells which type is needed the most in this particular invasion.

The helper T - cells tell the plasma cells which type is needed the most in this particular invasion .


Millions of them flood the blood and saturate the body.

Millions of them flood the blood and saturate the body .


Meanwhile, at the site of infection, the situation is getting dire.

Meanwhile , at the site of infection , the situation is getting dire .


The intruders have multiplied in number and start hurting the body.

The intruders have multiplied in number and start hurting the body .


The guard and attack cells fight hard but also die in the process.

The guard and attack cells fight hard but also die in the process .


Helper T-cells support them by ordering them to be more aggressive and to stay alive longer.

Helper T - cells support them by ordering them to be more aggressive and to stay alive longer .


But without help, they can't overwhelm the bacteria.

But without help , they ca n't overwhelm the bacteria .


But now the second line of defense arrives.

But now the second line of defense arrives .


Billions of antibodies flood the battlefield and disable lots of the intruders, rendering them helpless or killing them in the process.

Billions of antibodies flood the battlefield and disable lots of the intruders , rendering them helpless or killing them in the process .


They also stun the bacteria and make them an easy target.

They also stun the bacteria and make them an easy target .


Their back is built to connect to killer cells so they can connect and kill the enemy more easily.

Their back is built to connect to killer cells so they can connect and kill the enemy more easily .


Macrophages are especially good at gnoming up the bacteria which antibodies have attached to.

Macrophages are especially good at gnoming up the bacteria which antibodies have attached to .


Now the balance shifts.


In a team effort, the infection is wiped out.

In a team effort , the infection is wiped out .


At this point, millions of body cells have already died.

At this point , millions of body cells have already died .


No big deal, the losses are quickly replenished.

No big deal , the losses are quickly replenished .


Most immune cells are now useless and without the constant signals, they commit suicide.

Most immune cells are now useless and without the constant signals , they commit suicide .


But some stay behind.


If this enemy is encountered ever again in the future, they will be ready for it and probably kill it before you even notice.

If this enemy is encountered ever again in the future , they will be ready for it and probably kill it before you even notice .


This was a very, very simplified explanation of parts of the immune system at work.

This was a very , very simplified explanation of parts of the immune system at work .


Can you imagine how complex this system is?

Can you imagine how complex this system is ?


Life is awfully complicated.


But if we take the time to understand it, we always encounter endless wonders and great beauty.

But if we take the time to understand it , we always encounter endless wonders and great beauty .


In 2022, nearly half of Americans expected a civil war in the next few years.

In 2022 , nearly half of Americans expected a civil war in the next few years .


One in five now believes political violence is justified.

One in five now believes political violence is justified .


And it's not just the US, but around the world.

And it 's not just the US , but around the world .


People increasingly see themselves as part of opposing teams.

People increasingly see themselves as part of opposing teams .


There are many different reasons for this, but one gets blamed a lot.

There are many different reasons for this , but one gets blamed a lot .


Social media divides us, makes us more extreme and less empathetic.

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 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.

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.

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.

It turns out that the social media internet may uniquely undermine the way our brains work , but not in the way you think .


You've probably heard about online filter bubbles.

You 've probably heard about online filter bubbles .


Algorithms give you exactly what you want or what they think you want.

Algorithms give you exactly what you want or what they think you want .


You only see information that shows you opinions that agree with yours, while dissenting opinions or information are filtered out.

You only see information that shows you opinions that agree with yours , while dissenting opinions or information are filtered out .


Since you only see content close to your world view, more extreme and toxic opinions suddenly seem less extreme.

Since you only see content close to your world view , more extreme and toxic opinions suddenly seem less extreme .


You're trapped in a radicalizing filter bubble, and your view of the world becomes narrower and more extreme.

You 're trapped in a radicalizing filter bubble , and your view of the world becomes narrower and more extreme .


But is that true?


Extreme filter bubbles seem to be rather rare.

Extreme filter bubbles seem to be rather rare .


Studies that investigated what people actually look at online, or are shown by search engines, found little evidence that you're ideologically isolated.

Studies that investigated what people actually look at online , or are shown by search engines , found little evidence that you 're ideologically isolated .


It's the exact opposite.


Online, you are constantly confronted with opinions and world views that are not your own.

Online , you are constantly confronted with opinions and world views that are not your own .


It turns out that the place where you are the most ideologically isolated is your real life, in the real world, with real people.

It turns out that the place where you are the most ideologically isolated is your real life , in the real world , with real people .


Your real world interactions with your friends, family, colleagues and neighbors are much less diverse than your online bubble.

Your real world interactions with your friends , family , colleagues and neighbors are much less diverse than your online bubble .


The filter bubble exists in your real life, not online.

The filter bubble exists in your real life , not online .


Online filter bubbles have been the prevailing explanation as why we've all started hating each other more over the last two decades?

Online filter bubbles have been the prevailing explanation as why we 've all started hating each other more over the last two decades ?


If that's not the case, shouldn't the internet open our minds and make us more empathetic with each other?

If that 's not the case , should n't the internet open our minds and make us more empathetic with each other ?


Unfortunately, your brain is stupid.


Your brain is stupid.


Human brains didn't evolve to understand the true nature of reality, but to navigate and maintain social structures.

Human brains did n't evolve to understand the true nature of reality , but to navigate and maintain social structures .


Our ancestors desperately needed each other to survive, so our brains had to make sure we cooperated.

Our ancestors desperately needed each other to survive , so our brains had to make sure we cooperated .


That's why social isolation or exclusion feels so horrible, because it was actually life-threatening.

That 's why social isolation or exclusion feels so horrible , because it was actually life - threatening .


A tribe that worked together survived.


A divided tribe died.


The way communities worked for thousands of years is that, sure, you may have disliked a neighbor, but because you lived close to each other, you also rooted for the same sports club or saw them at church.

The way communities worked for thousands of years is that , sure , you may have disliked a neighbor , but because you lived close to each other , you also rooted for the same sports club or saw them at church .


You both thought that the people from the other village were idiots.

You both thought that the people from the other village were idiots .


Being physically close made you familiar, and created similarities that bridged the gap of different worldviews, so you didn't murder each other.

Being physically close made you familiar , and created similarities that bridged the gap of different worldviews , so you did n't murder each other .


And your worldview was probably not that different in the first place because it was formed by the same local culture.

And your worldview was probably not that different in the first place because it was formed by the same local culture .


When our brains evolved, this was enough.

When our brains evolved , this was enough .


Whoever was around was similar to us.


We liked what was similar to us.


This kept us aligned enough to work together despite our differences.

This kept us aligned enough to work together despite our differences .


As humanity moved on from small tribes to towns and cities, from chiefdoms to kingdoms to nations, our brains and our communities had to adapt to more diverse sets of neighbors.

As humanity moved on from small tribes to towns and cities , from chiefdoms to kingdoms to nations , our brains and our communities had to adapt to more diverse sets of neighbors .


We began to meet on the town square or in universities where we argued and screamed at each other.

We began to meet on the town square or in universities where we argued and screamed at each other .


But in the grand scheme of things, communities were still relatively isolated, we were still pretty similar, and aligned with the people around us.

But in the grand scheme of things , communities were still relatively isolated , we were still pretty similar , and aligned with the people around us .


Conflict and disagreement are not a bad thing per se.

Conflict and disagreement are not a bad thing per se .


Tension over how we should live can create new and wonderful things.

Tension over how we should live can create new and wonderful things .


Our values, norms, and taboos are always evolving, and whatever we think is normal today, will not be normal in the future.

Our values , norms , and taboos are always evolving , and whatever we think is normal today , will not be normal in the future .


But we also need social glue to hold our societies together because our brains don't care about the meta-level of humanity, but about being safe in a tribe.

But we also need social glue to hold our societies together because our brains do n't care about the meta - level of humanity , but about being safe in a tribe .


Until about 20 years ago, we did something truly new that hit our brains like a freight train.

Until about 20 years ago , we did something truly new that hit our brains like a freight train .


Don't you dare disagree with me.


In a nutshell, our brains are not able to process the amount of disagreement we encounter on the social internet.

In a nutshell , our brains are not able to process the amount of disagreement we encounter on the social internet .


The very mechanisms that made it possible for our ancestors to work together in the first place are derailed in ways we were not prepared for.

The very mechanisms that made it possible for our ancestors to work together in the first place are derailed in ways we were not prepared for .


Whether you want it to or not, your brain sorts people by world views and opinions into teams.

Whether you want it to or not , your brain sorts people by world views and opinions into teams .


This is not simply tribalism, it goes further.

This is not simply tribalism , it goes further .


Researchers have called this process social sorting.

Researchers have called this process social sorting .


On the digital town square, you encounter people that express opinions and share information that clash with your world view.

On the digital town square , you encounter people that express opinions and share information that clash with your world view .


But unlike your neighbor, they don't root for your local sports club.

But unlike your neighbor , they do n't root for your local sports club .


You're missing the local social glue your brain needs to align with them.

You 're missing the local social glue your brain needs to align with them .


For your brain, the disagreement between yourself and them becomes a central part of their identity.

For your brain , the disagreement between yourself and them becomes a central part of their identity .


And this makes it less likely that you will seriously consider their position or opinion in the future.

And this makes it less likely that you will seriously consider their position or opinion in the future .


If you hear bad things about them, your brain is much more likely to believe it uncritically.

If you hear bad things about them , your brain is much more likely to believe it uncritically .


On the flip side, there are people who share your world view, and are maybe even more similar to you than many people in your real life.

On the flip side , there are people who share your world view , and are maybe even more similar to you than many people in your real life .


People who think like you are probably good people because you're a good person, and whatever social group you belong to is good.

People who think like you are probably good people because you 're a good person , and whatever social group you belong to is good .


So your brain is more likely to believe their opinions.

So your brain is more likely to believe their opinions .


If you hear bad things about them, your brain is much more likely to dismiss it uncritically.

If you hear bad things about them , your brain is much more likely to dismiss it uncritically .


The engagement-driven social internet makes it worse because it wants to keep you online as long as possible.

The engagement - driven social internet makes it worse because it wants to keep you online as long as possible .


And the most engaging emotion is, unfortunately, anger.

And the most engaging emotion is , unfortunately , anger .


The more angry you get, the more likely you are to share and engage.

The more angry you get , the more likely you are to share and engage .


And this leads to social media amplifying the most extreme and controversial opinions.

And this leads to social media amplifying the most extreme and controversial opinions .


It optimizes not only to show us disagreement, but the worst disagreement possible.

It optimizes not only to show us disagreement , but the worst disagreement possible .


And because your stupid brain is sorting people into teams, whatever the worst opinions are, it assigns the same opinions to everybody on the other team.

And because your stupid brain is sorting people into teams , whatever the worst opinions are , it assigns the same opinions to everybody on the other team .


What's striking and new about online polarization is that all the aspects of our lives that make us individuals,

What 's striking and new about online polarization is that all the aspects of our lives that make us individuals ,


our lifestyle choices, the comedians or shows we watch, our religion, sense of fashion, and so on, are condensed,

our lifestyle choices , the comedians or shows we watch , our religion , sense of fashion , and so on , are condensed ,


This simplifies and distorts disagreements about how we should run society so much that it often seems as if the people on the other team are actively, willfully making the world worse.

This simplifies and distorts disagreements about how we should run society so much that it often seems as if the people on the other team are actively , willfully making the world worse .


That they're almost evil, beyond convincing with rationality, facts, or civil discussion.

That they 're almost evil , beyond convincing with rationality , facts , or civil discussion .


While you are, of course, on the correct team, it may be hard to process that you may seem like that to people on the other team.

While you are , of course , on the correct team , it may be hard to process that you may seem like that to people on the other team .


On a societal level, this is dissolving the social glue that's the foundation of our democracies.

On a societal level , this is dissolving the social glue that 's the foundation of our democracies .


If we think our neighbors are evil, how can we live together?

If we think our neighbors are evil , how can we live together ?


This is especially bad in the US, where the two-party system makes it extra easy to think of people in terms of teams.

This is especially bad in the US , where the two - party system makes it extra easy to think of people in terms of teams .


Negative opinion about the other party has reached record highs.

Negative opinion about the other party has reached record highs .


Okay, is there something we can learn from this?

Okay , is there something we can learn from this ?


Is there something we can do?


In the end, it's important to be aware of what social media does to your brain.

In the end , it 's important to be aware of what social media does to your brain .


It's easier to change yourself than to change the world,

It 's easier to change yourself than to change the world ,


so you can self-examine why you believe the things you believe, and whether you dismiss or believe information based on who the person is who is stating that information.

so you can self - examine why you believe the things you believe , and whether you dismiss or believe information based on who the person is who is stating that information .


The internet comes with a lot of upsets, and downs,

The internet comes with a lot of upsets , and downs ,


and just like we had to adapt from living in small tribes to living in cities, we need to adapt to the information age where we have access to billions of people.

and just like we had to adapt from living in small tribes to living in cities , we need to adapt to the information age where we have access to billions of people .


Evolution is too slow, so we need to find models that work with what our brains are able to tolerate.

Evolution is too slow , so we need to find models that work with what our brains are able to tolerate .


One model that seemed to work well was the pre-social media internet old people might remember.

One model that seemed to work well was the pre - social media internet old people might remember .


The main difference to today was twofold.

The main difference to today was twofold .


For one, there were no algorithms fighting to keep you online at any time.

For one , there were no algorithms fighting to keep you online at any time .


At some point, you were done with the internet for the day, as mind-blowing as this may sound.

At some point , you were done with the internet for the day , as mind - blowing as this may sound .


But more importantly, the old internet was very fractured, split into thousands of different communities, like small villages gathering around shared beliefs and interests.

But more importantly , the old internet was very fractured , split into thousands of different communities , like small villages gathering around shared beliefs and interests .


These villages were separated from each other by digital rivers or mountains.

These villages were separated from each other by digital rivers or mountains .


These communities worked because they mirrored real life much more than social media.

These communities worked because they mirrored real life much more than social media .


Each village had its own culture and set of rules.

Each village had its own culture and set of rules .


Maybe one community was into rough humor and soft moderation, another had strict rules and banned easily.

Maybe one community was into rough humor and soft moderation , another had strict rules and banned easily .


If you didn't play by the village rules, you'd be banned.

If you did n't play by the village rules , you 'd be banned .


Or you could just go and move to another village that suited you better.

Or you could just go and move to another village that suited you better .


So instead of all of us gathering in one place, overwhelming our brains at a town square that in the end just leads us to going insane, one solution to achieve less social sorting may be extremely simple.

So instead of all of us gathering in one place , overwhelming our brains at a town square that in the end just leads us to going insane , one solution to achieve less social sorting may be extremely simple .


Go back to smaller online communities.


Because what our stupid brains don't realize, is that we are actually all on the same team.

Because what our stupid brains do n't realize , is that we are actually all on the same team .


We are all in this together.


But until our brains adjust to being able to deal with that, we might be better off being a tiny bit separated.

But until our brains adjust to being able to deal with that , we might be better off being a tiny bit separated .


One of the worst things about the media we consume is that most news organizations tend to cater to one team, making you feel you're on the correct side.

One of the worst things about the media we consume is that most news organizations tend to cater to one team , making you feel you 're on the correct side .


Ground News, the sponsor of this video, is trying to make these biases more transparent by giving you tools that help you think critically about the information you consume, a mission we wholeheartedly support.

Ground News , the sponsor of this video , is trying to make these biases more transparent by giving you tools that help you think critically about the information you consume , a mission we wholeheartedly support .


Ground News gathers related articles from around the world in one place, so you can compare how different outlets and sites cover them.

Ground News gathers related articles from around the world in one place , so you can compare how different outlets and sites cover them .


They provide context about the source of the information, if they have a political bias, how reliable their reporting is, and who owns them.

They provide context about the source of the information , if they have a political bias , how reliable their reporting is , and who owns them .


This makes the news less stressful and makes you understand the world much better.

This makes the news less stressful and makes you understand the world much better .


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Our favorite tool has a personal background.

Our favorite tool has a personal background .


In 2018, Kurzgesagt founder Philip, who wrote this video, was going through chemotherapy and was intensely bored,

In 2018 , Kurzgesagt founder Philip , who wrote this video , was going through chemotherapy and was intensely bored ,


so he ended up reading all the big German newspapers, even the ones he hated, front to back, every single day.

so he ended up reading all the big German newspapers , even the ones he hated , front to back , every single day .


Aside from the obvious biases, what was the most shocking were the stories each side did not talk about.

Aside from the obvious biases , what was the most shocking were the stories each side did not talk about .


Both sides ignored things that are inconvenient to their world views.

Both sides ignored things that are inconvenient to their world views .


The Ground News Blind Spot feed highlights this exact thing, showing you news stories that are heavily covered by one side of the political spectrum and ignored by the other.

The Ground News Blind Spot feed highlights this exact thing , showing you news stories that are heavily covered by one side of the political spectrum and ignored by the other .


So check them out at ground.news.nutshell to make sure you're seeing the full picture.

So check them out at ground.news.nutshell to make sure you 're seeing the full picture .


The largest things in the universe are black holes.

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.

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.

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?

And how large is the largest of them all ?


This video will not discuss how black holes work or how they form, since we've looked at that in detail in our Black Hole and Neutron Star series.

This video will not discuss how black holes work or how they form , since we 've looked at that in detail in our Black Hole and Neutron Star series .


You can check them out afterwards.


For now, we're interested in finding the largest thing in the universe.

For now , we 're interested in finding the largest thing in the universe .


Let's start really, really small.


If they do, they're probably the oldest objects in the universe, older even than atoms.

If they do , they 're probably the oldest objects in the universe , older even than atoms .


They would have formed just after the Big Bang,

They would have formed just after the Big Bang ,


when the universe was so dense with violent energy that any tiny pocket that was just slightly more dense than its neighbors could produce a black hole.

when the universe was so dense with violent energy that any tiny pocket that was just slightly more dense than its neighbors could produce a black hole .


The smallest primordial black hole that could still be around would be a trillion kilograms or so, the mass of a big mountain.

The smallest primordial black hole that could still be around would be a trillion kilograms or so , the mass of a big mountain .


And yet, they would be no bigger than a proton.

And yet , they would be no bigger than a proton .


A primordial black hole with the mass of Earth would barely be larger than a coin.

A primordial black hole with the mass of Earth would barely be larger than a coin .


This makes them very hard to find, so we haven't actually observed any yet.

This makes them very hard to find , so we have n't actually observed any yet .


If they exist, they may even be the mysterious dark matter that holds galaxies together.

If they exist , they may even be the mysterious dark matter that holds galaxies together .


Let's move on to the kinds of black holes that we know for sure are out there.

Let 's move on to the kinds of black holes that we know for sure are out there .


To make a black hole, we need to compress enough matter so that it collapses into itself.

To make a black hole , we need to compress enough matter so that it collapses into itself .


After that, the more mass we throw at it, the larger it becomes.

After that , the more mass we throw at it , the larger it becomes .


In today's universe, only the most violent cosmic events can create the necessary conditions,

In today 's universe , only the most violent cosmic events can create the necessary conditions ,


To have a unit to work with here, we'll use the mass of our Sun, about 2 million trillion trillion kilograms.

To have a unit to work with here , we 'll use the mass of our Sun , about 2 million trillion trillion kilograms .


The smallest known black hole has 2.7 times the mass of the Sun, which works out as a sphere around 16 kilometers in diameter, large enough to cover Paris.

The smallest known black hole has 2.7 times the mass of the Sun , which works out as a sphere around 16 kilometers in diameter , large enough to cover Paris .


Another lightweight black hole is the companion to the V723 Mon red giant star.

Another lightweight black hole is the companion to the V723 Mon red giant star .


This star is 24 times larger than our Sun, 30 million kilometers in diameter.

This star is 24 times larger than our Sun , 30 million kilometers in diameter .


And yet, it's thrown around by a tiny black hole just 17.2 kilometers wide.

And yet , it 's thrown around by a tiny black hole just 17.2 kilometers wide .


This tiny thing bullying the star is so much smaller that we can barely even show them in comparison.

This tiny thing bullying the star is so much smaller that we can barely even show them in comparison .


One of the largest known stellar black holes is M33X7.

One of the largest known stellar black holes is M33X7 .


It currently spends its time eating a 70 solar mass blue giant bit by bit.

It currently spends its time eating a 70 solar mass blue giant bit by bit .


As all that stolen matter circles towards the black hole, like water going down a drain,

As all that stolen matter circles towards the black hole , like water going down a drain ,


friction heats it up to temperatures high enough to shine 500,000 times brighter than our Sun.

friction heats it up to temperatures high enough to shine 500,000 times brighter than our Sun .


And yet, X7 is only 15.65 solar masses and 92 kilometers wide, just big enough to cast a shadow on Corsica.

And yet , X7 is only 15.65 solar masses and 92 kilometers wide , just big enough to cast a shadow on Corsica .


To grow much larger, black holes have to either devour a lot of stars, or better, merge with one another.

To grow much larger , black holes have to either devour a lot of stars , or better , merge with one another .


The instruments that make it possible to detect these mergers are very new, so we're currently discovering a lot of exciting things.

The instruments that make it possible to detect these mergers are very new , so we 're currently discovering a lot of exciting things .


As they spun around each other violently, they released more energy in the form of gravitational waves than the combined light from all the stars in the Milky Way in 4,400 years.

As they spun around each other violently , they released more energy in the form of gravitational waves than the combined light from all the stars in the Milky Way in 4,400 years .


The new black hole they formed is about the size of Germany and is 142 solar masses.

The new black hole they formed is about the size of Germany and is 142 solar masses .


And here, we hit a curious gap in scale.

And here , we hit a curious gap in scale .


There are lots of black holes up to 150 solar masses, and then, there's nothing for a long time.

There are lots of black holes up to 150 solar masses , and then , there 's nothing for a long time .


Until we suddenly hit black holes that are millions of times more massive.

Until we suddenly hit black holes that are millions of times more massive .


But for the most massive black holes, this process is not fast enough to explain their existence today.

But for the most massive black holes , this process is not fast enough to explain their existence today .


The universe is simply not old enough for these supermassive black holes to have formed by eating stars and merging with each other.

The universe is simply not old enough for these supermassive black holes to have formed by eating stars and merging with each other .


Something else must have happened.


To explain how we got the largest black holes in the universe, we might need the largest stars that ever existed.

To explain how we got the largest black holes in the universe , we might need the largest stars that ever existed .


To get a sense of scale, we can compare them to the largest stars that exist today.

To get a sense of scale , we can compare them to the largest stars that exist today .


Our Sun is like a grain of sand next to them.

Our Sun is like a grain of sand next to them .


We don't know if quasi-stars actually existed, but they're an interesting concept when it comes to supercharging black hole development.

We do n't know if quasi - stars actually existed , but they 're an interesting concept when it comes to supercharging black hole development .


The idea is that the matter in the early universe was so dense that quasi-stars could grow to thousands of times the mass of our Sun.

The idea is that the matter in the early universe was so dense that quasi - stars could grow to thousands of times the mass of our Sun .


The cores of these stars might have been crushed by their own weight so much to actually collapse into black holes while the star was still forming.

The cores of these stars might have been crushed by their own weight so much to actually collapse into black holes while the star was still forming .


In contrast to stars today that would destroy themselves in the process, inside quasi-stars, a deadly balance could emerge.

In contrast to stars today that would destroy themselves in the process , inside quasi - stars , a deadly balance could emerge .


Gravity pressed the supermassive star together, feeding the black hole and heating the material falling in to such a degree that the radiation pressure kept the star stable.

Gravity pressed the supermassive star together , feeding the black hole and heating the material falling in to such a degree that the radiation pressure kept the star stable .


And so these quickly growing black holes might have been able to consume the quasi-star for millions of years and grow far bigger than any modern stellar black hole.

And so these quickly growing black holes might have been able to consume the quasi - star for millions of years and grow far bigger than any modern stellar black hole .


These black holes might have become the seeds for supermassive black holes.

These black holes might have become the seeds for supermassive black holes .


So now we arrive at the kings of our universe, the largest single bodies in existence.

So now we arrive at the kings of our universe , the largest single bodies in existence .


The centers of most galaxies contain a supermassive black hole and they are monstrous.

The centers of most galaxies contain a supermassive black hole and they are monstrous .


In the Milky Way we have Sagittarius A star, a supermassive black hole with about 4 million solar masses that is calm and collected and just does its thing.

In the Milky Way we have Sagittarius A star , a supermassive black hole with about 4 million solar masses that is calm and collected and just does its thing .


We know it sits there because we can see a number of stars being thrown around by a seemingly empty spot.

We know it sits there because we can see a number of stars being thrown around by a seemingly empty spot .


And despite its incredible mass, its radius is still only 17 times our Sun.

And despite its incredible mass , its radius is still only 17 times our Sun .


Because supermassive black holes are so massive and located at the center of galaxies, many people imagine them as being a bit like the Sun in the solar system.

Because supermassive black holes are so massive and located at the center of galaxies , many people imagine them as being a bit like the Sun in the solar system .


Instead, it's the gravitational effect of dark matter which holds them together.

Instead , it 's the gravitational effect of dark matter which holds them together .


Many supermassive black holes aren't gentle giants, especially when they're feeding on the clouds of mass in their galaxy.

Many supermassive black holes are n't gentle giants , especially when they 're feeding on the clouds of mass in their galaxy .


The one at the center of the BL Lacerty galaxy is devouring so much material that it produces jets of plasma accelerated to nearly the speed of light.

The one at the center of the BL Lacerty galaxy is devouring so much material that it produces jets of plasma accelerated to nearly the speed of light .


If Earth were orbiting this huge body, it would seem 115 times larger than our Sun in the sky and we'd be burnt to a crisp in seconds by its glowing hot accretion disk.

If Earth were orbiting this huge body , it would seem 115 times larger than our Sun in the sky and we 'd be burnt to a crisp in seconds by its glowing hot accretion disk .


At this point, black holes become so large that stars seem ridiculously tiny compared to them.

At this point , black holes become so large that stars seem ridiculously tiny compared to them .


The galaxy Cygnus A has a supermassive black hole with 2.5 billion solar masses and 14.7 billion kilometers wide,

The galaxy Cygnus A has a supermassive black hole with 2.5 billion solar masses and 14.7 billion kilometers wide ,


which would mean that if it took the place of our Sun, it would swallow all the planets and stretch halfway to the edge of our solar system.

which would mean that if it took the place of our Sun , it would swallow all the planets and stretch halfway to the edge of our solar system .


The billions of stars in galaxies are not gravitationally bound to them.

The billions of stars in galaxies are not gravitationally bound to them .


But this is a misconception.


While the Sun makes up 99.86% of all the mass in the solar system, supermassive black holes usually only have 0.001% of the mass of their galaxy.

While the Sun makes up 99.86 % of all the mass in the solar system , supermassive black holes usually only have 0.001 % of the mass of their galaxy .


It's devouring so much mass and material that it churns its disk into a kind of magnetic funnel,

It 's devouring so much mass and material that it churns its disk into a kind of magnetic funnel ,


That's two and a half Milky Ways wide.

That 's two and a half Milky Ways wide .


Another pretty large supermassive black hole sits in the galaxy Messier 87.

Another pretty large supermassive black hole sits in the galaxy Messier 87 .


It has 6.5 billion solar masses and was the first black hole we got an actual photo of, or rather, of the glowing gas around the edge of a menacing shadow.

It has 6.5 billion solar masses and was the first black hole we got an actual photo of , or rather , of the glowing gas around the edge of a menacing shadow .


This sphere of darkness is so large that it covers our entire solar system.

This sphere of darkness is so large that it covers our entire solar system .


And yet, there is a scale even above these kinds of objects.

And yet , there is a scale even above these kinds of objects .


Now, we reach the most massive black holes, perhaps the largest single bodies that will ever exist.

Now , we reach the most massive black holes , perhaps the largest single bodies that will ever exist .


These black holes have eaten so much that they've grown to tens of billions of solar masses,

These black holes have eaten so much that they 've grown to tens of billions of solar masses ,


The ultramassive black hole at the center of galaxy OJ 287 is 18 billion solar masses.

The ultramassive black hole at the center of galaxy OJ 287 is 18 billion solar masses .


It's so big that it has a supermassive black hole nearly 40 times larger than Sagittarius A star orbiting it.

It 's so big that it has a supermassive black hole nearly 40 times larger than Sagittarius A star orbiting it .


This thing defies imagination and is really hard to compare to anything.

This thing defies imagination and is really hard to compare to anything .


It can comfortably fit three solar systems side by side inside of it.

It can comfortably fit three solar systems side by side inside of it .


Let's end this insane competition and get to the king of kings.

Let 's end this insane competition and get to the king of kings .


TON 618, a black hole that we can observe consuming galaxies worth of matter, is shining with the brightness of a hundred trillion stars, visible from 18 billion light years away.

TON 618 , a black hole that we can observe consuming galaxies worth of matter , is shining with the brightness of a hundred trillion stars , visible from 18 billion light years away .


It has an incredible 66 billion solar masses, a black hole so large that it would take light a week to reach the singularity after crossing the event horizon.

It has an incredible 66 billion solar masses , a black hole so large that it would take light a week to reach the singularity after crossing the event horizon .


About 11 solar systems could sit inside of it side by side.

About 11 solar systems could sit inside of it side by side .


It may very well be the largest single body in the universe, but in reality it's probably even larger.

It may very well be the largest single body in the universe , but in reality it 's probably even larger .


Since TON 618 is so far away, we only see what it looked like 10 billion years ago.

Since TON 618 is so far away , we only see what it looked like 10 billion years ago .


In any case, black holes are scary and mysterious and gigantic.

In any case , black holes are scary and mysterious and gigantic .


They'll be here after everything else dies and growing larger and larger.

They 'll be here after everything else dies and growing larger and larger .


Okay, now let's do the trip again.


Let's try something new today.


We can call it Behind the Lies, a short behind the scenes bit about the necessary inaccuracies in this video.

We can call it Behind the Lies , a short behind the scenes bit about the necessary inaccuracies in this video .


Because it's not really actually possible to rank black holes like trading cards.

Because it 's not really actually possible to rank black holes like trading cards .


Well, while we've cataloged millions of stars, we really only have good data on a couple of dozen black holes.

Well , while we 've cataloged millions of stars , we really only have good data on a couple of dozen black holes .


That's because black hole gazing wasn't really a thing until 50 years ago, and technically still isn't because we can't see black holes.

That 's because black hole gazing was n't really a thing until 50 years ago , and technically still is n't because we ca n't see black holes .


We can only derive their properties from studying their gravitational effects on the matter around them, like the orbit of stars that come close to them.

We can only derive their properties from studying their gravitational effects on the matter around them , like the orbit of stars that come close to them .


This effect depends on the mass of the black hole, which we can approximate at the most basic level with Kepler's laws.

This effect depends on the mass of the black hole , which we can approximate at the most basic level with Kepler 's laws .


But this comes with huge uncertainties and error bars.

But this comes with huge uncertainties and error bars .


Then we have to convert mass to size next, which brings new uncertainties.

Then we have to convert mass to size next , which brings new uncertainties .


For example, we calculated the radius from the mass using the Schwarzschild equation, which for the sake of simplicity assumes black holes are perfectly round and don't spin.

For example , we calculated the radius from the mass using the Schwarzschild equation , which for the sake of simplicity assumes black holes are perfectly round and do n't spin .


The reality is that physics on these scales is a bit fuzzy.

The reality is that physics on these scales is a bit fuzzy .


So some of the black holes we talked about here may be way smaller or way bigger.

So some of the black holes we talked about here may be way smaller or way bigger .


We just don't know for sure.


We shimmied around this problem by comparing different sources with different kinds of values and using different mass calculations to arrive at a standardized list


that allowed us to be as accurate as humanly possible.

that allowed us to be as accurate as humanly possible .


You can look at all of this in our source doc.

You can look at all of this in our source doc .


As a result, this script was written with the tears of experts we drove crazy with our obsession for the best values they could live with.

As a result , this script was written with the tears of experts we drove crazy with our obsession for the best values they could live with .


In this process, tons of stuff got cut and didn't make it into the final video.

In this process , tons of stuff got cut and did n't make it into the final video .


But luckily, we found a way to not waste all of it.

But luckily , we found a way to not waste all of it .