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The White Death

John Green recently teamed up with Kurzgesagt for a video on one of the world’s deadliest diseases: tuberculosis.

The white death has haunted humanity like no other disease following us for thousands, maybe millions of years. In the last 200 years it killed a billion people โ€” way more than all wars and natural disasters combined. Even today it’s the infectious disease with the highest kill count.

The maddening bit is that tuberculosis is curable…it’s just that the cure is not equally distributed around the world.

4,000 people died of tuberculosis yesterday, and we simply don’t have to accept a world where so many of us still die of a disease we know how to cure. The White Death has been with us for millions of years. It is time to continue our journey without it.

Reply ยท 1

Are You an NPC? (Or Do You Have Free Will?)

Kurzgesagt attempts to answer the question (from the perspective of physics): Do we have free will? Here’s the deterministic perspective (from the show notes):

Now imagine that if right after the Big Bang, a supersmart supercomputer looked at every single particle in the universe and noted all their properties. Just by applying the deterministic laws of physics, it should be able to predict what all the particles in existence would be doing until the end of time.

But if you are made of particles and it’s technically possible to calculate what particles will do forever, then you never decided anything. Your past, present and future were already predetermined and decided at the Big Bang. This would mean there is a kind of fate and you are not free to decide anything.

You may feel like you make decisions, but you are on autopilot. The motions of the particles that make up your brain cells that made you watch this video were decided 14 billion years ago. You are just in the room when it happens. You are only witnessing how the universe inside you unfolds in real time.

And the other side of the argument (in favor of free will):

We know that we can reduce everything that exists to its basic particles and the laws that guide them. While this makes physics feel like the only scientific discipline that actually matters, there is a problem: You can’t explain everything in our universe only from particles.

One key fact about reality that we can’t explain by looking just at electrons and quantum stuff is emergence. Emergence is when many small things together create new fundamental traits that didn’t exist before.

Emergence occurs at all levels of reality, and reality seems to be organized in layers: atoms, molecules, cells, tissues, organs, you, society. Put many things in one layer together and they’ll create the next layer up. Every time they do, entirely new properties emerge.

Having thought about this for all of 20 minutes (or, practically all of my life), the emergence argument against determinism makes a lot of sense to me. Then again, James Gleick’s Chaos and Steven Johnson’s Emergence both made a huge impression on me when I read it more than 20 years ago.

Reply ยท 8

Do We Live in an Infinite Nesting Doll of Black Hole Universes?

Kurzgesagt is back with another video about black holes; it has the innocuous-seeming title of The Easiest Way To Build a Black Hole. But the main topic of the video is the speculation that universes (like ours!) might exist within black holes.

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

This one is a bit of a brain-bender. From the show notes:

The first part of the script is based on the empirical fact that, somewhat intriguingly, the observable universe seems to have the exact size and mass that would be required to make a black hole as big as the observable universe itself.

The second, completely independent proposal we explore is the idea that our Universe could be born from the singularity of a black hole, and that in turn the universe that contains that black hole could be born from a black hole itself. If so, universes in later generations of this process could be better fitted to produce an abundance of black holes, in a sort of “natural selection” towards efficient black hole production.

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The Paradox of an Infinite Universe

Is the universe finite or infinite? If finite, what shape is it and how does that shape influence its overall size and properties? If it’s infinite, what meaning of “expanding” can be applied to it? I don’t know if this video provides any satisfying answers, but even being able to ponder these questions is thrilling.

Infinity gets much weirder though. As you travel with your spaceship in a straight line, you find new galaxies, stars and planets, new wonders, new weird stuff, probably new aliens and new lifeforms stranger than you could ever imagine. But after a long time, you might find the most special thing in the universe: Yourself. An exact copy of you watching this video right now.

How can that be? Well, everything in existence is made of a finite amount of different particles. And a finite number of different particles can only be combined in a finite number of ways. That number may be so large that it feels like infinity to our brains โ€” but it is not really. If you have finite options to build things, but infinite space that is full of things in all directions forever, then it makes sense that by pure chance, there will likely be repetition.

Reply ยท 2

Did The Future Already Happen?

Kurzgesagt’s latest video on the paradox of time is a bit more of a brain-bender than their usual videos. From the accompanying sources document:

This video summarizes in a narrative format two well-known theories about time: the so-called “block universe” and the “growing block”.

The block universe is an old theory of time which appears to be an unavoidable consequence of Einstein’s theory of special relativity. In philosophical contexts, basically the same idea is known as “eternalism”. Simplified, this theory posits that, although not apparent to our human perception, both the past and the future exist in the same way as the present does, and are therefore as real as the present is: The past still exists and the future exists already. As a consequence, time doesn’t “flow” (even if it looks so to us) and things in the universe don’t “happen” - the universe just “is”, hence the name “block universe”.

But then: “Quantum stuff is ruining everything again.” And so we have the growing block theory:

The Evolving/Growing Block: A relatively new alternative to the classical block universe theory, which asserts that the past may still exist but the present doesn’t yet, and all that in a way that is still compatible with Einstein’s relativity.

And there are still other theories about how time works:

Some scientists think that the idea of “now” only makes sense near you, but not in the universe as a whole. Others think that time itself doesn’t even exist โ€” that the whole concept is an illusion of our human mind. And others think that time does exist, but that it’s not a fundamental feature of the universe. Rather, time may be something that emerges from a deeper level of reality, just like heat emerges from the motion of individual molecules or life emerges from the interactions of lifeless proteins.

Like I said, a brain-bender.

From The Smallest to the Largest Thing in The Universe

I’ve posted more than a few size comparison videos here over the years โ€” Powers of Ten is the obvious one โ€” but this one from Kurzgesagt is one of the best, showing how big everything in the universe is compared to humans, who seemingly find themselves smack in the middle. This video does an excellent job illustrating the similarity of structures and interdependency across different scales โ€” how blood vessels are like city streets for instance or how very tiny proteins can affect the entire Earth.

Reply ยท 0

How Would Interstellar Weaponry Work?

In their latest video, Kurzgesagt takes a break from their more serious topics to consider a scenario from the realm of science fiction: interstellar combat. Using technology that is theoretically available to us here on Earth, could a more advanced civilization some 42 light years away destroy our planet without any warning? They outline three potential weapons: the Star Laser, the Relativistic Missile, and the Ultra-Relativistic Electron Beam.

Here’s what I don’t understand though: how would the targeting work? In order for an alien civilization to hit the Earth with a laser from 42 light years away, it has to not only predict, within a margin of error of the Earth’s diameter, precisely where the Earth is going to be, but also have a system capable of aiming across 42 light years of distance with that precision. Is this even possible? How precisely do we know where the Earth is going to be in 42 years? And if you’re aiming at something 42 light years away, if you move the sights a nanometer, how much angular distance does that shift the the destination by? And how much does the gravity of matter along the way shift the trajectory and is it possible to accurately compensate for that? Maybe this should be their next video…

Reply ยท 6

A 4.5 Billion Year Video Timeline of Earth in 60 Minutes

To mark the 10th anniversary of their YouTube channel, Kurzgesagt has released a video timeline of the Earth’s evolution, all 4.5 billion years of it. The video is 60 minutes long, which means that each second shows about 1 million years. And it’s kind of a music video…of sorts? There’s talking but there are definitely stretches of just music and visuals…it’s not your usual science explainer video.

Hop on a musical train ride and experience how long a billion years really is. It’s the perfect background for your next party, a great way to take a break from studying, or a fascinating companion while you’re on the go.

What Happens If You Destroy A Black Hole?

Here’s a fun thought experiment: can you destroy a black hole? Nuclear weapons probably won’t work but what about antimatter? Or anti black holes? In this video, Kurzgesagt explores the possibilities and impossibilities. This part baked my noodle (in a good way):

Contrary to widespread belief, the singularity of a black hole is not really “at its center”. It’s in the future of whatever crosses the horizon. Black holes warp the universe so drastically that, at the event horizon, space and time switch their roles. Once you cross it, falling towards the center means going towards the future. That’s why you cannot escape: Stopping your fall and turning back would be just as impossible as stopping time and traveling to the past. So the singularity is actually in your future, not “in front of you”. And just like you can’t see your own future, you won’t see the singularity until you hit it.


The Reason Why Cancer Is So Hard to Beat

Using the metaphor of a cancerous tumor as an unruly village, Kurzgesagt explains how cancer develops in the human body, how the body fights against it, and how, sometimes, the cancer develops into something unmanageable.

In a sense this tiny tumor is like a rogue town. Imagine a group of rebels in Brooklyn decided that they were no longer part of New York but started a new settlement called Tumor Town, which happens to occupy the same space. The new city wants to grow, so it orders tons of steel beams, cement and drywall. New buildings follow no logic, are badly planned, ugly and dangerously crooked. They are built right in the middle of streets, on top of playgrounds and on existing infrastructure. The old neighborhood is torn down or overbuilt to make room for new stuff. Many of the former residents are trapped in the middle of it and begin to starve. This goes on for a while until the smell of death finally attracts attention. Building inspectors and police show up.

The Black Hole That Kills Galaxies

Astronomers believe that there’s a black hole at the center of almost every large galaxy in the universe. Some of those black holes are particularly energetic, chewing up the galaxies in which they reside and releasing massive amounts of energy out into the cosmos. Those black holes and the energy emitted from matter and gas falling towards their centers are what astronomers call quasars.

But if we look closely, we see who is actually in charge. Small as a grain of sand compared to the filaments, the centers of some of these galaxies shine with the power of a trillion stars, blasting out huge jets of matter, completely reshaping the cosmos around them. Quasars, the single most powerful objects in existence, so powerful that they can kill a galaxy.

Your Body Is Never Not Killing Cancer

From Kurzgesagt, this video is a good overview of the arms race going on in all human bodies between cancer cells and the defenses developed by our immune systems over the years.

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

What is cancer and how does your body kill it all the time?

What Happens When You Get Sick?

From Kurzgesagt, an accessible explanation of what happens to the human body when you get sick.

Your brain activates sickness behavior and reorganizes your body’s priorities to defense. The first thing you notice is that your energy level drops and you get sleepy. You feel apathetic, often anxious or down and you lose your appetite. Your sensitivity to pain is heightened and you seek out rest. All of this serves to save your energy and reroute it into your immune response.

They also reveal the best way to boost your immune system to protect yourself against disease. I don’t want to spoil it but it’s vaccines. Vaccines are one of the best things humans have ever invented.

Happy 10th Anniversary to Kurzgesagt

This year, Kurzgesagt celebrates 10 years of making videos on YouTube and to mark the occasion, they’ve produced this video about their history, how their business works (their shop accounts for a large chunk of their revenue), and the values that guide their work.

Kurzgesagt’s foundation was laid when Philipp, our founder, dropped out of high school as a teenager. Learning seemed daft and useless and he was not interested in anything. Until a very special teacher at a school for dropouts grabbed him by the neck. The way she taught was different. She talked about connections and the big picture. She told a story. For the first time ever, Philipp wanted to learn more without being forced. It was a key life experience.

Kurzgesagt tries to recreate this experience for you. “Nothing is boring if you tell a good story, and we try to tell these stories to spark excitement and make you want to go on and learn more. Because of the one teacher that could do this, Philipp got a high school degree, studied history and design and eventually started Kurzgesagt as a passion project, inspired by Crash Course World history.

Some of you might not be interested in something that seems pretty inside baseball, but I post a lot of Kurzgesagt’s videos here and I’ve always admired the way they go about their business โ€” their commitment to quality, painstaking research, an ability to admit when they got it wrong, non-extractive revenue streams with a heavy emphasis on direct reader support โ€” and it was great to hear them talk about it.

Travelling to The Most Extreme Place in The Universe

In a 1959 talk entitled There’s Plenty of Room at the Bottom, physicist Richard Feynman casually invented nanotechnology, inviting the audience and then the world to imagine exploring and making use of the “inner space” of the micro and nano realms. In this video from Kurzgesagt, thye imagine how things would seem if you could somehow shrink yourself down to the size of a grain of sand or a molecule or even smaller, sort of a more educational (but still fun) Ant-Man and the Wasp: Quantumania.

You are the size of a grain of sand just 2 mm high, standing on a blade of grass that seems as tall as an eight storey building to you. A square meter of lawn is now a dense metropolitan area, with 100,000 blades, or two Manhattans worth of grass towers. From your new tiny perspective, the park that you could quickly stroll through before, is now the size of France. Crossing it would take at least a week. Human-sized humans loom over you, 4 times taller than the Empire state building, their steps falling from horizon to horizon.

A bee the size of a helicopter lands near you, making the ground shake, as its hairy carapace vibrates with each wingbeat. You try to escape but are barely able to move because the air is so… gooey. Before you clicked the button air resistance was barely noticeable โ€” but as you’re now a thousand times smaller, it is as if the air has become a thousand times denser. It feels like you are moving through honey.

Flying insects like bees use this to their advantage. Their wings are not made for gliding but like paddles that row through the air. Scaled up to human size, the bee would outrun a Concorde Jet โ€” except it couldn’t even take off because it would be too heavy for its wings.

See also Meet the Nano Sapiens, Scaling Laws and the Speed of Animals, The Biology of B-Movie Monsters, and Powers of Ten.

Proteins and Life: How Do Dead Things Become Alive?

DNA and RNA get all of the headlines, but it’s not difficult to argue that much of the glorious complexity and possibility of life is due to proteins. In the latest episode of Kurzgesagt, they explain the role of cellular proteins in creating life.

You are cells. Your muscles, organs, skin and hair. They are in your blood and in your bones.

Cells are biological robots. They don’t want anything, they don’t feel anything. They are never sad or happy. They just are, right here, right now. They are as conscious as a stone or a chair or a neutron star. Cells just follow their programming that has been evolving and changing for billions of years, molded by natural selection.

They are impossible machines and yet, here they are, driven entirely by the fundamental forces of the universe. The smallest unit of life, right at the border where physics becomes biology.

Sometimes, to get a truer understanding of how amazing something is, you need to hold your breath and dive in really deep. So, what are cells and how do they work?

As always, you can see a list of their sources and further reading for the video.

How to Change Your Life, One Tiny Step at a Time

Here’s Kurzgesagt on the deceptively simple way we can make changes in our life: build new routines and turn them into habits.

If you are like most people, there is a gap between the person you are and the person you wish to be. There are little things you think you should do and big things you ought to achieve โ€” from working out regularly, eating healthy, learning a language, working on your novel, reading more or simply actually doing your hobby instead of browsing Reddit.

But it can seem that to achieve your goals, you have to become a different person. Someone who is consistent, puts in more effort, has discipline and willpower. Maybe you have tried your hardest to be like that. And it worked! For a while. Until you find yourself slipping back into your old ways. In the end, you always seem to fail. And with every failed attempt, you become more and more frustrated and annoyed with yourself.

If you believe “success and hustle” internet, it is all your own fault: if you don’t succeed, you just didn’t want it enough and the failure is all you. But change is actually hard. But as with most things in life, understanding why makes things easier.

The Brain Eating Amoeba, the Most Overhyped Monster on Earth

In retrospect, maybe today wasn’t such a good day to watch a video about how incredibly scary brain-eating amoebas are. But, as you might guess from the title, we don’t actually need to worry too much about them.

While the Naegleria fowleri is clearly extremely deadly and the infection truly horrible, there have only been a few hundred cases in the last few decades. You are way more likely to drown in a pool than to get infected.

A reminder that in our current media environment, calibrating personal risk can be challenging.

We Have the Tools to Fix the Climate. We Just Need to Use Them.

A new video from Kurzgesagt is designed to provide a little hope that humans can figure a way out of the climate crisis, without being overly pollyannish.

And so for many the future looks grim and hopeless. Young people feel particularly anxious and depressed. Instead of looking ahead to a lifetime of opportunity they wonder if they will even have a future or if they should bring kids into this world. It’s an age of doom and hopelessness and giving up seems the only sensible thing to do.

But that’s not true. You are not doomed. Humanity is not doomed.

There’s been progress in the last decade, in terms of economics, technology, policy, and social mores. It’s not happening fast enough to limit warming to 1.5ยฐC, but if progress continues, gains accumulate, people keep pushing, and politicians start to figure out where the momentum is heading, we can get things under control before there’s a global apocalypse.

Are There Lost Civilizations in Earth’s Past?

The Earth is some 4.5 billion years old and the first life on Earth appeared 3.7 billion years ago (if not earlier). That’s a lot of time…so maybe it’s possible that a civilization existed at some point during that time and then vanished without a trace. In this video, Kurzgesagt explores the Silurian hypothesis.

When we think about alien civilizations we tend to look into the vastness of space, to far away planets. But there is another incredibly vast dimension that we might be giving too little thought to: time.

Could it be that over the last hundreds of millions of years, other civilizations existed on earth? Indigenous technological species that rose and died out? And that they or their artifacts are buried beneath our feet? What does science have to say about this and what are the implications for us?

See also Could an Industrial Prehuman Civilization Have Existed on Earth Before Ours? and Was There a Civilization on Earth Before Humans?.

The Dark Forest (Or, Why We Should Keep Still and Not Look for Aliens)

Inspired by the second book in Liu Cixin’s excellent Three-Body Problem trilogy, Kurzgesagt made a video about the Dark Forest solution to the Fermi paradox.

Confronted with the seemingly empty universe, humanity faces a dilemma. We desperately want to know if we are alone in the Milky Way. We want to call out and reveal ourselves to anyone watching but that could be the last thing we ever do. Because maybe the universe is not empty. Maybe it’s full of civilizations but they are hiding from each other. Maybe the civilizations that attracted attention in the past were wiped away by invisible arrows. This is the Dark Forest solution to the Fermi paradox.

I have The Dark Forest on the Kindle, so I looked up how this is explained in the book (spoilers, obvs):

“The universe is a dark forest. Every civilization is an armed hunter stalking through the trees like a ghost, gently pushing aside branches that block the path and trying to tread without sound. Even breathing is done with care. The hunter has to be careful, because everywhere in the forest are stealthy hunters like him. If he finds other life-another hunter, an angel or a demon, a delicate infant or a tottering old man, a fairy or a demigod-there’s only one thing he can do: open fire and eliminate them. In this forest, hell is other people. An eternal threat that any life that exposes its own existence will be swiftly wiped out. This is the picture of cosmic civilization. It’s the explanation for the Fermi Paradox.”

Shi Qiang lit another cigarette, if only to have a bit of light.

“But in this dark forest, there’s a stupid child called humanity, who has built a bonfire and is standing beside it shouting, ‘Here I am! Here I am!’” Luo Ji said.

“Has anyone heard it?”

“That’s guaranteed. But those shouts alone can’t be used to determine the child’s location. Humanity has not yet transmitted information about the exact position of Earth and the Solar System into the universe. From the information that has been sent out, all that can be learned is the distance between Earth and Trisolaris, and their general heading in the Milky Way. The precise location of the two worlds is still a mystery. Since we’re located in the wilderness of the periphery of the galaxy, we’re a little safer.”

That’s the basic idea, but there’s more to it…you should watch the video or, even better, read the series โ€” I’ve read the entire trilogy twice and this makes me want to read it again! (I loved the Drive Easter egg towards the end of the video. Well played.)

Reimagining Dinosaurs

The fossil record has provided us with so much information about plants, animals, and organisms that lived hundreds, thousands, millions, and even billions of years ago. But we are actually only seeing evidence of a tiny fraction of the species that lived then and even for those we do know about, there’s often much we still don’t know. Traditionally, dinosaurs have been depicted as drab and often terrible lizards but recent finds of soft tissues (skin, feathers, etc.) and an increased sense of imagination based on our current vibrant biodiversity has people thinking differently about how they looked and behaved.

This Virus Shouldn’t Exist (But it Does)

In one of their most popular videos in awhile, favorite Kurzgesagt tells us about something I’d never heard of before: giruses. These giant viruses have only been discovered within the last 20 years and are so large and contain so much genetic material that maybe they are actually alive?

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

It turns out that there are giant viruses that blur the line between life and death โ€” and other viruses hunting them.

How the Human Immune System Works

In the first part of a multi-video series on how the human immune system works, Kurzgesagt describes how the system’s first lines of defense work when your body is invaded by microorganisms.

The human immune system is the most complex biological system we know, after the human brain, and yet, most of us never learn how it works. Or what it is. Your immune System consists of hundreds of tiny and two large organs, it has its own transport network spread throughout your body. Every day it makes hundreds of billions of fresh cells.

It is not some sort of abstract entity. Your immune system is YOU. Your biology protecting you from the billions of microorganisms that want to consume you and from your own perverted cells that turn into cancer.

Kurzgesagt founder Philipp Dettmer is publishing a companion book to the series, Immune: A Journey Into the Mysterious System That Keeps You Alive; it’s out in late September.

I have read a lot about the human immune system over the past 18 months, but this video was still helpful in understanding how it all fits together. For more information, consult their extensive list of sources or watch their earlier video on what the SARS-CoV-2 virus does to a human body.

Size Comparison: The Largest Black Hole in the Universe

Black holes are the largest single objects in the universe, many times larger than even the biggest stars, and have no upper limit to their size. But practically, how big is the biggest, heaviest black hole in the universe? (A: More massive than the entire Milky Way.)

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

Videos about space are where Kurzgesagt really shines. I’ve seen all their videos about black holes and related objects, and I always pick up something I never knew whenever a new one comes out. This time around, it was quasistars and the surprisingly small mass of supermassive black holes located at galactic centers compared to the galaxies themselves.

A Minute by Minute Account of the Day the Dinosaurs Died

Perhaps the most consequential day in the Earth’s recent history was when a massive asteroid struck the planet 66 million years ago. It resulted in earthquakes, tsunamis, fireballs raining from the sky, volcanoes, atmospheric heat shocks, wildfires, global winter, and the extinction of 75% of all species on Earth, including the dinosaurs. This video by Kurzgesagt leads us through what happened that day, minute by minute.

This video reminded me of Peter Brannen’s eye-popping description of this event from his book The Ends of the World:

“The meteorite itself was so massive that it didn’t notice any atmosphere whatsoever,” said Rebolledo. “It was traveling 20 to 40 kilometers per second, 10 kilometers โ€” probably 14 kilometers โ€” wide, pushing the atmosphere and building such incredible pressure that the ocean in front of it just went away.”

These numbers are precise without usefully conveying the scale of the calamity. What they mean is that a rock larger than Mount Everest hit planet Earth traveling twenty times faster than a bullet. This is so fast that it would have traversed the distance from the cruising altitude of a 747 to the ground in 0.3 seconds. The asteroid itself was so large that, even at the moment of impact, the top of it might have still towered more than a mile above the cruising altitude of a 747. In its nearly instantaneous descent, it compressed the air below it so violently that it briefly became several times hotter than the surface of the sun.

“The pressure of the atmosphere in front of the asteroid started excavating the crater before it even got there,” Rebolledo said. “Then when the meteorite touched ground zero, it was totally intact. It was so massive that the atmosphere didn’t even make a scratch on it.”

Unlike the typical Hollywood CGI depictions of asteroid impacts, where an extraterrestrial charcoal briquette gently smolders across the sky, in the Yucatan it would have been a pleasant day one second and the world was already over by the next. As the asteroid collided with the earth, in the sky above it where there should have been air, the rock had punched a hole of outer space vacuum in the atmosphere. As the heavens rushed in to close this hole, enormous volumes of earth were expelled into orbit and beyond โ€” all within a second or two of impact.

“So there’s probably little bits of dinosaur bone up on the moon,” I asked.

“Yeah, probably.”

Your Wild and Precious Life

How do you know what to do with your life? The introduction to this new and uncharacteristically existential Kurzgesagt video is some real truth:

Wrapping your mind around your life is pretty hard, because you are up to your neck in it. It’s like trying to understand the ocean while learning how to swim. On most days you are busy just keeping your head above water. So it is not easy to figure out what to do with your life and how to spend your time. There are a million distractions. Your family, friends and romantic partners, boring work, and exciting projects. Video games to play and books to read. And then there is your couch that somebody needs to lie on. It’s easy to get lost.

Thinking about this stuff can be kind of a downer, as the writer of this video admits in a comment:

It’s so easy to get lost in your daily life: there are so many “urgent” and “annoying” things that you forget that actually every day is special, sort of. And even more so the days we have with friends and family. I know watching a video like this can hit pretty hard. But at least for me, the message it tries to convey does make me actually change my behavior. Reprioritize things. You know. Hope it had a similar effect for some of you.

See also Your Life in Weeks by Tim Urban.

The Final Border Humanity Will Never Cross

This video focuses on one of my favorite astrophysics facts: 94% of the observable universe is permanently unreachable by humans. (Unless we discover faster-than-light travel, but that’s fantasy at this point.)

This expansion means that there is a cosmological horizon around us. Everything beyond it, is traveling faster, relative to us, than the speed of light. So everything that passes the horizon, is irretrievably out of reach forever and we will never be able to interact with it again. In a sense it’s like a black hole’s event horizon, but all around us. 94% of the galaxies we can see today have already passed it and are lost to us forever.

“Since you started watching this video, around 22 million stars have moved out of our reach forever.” And future generations, billions of years from now, won’t even be able to see any other galaxies or detect cosmic background radiation, making knowledge about the Big Bang impossible.

An Animated Primer on Black Holes

You’re probably aware that black holes are weird. You can learn more about just how extremely odd they are by watching this animated primer on black holes by Kurzgesagt. The explanation about how long black holes live starting at ~9:30 is legitimately mindblowing โ€” that hourglass metaphor especially.

Using Nuclear Energy to Stop Climate Change

This new video from Kurzgesagt takes a look at the possible role of nuclear energy in helping to curb the effects of our climate emergency.

Do we need nuclear energy to stop climate change? More and more voices from science, environmental activists and the press have been saying so in recent years โ€” but this comes as a shock to those who are fighting against nuclear energy and the problems that come with it. So who is right? Well โ€” it is complicated.

Rebecca Tuhus-Dubrow wrote about climate change activists who are embracing nuclear energy for the New Yorker back in February.

In the course of years, Hoff grew increasingly comfortable at the plant. She switched roles, working in the control room and then as a procedure writer, and got to know the workforce โ€” mostly older, avuncular men. She began to believe that nuclear power was a safe, potent source of clean energy with numerous advantages over other sources. For instance, nuclear reactors generate huge amounts of energy on a small footprint: Diablo Canyon, which accounts for roughly nine per cent of the electricity produced in California, occupies fewer than six hundred acres. It can generate energy at all hours and, unlike solar and wind power, does not depend on particular weather conditions to operate. Hoff was especially struck by the fact that nuclear-power generation does not emit carbon dioxide or the other air pollutants associated with fossil fuels. Eventually, she began to think that fears of nuclear energy were not just misguided but dangerous. Her job no longer seemed to be in tension with her environmentalist views. Instead, it felt like an expression of her deepest values.

For more reading on the topic, check out Kurzgesagt’s list of source materials used to make their video.