Kurzgesagt - In a Nutshell 2024

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

A nuclear bomb is the most devastating explosion ever created. One bomb can end tens of thousands of lives immediately and hundreds of thousands through the radioactive aftermath. However, the worst part comes afterward: a nuclear winter that might kill billions, potentially leading to the complete collapse of our civilization. In a nuclear winter, there are no winners – only starving losers. How exactly does it work and what would it look like?

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

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

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

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

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.

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

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 – way more than all wars and natural disasters combined. Even today it’s the infectious disease with the highest kill count. But what is this horrible disease?

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

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

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

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

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

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

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

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

“Your blood vessels stretch a staggering 100,000 kilometers, enough to wrap around Earth twice!" Sounds amazing, right? We spent over a year trying to confirm this claim, and let's just say – things aren't as they seem. Join us on our year-long journey that uncovered outdated science, speculation, and a lot of dead ends.

At the height of the Cold War, a terrifying concept emerged: a bomb so powerful it wouldn’t need to be dropped. Known as Project Sundial, this doomsday device would have left a 400-km radius in flames and plunged the world into darkness. It was a bomb that would destroy everything – not a weapon, but an apocalypse. How close did we come to pressing the button?

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

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

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

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

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