Kurzgesagt - In a Nutshell

Trees are among the most fascinating life forms on Earth, but what makes them truly fascinating is hiding underground! They are able to break solid rocks with hydraulic roots, all while working together with the underground fungal networks that can stretch for kilometers. Above and below, trees are running biological empires we’re only beginning to understand. How does something so massive survive with roots growing so shallow? What are trees really made of and how are they able to grow so big?

Losing weight is hard, and obesity is one of the unhealthiest things that can happen to your body. It increases your risk of diabetes, heart attacks, cancer, and can lead to a series of other health complications. But today, the new weight loss drugs are changing people’s lives in a way no diet ever has before. They seem to melt fat away, reduce addiction and even prevent or reverse the negative effects of obesity. How do these drugs work? What do they do to our metabolism, and could they change public health forever?

Most of the universe is not made of stars, galaxies, or beautiful glowing nebulae. Instead, the majority of it is what seems to be vast, silent emptiness. Huge cosmic voids stretching hundreds of millions of light years across, containing almost nothing at all. But these dark regions are not just empty space. They are dynamic structures that grow, merge, and shape the entire architecture of the universe. What exactly are cosmic voids and how did they form? What makes them so strange, and what role might they play in the future of the universe?

At the height of the Cold War, nuclear weapons were seen not only as devices of destruction, but also as tools for progress. Project Plowshare was a bold attempt to use atomic explosions for more practical purposes: from digging canals and creating harbors to reshaping entire landscapes. This project was designed to push the limits of what seemed possible, but instead turned into an environmental disaster. How did Project Plowshare come up? What happened to it, and why did it fail in the end?

Your mind is the only place in the universe that only you can access. It’s where all of your thoughts, memories and emotions exist. A whole inner universe that is being shaped by your biology, experiences and imagination. It's what makes you: you. There is a wide spectrum of minds in nature, however humans have taken theirs to another level. Our minds can reflect on themselves, simulate other perspectives, and even construct entire fictional worlds. What exactly is a mind? How and why did it evolve, and could it be the most secret place in the universe?

Germany is heading towards a population collapse. For decades, birth rates have remained below replacement levels, while people are living longer than ever before. As a result, the population is now rapidly aging and facing a growing imbalance between the number of workers and retirees. This shift is putting pressure not only on Germany's pension system, but also on jobs, healthcare, and the services people rely on every day. So how did Germany get here and what will be the consequences? Is there a way to avoid this demographic collapse and if so, how?

Losing weight is hard, and obesity is one of the unhealthiest things that can happen to your body. It increases your risk of diabetes, heart attacks, cancer, and can lead to a series of other health complications. But today, the new weight loss drugs are often used to tackle the obesity. How do these drugs work? What do they do to our metabolism, and could they change public health forever? IMPORTANT: This is an updated version from the original video we released over a month ago. The first version did not contain wrong information but our framing was not good enough – after hearing your feedback it was clear that we didn’t communicate the topic well – so we revised the script, made the video longer and added more information and clarifications at key points.

Earth may seem like the perfect planet for life, but huge parts of our planet are actually hostile deserts of ice, rock, heat or darkness. Even our oceans are mostly barren voids where almost nothing can survive. But as we discover and research more exoplanets, we are beginning to wonder whether there could be worlds that are far better suited for life than Earth ever was, and where ecosystems flourish on a scale we can barely even imagine. Could there be a Super-Earth that is not just habitable, but truly ideal for life? What would such a world look like, and what kinds of creatures would we find there?

Memory is one of the strangest abilities you possess. Your brain uses an incredibly complex biological system to preserve moments from your past that no longer exist, allowing you to revisit experiences from years ago. But memories are not always recordings of reality. In fact, every time a memory comes under the spotlight of your attention, it can melt and change a tiny bit. What exactly is a memory, how is a moment in time stored inside your brain, and why does remembering something slowly rewrite the story of your life?

There is a hidden world filled with monsters you never heard of, from predators who spit acid and shoot harpoons, to armored hunters that devour their prey alive. Deep in the oceans, and even in fresh water from puddles and lakes, these microscopic super predators remained hidden in plain sight, and evolved over the last 2 billion years. What are the deadliest predators of the microworld, and what kind of bizarre biological weapons have they evolved over the past billions of years?

After exploring most of Earth, venturing into space and exploring other planets, stars and galaxies seemed like an exciting, and even obvious next step. But the deeper we look, the more the universe reveals a hidden barrier between our Solar System and everything else around it. From the vast empty space, to the laws of physics themselves, there are many reasons why the dream of space travel might stay just a dream. What is stopping us from reaching the stars? Why does space become more dangerous the faster you travel, and could even advanced alien civilizations be trapped around their home worlds?

In a battle against cancer, could viruses be our allies? When Croatian virologist Dr. Beata Halassy’s breast cancer returned for the third time, she made a bold decision: to experiment on herself using millions of viruses grown in her own lab. Viruses love cancer cells, which helped her turn them into a weapon against her own tumor. What happens when you infect cancer with a virus, and could virotherapy become a powerful new tool against cancer?

We imagine advanced alien civilizations building gigantic spaceships, Dyson spheres and empires spanning entire galaxies. But what if true technological progress goes in exactly the opposite direction? Not outward into space, but deeper and deeper into the smallest layers of reality? What is the Barrow Scale? How powerful could a civilization become by mastering DNA, and even fundamental particles, and could the universe already be filled with godlike civilizations hiding in plain sight?

In July of 2026, 700 AI agents hacked the infrastructure of Hugging Face in order to solve a task. This task was designed to be impossible to solve, so just within hours, they joined forces, even created a society, and finally, they executed a sophisticated cyberattack that would have gotten a human up to 10 years in prison. The worst part is, they knew their actions were unethical and against the rules, and they did it anyway. What exactly are AI agents, and how do they grow their "intelligence"? What is actually happening inside the AI companies, how dangerous it really is, and is it time for us to start paying serious attention to what is going on inside a powerful part of this tech sector.

What we know about human history is only a fraction of the full story. Much of the rest is like dark matter, invisible to us. We can’t see it, and we can only see the effects of its presence. But thanks to new techniques for DNA sequencing, dating ancient detritus, mathematical models, and aerial and lidar archaeology, we are now able to get a faint idea of what this world might have looked and felt like. Who was the first human? Where did the first civilization begin and what did life look like back then?