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

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

Being a citizen of the European Union means that many aspects of our lives are regulated by a weird entity. It feels like a huge bureaucracy is making decisions over our heads. How democratic is the EU really and does your vote actually affect anything?

Getting to space is incredibly hard, expensive and needs a lot of resources. A more efficient way to get there is a Skyhook (or Spacetether), an ever rotating cable with a counter weight, that catapults spaceships from earth orbit into the depths of space.

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

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?

How will the Universe die?

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

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

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

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

Life has existed on one planet for about 4 billion years, for all we know. But it might have started right after the Big Bang, when the universe was much stranger and more fantastic than today. A universe that might have allowed life to develop absolutely anywhere. The cosmos might be full of the seeds of life, sleeping in a dead desert, waiting for a few drops of rain to explosively bloom and grow. Tiny and not so tiny aliens might be everywhere.

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.

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?

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

The current crisis in Iraq explained in under 5 minutes.

Black holes. Lets talk about them.

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

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

Nothing in the Universe is static. In the milky way, billions of stars orbit the galactic center. Some, like our sun, are pretty consistent, keeping a distance of around 30,000 light years from the galactic center, completing an orbit every 230 million years. This dance is not an orderly ballet - more like a skating rink filled with drunk toddlers. This chaos makes the galaxy dangerous. Our solar neighbourhood is constantly changing, with stars moving hundreds of kilometers every second. Only the vast distances between objects protect us from the dangers out there. But we might get unlucky in the future. At some point we could encounter a star going supernova. Or a massive object passing by and showering earth with asteroids. If something like this were to happen we would likely know thousands, if not millions of years in advance. But we still couldn’t do much about it. Unless… we move our whole solar system out of the way.

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

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

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

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