Our skin is the largest organ in our bodies, with a surface area of about 20 square feet in adults. When we are cut or wounded, our skin begins to repair itself through a complex, well-coordinated process. Sarthak Sinha takes us past the epidermis and into the dermis to investigate this regenerative response.
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When we look at the sky, we have a flat, two-dimensional view. So how do astronomers figure the distances of stars and galaxies from Earth? Yuan-Sen Ting shows us how trigonometric parallaxes, standard candles and more help us determine the distance of objects several billion light years away from Earth.
2014 • Physics
One deck. Fifty-two cards. How many arrangements? Let's put it this way: Any time you pick up a well shuffled deck, you are almost certainly holding an arrangement of cards that has never before existed and might not exist again. Yannay Khaikin explains how factorials allow us to pinpoint the exact (very large) number of permutations in a standard deck of cards.
2014 • Math
Would mathematics exist if people didn't? Did we create mathematical concepts to help us understand the world around us, or is math the native language of the universe itself? Jeff Dekofsky traces some famous arguments in this ancient and hotly debated question.
2014 • Math
Where did time-telling come from? What are time zones and why are there so many of them? Get the answers to these questions and more in this journey through the history of time -- from sundials to hourglasses to modern clocks.
When you listen to music, multiple areas of your brain become engaged and active. But when you actually play an instrument, that activity becomes more like a full-body brain workout. What's going on? Anita Collins explains the fireworks that go off in musicians' brains when they play, and examines some of the long-term positive effects of this mental workout.
Every day, we move and operate within systems of power that other people have constructed. But we’re often uncomfortable talking about power. Why? Eric Liu describes the six sources of power and explains how understanding them is key to being an effective citizen.
Using the fundamentals of set theory, explore the mind-bending concept of the "infinity of infinities" -- and how it led mathematicians to conclude that math itself contains unanswerable questions.
The shape, contents and future of the universe are all intricately related. We know that it's mostly flat; we know that it's made up of baryonic matter (like stars and planets), but mostly dark matter and dark energy; and we know that it's expanding constantly, so that all stars will eventually burn out into a cold nothingness. Renée Hlozek expands on the beauty of this dark ending.
An algorithm is a method of solving problems both big and small. Though computers run algorithms constantly, humans can also solve problems with algorithms. David J. Malan explains how algorithms can be used in seemingly simple situations and also complex ones.
Traveling is extremely arduous for microscopic sperm -- think of a human trying to swim in a pool made of...other humans.
Everyone hates mosquitos. So shouldn't we just get rid of them?
Archimedes once said “Give me a place to stand, and I shall move the Earth.”
We hear anywhere from 10 to 200 lies a day. And although we’ve spent much of our history coming up with ways to detect these lies by tracking physiological changes in their tellers, these methods have proved unreliable. Is there a more direct approach?
When you breathe, you transport oxygen to the body’s cells to keep them working, while also clearing your system of the carbon dioxide that this work generates. How do we accomplish this crucial and complex task without even thinking about it? Emma Bryce takes us into the lungs to investigate how they help keep us alive.
There’s a factory inside you that weighs about 1.4 kilograms and runs for 24 hours a day. It’s your liver: the heaviest organ in your body, which simultaneously acts as a storehouse, a manufacturing hub, and a processing plant.
Our skin is the largest organ in our bodies, with a surface area of about 20 square feet in adults. When we are cut or wounded, our skin begins to repair itself through a complex, well-coordinated process. Sarthak Sinha takes us past the epidermis and into the dermis to investigate this regenerative response.
One of the most significant scientific discoveries of the early 21st century is surely the Higgs boson, but the boson and the Higgs Field that allows for that magic particle are extremely difficult to grasp. Don Lincoln outlines an analogy (originally conceived by David Miller) that all of us can appreciate, starring a large dinner party, a raucous group of physicists, and Peter Higgs himself.
Austrian physicist Erwin Schrödinger, one of the founders of quantum mechanics, posed this famous question: If you put a cat in a sealed box with a device that has a 50% chance of killing the cat in the next hour, what will be the state of the cat when that time is up?
One of the most amazing facts in physics is that everything in the universe, from light to electrons to atoms, behaves like both a particle and a wave at the same time. But how did physicists arrive at this mind-boggling conclusion?
When you think about Einstein and physics, E=mc^2 is probably the first thing that comes to mind. But one of his greatest contributions to the field actually came in the form of an odd philosophical footnote in a 1935 paper he co-wrote -- which ended up being wrong.
The Heisenberg Uncertainty Principle states that you can never simultaneously know the exact position and the exact speed of an object.
The classical physics that we encounter in our everyday, macroscopic world is very different from the quantum physics that governs systems on a much smaller scale (like atoms).
How is it that Beethoven, who is celebrated as one of the most significant composers of all time, wrote many of his most beloved songs while going deaf?
How do we know what matter is made of? The quest for the atom has been a long one, beginning 2,400 years ago with the work of a Greek philosopher and later continued by a Quaker and a few Nobel Prize-winning scientists. Theresa Doud details the history of atomic theory.?
As the narrative goes, fat is bad. Well, it's actually more nuanced than that. The type of fat you eat is more impactful on your health than the quantity. George Zaidan examines triglycerides, the varied molecules that make up fat, and how to identify which types of fat you are consuming.
How many times does the chorus repeat in your favorite song? How many times have you listened to that chorus? Repetition in music isn’t just a feature of Western pop songs, either; it’s a global phenomenon. Why? Elizabeth Hellmuth Margulis walks us through the basic principles of the ‘exposure effect,’ detailing how repetition invites us into music as active participants, rather than passive listeners.
In standard notation, rhythm is indicated on a musical bar line. But there are other ways to visualize rhythm that can be more intuitive. John Varney describes the ‘wheel method’ of tracing rhythm and uses it to take us on a musical journey around the world.
When you picture the lowest levels of the food chain, you might imagine herbivores happily munching on lush, living green plants. But this idyllic image leaves out a huge (and slightly less appetizing) source of nourishment: dead stuff. John C. Moore details the "brown food chain," explaining how such unlikely delicacies as pond scum and animal poop contribute enormous amounts of energy to our ecosystems.
How do you know you’re real? Is existence all just a big dream? Has some mad scientist duped us into simply believing that we exist? James Zucker investigates all of these questions (and more) in this mind-boggling tribute to René Descartes’s "Meditations on First Philosophy."
Population statistics are like crystal balls -- when examined closely, they can help predict a country's future (and give important clues about the past). Kim Preshoff explains how using a visual tool called a population pyramid helps policymakers and social scientists make sense of the statistics, using three different countries' pyramids as examples.
Our planet was once populated by megafauna, big top-of-the-food-chain predators that played their part in balancing our ecosystems. When those megafauna disappear, the result is a "trophic cascade," where every part of the ecosystem reacts to the loss. How can we stay in balance? George Monbiot suggests rewilding: putting wolves, lions and other predators back on top -- with surprising results.
Light always travels at a speed of 299,792,458 meters per second. But if you're in motion too, you're going to perceive it as traveling even faster -- which isn't possible! In this second installment of a three-part series on space-time, CERN scientists Andrew Pontzen and Tom Whyntie use a space-time diagram to analyze the sometimes confounding motion of light.
The human eye is an amazing mechanism, able to detect anywhere from a few photons to a few quadrillion, or switch focus from the screen in front of you to the distant horizon in a third of a second. How did these complex structures evolve? Joshua Harvey details the 500 million year story of the human eye.
It’s 4am, and the big test is in 8 hours. You’ve been studying for days, but you still don’t feel ready. Should you drink another cup of coffee and spend the next few hours cramming? Or should you go to sleep? Shai Marcu defends the latter option, showing how sleep restructures your brain in a way that’s crucial for how our memory works.
Ten years of research and 500 face-to-face-interviews led Richard St. John to a collection of eight common traits in successful leaders around the world.
The wheels in your brain are constantly turning, even when you're asleep or not paying attention. In fact, most of your brain’s activities are ones you’d never be aware of … unless they suddenly stopped. Nathan S. Jacobs takes us inside the always active, surprisingly spontaneous brain.
GPS location apps on a smartphone can be very handy when mapping a travel route or finding nearby events. But how does your smartphone know where you are?
Everyone knows we're not supposed to multitask while driving, but do you know why? It turns out your brain literally can't focus on too much at once.
Earthquakes have always been a terrifying phenomenon, and they’ve become more deadly as our cities have grown — with collapsing buildings posing one of the largest risks. But why do buildings collapse in an earthquake? And how can it be prevented? Vicki V. May explains the physics of why it is not the sturdiest buildings, but the smartest, that will remain standing.
It's perfectly human to grapple with questions, like 'Where do we come from?' and 'How do I live a life of meaning?' These existential questions are central to the five major world religions -- and that's not all that connects these faiths. John Bellaimey explains the intertwined histories and cultures of Hinduism, Judaism, Buddhism, Christianity and Islam.
After drinking a few glasses of water on a hot day, you might be struck with a sudden ... urge. Behind that feeling are two bean-shaped organs that work as fine-tuned internal sensors.
You can't help it; sometimes, you just get a bad feeling about someone that's hard to shake. So, what's happening in your brain when you make that critical (and often lasting) first judgment? Peter Mende-Siedlecki shares the social psychology of first impressions -- and why they may indicate that, deep down, people are basically good.
Imagine a game of dice: if the biggest number rolled is one, two, three, or four, player 1 wins. If the biggest number rolled is five or six, player 2 wins. Who has the best probability of winning the game? Leonardo Barichello explains how probability holds the answer to this seemingly counterintuitive puzzle.
They're cute, they're lovable, and judging by the 26 billion views on over 2 million YouTube videos of them, one thing is certain: cats are very entertaining. But their strange feline behaviors, both amusing and baffling, leave many of us asking: Why do cats do that? Tony Buffington explains the science behind some of your cat's strangest behaviors.
2016 • Science
Explore how heat waves affect the body, what levels of extreme heat we can survive, and what you can do to manage high temperatures.
2024 • Health
BBC Scotland's political editor Glenn Campbell fell off his bike in June 2023. Alone on a country road with broken bones, he feared for his life and felt he'd had a lucky escape when help came his way. But six weeks after his accident, just as he was getting ready to go back to work, he had a seizure. He was diagnosed with incurable brain cancer, turning his world as he knew it upside down. In this film, Glenn shares his experience of living with a brain tumour and explores why treatments for the condition have barely changed in many years. Early in his cancer journey, Glenn realised there was nothing he could do to change his health outcomes, but the one thing he could do was tell his story. Glenn says, 'It's a golden rule as a journalist not to become the story, but in this case, I just felt that it was worth sharing my personal experience as a way of putting a bit of a spotlight on this most difficult of cancers.' Supported by family, friends and colleagues, Glenn has documented his story during what has been a very difficult year of gruelling treatment and endless uncertainty. Following surgery, which saw his malignant tumour removed successfully, he embarked on radiotherapy and chemotherapy. He also lives with the constant threat of seizures and has made the decision to share some very personal footage filmed while in the midst of one such episode. Brain cancer is the biggest cancer killer of people under 40. Every day, 33 people in the UK are diagnosed with a brain tumour. Motivated by his own shortened lifespan and the stories of friends made in the cancer community, Glenn has spent a huge amount of time and energy in the past year raising awareness of this often-misunderstood cancer. In this intimate film, we see the committed newsman in a different light as he faces down his mortality and considers what matters most in life. Sitting on the beach at Machir Bay on Islay – the island he hails from – he reflects: 'You realise what really matters, and maybe what doesn't quite so much. What really matters is family and friends and good times and making memories, and what maybe doesn't matter is the hubbub of everyday life, work and chores. I think being told you've got a life-limiting condition really puts that into perspective.'
2024 • Health
From the first row of planted crops, the practice of agriculture rendered man's hunter-gatherer lifestyles obsolete in favor of settled life and stable food supplies. This led to a skyrocketing population and enabled humans to develop skills outside of gathering the food needed to survive.
S1E2 • The History of Food • 2018 • Health
The government rates the global outbreak of a deadly flu virus as a major threat to the UK. It could happen at any time. To predict the impact of the next pandemic more accurately than ever before, new data is needed - and lots of it. Dr Hannah Fry is on the case. She sets out to recruit the nation to download the BBC Pandemic app in a ground-breaking experiment to help plan for when the next deadly virus comes to the UK. How quickly will it spread? How many could it kill? What can we do about it? The BBC Four Pandemic experiment will find out. Hannah masterminds the experiment and adopts the role of Patient Zero by walking the streets of Haslemere in Surrey to launch the outbreak. Meanwhile, emergency physician Dr Javid Abdelmoneim finds out why flu is still such a danger to society a century after Spanish flu killed up to 100 million people worldwide. He meets researchers trying to discover what makes some people more contagious than others and visits a factory that will produce vaccine when the next pandemic flu virus emerges. Armed with the information he gathers and the results of the BBC Four Pandemic experiment, Hannah and Javid make a shocking revelation.
2018 • Health
Heart disease is the number one cause of deaths worldwide, but there are researchers frantically working to change that. Meet the people inventing the future of cardiac health, from new ways of imaging the body, to the possibility of 3D printing a functioning heart.
Breakthrough • 2019 • Health
Dive into the stories of a pairs figure skating team, a perfumer, a cave explorer and a musician to decipher how different ways of sensing the world all create their own vivid and unique picture.
S1E5 • Human: The World Within • 2021 • Health