Physicist Brian Greene explains superstring theory, the idea that minscule strands of energy vibrating in 11 dimensions create every particle and force in the universe.

Physicist Patricia Burchat sheds light on two basic ingredients of our universe: dark matter and dark energy. Comprising 96% of the universe between them, they can't be directly measured, but their influence is immense.

Accepting his 2008 TED Prize, physicist Neil Turok speaks out for talented young Africans starved of opportunity: by unlocking and nurturing the continent's creative potential, we can create a change in Africa's future.

"Rock-star physicist" Brian Cox talks about his work on the Large Hadron Collider at CERN. Discussing the biggest of big science in an engaging, accessible way, Cox brings us along on a tour of the massive project.

Physicist and surfer Garrett Lisi presents a controversial new model of the universe that -- just maybe -- answers all the big questions. If nothing else, it's the most beautiful 8-dimensional model of elementary particles and forces you've ever seen.

Is there an equation for intelligence? Yes. It's F = T ∇ Sτ. In a fascinating and informative talk, physicist and computer scientist Alex Wissner-Gross explains what in the world that means.

For tens of thousands of years our ancestors understood the world through myths, and the pace of change was glacial. The rise of scientific understanding transformed the world within a few centuries. Why? Physicist David Deutsch proposes a subtle answer.

Seemingly pointless scientific research can lead to extraordinary discoveries, says physicist Suzie Sheehy. In a talk and tech demo, she shows how many of our modern technologies are tied to centuries-old, curiosity-driven experiments -- and makes the case for investing in more to arrive at a deeper understanding of the world.

Physicist Lee Smolin talks about how the scientific community works: as he puts it, "we fight and argue as hard as we can," but everyone accepts that the next generation of scientists will decide who's right. And, he says, that's how democracy works, too.

What do 24,000 ideas look like? Ecologist Eric Berlow and physicist Sean Gourley apply algorithms to the entire archive of TEDx Talks, taking us on a stimulating visual tour to show how ideas connect globally.

What's it like to be pals with a genius? Physicist Leonard Susskind spins a few stories about his friendship with the legendary Richard Feynman, discussing his unconventional approach to problems both serious and ... less so.

Physicist Steven Cowley is certain that nuclear fusion is the only truly sustainable solution to the fuel crisis. He explains why fusion will work -- and details the projects that he and many others have devoted their lives to, working against the clock to create a new source of energy.

In this archival footage from BBC TV, celebrated physicist Richard Feynman explains what fire, magnets, rubber bands (and more) are like at the scale of the jiggling atoms they're made of. This accessible, enchanting conversation in physics reveals a teeming nano-world that's just plain fun to imagine.

Theoretical physicist David Deutsch delivers a mind-bending meditation on the "great monotony" -- the idea that nothing novel has appeared in the universe for billions of years -- and shows how humanity's capacity to create explanatory knowledge could be the thing that bucks this trend. "Humans are not playthings of cosmic forces," he says. "We ...

How did the universe begin -- and how is it expanding? CERN physicist Tom Whyntie shows how cosmologists and particle physicists explore these questions by replicating the heat energy and activity of the first few seconds of our universe from right after the Big Bang. [Directed by Dan Abdo and Jason Patterson, narrated by R.J. Glass].

During the hot summer months, watching an outdoor sports match or concert can be tantamount to baking uncomfortably in the sun -- but it doesn't have to be. At the TEDxSummit in Doha, physicist Wolfgang Kessling reveals sustainable design innovations that cool us from above and below, and even collects solar energy for later use.

We think of space as a silent place. But physicist Janna Levin says the universe has a soundtrack -- a sonic composition that records some of the most dramatic events in outer space. (Black holes, for instance, bang on spacetime like a drum.) An accessible and mind-expanding soundwalk through the universe.

Physicist Freeman Dyson suggests that we start looking for life on the moons of Jupiter and out past Neptune, in the Kuiper belt and the Oort cloud. He talks about what such life would be like -- and how we might find it.

Our energy future depends on nuclear fusion, says Michel Laberge. The plasma physicist runs a small company with a big idea for a new type of nuclear reactor that could produce clean, cheap energy. His secret recipe? High speeds, scorching temperatures and crushing pressure. In this hopeful talk, he explains how nuclear fusion might be just arou...

Curious how stuff works? Do a hands-on experiment at home, says physicist Nadya Mason. She shows how you can demystify the world around you by tapping into your scientific curiosity -- and performs a few onstage experiments of her own using magnets, dollar bills, dry ice and more.

Physics doesn't just happen in a fancy lab -- it happens when you push a piece of buttered toast off the table or drop a couple of raisins in a fizzy drink or watch a coffee spill dry. Become a more interesting dinner guest as physicist Helen Czerski presents various concepts in physics you can become familiar with using everyday things found in...

India has a historic opportunity to power its industrialization with clean energy -- and its energy choices will make or break the world's fight against climate change, says clean energy executive, physicist and author Varun Sivaram. Bringing on-the-ground experience as CTO of India's largest renewable energy company, Sivaram proposes a plan for...

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? Chad Orzel investigates this thought experiment. [Directed by Agota Vegso, na...

Space physicist Miho Janvier studies solar storms: giant clouds of particles that escape from the Sun and can disrupt life on Earth (while also producing amazing auroras). How do you study the atmosphere on the Sun, which burns at temperatures of up to around 10 million degrees Kelvin? With math! Join the TED Fellow as she shares her work trying...

Physicist Geoffrey West has found that simple, mathematical laws govern the properties of cities -- that wealth, crime rate, walking speed and many other aspects of a city can be deduced from a single number: the city's population. In this mind-bending talk from TEDGlobal he shows how it works and how similar laws hold for organisms and corporat...

"I love paper, and I love technology," says physicist and former sheep herder Kate Stone, who's spent the past decade working to unite the two. Her experiments combine regular paper with conductive inks and tiny circuit boards to offer a unique, magical experience. To date, applications include a newspaper embedded with audio and video, posters ...

Why is there something rather than nothing? Why does so much interesting stuff exist in the universe? Particle physicist Harry Cliff works on the Large Hadron Collider at CERN, and he has some potentially bad news for people who seek answers to these questions. Despite the best efforts of scientists (and the help of the biggest machine on the pl...

What if we could use the cold darkness of outer space to cool buildings on earth? In this mind-blowing talk, physicist Aaswath Raman details the technology he's developing to harness "night-sky cooling" -- a natural phenomenon where infrared light escapes earth and heads to space, carrying heat along with it -- which could dramatically reduce th...

Physicist Garrett Lisi has proposed a new "theory of everything" -- a grand unified theory that explains all the elementary particles, as well as gravity.

Physicist Werner Heisenberg said, "When I meet God, I am going to ask him two questions: why relativity? And why turbulence? I really believe he will have an answer for the first." As difficult as turbulence is to understand mathematically, we can use art to depict the way it looks. Natalya St. Clair illustrates how Van Gogh captured this deep m...