TED Talks Daily (HD video)

How much land mass would renewables need to power a nation like the UK? An entire country's worth. In this pragmatic talk, David MacKay tours the basic mathematics that show worrying limitations on our sustainable energy options and explains why we should pursue them anyway. (Filmed at TEDxWarwick.)

Reggie Watts’ beats defy boxes. Unplug your logic board and watch as he blends poetry and crosses musical genres in this larger-than-life performance.

There is an epidemic of HIV, and with it an epidemic of bad laws -- laws that effectively criminalize being HIV positive. At the TEDxSummit in Doha, TED Fellow Shereen El-Feki gives a forceful argument that these laws, based in stigma, are actually helping the disease spread.

Even a death-defying magician has to start somewhere. High-wire artist Philippe Petit takes you on an intimate journey from his first card trick at age 6 to his tightrope walk between the Twin Towers.

Hans Rosling had a question: Do some religions have a higher birth rate than others -- and how does this affect global population growth? Speaking at the TEDxSummit in Doha, Qatar, he graphs data over time and across religions. With his trademark humor and sharp insight, Hans reaches a surprising conclusion on world fertility rates.

We've been to the moon, we've mapped the continents, we've even been to the deepest point in the ocean -- twice. What's left for the next generation to explore? Biologist and explorer Nathan Wolfe suggests this answer: Almost everything. And we can start, he says, with the world of the unseeably small.

Michael McDaniel designed housing for disaster relief zones -- inexpensive, easy to transport, even beautiful – but found that no one was willing to build it. Persistent and obsessed, he decided to go it alone. At TEDxAustin, McDaniel show us his Exo Reaction Housing Solution and shares how he's dedicating his free time to working with suppliers and manufacturers to prepare for the next natural disaster. (Filmed at TEDxAustin.)

Street artist JR made a wish in 2011: Join me in a worldwide photo project to show the world its true face. Now, a year after his TED Prize wish, he shows how giant posters of human faces, pasted in public, are connecting communities, making change, and turning the world inside out. You can join in at insideoutproject.net

There have been remarkable advances in understanding the brain, but how do you actually study the neurons inside it? Using gorgeous imagery, neuroscientist and TED Fellow Carl Schoonover shows the tools that let us see inside our brains.

Is your school or workplace divided into "creatives" versus practical people? Yet surely, David Kelley suggests, creativity is not the domain of only a chosen few. Telling stories from his legendary design career and his own life, he offers ways to build the confidence to create... (From The Design Studio session at TED2012, guest-curated by Chee Pearlman and David Rockwell.)

What can mathematics say about history? According to TED Fellow Jean-Baptiste Michel, quite a lot. From changes to language to the deadliness of wars, he shows how digitized history is just starting to reveal deep underlying patterns.

Are we born to be optimistic, rather than realistic? Tali Sharot shares new research that suggests our brains are wired to look on the bright side -- and how that can be both dangerous and beneficial.

Oops! Nobody wants to see the 404: Page Not Found. But as Renny Gleeson shows us, while he runs through a slideshow of creative and funny 404 pages, every error is really a chance to build a better relationship.

There are people who can quickly memorize lists of thousands of numbers, the order of all the cards in a deck (or ten!), and much more. Science writer Joshua Foer describes the technique -- called the memory palace -- and shows off its most remarkable feature: anyone can learn how to use it, including him.

At TED2012, filmmaker Karen Bass shares some of the astonishing nature footage she's shot for the BBC and National Geographic -- including brand-new, previously unseen footage of the tube-lipped nectar bat, who feeds in a rather unusual way …