Jim Al-Khalili investigates the amazing science of gravity, recreating groundbreaking experiments, including the moment when Galileo first worked out how to measure it. He investigates gravity waves, finds out from astronauts what it's like to live without gravity, sets out to find where in Britain gravity is weakest and so where we weigh the least, and helps design a smartphone app that volunteers use to demonstrate how gravity affects time and makes us age at slightly different rates.
Adam Savage walks through two spectacular examples of profound scientific discoveries that came from simple, creative methods anyone could have followed -- Eratosthenes' calculation of the Earth's circumference around 200 BC and Hippolyte Fizeau's measurement of the speed of light in 1849.
2012 • Physics
Time travel is not forbidden by the laws of nature, but to build a time machine, we would need to understand more about those laws and how to subvert them than we do now. And every day, science does learn more. In this film Horizon meets the scientists working on the cutting edge of discovery - men and women who may discover how to build wormholes, manipulate entangled photons or build fully functioning time crystals. In short, these scientists may enable an engineer of the future to do what we have so far been only able to imagine - to build a machine that allows us travel back and forward in time at the touch of a button. It could be you! Science fiction?
A sword made of pure light that can cut through anything, the lightsaber is a truly awesome weapon. But it's not just a science fiction fantasy, Dr Michio Kaku reveals how we could one day build a real working lightsaber.
Meet Nikola Tesla, the genius engineer and tireless inventor whose technology revolutionized the electrical age of the 20th century. Although eclipsed in fame by Edison and Marconi, it was Tesla's vision that paved the way for today's wireless world. His fertile but undisciplined imagination was the source of his genius but also his downfall, as the image of Tesla as a "mad scientist" came to overshadow his reputation as a brilliant innovator.