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.?
Horizon looks at dark energy - the mysterious force that is unexpectedly causing the universe's expansion to speed up. The effects of dark energy were discovered in 1998 but physicists still don't know what it is. Worse, its very existence calls into question Albert Einstein's general theory of relativity - the cornerstone of modern physics. The hunt for the identity of dark energy is on. Experiments on earth and in space generate data that might provide a clue, but there are also hopes that another Einstein might emerge - someone who can write a new theory explaining the mystery of the dark energy.
Engineer Jem Stansfield looks back through the Horizon archives to find out how scientists have come to understand and manipulate the materials that built the modern world. Whether it's uncovering new materials or finding fresh uses for those we've known about for centuries, each breakthrough offers a tantalising glimpse of the holy grail of materials science - a substance that's cheap to produce and has the potential to change our world. Jem explores how a series of extraordinary advances have done just that - from superconductors to the silicon revolution.
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.
Just how small are atoms? And what's inside them? The answers turn out to be astounding, even for those who think they know. This fast-paced animation uses spectacular metaphors (imagine a blueberry the size of a football stadium!) to give a visceral sense of the building blocks that make our world.
Hurtling across the galaxy in a starship powered by anti-matter isn't some sci fi writer's impossible dream, as Dr Michio Kaku proves when he reveals his blueprints for a spacecraft that can journey to the stars. Alpha Centaurii is nearer than you think.