You've felt cold before. Sometimes it's cold outside. But what if I told you that "cold" isn't real? There's no substance or quantity called "cold" in science. We can't measure the amount of "cold" in something. Instead it's about what's NOT there.
Deep underground in a vault beneath Paris lives the most important lump of metal in the world - Le Grand K. Created in the 19th century, it's the world's master kilogramme, the weight on which every other weight is based. But there is a problem with Le Grand K - it is losing weight. Professor Marcus du Sautoy explores the history of this strange object and the astonishing modern day race to replace it.
We feel it every moment of our lives but for physicists, gravity is the longest running unsolved mystery of the universe. Why do all objects that have mass pull on one another? Cutting-edge theories are proposing unexpected answers.
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.
Scientists genuinely don't know what most of our universe is made of. The atoms we're made from only make up four per cent. The rest is dark matter and dark energy (for 'dark', read 'don't know'). The Large Hadron Collider at CERN has been upgraded. When it's switched on in March 2015, its collisions will have twice the energy they did before. The hope is that scientists will discover the identity of dark matter in the debris. The stakes are high - because if dark matter fails to show itself, it might mean that physics itself needs a rethink.
It's called the speed limit of the universe. Einstein blew all of our minds when he worked out the Theory of Relativity, and showed that space and time were malleable substances. He also theorized that we as humans can never travel faster than the speed of light, which leaves the stars and other galaxies almost impossibly out of our reach. But the dreams of Star Wars and Star Trek are not dead. In fact, there could be ways to travel faster than the speed of light - and some of them are already being tested in labs around the world.