What do you get if you smash two hydrogen nuclei together? Helium and lots of energy. That’s no joke – it's nuclear fusion! Nuclear fusion is the power source of the sun and the stars. Physicists and engineers here on earth are trying to build reactors than can harness fusion power to provide...

Sneezes, wheezes, runny noses and red eyes - this episode is all about allergies. An allergic reaction is when your immune system reacts to something harmless – like peanuts or pollen – as if it was a parasitic invader. It’s a case of biological mistaken identity. Professor Judith Holloway...