Yesterday, one of the grandest experimental fusion reactors in the world flared to life, converting hydrogen into a plasma for less than a second. The honor of pressing the button went to a PhD in Quantum Chemistry (who also happens to be the Chancellor of Germany), Angela Merkel.

Why such a high-profile ribbon-cutting? Fusion power is a kind of nuclear power source, the same thing that happens on a much larger scale in the hearts of stars. Theoretically, if you could get light atoms to fuse into heavier atoms, the energy produced by the reaction (which happens at immense temperatures and pressures) would be a clean source of energy that could continue almost indefinitely, without the radiation byproducts of nuclear fission (the method currently employed at nuclear power plants).