Thomas H. Speak

A ball rolls up a hill, but it doesn't have enough energy, so it rolls back down. That's classical mechanics for you. But in the quantum world, a tiny particle can sometimes pass right through the hill, as if the barrier weren't there. This trick, tunneling, is business as usual for a light atom like hydrogen.

In the cold Taurus cloud, where stars are born, telescopes have detected molecules with the smell of bitter almonds — aromatic nitriles. On Earth, you can find them in peach pits, but in space they hang in icy dust. What happens to them under the harsh ultraviolet light of young stars? Chemists recreated this process in the lab.