The vast expanse of interstellar space is supposed to be too cold for most chemical reactions to occur. The more frigid it gets, the harder it is to spark a chemical reaction, for lack of energy – the very definition of cold. Yet a vast variety of complex organic molecules are formed in space. Some reactions transpire on the surface of cosmic dust grains, or with a little help from gamma rays or stray high-energy electrons. But most happen beyond the laws of chemistry.