The primary reactions in photosynthesis—the first steps in plants' conversion of sunlight energy into energy stored in carbohydrates—are incredibly efficient. And in a new study in Nature, chemists reveal that they may have found part of the reason why: quantum mechanics. A couple years ago, scientists first showed in bacteria proteins that the electrons were moving according to a quantum mechanical phenomenon called coherence, rather than abiding by the classical laws of physics. But where those early experiments