Over on the Facebooks, Matt Strassler points to a BBC story about the role of quantum mechanics in explaining our sense of smell. There aren’t any equations in the article, and I haven’t read the research papers, but the idea seems to be that electrons move from one part of a protein to another part via quantum tunneling. The potential that allows this to happen is only set up if you have the right chemical involved, which is how the protein purportedly “smells” the existence of this chemical. The resulting mechanism is just absurdly sensitive — apparently fruit flies can smell the difference between hydrogen and deuterium (chemically identical, but tiny differences in atomic energy levels from having an extra neutron in the nucleus).
It’s still a controversial theory, but apparently not crackpotty. The question of how important quantum mechanics (as opposed to just its classical limit) is for biological processes was brought up in our earlier post on quantum photosynthesis. Which reminds me in turn of this worthwhile talk by Seth Lloyd, on the basic topic of “quantum life” and photosynthesis in particular. In between learning about how quantum phenomena might remain relevant in the hot, warm environment of a plant, you can enjoy Lloyd’s principled stance not to use PowerPoint under any circumstances.