Yesterday afternoon I ran into a friend, by chance, for the third time that day.
“Why do I keep seeing you?” he asked.
“Good question,” I said, “you see, about eight light-minutes in that direction is a giant ball of gas called the sun. Inside, hydrogen under high pressure and temperature fuses into Helium. The Helium nucleus is lighter, so by E=mc^2 energy is given off in the form of photons…” and went on discussing atmospheric scattering, optics, the physiology of the retina, nerve impulses, a hierarchy of vision-processing mechanisms in the brain, the fusiform gyrus, grandfather neurons, and the nature of consciousness, all contributing to why he saw me.
But I was a bit surprised, as I dragged the joke on for a few minutes, how often I didn’t really understand what I was saying (and said it rather poorly). Hydrogen fuses to form Helium in the sun? Why does it do that? I thought I knew most of what there is to know about a single Hydrogen atom from my quantum mechanics courses, but put two of them together (and give the nucleus actual degrees of freedom) and i have no idea why they do what they do.
Today I ran across this quote from Tom Stoppard’s Arcadia:
It makes me so happy. To be at the beginning again, knowing almost nothing…. The ordinary-sized stuff which is our lives, the things people write poetry about—clouds—daffodils—waterfalls….these things are full of mystery, as mysterious to us as the heavens were to the Greeks…It’s the best possible time to be alive, when almost everything you thought you knew is wrong.
(quoted in Melanie Mitchell’s Complexity: A Guided Tour)
There is a lot of mystery in something as mundane as seeing a face you recognize. Fortunately, today many of the answers to these mysteries are known, if not in full detail, then at least in much greater detail than I know now. It’ll be interesting to find a few of these things out.