Wednesday, January 11, 2012

Thinking about molecules on a lazy afternoon

I was sitting on the beach yesterday with my pal Dwight, just sittin', watching the waves roll in, all that beautiful turquoise water reaching to the far horizon, lapping our toes. And I suppose I was still thinking about Lucretius, because I said, apropos of nothing, "All those molecules of H2O."

That silky, continuous liquid -- made up, said Democritus, Epicurus and Lucretius, of tiny indestructible particles. And of course they were right. Was it a brilliant intuition? Or a lucky guess? In The Swerve, Stephen Greenblatt quotes the Spanish-born Harvard philosopher George Santayana, who called this idea -- the ceaseless mutation of forms composed of indestructible particles -- "the greatest thought that mankind has ever hit upon."

Well, that's a big claim. It may not be the greatest thought, but it's surely near the top.

"All those molecules," I said to Dwight, as I gazed dreamily out to sea.

And I remembered a calculation I did here last year while on my voyage through the Panama Canal.

"There are as many water molecules in a thimbleful of water as there are thimblefuls of water in the Atlantic Ocean," I said.

It's not a hard order-or-magnitude calculation. Mass of a proton. Radius of the Earth. Average depth of the ocean. That's all you need. Still, it's a mind-blowing result. Sitting there on the beach looking out at all those thimblefuls of water in the Atlantic Ocean, of which we were seeing only the tiniest fraction -- a good way to visualize the teeming numbers of particles that the ancients intuited.

Those hydrogen and oxygen atoms are, as the ancient guessed, permanent, forged in the big bang and the cores of stars, flowing, flowing, through interstellar nebulas, gathered by gravity in proto-stars, spun out in a planetary disk, condensing as liquid on a planet with just the right temperature, just the right distance from a star of just the right size. Oceans come and go. You and I come and go. The atoms endure.