Friday, April 5, 2013


For the first half of my lunch hour today, I watched the opening lecture in a DVD geology course, and was pleased that the lecturer chose to set the stage for geology by discussing the origins of the universe and its constituent elements. I am endlessly delighted by the fact that the world around us consists primarily of atoms made in the cores of long-ago stars and flung out in catastrophic explosions billions of years in the past.

I first read about stellar nucleosynthesis in one of Isaac Asimov's astronomy books when I was in high school. As with today's lecturer, Asimov was able to run through the conceptual basics at a brisk pace: you start with hydrogen, pulled together by gravity until the pressure becomes immense, crushing the hydrogen atoms together into helium and giving off light as a byproduct. If the star is massive enough, helium can then be squashed together as well, until elements successively higher in atomic number are created, all the way up to iron. Big stars tear themselves apart in supernovas, unbelievably powerful explosions that create still more elements and spread all these multifarious kinds of atoms across space in great clouds of gas and dust that eventually aggregate into solar systems like our own, again by way of gravity.

In this way, the humblest element in the universe, hydrogen, becomes both the grandest, mightiest objects conceivable -- stars -- and also the building blocks of the most complex, mysterious phenomenon -- life -- that we can observe or imagine.

So I'm a big fan of nucleosynthesis. Maybe I should have a t-shirt made.

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