February 16th, 2004

Aristotle vs. Ptolemy

Yes, those are the 2 guys who, as the middle ages ground to a close, were responsible for people's understanding of how the sun, stars, and planets, all circled the earth.

Aristotle's system is noticeably wronger than that of Ptolemy, who came a bit later in ancient times. Ptolemy worked out a mathematical way to account for the apparent "retrograde" motions of the planets. It was a bit kludgey, but it worked better than anything else. When I say "it worked" I mean it worked to predict where the planets and stars would appear in the sky on a given night. It was spectacularly incorrect in terms of the real physical relationships. But reality had to wait for modern science and the whole crew of Copernicus, Kepler, Galileo, and Newton.

But here is what is peculiar. People mostly believed Aristotle's physical account, which involved concentric crystal spheres, even though they knew it was incompatible with Ptolemy's account, which gave the better predictions. So what on earth were they thinking? If Aristotle had miraculously returned, he would have been much amused by those who insisted on continuing to believe his outdated opinions.

Rhyme for the day:

The music of the spheres
Is nonsense to my ears.