Wednesday, December 05, 2012

The refining fire of experience

During the academic year 1968-69 I was studying the history of science at the Imperial College in London. In a second-hand bookshop in Hampstead I found a book I had never heard of, Robert Small's An Account of the Astronomical Discoveries of Kepler, published in 1804. I paid a few pound for it, and took it home to read. It inspired an epic engagement with the mathematical theories of Ptolemy, Copernicus, Tycho Brahe, and Kepler that I described in Walking Zero: Discovering Cosmic Space and Time Along the Prime Meridian. I applied the theories of all four astronomers to the motion of Mars in that year of 1968-69. I'm sure someone, somewhere has done something similar, but if so I don't know about it. Here, for example, is the diagram representing my calculations for Ptolemy's theory. Click to enlarge.
I'll not repeat the story here. Small's book fell off the shelf into my hands the other day and it all came rushing back, those joyous weeks of plowing though the ancient texts and matching the results to the motion of the planet in the 20th-century sky.

Small makes a big claim for Kepler: "[His work] exhibited, even prior to the publication of Bacon's Novum Organum, a more perfect example, than perhaps ever was given, of legitimate connection between theory and experiment; of experiments suggested by theory, and of theory submitted without prejudice to the test and decision of experiments." Small's book is bound with all of the figures and diagrams collected at the back. I have scanned two of the 11 pages of figures, enough to give you a visual sense of what when into Kepler's achievement.

Having followed Kepler, with Small, down every blind alley, every minute deviation of calculation from observed positions of Mars, every agonizing surrender of accepted practice, I had nothing but admiration for a man who set the stage more than any other for the Newtonian Revolution, all while afflicted with illness, weak eyesight, religious persecution, and interminable financial and family problems, including an almost endless struggle to keep his quarrelsome mother from being burned as a witch.