John Milton on Kepler

A relatively poor journey down to London this morning - a very heavy frost delayed my departure from home and the coaches were also affected also. So we had not even left the Park and Ride by 7:00.

But still time for an hour or so reading in the library - mainly a Shea article on Galileo. My ipod listening remains mainly Boris - today it was Smile live again

I was surprised to discover this morning that Caroline has heart trouble of some sort - she was struggling with the top of a water bottle and volunteered this as an explanation. Yet she is only 29 I think.

John Milton's talk today was on Kepler - no sign that these are moving towards seminars as such. Though I know alot about K, there was still some good stuff in this talk - esp Gingerich idea of K's zero'th law (i.e. pre- first), that the plane of all planetary orbits passes through the sun (not the earth, as in Copernicus) - i.e. it is the sun that drive the solar system. Years ago, I tried to establish this from my own observations but wasn't able to conceptualise the geometry adequately. Still, I was only 14 or so at the time

John also covered the "vicarious hypothesis" in more detail than I would have expected and noted Kepler's first use of the terms "satellite" and "orbit".

I was particularly impressed with the discussion of why mars is the "only" candidate by which Kepler could have discovered first two laws. We also covered how the observations of Mars at opposition were used so that observers on the Earth sees Mars as an observer on the Sun would - what I think is called "heliocentric longitude"

Also lots of material on how Kepler is not a "curve fitter" and discussions of the various alternatives to circles - various ovals, egg shapes etc - so it is not obvious that ellipse is a good choice. Overall, a very good talkk (but not a seminar). And my admiration for Kepler contnues to grow

Lunch with Caroline and Victor downstairs at the Garrick. Once again I have skipped the "Philosophy of Economics" seminar - not done the necessary reading

Back home, the recent book on Dirac has arrived.