I spent a couple hours at NYU Philosophy, attending a seminar by Jim Weatherall (UC Irvine) about the status of geodesic motion in the absence of force (the law of inertia) in General Relativity and also Newtonian Gravity. He gave a nice demonstration that when you view both theories in their geometric forms (natural for GR, lately done for Newtonian), the proofs
of Newton's First Law in each case look pretty similar. He is attacking a long-held view (promoted by Einstein himself) that only in GR does inertial motion have a clear explanation, that is, is not a postulate. Apparently Eddington first made this point to Einstein, and Einstein was stoked about it. What Weatherall showed is that it is not really correct: In its geometric form, Newtonian Gravity provides the same proof (with actually slightly fewer assumptions, in part because causal structure is so simple in Newtonian Gravity).
As usual when going on safari in other departments (Math, CS, Biology, and so on), I learn as much about the practices of the other field as I do from the talk itself. Philosophy talks are scheduled for two hours, seminar for an hour, then questions for an hour, with a short break in-between. Questions are handled formally by a moderator. It is an absolutely excellent format that encourages well thought-out questions and serious, detailed answers; maybe we should consider adopting it?
Very interesting.
ReplyDeleteIs this work published?
Btw , in case anyone is interested last year found a very interesting paper on equivalence principle in GR (and its various quantum incarnations)
by two philosophers
http://arxiv.org/abs/1008.5192
While I don't like the idea of folks coming to a conference and literally reading their paper, some things from other fields could be adopted, and this is one. On a similar note, when I look at old conference proceedings, the most interesting thing are the questions and answers. I think all conference proceedings should include these. In the days of arXiv, conference proceedings don't even have the justification of providing a rough mix of the definitive paper to appear later. (Conferences themselves, of course, are still valid; in fact, since this aspect (latest data) is no longer important, other things (discussion with colleagues, overview of fields one does not work in) have more space.)
ReplyDelete@Shantanu: I think the Weatherall results are published; check his web pages, or send him email; don't have references handy.
ReplyDelete@Phillip: Agreed completely! I love those Q&A parts; I even included that in one of my arXiv papers here: http://arxiv.org/abs/1008.0738.pdf (Section 4 is a list of *actual* questions asked during the talk).