Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site utastro.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!ut-sally!utastro!bill From: bill@utastro.UUCP (William H. Jefferys) Newsgroups: net.physics Subject: Re: the multi-body problem Message-ID: <100@utastro.UUCP> Date: Thu, 24-Oct-85 09:44:14 EST Article-I.D.: utastro.100 Posted: Thu Oct 24 09:44:14 1985 Date-Received: Thu, 31-Oct-85 02:41:36 EST References: <1330@teddy.UUCP> <218@redwood.UUCP> <10781@ucbvax.BERKELEY.EDU> Distribution: na Organization: U. Texas, Astronomy, Austin, TX Lines: 24 > I think that multi-body systems can become chaotic in the sense > that small perturbations can grow to macroscopic size. Thus it is > impossible to predict the exact state in the future even with an > arbitrarily small delta-t iteration. Absolutely correct. It's even true for n=3. It is the real reason why the three body problem is not solvable (although this fact was not appreciated until recently). Note that for a system to be chaotic, the small perturbations have to grow exponentially fast. In the two-body problem, for example, a small error in the initial conditions eventually produces a macroscopic perturbation, but it only grows linearly. The two-body problem is not chaotic. -- Glend. I can call spirits from the vasty deep. Hot. Why, so can I, or so can any man; But will they come when you do call for them? -- Henry IV Pt. I, III, i, 53 Bill Jefferys 8-% Astronomy Dept, University of Texas, Austin TX 78712 (USnail) {allegra,ihnp4}!{ut-sally,noao}!utastro!bill (UUCP) bill@astro.UTEXAS.EDU. (Internet)