Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!genrad!panda!talcott!harvard!seismo!brl-tgr!gwyn From: gwyn@brl-tgr.ARPA (Doug Gwyn ) Newsgroups: net.physics Subject: Re: predicting the universe with computers Message-ID: <7818@brl-tgr.ARPA> Date: Tue, 29-Jan-85 13:35:24 EST Article-I.D.: brl-tgr.7818 Posted: Tue Jan 29 13:35:24 1985 Date-Received: Sat, 2-Feb-85 13:24:36 EST References: <1027@sunybcs.UUCP> <215@looking.UUCP> <6861@watdaisy.UUCP> <19974@lanl.ARPA> Organization: Ballistic Research Lab Lines: 29 > Einstein not only DIDN'T prove the universe finite, he didn't believe it. > For a long time Einstein supported the steady-state theory (more because he > was a relativist and didn't want to admit that there were special reference > times than because he was attached to an infinite duration universe). He > even introduced a so-called cosmological constant into his equations for > general relativity in order to prevent it from predicting that the universe > would expand or contract. When the evidence came that the universe was > expanding, Einstein retracted the cosmological constant - calling it the > worst error he had ever made (to introduce an idea merely to support his > own preconceived beliefs). I don't think this abbreviated history is correct. The "steady-state" theory postdates Einstein's cosmological constant by several decades. Einstein preferred a static isotropic cosmology and thought he could only get one if there were a cosmological term. When Friedmann was able to obtain these properties from the original (non-cosmological-term) equations, Einstein retracted the cosmological term. Evidence of the expansion of the universe had nothing to do with this, and indeed is contrary to the development that caused Einstein to repudiate the cosmological constant. Interestingly, the cosmological constant reappears in a pure-affine version of the theory. Its presence or absence cannot be tested on the medium scale, although it would have an impact on the very large or the very small. Because with a cosmological constant the universe becomes "self-gauging" (Eddington's terminology), such a theory has some attractive aspects. Einstein's regret at warping a theory to fit preconceived notions should not prevent investigation of such theories when they arise naturally.