From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.science.mathematics.categories/3135 Path: news.gmane.org!not-for-mail From: "Robert J. MacG. Dawson" Newsgroups: gmane.science.mathematics.categories Subject: Re: cracks and pots Date: Fri, 17 Mar 2006 14:29:16 -0400 Message-ID: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1241019114 7386 80.91.229.2 (29 Apr 2009 15:31:54 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 29 Apr 2009 15:31:54 +0000 (UTC) To: categories@mta.ca Original-X-From: rrosebru@mta.ca Fri Mar 17 23:27:15 2006 -0400 Return-path: Envelope-to: categories-list@mta.ca Delivery-date: Fri, 17 Mar 2006 23:27:15 -0400 Original-Received: from Majordom by mailserv.mta.ca with local (Exim 4.52) id 1FKS2p-0003t0-Be for categories-list@mta.ca; Fri, 17 Mar 2006 23:23:59 -0400 Original-Sender: cat-dist@mta.ca Precedence: bulk X-Keywords: X-UID: 81 Original-Lines: 30 Xref: news.gmane.org gmane.science.mathematics.categories:3135 Archived-At: jim stasheff wrote: > > > Robert J. MacG. Dawson wrote: > > And, as you know, there are > still scales, almost a century later, on which its predictions are > unsatisfactory. > > For us ignorant of these, please explicate. (1) At the very small scale, nobody has really managed to unify quantum mechanics (which is as thoroughly tested on its home turf as relativity is on its own) with general relativity. QM works astonishingly well on the atomic scale, GR works astonishingly well on the astronomical scale, but there is a big gap, "in which we live", in which neither is particularly evident and classical Newtonian mechanics works pretty well for most purposes. (2) At very large scales there is some question as to whether additional forces, not predicted by general relativity, are needed to explain some cosmological observations. This is more speculative, but a lot of physicists seem to think *something* needs to be done. -Robert