Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!microsoft!uw-beaver!cornell!vax135!ariel!houti!hogpc!houxm!hocda!spanky!burl!duke!unc!tim From: tim@unc.UUCP Newsgroups: net.religion,net.misc Subject: Re: Earth Centered Universe Message-ID: <5579@unc.UUCP> Date: Mon, 18-Jul-83 15:31:05 EDT Article-I.D.: unc.5579 Posted: Mon Jul 18 15:31:05 1983 Date-Received: Tue, 19-Jul-83 19:03:17 EDT References: dciem.249 Lines: 47 What could a "stationary earth" mean in relativistic terms? To have a "stationary earth" means that there must be an absolute frame of reference with respect to which the earth is stationary. All right, so I used slightly misleading terms. My meaning was still clear, so let's not pick nits. What I meant to say was that there exists a consistent formulation of the laws of physics in which the earth is considered to be non-rotating. This is an extension of relativity that was in the general theory, which applies to accelerating frames of reference as well. Sure the earth is stationary with respect to me (when I am pursuing my favourite pastime). The rest of the universe isn't moving faster than the speed of light with respect to me, though. Very perceptive. The reason for this is that the special theory of relativity introduced a new equation for computing relative velocity. Consider two rockets hurtling away from an asteroid in opposite directions. Each has a speed of three quarters of the speed of light, as measured by an observer on the asteroid. However, the speed of one relative to the other is NOT half again the speed of light -- it is a (large) fraction of the speed of light. This is totally counterintuitive, but that's how it works. Similarly, no matter how fast Earth spins, we will never percieve any object as moving faster than the speed of light relative to our point on the surface of the planet. It is moving faster than the speed of light with respect to some mythical Newtonian absolute frame of reference connected to me, but who cares? The objects in that universe do not change their motions relative to one another or with respect to potential other observers just because I happen to take myself as a reference observer for now, and the earth is stationary in my frame. I'm sorry, I'm not clear on what it is you're saying here. ______________________________________ The overworked keyboard of Tim Maroney duke!unc!tim (USENET) tim.unc@udel-relay (ARPA) The University of North Carolina at Chapel Hill