Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site spuxll.UUCP Path: utzoo!watmath!clyde!burl!hou3c!hocda!houxm!houxz!vax135!floyd!whuxle!spuxll!ech From: ech@spuxll.UUCP (Ned Horvath) Newsgroups: net.physics,net.astro Subject: Re: RE: FLASHING QUASARS Message-ID: <492@spuxll.UUCP> Date: Sat, 9-Jun-84 01:24:49 EDT Article-I.D.: spuxll.492 Posted: Sat Jun 9 01:24:49 1984 Date-Received: Sun, 10-Jun-84 00:32:27 EDT References: <3560@fortune.UUCP> Organization: AT&T Information Systems, South Plainfield NJ Lines: 33 Question: could one build a bigger-than-one-light-second object that "flashed" with a period less than a second? As viewed from SOMEWHERE? Sure; to take a trivial example, place yourself at the center of an arbitrarily large shell, and make a BIG flash at an arbitrary frequency. The reflections off the shell will appear to come from all directions simultaneously. The upper bound on size based on frequency is based on the assumption that one is NOT at any such privileged position with respect to the periodic system; given that there is a large number of (pulsars, quasars, you name it) that exhibit the periodic behavior, the suggestion that one is at some privileged position for ALL of them is absurd. So, throw that out. Contrived examples, at least as gedanken experiments, can always be had. The argument goes 1. We assume that we are viewing a single periodic system in each case, and 2. In order for a physical system to display any sort of behavior the various "parts" must be able to interract, and 3. No interraction can propagate at more than the speed of light. You don't have to accept ANY of these assumptions; the contrived example with the shell, for example, violates assumption 2, i.e. that the various parts of the shell are interracting. If you are willing to accept the first two assumptions as reasonable, and the speed of light limit (an axiom of relativity, by the way, not a theorem!), then the argument yields a (very crude) upper bound on the size of the system. Does that help? =Ned=