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!linus!philabs!cmcl2!seismo!brl-tgr!gwyn
From: gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>)
Newsgroups: net.physics
Subject: Re: A Question on Time Dilation
Message-ID: <11210@brl-tgr.ARPA>
Date: Sun, 2-Jun-85 22:53:04 EDT
Article-I.D.: brl-tgr.11210
Posted: Sun Jun  2 22:53:04 1985
Date-Received: Tue, 4-Jun-85 00:18:05 EDT
References: <15000004@haddock.UUCP>
Organization: Ballistic Research Lab
Lines: 21

> I am very puzzled over something in Einstein's theory of time 
> dilation, that is, that time passes more slowly for objects in 
> motion then for objects at rest.

Probably the reason that you are puzzled is that you are not
stating the phenomena correctly.  The time dilation effect is:

The proper time of a (relatively) moving object appears to be
advancing slower that that of the (stationary) observer, by an
amount sqrt( 1 - (v / c)^2 ) where v is the apparent speed of
the moving object and c is the speed of light.

The only reason "c" is in the equation is to obtain natural
units for space & time coordinates; the time dilation effect
is not dependent on any communication by light, although such
communication is often used in elementary texts to try to make
the effect more intelligible.

> I can't believe Einstein wouldn't have thought of this!

Don't worry, Einstein knew what he was doing.