Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/3/84; site talcott.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!genrad!panda!talcott!gjk From: gjk@talcott.UUCP (Greg Kuperberg) Newsgroups: net.space,net.physics Subject: Re: reflection of photons from a lightsail Message-ID: <337@talcott.UUCP> Date: Fri, 8-Mar-85 00:28:11 EST Article-I.D.: talcott.337 Posted: Fri Mar 8 00:28:11 1985 Date-Received: Sun, 10-Mar-85 07:20:52 EST References: <141@ihlpa.UUCP> Distribution: net Organization: Harvard Lines: 11 Xref: watmath net.space:3688 net.physics:2218 It is indeed the case that when light bounces off of a moving mirror/light sail it red shifts. This can be interpreted as follows: Because the light accelerates the craft with a light sail, it transfers some of its energy to the ship. The red shift is precisely this loss of energy. And finally, photons, shmotons---it works just as well with Maxwell's equations. In fact, special relativity predates photons by a decade or two. --- Greg Kuperberg harvard!talcott!gjk "2*x^5-10*x+5=0 is not solvable by radicals." -Evariste Galois.