Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site mordor.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!genrad!mit-eddie!godot!harvard!seismo!umcp-cs!gymble!lll-crg!dual!mordor!space@mit-mc From: space@mit-mc Newsgroups: net.space Subject: Re: Light Sails Message-ID: <942@mordor.UUCP> Date: Tue, 5-Mar-85 12:34:47 EST Article-I.D.: mordor.942 Posted: Tue Mar 5 12:34:47 1985 Date-Received: Sun, 10-Mar-85 06:23:46 EST Sender: daemon@mordor.UUCP Lines: 18 From: jrv@Mitre-Bedford >> There are these little globes with vacuum and a paddle/pivot mechanism >> inside which work on this principle. The four paddles are arranged so >> that the intersection of the two planes is the axis of rotation of the >> pivot. Each paddle has a black side and a silver side with radial >> symmetry. > This says that the beast should rotate with the white (reflective) side > retreating. Take a close look at one. They rotate in the other > direction! Those globes really have a small amount of air in them. The black side of each paddle gets hotter than the white side, so the air molecules that strike the black side recoil with a higher velocity than those striking the white side. Those air molecules push the paddles, not the photons. - Jim Van Zandt