From: jgalla@orca.esd114.wednet.edu (John Gallagher)
Subject: Re: Atomic density of interplanetary space
Date: Tue, 28 Oct 1997 13:33:25 +0100
>Date: Tue, 28 Oct 1997 13:32:55 +0100 >To:dlgsam@LanMinds.Com (Sandra A.M. & David G.) >From:jgalla@orca.esd114.wednet.edu (John Gallagher) >Subject:Re: Atomic density of interplanetary space > >Don't know the accuracy of the following but have been told that the total ># of particles in the entire universe is 10 to the 51st power. The atomic >density is so small that for every 1000 galaxy collisions there would be 1 >pair of stars that actually collide (Pinky Nelson gave me that number this >weekend at WSTA). > > > >>I'm teaching some physics now and I wanted the figure for the atomic >>density of interplanetary space in atoms/cubic cm so that I can make it >>clear to my students why there is no friction in space to slow down planets >>or spaceships. I've spent way too much time unsuccessfully surfing the web >>for this statistic, and I thought maybe someone on this list may have a >>reference book which has it. Clearly, my web searching skills need some >>work! >> >>David Glaser >>Willard M.S. >