Re: Atomic density of interplanetary space

From: (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.)
> (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
>>David Glaser
>>Willard M.S.