Re: Empty Space

["Paul Camp" <pjcamp@coastal.edu>]

> I have two questions -- well, actually I have a lot more, but I am going to
> tell the list of only two -- unless I think of another while I type:
>
> 1)  What would it mean to say that space is empty?  Empty of what?
Empty of you  and me -- lonely, ain't it? 8-)

Empty of matter, one would suppose, excluding vacuum fluctuations 
(we'll avoid quantum gravity for now). If you want to include 
photons, however, there is a great deal there in the form of the 
cosmic background, and neutrinos even more so. So it sort of depends 
on what you are willing to admit as worth considering.

> 2)  What is the density of "empty" space"?  For example how much mass is
> there "between" Sol and a-Centauri?  
For ordinary matter, it is very patchy but on average somewhat less 
than 1 million H atoms per cubic meter.

> Jim.Green@Snow.edu                                      
Paul J. Camp                   "The Beauty of the Universe
Assistant Professor of Physics  consists not only of unity
Coastal Carolina University     in variety but also of 
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