Re: Dark Matter

[dykstrad@varney.idbsu.edu (Dewey Dykstra, Jr.)]

> I am wondering when/where/who the idea of "dark matter" in the universe came
> about.

The idea of dark matter, I believe, came out of considerations as to
whether there is enough matter to cause the universe to 'bounce' or quit
expanding and contract.  The visible matter (what's bright, stars) is
apparently not enough.  But, people seem not to relish the idea of the
universe just whimpering out.

> And is any of it close to the Earth?

The Earth _is_ dark matter! ;^)

> Is it "localized" or is it thought to permeate the universe?

Most thoughts about it I think suggest that it is in lots of places.

> Doesn't "dark" just mean that (whatever it is) it does not radiate in the
> visible?

Technically, I think, "dark" means that no (or an undetectably small amount
of) radiation of any sort (that we have telescopes for) gets to us.  This
would include but not be restricted to the visible spectrum.

Dewey

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Dewey I. Dykstra, Jr.                   Phone: (208)385-3105
Professor of Physics                    Dept:  (208)385-3775
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