At 22:13 10-11-00 -0800, you wrote:
>The model most often used to describe the expanding universe is the "skin" of
>a balloon. How literal is that example? Does all matter expand away from a
>point of origin leaving a void in the center?
>
>Doug
No.
Another model is a loaf of raisin bread rising. The raisins are the
galaxies (or, probably more accurately, clusters of galaxies). As the
bread rises, say it doubles in diameter in one hour. Then the distance
between any two raisins also doubles during that hour. If two raisins
were, say, 5 cm apart at the start, they would be 10 cm apart an hour
later, and the average velocity of separation would be 5 cm/hour. Two
raisins that were 10 cm apart at the start would be 20 cm apart at the end,
and would be separating at 10 cm/hour, and so on, so the velocity is
proportional to the distance between the raisins, which is the same thing
we see with Hubble's law v=Hd.
Does that help?
-- Ronn! :)
