WI wide body |
01-02-2008 07:34 PM |
Quote:
Originally Posted by Bill Verburg
(Post 3678750)
You are currently sitting in the middle of it, do you notice anything?
expansion of the universe is like expansion due to temp. Each little piece expands a little bit, individually imperceptible, but when taken as whole in large structures the result is large the bigger the structure the bigger the expansion.
Supposedly gravitationally bound objects like the solar system or the galaxy don't experience expansion, but I am not so sure about that as all matter in the universe is gravitationally bound to all other matter, perhaps there is a threshold, I dunno.
Gravitational filds change the rate of time flow. Time is flowing more slowly on the space station than here on earth. Taken to the extreme of falling into a black hole, and assuming a large enough black hole so that the gravitational gradient doesn't shred you from tidal forces, time would so slow further and further as you fell further and further. From your perspective you would never reach bottom but your local time would be flowing at a rate that would allow you to watch the death of the universe, whether it be w/ a bang(unlikely) or a wisp of diasappering matter(seems most likely at this point).
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Well, according to Einstein's general theory of relativity, the expansion of the Universe is actually an expansion of space itself, and galaxies are moving away from each other because they are "being carried along by space." The theory does NOT limit the speed at which space expands, only the motion through space. Thus, the distance to this quasar can be greater than 13 billion light years. In fact, if we ask the question, "How fast is the distance between us and this quasar increasing?" we get the seemingly amazing answer of 540,000 km/sec or about 1.8 times the velocity of light. This number is ultimately not very interesting, both because this is not the best way to think about distant objects, and because there are objects farther away whose distance is growing even faster. To quote Fermilab's Judy Jackson, "there is no speed limit on the Universe."
When we run the numbers, we find that this quasar is about 27 billion light years away today. This is the value we would obtain if we could magically freeze the Universe in time and then measure the distance with a meterstick. From the redshift, we can then compute the distance to this quasar when the light we see today was emitted: it is 27 billion light years divided by 6.82, or about 4.0 billion light years. These numbers may seem paradoxical (and to be sure they depend somewhat upon our knowledge of the cosmological parameters; the uncertainties are -2.8 to +3.6 billion light years), but they do make perfectly good sense within Einstein's theory. The theory is well tested and its predictions make sense when carefully examined.
Found that in my Draft Folder...but it makes sense to me...I think.;)
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