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Old January 26th 07, 05:38 PM posted to sci.astro.amateur
Greg Crinklaw
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Posts: 886
Default Looking into the past with a telescope

cantseeboo wrote:
Since the distribution of galaxies on the large scale is isotropic, ....


Where do astronomers think the Milky Way is *in the Universe*? Towards
the center? Close to the edge? Any idea?

Do astronomers know where the universal center is? I guess that's the
same as asking where's the universe's center of gravity....Maybe
not....


The Universe has no true center. The frames of reference we are used to
on the earth are only illusions. In the universe at large no two
observers (people) can be expected to keep the same time much less agree
where to measure everything from.

Imagine that you live on the earth but think it is flat. The flatness
of the earth is an illusion. For a person who sees the earth in terms
of this illusion, where then is the center of the earth? If you put a
marker into the ground and start walking in a straight line you will
eventually come back to the marker... So where is the edge of the earth?
Where is the center? Is it infinite? The universe is like that; it
isn't that the universe is weird, it's that we perceive it in a
simplistic way--just like the person who perceives the earth as flat.

In a very real sense the position of each observer is the center of the
universe. Relativity teaches us that everything is relative--which
means there are no absolutes. A universal center is an absolute. Every
observer sees the universe from their own perspective, both in space and
time. As we cling to this tiny planet the differences in perspective
are small, so we ignore them. Not so with the universe at large!

So from our point of view on this planet we are the only center that can
be defined with any meaning; the universe appears around us as if we are
at its center.

Greg

--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)

SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://www.skyhound.com/sh/comets.html

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