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Old Nov 25th 2013, 12:57 PM   #1
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Is this experiment possible?

If the universe is expanding at an accelerating rate, it seems to me at some point, distant bodies would seem to pass out of our observable universe. The most distant body I can find a reference to is UDFj-395462284, it is at a distance of 13.37 Gly, It's Red Shift is z≅11.9. How does that relate to the speed of it's recession and if it is accelerating won't it eventually exceed the speed of light relative to us and seem to "pass out" of our observable universe?

Even if we cannot directly observe bodies more distant than UDFj-395462284 is it possible that we could detect the effect of such bodies on UDFj-395462284?

Would such an observation help us to find more distant bodies?

If the universe is expanding at an accelerating rate wouldn't that be represented by a thinning distribution of distant bodies?
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Old Nov 25th 2013, 04:15 PM   #2
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Originally Posted by Troll View Post
If the universe is expanding at an accelerating rate, it seems to me at some point, distant bodies would seem to pass out of our observable universe. The most distant body I can find a reference to is UDFj-395462284, it is at a distance of 13.37 Gly, It's Red Shift is z≅11.9. How does that relate to the speed of it's recession and if it is accelerating won't it eventually exceed the speed of light relative to us and seem to "pass out" of our observable universe?

Even if we cannot directly observe bodies more distant than UDFj-395462284 is it possible that we could detect the effect of such bodies on UDFj-395462284?

Would such an observation help us to find more distant bodies?

If the universe is expanding at an accelerating rate wouldn't that be represented by a thinning distribution of distant bodies?
Remember that as we look further "out" we are actually looking at the Universe when it was younger. The distribution of galaxies would be expected to be denser at those times. At least that's my thoughts on the subject.

Relativity says that no object can move faster than the speed of light. The same is true of galaxies. At high speeds we need to put more "effort" to accelerate the object. The relativistic 4-momentum is harder to increase as its speed increases.

-Dan
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Old Nov 26th 2013, 09:23 AM   #3
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Speed of Information

My understanding of the expanding universe, redshifts, etc.
is that the galaxies are not actually accelerating relative to each other,
Rather the parameter we generally refer to as distance is changing with time.

Taking receeding galaxies and redshift to the limit does suggest that there will be an observable limit beyond which galaxies will be receeding, relative to us, at beyond the speed of light.

I think Trolls question relates to the information limit,
If a galaxy is observed right at the edge of the observable universe, would it be possible to infer that (for example) the observed galaxy is part of a galaxy cluster, some of which are beyond direct observation range.
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Old Nov 26th 2013, 12:19 PM   #4
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I see a problem... If the universe is expanding but that expansion is limited to what we perceive as the speed of light, the dark energy fueling that expansion would eventually condense to a point where the temperature of the universe would be equivalent to the temperature of the big bang! The universe would not end in a freeze, but rather... well what?

The alternative IMHO is that the universe is not actually expanding (regardless our observations) but rather it is static and space/time is fooling us.
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Old Nov 26th 2013, 12:46 PM   #5
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Originally Posted by MBW View Post
My understanding of the expanding universe, redshifts, etc.
is that the galaxies are not actually accelerating relative to each other,
Rather the parameter we generally refer to as distance is changing with time.

Taking receeding galaxies and redshift to the limit does suggest that there will be an observable limit beyond which galaxies will be receeding, relative to us, at beyond the speed of light.

I think Trolls question relates to the information limit,
If a galaxy is observed right at the edge of the observable universe, would it be possible to infer that (for example) the observed galaxy is part of a galaxy cluster, some of which are beyond direct observation range.
You could also state this as "The observed universe is part of a universe cluster"?
Possibly, I rather favor the idea that the observable universe is just a small part of the whole, in fact if the whole is infinite, the observable universe is an infinitesimal part of the whole(Don't get me started on my fractals, I will save them for when the other thread is reopened).

From my "duality" viewpoint, the universe(that means everything) is expanding at a rapidly accelerating pace... but it is an infinite universe expanding into infinity... ergo it is static.
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