What's really happening here?

  • Thread starter Tyger
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  • #1
Tyger
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If we look in the distant past we see evidence that the rate of universal expansion is increasing. If we look in the recent past we see that our own galactic cluster and many around it, including the huge Coma cluster, are headed toward a "great attractor". These are definately opposing scenarios.

Does the rate of expansion reverse at times?
 

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  • #2
maximus
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yes.

not all of the galaxies we observe our red shifed. local regions will clump together, but then continue to expand. the distanct past was going through a period of hyperinflation, so there was no time to have the galaxies clump together.
 
  • #3
Tail
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Generally the Universe is expanding, but locally it might seem different because of the gravitation.
 
  • #4
Phobos
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There is "small-scale" (and I use that term very loosely) non-expansion if there is enough gravitational effect in a particular region (like in a galaxy or a galaxy cluster), but the overall universe is expanding.
 
  • #5
Ivan Seeking
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I have read that anti-gravity [or whatever dark energy is] dominates in the regions between galaxies. Is the nature of deep inter-galactic space fundamentally different than the space in between stars? Is this related to the distribution of dark matter?
 
  • #6
Originally posted by Tyger
If we look in the distant past we see evidence that the rate of universal expansion is increasing. If we look in the recent past we see that our own galactic cluster and many around it, including the huge Coma cluster, are headed toward a "great attractor". These are definately opposing scenarios.

Does the rate of expansion reverse at times?

Firstly, they are not opposing scenarios. You're confusing the issue here - space itself is expanding. Within that expansion mass can experience velocity and mass. So in the scenario you describe, there is simply the motion of mass within expanding space.

However, to that I should also point out that I am still very much against the "standard candle" explanation of the expansion of the universe acceleratnig. :) There are too many easily flawed assumptions involved to take the idea seriously. Unfortunately, it has fast become a paradigm in its own right. :(
 
  • #7
Tyger
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Originally posted by I, Brian
Firstly, they are not opposing scenarios. You're confusing the issue here - space itself is expanding. Within that expansion mass can experience velocity and mass. So in the scenario you describe, there is simply the motion of mass within expanding space.

However, to that I should also point out that I am still very much against the "standard candle" explanation of the expansion of the universe acceleratnig. :) There are too many easily flawed assumptions involved to take the idea seriously. Unfortunately, it has fast become a paradigm in its own right. :(

First, welcome to the board and thanks for your input.

I know about "space is expanding" and the dynamics of gravity and the universal expansion, I'm just trying to get people to ask a few questions as opposed to accepting "ober dictum". And yes, I agree that there are too many assumptions used to justify too many conclusions, especially in Cosmology where expermental data is thin and hard to come by. People don't always recognize that any hypothesis carries many often unstated assumptions.

I believe the road to discovery lies in asking the right question. There are usually far fewer right questions than right answers, so looking for the right answer is like looking for a needle in a haystack. But if you ask the right question the right answers will come thick and fast.
 

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