Center of the universe the origin of the big bang?

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marcus
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I know that the supernova studies showed objects as more distant than expected, but if those objects are further away due to a stretching of spacetime then we should perceive an increase in object size. Matter is not independent of spacetime and surely must be affected by this stretching. Are those distant galaxies larger than expected? Has anyone tested for this?
matter-to-matter couplings tend to be vastly stronger than matter-geometry coupling.
So objects the size of galaxies hold themselves together at a stable size. The effect of geometry (Hubble-law distance growth) is not noticeable at that scale.

Personally I never talk about "stretching of spacetime". Or about "stretching of space". I don't think of space as a material. If you use the balloon analogy as a help, ignore the rubber. Pretend the rubber isn't there and that the picture is meant only to illustrate evolving geometry. The galaxies are not moving, they are only all getting farther apart. All existence concentrated on the infinitely thin sphere, no inside or outside, or rubber :biggrin:.

It takes some concentration to think in terms of an evolving geometry (rather than material being deformed stretched/compressed within a fixed geometry). But the concentration gets you closer to what GR is really saying.

"Dadurch verlieren Zeit und Raum den letzten Rest von physicalische Realität". In other words "it's not a material, don't think of it that way!"
 
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Something struck me about the ripples analogy. What if the 7 billion year old deceleration is a shock wave?
 
If we imagine a singularity which will have an event horizon. Say this singularity suddenly ejects it's matter for some unknown reason. The gravity waves propagating at the speed of light would be holding back this escaping material under immense pressure until the event horizon was reached. The matter would just be expressed as energy at this point and no particles would exist. Because this matter has no chance to expand significantly until reaching the event horizon you would possibly get a following shock wave instead of one with a leading edge. This could be the 7 billion year old deceleration.
 
marcus
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You posted #27 while I was still working on #26 so you may have missed what I said due to my slow typing:

===quote===
matter-to-matter couplings tend to be vastly stronger than matter-geometry coupling.
So objects the size of galaxies hold themselves together at a stable size. The effect of geometry (Hubble-law distance growth) is not noticeable at that scale.

Personally I never talk about "stretching of spacetime". Or about "stretching of space". I don't think of space as a material. If you use the balloon analogy as a help, ignore the rubber. Pretend the rubber isn't there and that the picture is meant only to illustrate evolving geometry. The galaxies are not moving, they are only all getting farther apart. All existence concentrated on the infinitely thin sphere, no inside or outside, or rubber :biggrin:.

It takes some concentration to think in terms of an evolving geometry (rather than material being deformed stretched/compressed within a fixed geometry). But the concentration gets you closer to what GR is really saying.

"Dadurch verlieren Zeit und Raum den letzten Rest von physicalische Realität". In other words "it's not a material, don't think of it that way!"
==endquote==
Shockwaves are something that happen to material thought of WITHIN A FIXED GEOMETRY. that's not what we're trying to understand.
GR is about the evolution of geometry itself. It is our theory of geometry (explaining why it is approximately Euclidean in some cases and not in other cases.) Hopefully it will soon be improved on, people are working on a quantum version of geometry theory. But GR where it applies is amazingly accurate in its predictions so one has to take it seriously and accept it as the best we can do so far.

It says please do not persist in using material analogies :biggrin:
Geometry has its own distinctive equation that it evolves according to, and according to which it is influenced by matter.
 

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