Quote:
Originally Posted by Steve Limpus
... Those distant galaxies don't move through their own local space faster than light, even though they appear to recede from us faster than light.
Did I get that right?  |
I think that's exactly what Pamela said.
Quote:
Originally Posted by Steve Limpus
Here's another thought: is 'expansion' always the right term? If I understand it right, the Planck length/volume/time is not expanding--so then neither is spacetime really? (Even if the Planck length was expanding, we couldn't tell anyway, because our 'measuring stick' would be expanding too?) Wouldn't it be more accurate to say spacetime is 'multiplying?' In other words: Planck spaces aren't expanding as such, there are just *more* of them between us and distant galaxies? If that's right--is there any way to observe it?
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Does the force of gravity (and the other fundamental forces) hold back the expansion of spacetime--or does it somehow interrupt the mechanism by which spacetime multiplies?  |
Interesting thoughts, Steve. I think the jury is still out on the issue of
"is space expanding" or is there somehow just more space
"being generated between galaxies". Gravity does hold back the expansion of space and if it was not for dark energy, the expansion rate would have decreased forever, even possibly reversing one day.
Quote:
Originally Posted by Steve Limpus
What about in the past: does double the galaxy clusters mean half the expansion, one line of sight compared to the other? Should I perceive my observable, expanding universe to be perfectly spherical; or is it lumpy over time?
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Astronomers observe the expansion to be uniform over very large scales, but 'clumpy' on smaller scales. The reason is that on the large scale there are roughly an equal number of galaxies in all directions and it is the large scale that determines the overall expansion rate. The observable universe is more or less spherical, of course, with very tiny 'lumps'.