Linked Questions
14 questions linked to/from How is the expansion of space distinguishable from objects moving away?
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Why does space expansion not expand matter?
I have looked at other questions on this site (e.g. "why does space expansion affect matter") but can't find the answer I am looking for.
So here is my question: One often hears talk of space ...
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What does general relativity say about the relative velocities of objects that are far away from one another?
What does general relativity say about the relative velocities of objects that are far away from one another? In particular:--
Can distant galaxies be moving away from us at speeds faster than $c$? ...
user4552
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Can space expand with unlimited speed?
According to this article on the European Space Agency web site just after the Big Bang and before inflation the currently observable universe was the size of a coin. One millionth of a second later ...
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Superluminal expansion of the early universe how is this possible?
Is this a postulate? I get the expansion of the universe, the addition of discrete bits of space time between me and a distant galaxy, until very distant parts of the universe are moving relative to ...
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Is the universe actually expanding?
Up until recently I was fairly sure that the universe is expanding, i.e. the (spatial) metric is changing proportionally to the scale factor, such that the distance measured between objects is ...
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Some areas of the universe are moving away from us FTL but surely as we get closer to that area, the speed of expansion would gradually slow?
If the universe is expanding uniformly, then wouldn't the rate of expansion of the universe change if you were to move closer to a point that is currently moving away from us faster than light?
For ...
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3
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I just saw the Einstein's thought experiment about train
In the experiment, two lightning bolts strike at the same time and the stationary observer at the train sees the lightning simultaneously but the one in the middle of the train station would see at ...
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If the expansion of space causes the elongation of light waves, why isn't this elongation observed within the Milky Way?
The elongation of light waves occurs not because galaxies are moving away from each other, but because light waves are stretching along with the fabric of expanding space (cosmological redshift). ...
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“Negative energy” definition of “gravitationally bound” in expanding cosmology
First off, I realize that there is already a number of questions relating to gravitational binding in cosmology:
Gravitationally bound systems in an expanding universe
Gravitationally bound systems ...
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4
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Why does Hubble's Law indicate motion?
I have been trying to understand and find some justification about why Hubble's Law needs to implicate any sort of relative motion between galaxies.
I can understand why and how one would explain the ...
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If space is expanding isotropically, then why are distances between objects in the solar system not expanding [duplicate]
As I understand the metric expansion of space, space itself is expanding uniformly, isotropically. Distant light, passing through our solar system expands, as does the distance between atoms on earth. ...
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Movement of galaxies vs expansion of space
I can readily accept the theory that the universe is expanding as a mathematical model to explain the fact that all galaxies are moving away from each other, but I have difficulty understanding ...
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Making a scale factor invariant *density* in FRW spacetime
For a timelike observer in an FRW spacetime with a perfect fluid, the timelike energy density is given by $T_{\mu\nu}U^\mu U^\nu = \rho(t)$ for a comoving observer.
I want to be able to track changes ...
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Space expansion or generation [duplicate]
When physicists assert that space is expanding, does this imply the creation of new space? If so, why do they use the term "expansion" instead of "generation"?
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