- #1
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Are galaxies are really moving away.Or galaxies are stationary but space-time expends so galaxies move with it ? Or maybe they could be same thing ?
Are Galaxies Moving or is Space-Time Expanding?
- Context: Undergrad
- Thread starter Arman777
- Start date
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- Tags
- Galaxies
Click For Summary
Discussion Overview
The discussion revolves around the nature of galaxy movement in relation to the expansion of space-time. Participants explore whether galaxies are moving away from each other or if they remain stationary while space-time itself expands, potentially leading to a shared understanding of these phenomena.
Discussion Character
- Debate/contested
Main Points Raised
- Some participants propose that galaxies are moving away due to the metric expansion of space-time.
- Others argue that this movement is coordinate dependent, suggesting that in local coordinates, galaxies can be seen as moving away.
- A participant presents an analogy using a rubber belt with balls to illustrate the concept of expansion, suggesting that galaxies could be stationary while space-time carries them along.
- There is a reiteration of the idea that galaxies may not have proper motion relative to Earth, emphasizing the role of metric expansion.
Areas of Agreement / Disagreement
Participants express differing views on whether galaxies are moving or stationary with respect to the expansion of space-time, indicating that multiple competing perspectives remain without consensus.
Contextual Notes
Some statements reflect a dependence on coordinate systems and the interpretation of motion, which may not be universally applicable. The discussion includes analogies that may not fully capture the complexities of the concepts involved.
- #2
- 19,385
- 15,617
Google "metric expansion". There is no (well, very little and for a different reason) proper motion of far distant galaxies with respect to the Earth, it's metric expansion.
- #3
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This is a coordinate dependent statement. In "local" normal coordinates, galaxies are certainly moving away.phinds said:
- #4
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Orodruin said:
Like here its metric expention I guess.Here galaxies are standing still but universe expends so galaxies are moving with a velocity.Galaxies are moving away with a velocity v but not for they have a speed itself,Space time carries galaxies ?
- #5
acidmatic
- 7
- 0
Take a rubber belt and put 5-6 balls on it as if it's a kind of bead. Then pull the belt in opposite directions. You'll see the process itself.Arman777 said:
- #6
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acidmatic said:
I understand..
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