Why does redshift indicate that space-time is expanding

In summary, LS suggests that the redshift is a result of galaxies flying away from each other, not from space-time expanding. However, he notes that observations are necessary in order to explain this phenomenon.
  • #1
LSulayman
42
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Since nobody answered my last question I''l try it this way:

Why does redshift indicate that space-time is expanding and not that galaxy's are just flying away from each other?
 
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  • #2


Its the fact that the further away it is, the faster a galaxy appears to be travelling, and this points towards space-time itself expanding, rather than the galaxies moving away and nothing else.
 
  • #3


LSulayman said:
Since nobody answered my last question I''l try it this way:

Why does redshift indicate that space-time is expanding and not that galaxy's are just flying away from each other?

What you suggest requires that the universe have an edge and a non uniform distribution of galaxies and neither are observed.
 
  • #4


russ_watters said:
What you suggest requires that the universe have an edge and no such edge is observed.

How come? Maybe this is something we know now but when Hubble presented his observations of redshift people did not know. (I think)
 
  • #5


What does that have to do with anything? (...and see my late edit...)
 
  • #6


russ_watters said:
What you suggest requires that the universe have an edge and a non uniform distribution of galaxies and neither are observed.

Why do you have to observe these things in order to explain that redshift is not from expanding space-time but from galaxy's flying away from each other?
Or do I need heavy phisics to understand (I'm not a physisist or stronomer so)?

I'm trying to understand what made people (Hubble) back then think that the redshift was because of expanding space-time, that's why I asked.
 
  • #7


Btw, you'll need to be more patient - this place isn't continuously staffed and activity can be highly variable.
 
  • #8


LSulayman said:
Why do you have to observe these things in order to explain that redshift is not from expanding space-time but from galaxy's flying away from each other?
Or do I need heavy phisics to understand (I'm not a physisist or stronomer so)?

I'm trying to understand what made people (Hubble) back then think that the redshift was because of expanding space-time, that's why I asked.

LS, you should search this site for threads adressing cosmological redshift vs doppler redshift. On small enough scales they can both give same results, on large scales doppler redhift gives wrong numbers, although there are ways of treating cosmological as doppler, it only unnecessary complicates things.
 

1. What is redshift?

Redshift is a phenomenon that occurs when the wavelength of light from an object appears longer than it actually is. This is caused by the Doppler effect, where the source of the light is moving away from the observer.

2. How does redshift indicate that space-time is expanding?

Redshift is a result of the expansion of space-time. As the universe expands, the distance between objects increases, causing the light from those objects to appear more stretched out, or "redshifted". This is evidence of the expansion of the universe.

3. What is the relationship between redshift and the expansion of the universe?

The greater the redshift, the greater the expansion of the universe. This is because as objects move farther away, the light they emit is stretched out even more, resulting in a larger redshift.

4. Can redshift be used to measure the rate of expansion of the universe?

Yes, redshift can be used as a tool to measure the rate of expansion of the universe. By measuring the amount of redshift in the light from distant objects, scientists can calculate the rate at which the universe is expanding.

5. Is redshift the only evidence for the expansion of space-time?

No, redshift is not the only evidence for the expansion of space-time. Other evidence includes the cosmic microwave background radiation, the abundance of light elements in the universe, and the observed acceleration of distant objects.

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