Cosmological red shift and cosmic time dilation

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SUMMARY

The discussion centers on the validity of claims made in a paper regarding cosmological redshift and cosmic time dilation, specifically addressing the FLRW metric. Participants assert that the paper incorrectly states that the FLRW metric in conformal coordinates differs physically from the standard FLRW coordinates, which is established as false. Additionally, the paper's assertion that the standard derivation of the relationship between cosmological redshift and the expansion of the scale factor is incorrect is also disputed. The consensus highlights the importance of understanding the FLRW metric and its implications in general relativity.

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  • General Relativity (GR) principles
  • Friedmann-Lemaître-Robertson-Walker (FLRW) metric
  • Conformal coordinates in cosmology
  • Cosmological redshift and scale factor relationships
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andrew s 1905
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TL;DR
This paper claims the normal explanation of red shift is wrong and is in fact due to cosmic time dilation. I would like an expert view on its merit.
This https://www.frontiersin.org/articles/10.3389/fphy.2022.826188/full#h14 paper makes the claim as in the summary.

I don't have the experience to judge the merit of the claim. I would value any views on it is correct or not and if incorrect where the error(s) is (are).

I do have some understanding of the various coordinate system mentioned but the claim seem to be one of physical differences not just coordinate transform.

Thanks in advance Andrew
 
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This quotation shows that the author's knowledge of GR is shaky. Re the FLRW metric.

"In contrast to the space coordinates, the time coordinate is assumed to be invariable during the Universe history. This is somewhat strange and surprising, because other solutions in GR such as the well-known Schwarzschild solution [1113] involve distortions in space and time together."

This is poor.
 
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I see at least two obvious falsehoods in the paper:

(1) It claims that the FLRW metric in conformal coordinates is physically different from the FLRW metric in standard FLRW coordinates. This is false: conformal coordinates are a useful tool (see, for example, their usage in Davis & Lineweaver 2003 to clarify the meaning of various cosmological parameters), but transforming to conformal coordinates does not change anything about physical observables.

(2) It claims that the standard derivation of the relationship between cosmological redshift and the expansion of the scale factor, found in many textbooks and papers, is wrong.
 
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Thanks sorry I missed it. Andrew
 
Thanks, please close this thread. Regards Andrew
 

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