Talk:Redshift

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This article appeared on Wikipedia's Main Page as Today's featured article on December 29, 2006.

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December 17, 2005	Peer review	Reviewed
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October 15, 2006	Featured article candidate	Promoted
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October 18, 2006	Peer review	Reviewed
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Debate about "See Also" policy and relationship to "What links here" - /See Also Dispute June 2006
Policy debate about an edit that moved content from another article to Redshift - /Content Moved From Redshift Quantization Dispute June 2006

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Request for rearrangement

As the article stands, it mentions some simple formulas for z, then immediately wades into complicated General Relativity formulas, then goes back to much simpler formulas for Doppler Effect when v << c. Also it uses γ before any mention of what it is.

I request that the "Doppler effect" heading and its contents be moved to immediately follow the "Redshift formulae" heading, then a heading "General Relativity" above the general relativity text and the box of formulas, and then continuing as-is from the "Cosmic expansion" heading. (This is a bit beyond my editing capability.) 180.150.39.14 (talk) 10:52, 19 January 2025 (UTC)[reply]

Sorry I think the text is incorrect and you are thus drawing the wrong conclusions. The "Redshift formulae" section starts In general relativity one can derive several important special-case formulae for redshift in certain special spacetime geometries, ... which is true but not apply to all of the content and it is no what the section should emphasize. I agree the table fails because it does not define its terms. I think the simple fix is to move it more or less as you suggest. I will give a try. Johnjbarton (talk) 16:21, 19 January 2025 (UTC)[reply]

Ok I think this is fixed, thanks for the tips. Johnjbarton (talk) 00:29, 20 January 2025 (UTC)[reply]

Age of the universe by redshift

I am deleting one figure which is confusingly labeled "Age of the universe by redshift". The age of the universe does not depend upon redshift in normal terminology. The meaning of the figure might be "what would be the minimum age of the universe based on the largest observable redshift". One such observation is added as annotation in the middle of the figure, unsourced and undated. However, the graph includes a value of the age of the universe in the scale on the left hand side. That is, the scale on the left side is "Age - t" where t comes from the redshift formula from the scale at the bottom. So all in all I can't figure out what the figure means. The source gives nonograms which presumably verify the values but not the meaning. Johnjbarton (talk) 16:51, 19 January 2025 (UTC)[reply]

I guess the graph could be relabeled "Birth date of stars by redshift", then the left side is relative to zero. Johnjbarton (talk) 17:18, 19 January 2025 (UTC)[reply]

History section is WP:Original research

The entire History section contains maybe one secondary source. Johnjbarton (talk) 17:29, 19 January 2025 (UTC)[reply]