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This is correct. I have changed the text correspondingly. That is, the proper-motion distance is in general nost the same as the comoving distance, but rather the same as the transverse comoving distance. The proper-motion distance is the same as the comoving distance in a flat universe because
489:
Might be because of merging and stuff, but I notice at least two variables that are used without a real introduction or explanation. First, there's chi, which seems to first come up in "If and only if the curvature is zero, then proper motion distance and comoving distance are identical, i.e.
374:
I made this page because information about various "distance measures in cosmology" seems to be scattered about
Knowledge. Standard textbooks often devote a chapter to the idea of distance measures and then subsections to each of the various kinds, so why not Knowledge too?
411:. In my opinion this might be a bit much -- certainly comoving distance is important enough to have its own page? I think that the section regarding comparison with other distance measures on the comoving distance page, though, should go into this page. Any other opinions?
378:
Also, in looking around the articles, the articles on some distanc measures define other distance measures or talk about the relation between them, etc. There were also suggestions on some of the pages that a meta-distance measure page be created.
539:"Angular diameter distance or proper motion distance. Angular Diameter Distance is a good indication (especially in a flat universe) of how near an astronomical object was to us when it emitted the light that we now see." -- ie. They are equal.
898:
so we don't have to tackle the entire complexity of yet more distances in one go. Complex subjects are best dealt with in bite-sized bits. The distance-measures article is then a useful overview of all the different distances.
545:
Further, the lines: " * called the angular size distance by
Peebles 1993, but should not be confused with angular diameter distance )" and " * sometimes dpm is called the angular diameter distance" are contradictory.
382:
This page might be a useful introduction to what distance measures are used for, and a good place to describe how they are related to each other. For details we can just refer to the individual pages on each measure.
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Hi, I'm the editor who put the equation there. I'm not sure what the confusion is. E(z)=H(z)/H_0 is a common definition in cosmology for convenience, see e.g.
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merge; for those of us whose brains are not the size required for cosmology, it is helpful to have the longer, more explanatory article at
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I think the order in which we define the Ωs should be the same as the order they appear in the formula, and since
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which provides greater detail. This structure seems to work well for readers, and is consistent with policy.
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on
Knowledge. If you would like to participate, please visit the project page, where you can join
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there the transverse comoving distance and the proper-motion distance are the same.
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who put it there in the first place, and our version still says that it equals
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Yes the need for the factor (1+z) here and elsewhere is nowhere explained.
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The only opinions on here for six months (mine) say no to the merge of the
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816:. Would it help to call it the "normalized Hubble parameter"? Even though
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Well, no other comments since
December so I'll do the move.
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would be a dimensionless Hubble parameter, but that's what
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It's true that I don't understand why the expression for
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Meanwhile I am restoring the first two of these points.
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so now I'll remove the article merge suggestion tag.
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is given in terms of the others, it has to be last.
615:So why did you revert my addition of a wikilink to
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577:"d_a = d_pm / (1 + z)" -- ie.They are not equal.
542:"d_a = d_pm / (1 + z)" -- ie.They are not equal.
968:Start-Class Astronomy articles of Mid-importance
330:, a project which is currently considered to be
871:Distance measures (cosmology)#Comoving distance
953:Start-Class physics articles of Mid-importance
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223:, which collaborates on articles related to
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820:yields less results, for what it's worth.
460:article. I just merged the comparison to
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756:{\displaystyle {\frac {H(z)}{H_{0}}}.}
679:? Do you think it was correct before?
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326:This article is within the scope of
217:This article is within the scope of
106:This article is within the scope of
865:merge; the current structure is in
49:It is of interest to the following
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622:Why did you revert my addition of
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896:Comoving and proper distances
875:Comoving and proper distances
869:for, with a brief summary at
846:Distance measures (cosmology)
842:Comoving and proper distances
617:Dimensionless Hubble constant
591:09:42, 11 November 2019 (UTC)
562:22:08, 21 February 2014 (UTC)
462:distance measures (cosmology)
451:distance measures (cosmology)
449:removed article merge tag to
423:distance measures (cosmology)
421:merged comparison section to
409:Distance measures (cosmology)
388:09:58, 22 November 2006 (UTC)
275:This article is supported by
126:Knowledge:WikiProject Physics
120:and see a list of open tasks.
943:Start-Class physics articles
857:21:05, 12 January 2021 (UTC)
645:{\displaystyle -\Omega _{r}}
416:00:36, 6 December 2006 (UTC)
129:Template:WikiProject Physics
887:15:17, 14 August 2021 (UTC)
807:09:29, 5 January 2021 (UTC)
786:{\displaystyle \Omega _{k}}
672:{\displaystyle \Omega _{k}}
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926:07:42, 23 April 2022 (UTC)
830:07:44, 31 March 2022 (UTC)
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