Talk:Hubble's law

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Former good article Hubble's law was one of the Natural sciences good articles, but it has been removed from the list. There are suggestions below for improving the article to meet the good article criteria. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.
Article milestones
Date Process Result
January 22, 2006 Good article nominee Listed
September 5, 2009 Good article reassessment Delisted
Current status: Delisted good article
Wikipedia CD Selection
WikiProject icon Hubble's law is included in the Wikipedia CD Selection, see Hubble's law at Schools Wikipedia. Please maintain high quality standards; if you are an established editor your last version in the article history may be used so please don't leave the article with unresolved issues, and make an extra effort to include free images, because non-free images cannot be used on the DVDs.


File:Hubble-constant-vers2.png should be removed as it contains outdated data. Correct (up to date) information is more important to the reader than pretty pictures. 00:08, 10 April 2014 (UTC)

I would argue that it is not "outdated," but "historical" in nature. The entire section the image is found in pertains to the narrowing down of H0 and the different values researchers have found for it over the years. If anything should be changed it should be the description, so that it is more obvious that there is historical context. In the meantime, I'll start work on an updated graphic. Primefac (talk) 08:50, 10 April 2014 (UTC)

Variable Hubble constant[edit]

Since Hubble constant redirects here I suggest making more clear that the Hubble constant is actually not a constant but a variable that is increasing. Thank you (talk) 20:39, 20 December 2014 (UTC)

The "Interpretation" section states this fact, however I see your point that it could potentially be made more clear in the lede. Primefac (talk) 20:51, 20 December 2014 (UTC)
Why the so-called Hubble constant is called a "constant" when it is the inverse of the age of the universe and therefore not at all constant has been a conundrum for me for quite some time now. Only today I discovered the explanation buried in the article. The term is awfully misleading. I have to reiterate the call for making this clearer. The alternative (and far more accurate and less confusing) term "Hubble parameter" should be mentioned, in bold, in the intro. I would do it myself but I feel uncomfortable editing natural science articles (apart from tweaks) because I consider myself anything approaching well-versed only in the social sciences. --Florian Blaschke (talk) 13:32, 23 February 2015 (UTC)


This article defines the Hubble law in terms of Doppler shift, but it properly ought to be redshift or cosmological redshift. While cosmological redshifts and Doppler redshifts are observationally indistinguishable, they have very different causes. Thinking of it in terms of Doppler effect leads to problems. For instance, Doppler shifts greater than the speed of light are not possible, but cosmological redshifts greater than the speed of light are. (talk) 11:47, 5 January 2016 (UTC) Danny Faulkner

In the "combining redshifts" section, it states that it's not actually a Doppler shift, but I can see how just reading the lead may be confusing. Primefac (talk) 15:31, 5 January 2016 (UTC)

Hubble acceleration scale[edit]

I've seen in various astrophysical papers[1][2] mention of the "Hubble acceleration scale" a0 = cH06.59×10−10 m/s2. I'm guessing this is the gravitational acceleration requires to bind objects together against Hubble expansion, but all the sources I can find are rather technical and don't have a good WP-level explanation of the significance of the number.

It sould definitely be nice to have a subsection on this value. Has anyone got a simple explanation? (talk) 23:36, 11 November 2016 (UTC)

How did Hubble determine distances?[edit]

I can't see where this is mentioned here or in the linked articles. — Preceding unsigned comment added by Keith McClary (talkcontribs) 05:19, 2 December 2016 (UTC)

Keith McClary, see Hubble's_law#Cepheid_variable_stars_outside_of_the_Milky_Way. Primefac (talk) 12:46, 2 December 2016 (UTC)