Talk:Hubble's law

Fritz Zwicky related

https://en.wikipedia.org/wiki/Fritz_Zwicky Fritz Zwicky 176.208.32.160 (talk) 17:00, 7 December 2024 (UTC)

• @Johnjbarton: I find it intelligible enough.[1] The IP is right that Fritz Zwicky is related to Hubble's law, and that there's a gap in our coverage. We don't mention Zwicky at all, especially his Tired light hypothesis. Renerpho (talk) 05:59, 8 December 2024 (UTC)

  @Renerpho The original post was unintelligible. If you have a reliable source related to Zwicky and Hubble's Law, please add it. Johnjbarton (talk) 23:51, 8 December 2024 (UTC)

JWST update

On December 9, 2024 an update on the Hubble tension as measured by JWST was published in the ApJ. See here: https://iopscience.iop.org/article/10.3847/1538-4357/ad8c21

@Moleculewerks put in an entry for this. @Johnjbarton removed it based on a prior back and forth discussion about whether or not to include preprint results on this subject. However, I think this update was valid because it is peer reviewed and fully published. If there is not objection I would like to restore it on the basis of being published. Kt170 (talk) 16:23, 13 December 2024 (UTC)

Because of the long discussion above, we need consensus to make this addition. Here is my opinion.

Oppose Peer-review and publication are a minimum bar. We often exclude newly-published papers because historically their results are not "encyclopedic", meaning that subsequent publications dispute the work or (worse) ignore it. Wikipedia relies on secondary sources. In this case we already know that Freedman's work disputes Riess. To include Riess but not Freedman would present a non-neutral point of view. When both works are published they make each other notable;if Freedman never comes out a secondary ref will cite Riess and we can include it. (If Freedman were published and we knew about Riess I would also argue against using Freedman). We are not a news magazine. Johnjbarton (talk) 16:45, 13 December 2024 (UTC)

It seems like the goalpost were moved. Rereading the long discussion above it broke down along the lines of those who wanted to include latest results based on pre-prints (not peer reviewed) versus those who wanted to wait for peer-review and publication. The new entry by @Moleculewerks was based on peer-review and published so should satisfy either camp. In this case the published paper makes reference to both Riess and Freedman so it's not a this side or that side thing. I feel like @Johnjbarton has raised this bar higher after publication by saying these qualifications are minimum and that we now should allow more time or references to the work which makes the new threshold arbitrary and far more open to debate. — Preceding unsigned comment added by Kt170 (talk • contribs) 16:58, 13 December 2024 (UTC)

No, the goal posts have not changed in general. The goal posts are discussed in WP:PSTS. In general a newly published peer-reviewed primary publication is not acceptable by default. We could however have a discussion about it and agree to make an exception. For a publication from a major consortium like Riess or Freedman, I would lean towards including it. But that it is not the scenario we have here. We have one side of a contentious subject in print while the other side is in review. My opinion on Riess is different because it is in direct conflict with Freedman. But this much is open for debate and I've given my opinion. Johnjbarton (talk) 19:20, 13 December 2024 (UTC)

I agree with Johnjbarton, reluctantly. But I must admit, my first instinct was to ask them if they're of sound mind. Their edit summary for the revert (Sorry see the very very long Talk page discussion on 2024 sources) seems absurd, since we never had a discussion specifically about excluding sources published this year. What they write in their most recent comment makes sense though, and I think they're right.

We have an unusual case here -- a debate where one side has their arguments published before the other, which may lead to one-sided coverage on our part. We have agreed to wait for the articles to be peer-reviewed and published before including them (those are the infamous "goalposts", which we've fought over at length on this talk page), but it may not be immediately obvious that this meant "wait for both articles to be published before including either". Renerpho (talk) 19:57, 13 December 2024 (UTC)

Indeed, though Riess does address Freeman and Lee ("A study by W. L. Freedman et al. (2024, hereafter F24) and A. J. Lee et al. (2024, hereafter L24) compares three distance indicators measured with JWST but to each other rather than to the HST R22 Cepheid sample, the results of which we will address in Section 2."), etc... And there's a whole appendix dedicated to the Freedman preprint.

I haven't read the paper in details, but it's not clear that Freedman or Lee would be of note if Riess is correct (IMO, very likely given the small N problem of Freedman) that what we're seeing here are selection sampling effects. Freedman or Lee might even fail to clear review in light of Riess. Headbomb {t · c · p · b} 21:03, 13 December 2024 (UTC)

Following the proposal to use only secondary sources I took the summary of the JWST results verbatim from the Annual Reviews of Astronomy and Astrophysics (which is the most authoritative source of reviews of Astronomy and Astrophysics) Verde et al 2024 (though this is the status of a year ago) — Preceding unsigned comment added by Kt170 (talk • contribs) 01:42, 16 December 2024 (UTC)

I think the Verde review should be used to give an overall perspective rather than a summary of the 2023 JWST results. Based on my reading of the review, the 2023 JWST is just one of many inputs to their overall conclusions. Johnjbarton (talk) 17:01, 16 December 2024 (UTC)

Reorg of "Determining the Hubble constant"

I am going to boldly reorg the section "Determining the Hubble constant" to correct the chronological order and move the conclusions to the end in the Hubble Tension subsection. Johnjbarton (talk) 18:40, 16 December 2024 (UTC)

I made some progress.

• The Early Measurement section needs a work and bit more content.
• The 21st Century section has two big problems: too much content and more important the emerging story of this era -- CMB vs local universe -- is obscured by the presentation.
• The Hubble Tension section seems too long.

Johnjbarton (talk) 19:12, 16 December 2024 (UTC)

Ok I did more digital scissor work and resectioned. I split the Hubble tension section into a chronological piece and a status piece.

• Precision cosmology and the Hubble tension
  • The era 2000-2013
• Eliminating systematic errors
  • 2013+ is work on systematic errors;
• Other kinds of measurements
  • Post 2013 measurements other than CMB/distance ladder.
• Possible resolutions of the Hubble tension
  • experimental or theory paths

This organization makes the tension stand out and classifies the new work as systematic errors or "other kinds".

I think this is pretty good organizationally, but the content of the sections still needs work. Johnjbarton (talk) 00:37, 17 December 2024 (UTC)

Just another update in case I run out of energy on this topic. I added compact summaries of the early and late approaches to determining H_0 based mostly on the excellent Supplement to Verde's review. I was tempted to rework "Possible resolutions" because to me it fails to capture how unlikely it is that the existing proposals will pan out. But I think it's good enough.

The main issue then is the "Other kinds of measurements": it is newsy rather than encyclopedic. The section should also make clear that some of these approaches are "early" (use Lambda_CDM) and some are not.

To be sure I am not an expert on this topic so please review the entire section. Johnjbarton (talk) 00:40, 24 December 2024 (UTC)

Redshift of light as it goes (with no expansion) as an alternative explanation of the Hubble effect.

Suppose red shifting as it goes is just one of those things that light (EM waves) does. How much per km would that be, and how well could me measure that here on earth, or maybe to the moon and back. 2600:6C4E:3000:3232:9CF3:D7CC:2BB0:3A6C (talk) 00:29, 2 January 2025 (UTC)

See tired light — this hypothesis is generally considered refuted by the evidence. Banedon (talk) 00:58, 2 January 2025 (UTC)