Talk:Hadron era

This article was nominated for deletion on 6 February 2025. The result of the discussion was keep.

This page was proposed for deletion by Johnjbarton (talk · contribs) on 5 February 2025.

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@Bearian Informed me on my Talk page that:

• Several of the other languages' articles have additional sources that mention the term, such as this accessible blog linked to the French language article. What do you think?

I think it better to reply here as follows.

Thanks! In general self-published sources like blogs are not considered reliable sources. The linked page has no references but it does have a lot of links into Wikipedia. Another editor on Talk:Chronology of the universe has suggested that this term "Hadron epoch" appears in blog posts because it was added to Wikipedia. While the physics described seems generally ok, the blog post was written by a person not trained in cosmology. It seems to me that this is a circular source.

Please note that in addition to few sources with "Hadron epoch", the other issue is lack of coverage in major cosmology textbooks. I would say that the cosmology texts tend to talk about "events" rather than time periods. I suppose this reflects the continual nature of the expansion process: generally speaking the universe was continually changing so it was not constant in any time period. Johnjbarton (talk) 16:23, 5 February 2025 (UTC)Reply

I understand. Thanks. Bearian (talk) 17:56, 5 February 2025 (UTC)Reply

Johnjbarton & Bearian there is a fair amount of literature on this transition, for instance https://doi.org/10.1016/0375-9474(91)90115-M https://journals.aps.org/prd/abstract/10.1103/PhysRevD.85.084032 and https://escholarship.org/content/qt4vd2v2fc/qt4vd2v2fc.pdf plus a lot more. While the epoch may not be such a common term, the transition looks to be notable so maybe a PROD is too hasty. Well into my areas of incompetence. Ldm1954 (talk) 07:34, 6 February 2025 (UTC)Reply

I love your last sentence. Physics is my second favorite science and the only area that I've ever written articles. The late great Ralph Alpher reviewed two of my articles and trashed them, which tells you everything. Bearian (talk) 11:24, 6 February 2025 (UTC)Reply

Yes, indeed the "quark-hadron phase transition" is notable and is covered in cosmology textbooks. (Its success is in contrast to GUT and electroweak phase transitions which have produced many theoretical papers but no solid observational impact).

Based on textbooks, reviews, and comments in Talk pages, cosmology is viewed in terms of "events", like the quark-hadron phase transition, rather than "epochs" or "eras" as characterizes geology. I guess this is accidental, but it may also reflect reality. Geological events tend to be transitions between long stable "eras", but cosmology deals with a universe expanding by many orders of magnitude and changing states of matter over subsecond to a few hundred thousand years. Cosmology is more of a continuous change than a series of epochs. Johnjbarton (talk) 15:44, 6 February 2025 (UTC)Reply

Wikipedia could use a QCD phase transition page, but it would be better served redirecting to either QCD matter#Phase_diagram or Cosmological phase transition#QCD phase transition than having the content of this page. Aseyhe (talk) 04:29, 7 February 2025 (UTC)Reply

I added a redirect and some links between the two existing articles for now. Johnjbarton (talk) 17:11, 7 February 2025 (UTC)Reply

One of the two references in the article is:

• Fromerth, M. J.; Kuznetsova, I.; Labun, L.; Letessier, J.; Rafelski, J. (2012). "From Quark-Gluon Universe to Neutrino Decoupling: 200 < T < 2MeV". Acta Physica Polonica B. 43 (12): 2261. arXiv:1211.4297. doi:10.5506/APhysPolB.43.2261. ISSN 0587-4254. S2CID 118448487.

It does not use the term "Hadron epoch". It does say: The epoch we address begins just before the quark-gluon Universe turns into the hadron Universe and ends when we reach the era of the electron, positron, neutrino, and photon dominated Universe. This ref, like the only that says "Hadronic epoch", is also by Rafelski. Johnjbarton (talk) 22:43, 6 February 2025 (UTC)Reply