Evolution of radio sources mimics a non-expanding universe

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In summary, the article by Pengfei Li discusses a test of the distance duality relation using two samples of ultracompact radio sources. The test suggests that the universe may be nonexpanding, but this poses a problem as it contradicts the commonly accepted expanding universe theory. The author may be a different person than the Pengfei Li who has previously published astrophysics articles, and his hypothesis is more speculative than typical for his field. However, it is likely that this is the same person, and his co-authorships may reflect his PhD advisor's interests rather than his own.
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Madeleine Birchfield
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new article by Pengfei Li:

Distance Duality Test: The Evolution of Radio Sources Mimics a Nonexpanding Universe

Abstract:

Distance duality relation (DDR) marks a fundamental difference between expanding and nonexpanding universes, as an expanding metric causes angular diameter distance smaller than luminosity distance by an extra factor of (1 + z). Here we report a test of this relation using two independent samples of ultracompact radio sources observed at 2.29 GHz and 5.0 GHz. The test with radio sources involves only geometry, so it is independent of cosmological models. Since the observed radio luminosities systematically increase with redshift, we do not assume a constant source size. Instead, we start with assuming the intensive property, luminosity density, does not evolve with redshift and then infer its evolution from the resultant DDR. We make the same assumption for both samples, and find it results in the same angular size–redshift relation. Interestingly, the resultant DDR is fully consistent with a nonexpanding universe. Imposing the DDR predicted by the expanding universe, we infer the radio luminosity density evolves as ρL ∝ (1 + z)^3. However, the perfect agreement with a nonexpanding universe under the assumption of constant luminosity densities poses a conspiracy and fine-tuning problem: the size and luminosity density of ultracompact radio sources evolve in the way that precisely mimics a nonexpanding universe.
 
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Madeleine Birchfield said:
tl;dr I was wondering if this was the same person as the previously published astrophysics articles under this name. It is but may be his first solo article and so isn't influenced by the academic agendas of his PhD advisors.

One tricky point is that there are multiple currently publishing physicists named Pengfei Li (unsurprisingly, as "Li" is an exceedingly common Chinese surname, and "Pengfei" is not a particularly uncommon Chinese given name).

There is a Pengfei Li who is a co-author of quite a few publications, primarily in the astrophysics of galaxies, at the Department of Astronomy of Case Western Reserve University in Ohio. It isn't obvious to me whether or not this author is the same person.

It is a little outside the range of the typical work of the Case Western Reserve author, who usually publishes more mainstream empirical work in the astrophysics of galaxies and usually publishes papers with co-authors, but not all that far outside the range of the typical work of that author, so it is hard to tell.

The linked article is by a Pengfei Li, as a solo author, who is a Humboldt fellow at the Leibniz-Institute for Astrophysics in Potsdam, Germany, so I suspect that this is a different person (who is much less established in the field) pursuing a far more speculative hypothesis than is typical for the Pengfei Li of Case Western Reserve University.

Pengfei Li of Germany got his PhD in Astronomy from Case Western Reserve University in 2020, so it could very well be that this is the same person and that Pengfei Li's co-authorships were as a doctoral student and/or as a post-doc with a subject matter of the other papers that reflects his PhD advisor's scholarship interests, rather than his own. The bibliography at the link suggests that it is indeed the same person.
 
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