Non-velocity Redshifts and Photon–Photon Interactions
Jean-Claude Pecker · A. P. Roberts · Jean-Pierre Vigier
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In one page
A redshift is normally read as motion: the galaxy is receding, so its light is stretched. Jean-Claude Pecker, A. P. Roberts and Jean-Pierre Vigier used a page of Nature to ask whether every redshift has to mean that. Anomalies were on the books — extra reddening toward the edge of the Sun’s disc, a redshift excess reported for hot stars, and galaxies that look associated on the sky while carrying badly mismatched redshifts. Fred Hoyle and Jayant Narlikar had answered those with a proposal that a particle’s proper mass varies from place to place and time to time. Pecker, Roberts and Vigier offer a different one: light can lose a little energy by interacting inelastically with other light, so a photon crossing a dense radiation field arrives slightly redder without anything having moved. Their case for it is not that it is prettier. It is that it covers more of the anomalies, gives numbers at least to order of magnitude, and can be tested on a bench.
Why it matters hereChapter 13 asks what the universe looks like if the vacuum is a real medium that light propagates through and interacts with, and this paper is the sharpest early version of the question: how much of what we read as cosmic motion is a property of the medium instead? Chapter 1 gets the more useful lesson — the authors do not argue from preference, they argue from coverage, order-of-magnitude numbers and a laboratory test.
What it claims
01The paper opens by accepting its rival as serious. Recent data on galactic redshift anomalies had led Hoyle and Narlikar to propose a qualitative explanation in terms of a spatio-temporal variation of proper mass, and the authors say plainly that the consequences of hypotheses such as this are evidently worthy of study — before adding that there are other redshift anomalies which should also be considered in the same context.Abstract, first two sentences
Published and peer-reviewed02Their alternative is an inelastic photon-photon interaction: light that passes through a field of other light gives up a small part of its energy to it, and therefore arrives redder, with no recession involved. This is a mechanism acting along the path, so the size of the effect depends on what the light crossed rather than on how fast the source is moving.Abstract, third sentence
What to watch03The authors name three advantages, and the third is the one that makes the proposal a research programme rather than a preference. Compared with a spatio-temporal variation of proper mass, an inelastic photon-photon interaction is more inclusive, more quantitative at least in order of magnitude, and immediately testable in the laboratory.Abstract, third sentence
What to watch04The mechanism is not invented here; the paper revives a controversy of the 1950s and cites both sides of it. Erwin Finlay-Freundlich proposed in 1954 that light reddens in proportion to the radiation field it traverses, Max Born gave a theoretical account of such a photon-photon coupling in the same year and Melvin followed it in 1955 — while Dirk ter Haar’s 1954 objection is carried in the same reference list.Reference list, items 2, 3, 4 and 11
Published and peer-reviewed05The observational anomalies the argument draws on are named through the citations: the solar limb effect, the excess redshift measured toward the edge of the Sun’s disc, in the work of Lorand in 1962 and Roddier in 1965, and the redshift behaviour of pulsars and of dense stars through the 1970 annual reviews of Hewish and of Cameron.Reference list, items 6, 7, 8 and 9
What to watch06Any non-velocity redshift mechanism has to survive the precision measurements already on the books, and the paper cites the two that bind it hardest: the Williams, Faller and Hill test of Coulomb’s law from 1971, which sets the upper limit on the photon rest mass, and the Pound and Rebka measurement of the gravitational redshift from 1960. Both are settled physics, and both are constraints the proposal has to clear rather than results it disputes.Reference list, items 5 and 10
Settled physics
The way in
https://doi.org/10.1038/237227a0WHAT THIS PAGE IS WRITTEN FROM. Nature volume 237, issue 5352, pages 227 to 229, May 1972. The article is closed under the Springer text-and-data-mining terms and no open copy could be reached on 2026-09-08, so none of its text is reproduced here. Everything below was written from two things that could be read: the published abstract in full, and the complete eleven-item reference list deposited with Crossref, which shows exactly what the argument is built on — Hoyle and Narlikar 1971 for the variable-proper-mass alternative; Finlay-Freundlich 1954, Born 1954 and Melvin 1955 for the photon-photon redshift mechanism, with ter Haar 1954 for the contemporary objection to it; Lorand 1962 and Roddier 1965 for the solar limb effect; Hewish 1970 and Cameron 1970 for pulsars and dense stars; and Williams, Faller and Hill 1971 together with Pound and Rebka 1960 for the precision limits any such mechanism has to respect. Each locator says whether it cites the abstract or the reference list. REGISTRY NOTE. The record carried the three authors in capitals as J. C. PECKER, A. P. ROBERTS and J. P. VIGIER; they are restored to normal case here, with Jean-Claude Pecker and Jean-Pierre Vigier given in full. When the article itself can be read, this sheet should be rewritten from it.
How to cite it
Jean-Claude Pecker, A. P. Roberts, Jean-Pierre Vigier (1972) Non-velocity Redshifts and Photon–Photon Interactions. doi:10.1038/237227a0
Where it sits in the curriculum