November 05, 2018
Before, however, something about Lemaître. In 1922, the Russian cosmologist Alexander Friedmann (1888-1925) put forward a relativistic cosmological model that implied in the concept of an evolving universe departing from an initial state of extremely, if not infinitely, high density — a singularity. The idea had little impact until, some years later, when Georges Lemaître came with his investigation, independent of Friedmann, of a relativistic universe also dynamic and that evolved from a high-density initial state, which he called Primeval Atom. The English cosmologist Edward Harrison (1919-2007), in his Cosmology, 2000 edition, on page 413, states that, because Lemaître was a priest, some contemporary cosmologists looked at the Primeval Atom with reservations and considered Lemaître's theory as an amalgam of science and religion. Such a reputation also fell over the theory that succeeded the Primeval Atom, namely, the Hot Big-Bang theory, being one of its main detractors the English astrophysicist and cosmologist Fred Hoyle (1915-2001).
I return now to the controversial issue of the alleged “expansion of the universe”, motivated by the reading of a fairly interesting article, by the Irish, from Dublin, solid-state physicist Cormac O’Raifeartaigh. The article is entitled “The contribution of VM Slipher to the discovery of the expanding universe”, in which, on the pretext of claiming a nobler position for the American spectroscopist Vesto Slipher (1875-1969) in the worldwide pantheon of cosmology, O’Raifeartaigh makes a general account of modern relativistic cosmology. And, as I said, it is fairly interesting: it presents misplaced generalizations and, to some degree, acceptable overviews.
The article is at arxiv.org/abs/1212.5499, and on page 8, in the second before last paragraph, there is a discussion about Hubble's law, in which O’Raifeartaigh writes about the suggestions to change the law's name to “Hubble-Lemaître's law” or even “Lemaître' law”. The tale is not new. Amongst others, the French cosmologist Jean-Pierre Luminet praised the Belgian cosmologist, in 2011, in an article entitled Editorial note to “The beginning of the world from the point of view of quantum theory”, in which the author claims in the first line that “The year 1931 can undoubtedly be called Georges Lemaître's annus mirabilis”, and advocates in the following pages the idea that Hubble's law should be called “Lemaître's law”.
Let's recall: Lemaître published in 1927, in a Belgian scientific journal (Annales de la Société Scientifique de Bruxelles), an article, written in French, in which he puts forward a relativist model of an expanding universe. Lemaître makes a preliminary derivation of the constant of expansion (the future Hubble constant), using observational data of velocity and distance available at the time. Hubble would published his analysis of velocities and distances in 1929 — therefore, two years later —, where he presents his famous v×d diagram and the derivation of the constant of expansion. In 1931, Father Lemaître's article is translated to English and appears in the prestigious English scientific periodical Monthly Notices of the Royal Astronomical Society (MNRAS). In the translation, the derivation of the rate of expansion does not appear. Much speculation was done about this — who would have censored the text with the aim of excluding the calculation? —, until it was discovered (cf. Mystery of the missing text solved, 2011, by Mario Livio, astronomer of the Space Telescope science Institute) that it was Lemaître himself that had translated his paper to English, and that himself had omitted the passage in question.
Now, the Irishman mentions a statement of Lemaître's, in a letter, that accompanies the 1931 article, in which he writes that “I do not think it is advisable to reprint the provisional discussion of radial velocities which is clearly of no actual interest”. And many years later, in 1952, Lemaître remembers the case, with the following assertion, that I show in French and in English:
“Naturellement, avant la découverte et l'étude des amas des nebuleuses, il ne pouvait être question d'établir la loi de Hubble.”
“Naturally, before the discovery and study of the clusters of nebulae, it was not possible to establish Hubble's law.”
Why was not of “actual interest” the publication of the discussion of the expansion rate in MNRAS? Lemaître's later allegation, in 1952, points to his answer: since the existence of galaxies was not yet a fully established fact, it was not appropriate, or relevant, the discussion of their expansion rate.
I see two problems in this answer. First, why was the discussion relevant to the Belgian Annales but not for MNRAS? Second, the issue of the existence of galaxies was already being discussed, in objective and scientific manners, since, at least, 1920, when in April of that year, there occurred in the United States the famous Great Debate. Also called “Shapley–Curtis debate”, the Great Debate was a public discussion, very important and widely spread at the time, between the renowned astronomers Harlow Shapley (1885-1972) and Heber Curtis (1872-1942), about the nature of the spiral nebulae, ultimately, about the size of the universe. Curtis championed that the spiral nebulae were independent galaxies of enormous sizes, and Shapley defended the opposing view. This debate did not solve the question, which would only be solved by Edwin Hubble (1889-1953), whose research about the topic was published in a sequence of three articles about galaxies of the Local Group: NGC 6822 (Barnard's galaxy, in 1925), M33 (Triangulum galaxy, in 1926) and M31 (Andromeda galaxy, in 1929). Such a research is masterfully and clearly documented in Hubble's book, of 1936, The Realm of the Nebulae, in the chapters IV (Distances of Nebulae) and VI (The Local Group). In other words, already in 1925, galaxies were a scientifically proved reality (see, for example, the article about NGC 6822 in Astrophysical Journal, vol. 62, p. 409).
Hence, why did Lemaître avoid the controversial issue in the 1931 English version? The answer is simple: Lemaître, so to speak, sold his soul! — which, we should agree, does not bode well, not even for a common citizen, let alone for a member of a religious institution.
Let us now address the nature of the sale.
The main character is the English astrophysicist Arthur Eddington (1882-1944), whom is one of the most influential — if not the most influential — scientific personalities of the time. Eddington was Hubble's friend and admirer and had been Lemaître's advisor, in his initial studies of astronomy in Cambridge during 1923 and 1924. (Then he would depart to the United States, where he would undertake his doctorate under the orientation of Harlow Shapley at the Massachusetts Institute of Technology.) Lemaître in his secular eagerness to become a member of the Royal Astronomical Society, and knowing about the influence that Eddington would have in this quest, avoided the conflict with Hubble about the priority in the calculation of the “expansion rate”. Hubble had already expressed his will to Eddington that the questions relative to the “velocity” – distance diagram should be considered an undertaking of Mount Wilson Observatory — in other words, of himself and of his immediate collaborators. (And, conceptually, indeed and in practice it was, as all historical records show, if objectively analyzed.)
This is, therefore, the nature of the sale. Some corroborating details of such a hypothesis are in Mario Livio's article mentioned above. There, he states that on May 12, 1939, Father Georges Lemaître was elected member of the Royal Astronomical Society. And more, in 1953, he was the first to be awarded with the Eddington Medal, of this institution, for his important scientific contributions (for investigations of outstanding merit in theoretical astrophysics, cf. R.A.S. Eddington Medal).
Let us now examine one more argument against the use of the name Lemaître in the identification of the famous cosmology law. Father Lemaître, in a sense, neglected the importance of the phenomenology expressed in the law and, therefore, must not have any credit whatsoever in its naming. Surprisingly, we can find support for this view in a source that is distant from cosmology, namely, in the thoughts of the great naturalist Charles Darwin (1809-1882), who, as we shall see, would agree with me on this issue.
In an excerpt from the most important edition of his autobiography — that annotated by his granddaughter Nora Barlow —, I found a comment by Darwin in which he discards his primacy in certain discovery in favour of those that best expressed it. In the following text, the reference to his major work “The Origin of Species” is made by mentioning the “Origin”.
“Hardly any point gave me so much satisfaction when I was at work on the Origin, as the explanation of the wide difference in many classes between the embryo and the adult animal, and of the close resemblance of embryos within the same class. No notice of this point was taken, as far as I remember, in the early reviews of the Origin, and I recollect expressing my surprise on this head in a letter to Asa Gray. Within late years several reviewers have given the whole credit of the idea to Fritz Müller and Häckel, who undoubtedly have worked it out much more fully and in some respects more correctly than I did. I had materials for a whole chapter on the subject, and I ought to have made my discussion longer; for it is clear that I failed to impress my readers; and he who succeeds in doing so deserves, in my opinion, all the credit.”
Hubble indeed impressed his readers. Father Lemaître not. (Underlined is mine.)
It has already appeared another person suggesting that the law should be called “Hubble-Lemaitre-Slipher's law”! Look at Reasons in favor of a Hubble-Lemaitre-Slipher's (HLS) law.
Now, if it is to put in the name of the law everybody that collaborated for its formulation, I suggest one more, namely, “Hubble-Lemaître-Slipher-al-Khwarizmi's law”, because it would not be possible the formulation of the law without the extraordinary contribution of Muhammad ibn Musa al-Khwarizmi to the fundamentals of algebra and the concept of numbers.
Epilogue
The renaming of Hubble's law can still be seen from another point of view. The empirical relationship between redshift and apparent magnitude is an observational fact. This is what concerns Hubble's work. Lemaître's work is related to the theoretical relationship between recessional velocity and distance (cf. Redshifts versus paradigm shifts; against renaming Hubble's Law). The empirical relationship is firmly established, whereas the theoretical relationship is still a hypothetical statement. The 2018 IAU motion has the inconvenient and misleading result of equating a truly indisputable relation (Hubble's law) with a clearly disputable theoretical relation, since modern relativistic cosmology strives with multiple unknowns (dark energy, dark nonbaryonic matter, dark baryonic matter, etc.).
Acknowledgment – The epilogue resulted from message exchanges in a discussion group of A Cosmology Group, maintained by Louis Marmet at the address http://cosmology.info/. I acknowledge the contributions of Eric Lerner and Louis Marmet who, to my knowledge, were the first to draw attention to the above argument.