This story is a detective tale in which the crime was never committed. But the suspicion hung in the air for eighty years.
In March 1931, the Monthly Notices of the Royal Astronomical Society published an English translation of an article that Belgian cosmologist and Catholic priest Georges Lemaître had published four years earlier. The original — in French, in the small-circulation journal Annals of the Scientific Society of Brussels — had gone almost unnoticed. The translation was supposed to right that wrong. But it was shorter than the original. A table of observational data vanished from the text and, more importantly, so did the paragraphs in which Lemaître derived a numerical estimate for the rate of the Universe’s expansion. The very rate that the whole world had already been calling the Hubble constant for two years.
To historians of science, it looked like a classic plot: an obscure scientist from a small country had his wings clipped so as not to eclipse a star of the first magnitude. By 1931, Edwin Hubble was already a figure of global stature, working with the world’s largest telescope at Mount Wilson Observatory, publishing in the Proceedings of the National Academy of Sciences. Lemaître was a professor at the University of Louvain, an abbé, a man whose cosmology sounded to many contemporaries like theology wrapped in mathematics. The suspicion that someone — an editor, a colleague, Hubble himself — had cut out the inconvenient paragraphs seemed an almost inevitable conclusion.
The answer came eighty years later, and it was more prosaic than any conspiracy.
To understand what vanished from the translation, you have to understand what was in the original. And the 1927 original was a work of startling ambition for a nine-page article. Lemaître took the equations of general relativity and derived dynamic solutions from them, describing a Universe that did not stand still but expanded. That alone was a step Albert Einstein had not dared take: he had introduced the cosmological constant precisely so that the Universe in his model would remain static. Alexander Friedmann, in 1922, had shown the mathematical possibility of non-static solutions, but had not connected them to observations. Lemaître did both.
He took the recession velocities of galaxies measured by Vesto Slipher and compiled by Gustaf Strömberg in a 1925 publication — 41 galaxies with redshifts. He took the estimates of galactic distances that Hubble had published in 1926. And he combined the two datasets with his own theoretical model. The result: an expansion rate for the Universe of around 625 km/s per megaparsec, with variations — 575 and 670 depending on the method of analysis. The Universe was inflating like the surface of a balloon, and the speed of that inflation could be measured.
One detail still astonishes me: Lemaître did this by gathering other people’s data from other people’s publications, sitting in Louvain, with no access to major telescopes. His entire observational foundation consisted of borrowed numbers. But the theoretical framework into which he placed them was his own.
Edwin Hubble published his famous paper in 1929, two years after Lemaître. The work appeared in Proc. Natl Acad. Sci. USA (volume 15, pp. 168–173) and contained what Lemaître’s did not: his own, improved system of distances, based on Cepheids and novae. Hubble arrived at an estimate for the expansion constant of 500 km/s/Mpc — a number of the same order as Lemaître’s, but derived from a more reliable distance scale.
Yet the galaxy velocities Hubble used were, to a considerable degree, the very same data from Slipher. Slipher had begun measuring galactic redshifts back in the 1910s, working at Lowell Observatory. By February 1922, he had spectra for 41 galaxies, and the predominance of redshifts — that is, recession velocities — was already obvious. Arthur Eddington noted this fact in his book “The Mathematical Theory of Relativity” (1923), effectively spotlighting an anomaly that demanded explanation.
Slipher is the quiet hero of this story. For years, he collected data that everyone used: Lemaître and Hubble alike. But he himself offered no theoretical framework for his observations and did not plot the “distance–velocity” relation. Science often works this way: the person who mined the ore remains in the shadow of those who smelted it into metal. Hubble contributed improved distances and a compelling empirical relation. Lemaître contributed a theoretical justification from general relativity. Slipher contributed the redshifts themselves. Three people, three contributions, one law — and decades of argument over whose name it should bear.
Let us return to the missing paragraphs. The 1931 translation in MNRAS (volume 91, pp. 483–490) is a text from which precisely those sections in which Lemaître worked with observational data and derived a numerical value for the expansion constant were neatly removed. Everything else — the theoretical part, the equations, the model — is there. What was cut was exactly what made Lemaître a rival to Hubble in the matter of priority.
For decades, this gap spawned theories. The most popular was that someone in the MNRAS editorial office or in Hubble’s circle had removed the inconvenient paragraphs. A gentler version held that the journal’s editor had decided there was no point duplicating Hubble’s already known results. Both versions assumed outside interference — and both turned out to be wrong.
In 2011, astrophysicist Mario Livio of the Space Telescope Science Institute published the results of an archival investigation in Nature (volume 479, pp. 171–173). He found correspondence between MNRAS editor William Marshall Smart and Lemaître. Smart’s letter and Lemaître’s reply of March 9, 1931 told a simple story: Lemaître translated the article into English himself and decided for himself what would go into the translation. He deliberately omitted the discussion of the observational velocities, writing that it “is clearly of no actual interest”.
Why? By 1931, the data of Hubble and Milton Humason were already significantly better than what Lemaître had had at his disposal in 1927. Reprinting an outdated table with crude distance estimates seemed pointless to him. What is more, in that same issue of MNRAS, Lemaître published a new paper (pp. 490–501) — on the equations of an expanding Universe — and apparently considered that the relevant work.
Put bluntly, Lemaître crossed out his own priority. Not out of modesty — out of scientific integrity: the data were outdated, so why keep circulating them?
Lemaître’s decision now seems almost tragic — and at the same time entirely logical. He was a scientist, not a PR man. What concerned him was correctness, not his place in history. But the consequences of that decision dragged on for decades. The expansion constant was named the Hubble constant. The “distance–velocity” law became Hubble’s law. Lemaître’s name surfaced in histories of cosmology as a remark, a footnote, as “and there was also this Belgian priest who…”
I think a mechanism familiar to anyone who has worked in science kicked in here: the language was little-read, the journal peripheral, the author not pushy — so priority went to the one who was louder, more visible, who had an observatory with a two-meter telescope behind him. This was not a conspiracy. It was the inertia of a scientific community that reads in English and trusts major institutions.
At the same time, Hubble deserves his due: his contribution was not simply a repetition of someone else’s result. The distances he used in 1929 were substantially more accurate than those Lemaître had borrowed from the 1926 publication. Hubble built his empirical relation on his own observations, made with the 100-inch Hooker telescope. His value for the constant — 500 km/s/Mpc — was obtained by a different route and on a different distance scale. Lemaître went from theory to data; Hubble went from data to a pattern. Both paths led to the same conclusion, but the routes were different, and each had its own value.
In 2018, the General Assembly of the International Astronomical Union (IAU) adopted Resolution B4. It recommended renaming Hubble’s law the Hubble–Lemaître law. The wording was cautious: this was not about correcting a historical injustice, nor about recognizing a “theft,” but about the fact that modern cosmology had grown out of several independent lines of work. The theoretical line — Friedmann and Lemaître. The observational one — Slipher, Hubble, Humason. The law received a double name in recognition that the discovery of the expanding Universe was not a single person’s moment of illumination.
The resolution passed by vote, and in essence it was a vote about the history of science — a rare instance in which astronomers were deciding not a problem of physics but a matter of fairness in naming. The vote itself sparked debate: some astronomers believed changing established names was a pointless undertaking; others insisted that Lemaître’s name be included.
The missing paragraphs remain missing — in the sense that no one has retrospectively supplemented the 1931 translation. But the 1927 French original is available, Livio has published Lemaître’s correspondence with Smart, and anyone can verify it: the Belgian priest was the first to write down the number that links the speed at which galaxies fly apart with their distance from us. He was also the first to cross that number out — because he believed science moves forward rather than clinging to old tables. Today the constant is estimated at roughly 67–74 km/s/Mpc — an order of magnitude lower than the values obtained by both Lemaître and Hubble — and the argument over its exact value is still going on.