Did famed American astronomer Edwin Hubble (or someone acting upon his behalf) conspire to deprive another astronomer of credit for a major discovery? Recent scholarship suggests not.
In 1927, Monsignor George Lemaître published an article1 in a little-known Belgian journal, Annals of the Scientific Society of Brussels. In the article, he proposed the concept that the universe is in a state of expansion. This conjecture was based upon the existing body of redshift measurements and calculations published by astronomers such as Vesto Slipher, Gustaf Strömberg, Edwin Hubble, and others. From General Relativity, Lemaître derived a linear formula for describing the expansion rate of the cosmos, and, making the faulty assumption that the absolute magnitude of a galaxy could be used as a “standard candle” for calculating the distances to galaxies, calculated an estimate for the expansion rate at 625 km/s/Mpc.
In 1929, Hubble published a paper2 in which he also derived a linear formula for describing cosmological expansion practically identical to the formula earlier devised by Lemaître, as well as computing a value for the expansion constant of 500 km/s/Mpc. The calculation was made using more refined estimates of galactic distances using the brightest stars in each galaxy as the standard candles for distance determination. (These days, Cepheid variable stars and the luminosity curves of Type 1a supernovae are typically used to provide more accurate distance determinations.) The relationship published by Hubble has come to be known as “Hubble’s law,” and serves to this day as the foundation (alongside the field equations from Einsteins Theory of General Relativity) of modern cosmology.
But what about Lemaître’s formula? Why don’t we call the expression describing the expansion of the cosmos Lemaître’s Law instead of Hubble’s Law?
Well, in 1931, an English translation of Lemaître’s 1927 paper was finally published.3 However, this translation was missing some rather significant portions, most notably the section where Lemaître derived the formula describing cosmological expansion. Recently, this omission has kicked off a firestorm of debate4,5,6,7,8 over the possibly that Lemaître’s results had been suppressed so that Hubble would get credit for the formula which now bears his name. So, who translated the paper? And who trimmed out the sections in question?
This controversy intrigued astronomer Mario Livio enough that he decided to get to the bottom of the issue.9 He actually managed to dig up the original correspondences between Lemaître and Dr. William Marshall Smart, then editor of the Monthly Notices of the Royal Astronomical Society. Among those letters, he found the following from Lemaître to Dr. Smart:
I highly appreciate the honour for me and for our society to have my 1927 paper reprinted by the Royal Astronomical Society. I send you a translation of the paper. I did not find advisable to reprint the provisional discussion of radial velocities which is clearly of no actual interest, and also the geometrical note, which could be replaced by a small bibliography of ancient and new papers on the subject. I join a french text with indication of the passages omitted in the translation. I made this translation as exact as I can, but I would be very glad if some of yours would be kind enough to read it and correct my english which am afraid is rather rough. Nor formula is changed, and even the final suggestion which is not confirmed by recent work of mine has not be modified. i did not write again the table which may be printed from the french text.
As regards to addition on the subject, I just obtained the equation of the expanding universe by a new method which makes clear the influence of the condensations and the possible causes of the expansion. I would be very glad to have them presented to your society as a separate paper.
So, it would seem that the person who censored Lemaître was Lemaître himself! He appeared to regard his derivation of the expansion relationship as being far too speculative and tentative, nor of any real interest to anyone in the wake of Hubble’s paper. He was far more interested in proceeding with the next step of his work, publishing papers10,11 in which he took his earlier speculation about cosmological expansion to its logical next step: the recognition that this expansion implies that the universe was once much hotter and denser in the past. Monsignor Lemaître was developing what Fred Hoyle would later derisively dub the “Big Bang Theory.”
Lemaître, it would seem, was not interested in establishing priority for credit for his discovery. Perhaps he recognized a fundamental truth of science that is all too easily disregarded: science is not done in isolation. It is a collaborative effort built upon the foundations of the work of others. Lemaître’s own work was built on observations and calculations done by many others, including Hubble and Einstein. (For a glimpse at the contributions of others, see the sidebar below on the history of redshift cosmology.) Einstein’s Theory of General Relativity was built on the work of Riemann and Hilbert. His Theory of Special Relativity was built on the work of Lorentz and Poincaré. Newton’s mechanics was built upon the work of Galileo and Kepler. As Newton himself observed (his spat with Gottfried Wilhelm Leibniz over credit for inventing the Calculus aside), “If I have seen a little further it is by standing on the shoulders of Giants.”
What counts is not the credit, but the results.
1. G. Lemaître, “Un univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extragalactiques”. Annals of the Scientific Society of Brussels 47A: 41.(1927)
2. E. Hubble, “A Relation between Distance and Radial Velocity among Extra-Galactic Nebulae”. Proceedings of the National Academy of Sciences, 15:168-173 (1929).
3. G. Lemaître, “A Homogeneous Universe of Constant Mass and Growing Radius Accounting for the Radial Velocity of Extragalactic Nebulae”. Monthly Notices of the Royal Astronomical Society 91: 483–490. 1931.
4. Reich, E. S., “Edwin Hubble in translation trouble“, Nature News (2011).
5. John Farrell, “Why Hubble’s Law… Wasn’t Really Hubble’s“, Forbes Tech Blog.
6. Nussbaumer, H. & Bieri, L. “Who discovered the expanding universe?”, preprint at http://arxiv.org/abs/1107.2281 (2011).
7. Van den Bergh, S. “The Curious Case of Lemaitre’s Equation No. 24”, preprint at http://arxiv.org/abs/1106.1195 (2011).
8. Block, D. “A Hubble Eclipse: Lemaitre and Censorship”, preprint at http://arxiv.org/abs/1106.3928 (2011).
9. Mario Livio. “Lost in translation: Mystery of the missing text solved”. Nature 479, 171–173 (10 November 2011) doi:10.1038/479171a
10. G. Lemaître. “The Expanding Universe”. Monthly Notices of the Royal Astronomical Society 91, 490-501 (1931).
11. G. Lemaître. “The Evolution of the Universe: Discussion”. Nature 128: 699–701. (1931) doi:10.1038/128704a0