Today’s arxiv find is a historical fact that I really should have known by now. From “The linear redshift-distance relationship: Lemaître beats Hubble by two years“:
The facts are simple: Friedman (1922) was the first to publish non- static solutions to Einstein’s field equations. However, he did not extend that into a cosmological model built on astronomical observations. In 1927 Lemaître rediscovered these dynamical solutions. In the same publication he extracted (on theoretical grounds) the linear velocity–distance relationship v=Hr. Combining redshifts published by Stromberg (1925) (who relied mostly on redshifts from Slipher (e.g. Slipher 1917)) and Hubble’s distances via magnitudes (Hubble 1926), he calculated for the “Hubble constant” two values, 575 and 670 km/sec/Mpc depending on how the data is grouped. For Lemaître these results showed that the Universe was expanding. Two years later Hubble found the same velocity–distance relationship v=Hr on observational grounds from practically the same observations that Lemaître used in 1927. However, Hubble does not credit anyone for the redshifts, most of which again came from Slipher.
Why is this not more widely known? In 1931, Lemaître’s paper was translated into English with the help of Eddington, but “the two pages from the 1927 paper that contain Lemaître’s estimates of the Hubble Constant are not in the 1931 MNRAS paper”.
The standard story is that Friedman discovered the equations. Lemaître rediscovered the equations and promoted them. Hubble used Slipher’s observations to show that the expansion predicted by the equations was actually true. It seems that Lemaître did it all! And, according to Wikipedia, was one of the inventors of the Fast Fourier Transform.
Letters to Nature 
Luke,
Unfortunately, the history of science is largely ignored. It makes our job (us folk who go to school to archive and write about the history of science) very difficult. Another classic example is how ignorant most people are about Galileo’s trial.
Hubble published in an American journal. QED.
Robertson (of RW metric fame) did the same thing in 1928. But although he made the same plot as Hubble, he didn’t publish it – just a description and a slope of the relation. Presentation is all…
Anyway, bear in mind that the data available in 1929 were far too shallow (<20 Mpc or so) to prove a linear distance-redshift relation. Irving Segal was still arguing in the mid-1980s that this wasn't very well verified locally (with some justice). Arguably "Hubble's Law" wasn't really proved properly until we got Supernova distances to 5% accuracy in the 1990s.
Slipher is the main hero in all of this, since he proved that most galaxies were redshifted, which is the main point. Hubble's distances were almost totally wrong (and not just from the Cepheid zero point) and added rather little to the story. Remarkable how this is all consistently misrepresented.
Thanks John! Do you know the reference for the Robertson paper in 1928? I just had a quick search on ADS:
* http://adsabs.harvard.edu/abs/1929PNAS…15..822R doesn’t mention the calculation of the Hubble parameter, though the last sentence mentions “a unique Doppler shift which will appear in the actual universe as a residual effect.”
* http://adsabs.harvard.edu/abs/1933RvMP….5…62R attributes the observations to Hubble and Humason, and the theoretical prediction to Weyl in 1923.
Did you see this;
[46] arXiv:1106.1195 (cross-list from physics.hist-ph) [pdf]
The Curious Case of Lemaitre’s Equation No. 24
Sidney van den Bergh
Comments: JRASC, in press
Subjects: History and Philosophy of Physics (physics.hist-ph); Cosmology and Extragalactic Astrophysics (astro-ph.CO)
The 1927 discovery of the expansion of the Universe by Lemaitre was published in French in a low-impact journal. In the 1931 high-impact English translation of this article a critical equation was changed by omitting reference to what is now known as the Hubble constant. That the section of the text of this paper dealing with the expansion of the Universe was also deleted from that English translation suggests a deliberate omission by the unknown translator.
[…] very revealing. He is writing within 5 years of the discovery of the expansion of the universe by Lemaitre (first!) and Hubble. Jeans […]
I have always assumed Lemaitre translated and shortened the paper himself, given the character of the man and his knowledge that Hubble had far better experimental data. Last year, a letter was discovered that supports this hypothesis
By who? Do you know if the text of the letter is online?
yes its by mario livio, and its called ‘lost in transaltion’, superb historical reserach!
It’s here: http://www.nature.com/nature/journal/v479/n7372/full/479171a.html
Great stuff!