The international astronomical union (IAU) is currently voting on a resolution put forward at their XXX General Assembly held in Vienna (August 2018) which would see astronomer, Catholic priest and St Edmund’s alumnus Georges Lemaître receive recognition for his contributions to the proof that the universe is expanding.

The expansion of the universe has been known since the early 1900s and is often erroneously attributed solely to the work of Edwin Hubble, an American astronomer, for which the Hubble space telescope bares his name. Hubble demonstrated in 1929 with observations from the Mount Wilson observatory that the recessional velocity (the speed at which galaxies are moving away from us) is proportional to the galaxy’s distance from us, which he correctly interpreted as evidence that the universe itself is expanding and this relationship became known as the Hubble law.

Two years before this however, in 1927, Georges Lemaître published his paper in which, using Einstein’s theory of general relativity, he derived what is now known as the Hubble law and backed this up with observational evidence of galaxy distances and recessional velocities that were available to him at the time.  That same year, he presented his theory to Einstein himself at a conference in Brussels to which Einstein now famously responded “Your calculations are correct, but your physics is atrocious”.  Einstein later went back on his words in 1933, describing Lemaître’s theory as “the most beautiful and satisfactory explanation of creation to which I have ever listened” but that’s another story.

So why is Hubble much more widely known for his work on the discovery of the expanding universe? The reason is that Lemaître published his work in French, in Annales de la Société Scientifique de Bruxelles (Annals of the Scientific Society of Brussels), a journal not widely read by astronomers outside Belgium. Hence when Hubble came along two years later most of the astronomical community (including, it is believed, Hubble himself) believed Hubble’s paper was the first to suggest the universe is expanding.

The rest, as they say, is history and the Hubble law was named. This could all be about to change however. The International Astronomical Union, the authoritative body on all thing’s astronomy (yes, the same organisation that declared that Pluto was not a planet in 2006) at their recent assembly in Vienna proposed the renaming of the “Hubble law” the “Hubble–Lemaître law”, in recognition of Lemaître’s contribution to the proof of the expanding universe. A full vote is currently taking place for all junior and individual members of the IAU and will conclude on 26 October, at 24:00 UTC. An initial “straw poll” during the Assembly however was 74 per cent in favour of the renaming of the Hubble law.

Dan Mortimer
(PhD Astrophysics, 2017)