This year marked my first opportunity to attend a general assembly of the International Astronomical Union. It was an exciting two weeks in which scientists from all branches of astronomy and space physics gathered in beautiful Vienna, Austria to discuss their research and to do the work of the IAU. Walking around the meeting venue, one could see astronomers of all stripes, from all over the world, and occasionally one could catch a glimpse of one of the “Big Names” in astronomy wandering about, usually in heated discussion with others about some important topic or other.
What makes the IAU different from other scientific meetings is that it serves as the governing body for those aspects of astronomy that require universal agreement, such as the naming of stars and asteroids or of features on planets and moons. It was the IAU that famously voted in 2006 to change the definition of a planet, which resulted in the “demotion” of Pluto to the status of dwarf planet. I was particularly excited to attend the business meetings of the IAU in order to participate in this process. I was not one of the national representatives—for the Vatican, that honor belonged to Fr. Paul Gabor, S.J., Fr. Chris Corbally, S.J., and Fr. Richard Boyle, S.J., all of whom are members of the Vatican Observatory—but the general membership was permitted to vote on all scientific matters. For the most part, these consisted of nothing important or controversial; most passed unanimously and I cannot even remember what they were.
One issue in particular created quite a bit of excitement and discussion, and ultimately they decided that the issue was too important to limit the vote to the members who were present at the assembly, but rather they extended a period of online voting for the entire membership of the IAU. This resolution regarded the renaming of the Hubble Law to the Hubble-Lemaître Law, thus recognizing Lemaître’s contributions to our understanding of the expansion of the universe as a result of the Big Bang.
Msgr. Georges Lemaître was a Catholic priest of the archdiocese of Leuven, Belgium. He was also an astrophysicist and professor of physics at the Catholic University of Leuven, and a contemporary of Albert Einstein. At a time when many cosmologists insisted on a steady-state model of a static, non-expanding universe, Lemaître noted that the geometry of Einstein’s theory of general relativity was more consistent with an expanding universe, and his expanding-universe model was also consistent with the observed redshift of galaxies. Also, if the universe was expanding, he inferred that at some point in the past, the entire universe would have been condensed into an infinitely dense, infinitely hot point. He referred to this theory as the primordial atom, but his detractors—in particular Fred Hoyle—thought the theory smacked of theism (if there is a moment of creation, there must be a Creator), and blew it off with the dismissive name, “big bang.”
Lemaître published work on this topic in 1927. Hubble and Lemaître then exchanged information about their work at the third IAU assembly in 1928, and Hubble published his own work on the velocity-distance relation of galaxies in 1929. When in 1931 Lemaître published an English translation of his 1927 paper, he intentionally omitted the section on the effects of expansion on the recession of galaxies because he “did not find advisable to reprint the provisional discussion of radial galaxies… which could be replaced by a bibliography of ancient and new papers” [e.g. Hubble] “on the subject.”
The voting period for the IAU resolution ended on Friday, October 26, 2018, and the results were just announced on Monday the 29th.With 78% of votes in favor, the resolution passed.
In addition to recognizing Lemaître’s obvious and valuable contributions to cosmology, the change of the name of the Hubble-Lemaître Law has another important implication for persons of faith. Astronomy textbooks will be adjusted to include this new name. Along with Gregor Mendel for biology, here is another religious scientist whose name will become recognizable to any high school or college student who takes a basic course in astronomy. In a culture that increasingly preaches a dichotomy between faith and science, it is important to have figures that we can hold up who exemplify the compatibility of the two. History is full of such examples, but most are hidden, forgotten, or actively ignored because they do not fit the narrative.
Lemaître had a profound respect for both faith and science, and recognized their respective roles and respective limitations. When Pope Pius XII wanted to proclaim the theory of the primordial atom as a scientific validation of the theology of Creation, Lemaître—with the help of Fr. Daniel O’Connel SJ, the director of the Vatican Observatory—talked him out of it, emphasizing the importance of allowing the science to proceed on its own without theological entanglements and vice versa.
Lemaître is also a good personal example in contradiction to today's culture of extreme partisanship and its effect on our interpersonal relationships. He and Fred Hoyle held opposite and occasionally antagonistic positions both in their science and in their faiths; where Lemaître was a devout Catholic priest, Hoyle was an agnostic who leaned toward atheism; and while Lemaître was a proponent of Big Bang cosmology, Hoyle supported a steady state model and was an outspoken critic of the Big Bang. Nevertheless, they had respect for each other and in fact became friends. In 1957 the Vatican Observatory hosted a meeting on stellar populations in which the two both participated, and afterwards they took a driving vacation together throughout Europe. They show that it is possible to strongly disagree and yet remain friends.
For more about the IAU resolution, follow this link.