This June 22 marks the 40th anniversary of the death of one of the Twentieth Century's most far-sighted scientists. But Georges Lemaître, in addition to being a first-rate mathematician and physicist, was also a diocesan Catholic priest -- and in these days when religion and science are often hyped into starkly opposing sides, it's instructive to recall the man's extraordinary scientific achievement as well as his views on science and religion and the careful distinction he maintained between them.
Lemaître is credited with being the Father of the Big Bang theory (Fred Hoyle once disparagingly referred to him as 'the big bang man'), but in fact, his contribution to the theory was almost an afterthought to his real achievement. Lemaître was in essence the first cosmologist, meaning, the first physicist not only conversant with Einstein's field equations of general relativity, but also the first to deliberately train himself in astronomy and astrophysics to find proof of what the equations suggested to him -- that the universe could be dynamic, expanding.
He spent a year at Cambridge with Arthur Stanley Eddington (Einstein's greatest champion in the UK at the time) and a year at Harvard with Harlow Shapley and at MIT before heading out west to Cal Tech, to Mount Wilson where Hubble was collecting new red shifts, and to Flagstaff in Arizona to meet with the veteran American astronomer Vesto Slipher, who first began noticing the redshifts of what were then called extra-galactic nebulae. This is quite an itinerary for a young scientist from a Catholic University, considering it was back in the days before air travel.
Lemaître derived what is known as Hubble's constant in 1927. In a landmark paper, he showed how the redshifts indicated a velocity of recession proportional to their distances. He did this two years before Hubble cautiously published his own findings. In 1932 Lemaître also devised a solution to Einstein's equations that allowed J. Robert Oppenheimer and his colleague to first model those fantastical objects of cosmic doom, now called black holes, in 1939. Lemaître referred to his solution as a "dust" solution because it examined the gravitational collapse of a sphere made of dust (and therefore of zero pressure), something that did not occur to Karl Schwarzschild when he derived his Schwarzschild limit in 1916.
If that isn't enough for distinction, Lemaître virtually alone amongst his peers argued tirelessly for the inclusion in Einstein's equations of the so-called cosmological constant, arguing that it was not just an ad-hoc factor to balance Einstein's preconceived notion of a static cosmos, but it represented a real force, counterbalancing that of gravity on the cosmic scale and even causing the acceleration of the universe's expansion. It now looks, based on data regarding the expansion's acceleration, that he was right.
Back in the early 1930s, the Nobel Laureate Paul Michael Dirac had a chance to discuss the expanding universe with Lemaître. Dirac was an atheist, and yet later he recalled, "When I was talking with Lemaître about this subject and feeling stimulated by the grandeur of the picture that he has given us, I told him that I thought cosmology was the branch of science that lies closest to religion. However Lemaître did not agree with me. After thinking it over he suggested psychology as lying closest to religion."
This is fascinating, not because Dirac was an atheist and feeling mystical stirrings when he contemplated the cosmos, but because Lemaitre was a priest -- and he did not.
There has always been something about cosmology, almost to the point of cliché, that is supposed to put the possibility of a Maker into the mind of even the most stubborn materialist, so it's interesting that Lemaître was not impressed by the cosmological approach to God. The sheer size and scope of the universe was evidently not a factor in his faith. Nor was he bothered by suggestions from colleagues and the media that his interest in the Big Bang was ultimately theological (a myth perpetuated most recently in Dan Brown's light-weight thriller Angels and Demons).
At the international physics conference is Solvay in 1958, he had a response to those who believed the Big Bang theory was inspired by religion:
"As far as I can see, such a theory remains entirely outside any metaphysical or religious question. It leaves the materialist free to deny any transcendental Being. He may keep, for the bottom of space-time, the same attitude of mind he has been able to adopt for events occurring in non-singular places in space-time. For the believer, it removes any attempt at familiarity with God... it is consonant with the wording of Isaiah speaking of the "Hidden God", hidden even in the beginning of creation.... Science has not to surrender in face of the Universe and when Pascal tries to infer the existence of God from the supposed infinitude of Nature, we may think that he is looking in the wrong direction."
We may think he is looking in the wrong direction.
What does that mean, the wrong direction? Well, if we go back to Lemaître's comment to Dirac, he seems to be suggesting that psychology rather than physics more poignantly suggests a transcendental meaning to the world -- which I interpret here in broad terms to be the study of what motivates men and women to act or not act -- to be heroes and saints...or criminals and dictators.
Nor was Lemaître impressed by a literal interpretation of the Bible:
"The writers of the Bible were illuminated more or less -- some more than others -- on the question of salvation. On other questions they were as wise or as ignorant as their generation. Hence it is utterly unimportant that errors of historic or scientific fact should be found in the Bible, especially if errors relate to events that were not directly observed by those who wrote about them.
The idea that because they were right in their doctrine of immortality and salvation they must also be right on all other subjects is simply the fallacy of people who have an incomplete understanding of why the Bible was given to us at all."
Cosmology, like evolution, brought the issue of science and faith to the forefront as soon as Lemaître detailed his expansion model and its origin with at time t=0. If there was a temporal origin to the universe's evolution, then it seemed to many scientists to imply the act of creation. Arthur Stanley Eddington, a Quaker, certainly thought so and found the whole idea repugnant.
In Lemaître's view it did not have to imply that.
In many ways, he felt, the argument was based on a misunderstanding of terms -- one that many scientists are prone to make and one theologians are less likely to: and that assumption is, what a theologian or philosopher means by creation is the same thing as what a scientist means by origin. Lemaître indeed would not ever have allowed a term like creation to be used credibly in a scientific paper. By its very nature, the word describes something that is empirically unverifiable -- how, in principle, could any experiment or theoretical quantification be made of an act or process (for want of a better term) that by definition precedes all things, including time, space and matter? Lemaître never made this mistake.
He was in a hospital in Belgium 40 years ago, suffering the aftermath of a heart attack as well as a form of leukemia. His colleague Odon Godart brought him the news just a day or two before he died on June 20th: that the Americans Penzias and Wilson had discovered the cosmic background radiation. Lemaître was fortunate therefore to live long enough to see the discovery of the strongest evidence for the Big Bang -- what he had initially called 'the primeval atom'. One wonders whether, had he lived another decade, he might have shared the Nobel Prize with Penzias and Wilson.
John Farrell is the author of The Day Without Yesterday: Lemaître, Einstein and the Birth of Modern Cosmology.