Science and faith: the origin of the universe. Georges Lemaître: the father of the big bang

Author: Mariano Artigas
Published in: Aceprensa, 79/95
date of on-line publication: 7 June 1995

The theory of the Big Bang, the Big Explosion that would have originated our world, belongs to the general culture of our time. It was originally formulated by the Belgian physicist and Catholic priest Georges Lemaître. On the occasion of the centenary of his birth, a book illustrating the life and work of Lemaître has been published.¹.

Everyone knows about Galileo, Newton and Einstein, to name three particularly illustrious names in physics. But few have heard of Georges Lemaître, the father of today's theories on the origin of the universe.

A unique trajectory

Lemaître was born in Charleroi (Belgium) on 17 July 1894, and died on 20 June 1966. He was neither a priest who became a scientist nor a scientist who became a priest: he was, from the beginning, both. From an early age he discovered his dual vocation, and discussed it with his family. His father advised him to study engineering first, and so he did, although his career was complicated by the fact that he switched to physics and also because, in the middle of his programs of study, the First World War broke out.

In 1911 he was admitted to the Engineering School. In the summer of 1914 he planned to spend his vacation going to the Tyrol on a bicycle with a friend, but had to change his vacation because of the war in which his country was involved until 1918. Then he returned to the University of Leuven and changed his orientation: he devoted himself to mathematics and physics. As he continued with his idea of becoming a priest, after obtaining the doctorate in physics and mathematics he entered the seminar of Mechelen and was ordained priest by Cardinal Mercier on September 22, 1923. That same year he was awarded two scholarships from research, one from the Belgian government and the other from an American Foundation, and was admitted to Cambridge University (England) as researcher in astronomy.

The Cambridge astronomical observatory was then directed by Sir Arthur Eddington, one of the most important astrophysicists of the 20th century. These were very important years for physics. Einstein had formulated special relativity in 1905, and in 1915 general relativity, which for the first time made it possible to study the universe as a whole scientifically. Lemaître followed the teachings of Eddington and also those of Rutherford, the father of nuclear physics. In June 1924 he returned to Brussels, but in the same year he travelled again for scientific purposes, this time to Canada and the United States. In America, in addition to meeting Eddington, he had the opportunity to meet directly some physicists who, at that time, were doing pioneering work in astronomical observations, and he spent the academic year 1924-1925 working at Harvard with one of them, Harlow Shapley.

From October 1925, Lemaître was a professor at the University of Louvain. Open and friendly, he had great gifts for research and was an unconventional teacher. He had a great influence on many students and promoted research at the University. In addition, in 1930 he made a name for himself on the world-wide academic community and his travels, especially to the United States, were a constant for many years.

Lemaître became famous for two closely related works on the universe as a whole: the expansion of the universe, and its origin from a "primeval atom".

The expansion of the universe

The equations of general relativity, formulated by Einstein in 1915, made it possible to study the universe as a whole. Einstein himself did so, but he found a universe he did not like: it was a universe that changed over time, and Einstein, for non-scientific reasons, preferred an unchanging universe as a whole. To achieve this, he performed a manoeuvre that, at least in science, is usually bad: he introduced into his equations a term whose only function was to keep the universe stable, from agreement with his personal preferences. This was a quantity he called the "cosmological constant". Years later, he said it was the worst mistake of his life.

Other physicists had also developed the programs of study of the universe on the basis of general relativity. Particularly important were the works of the Dutchman Willem de Sitter in 1917, and the Russian George Friedman in 1922 and 1924. Friedman hypothesised an expanding universe, but his work had little impact at the time.

Lemaître worked along these lines until he came up with a theoretical explanation of the expanding universe, which he published in article in 1927. agreement But, although this article was correct and in line with the data obtained by the leading astrophysicists in those years, it had no special impact for the time being, although Lemaître went to discuss this topic, personally, with Einstein in 1927 and with de Sitter in 1928: neither of them paid any attention to it.

To be listened to, it is often important to have a good intercessor. Lemaître's great intercessor was Eddington, who knew him from having had him as a pupil at Cambridge in 1923-1924. On 10 January 1930, the Royal Astronomical Society held a meeting in London. Reading the report that was published on that meeting, Lemaître noticed that both de Sitter and Eddington were dissatisfied with Einstein's static universe and were looking for another solution - a solution that he had already published in 1927! He wrote to Eddington reminding him of that 1927 work . Eddington, like Einstein and for similar reasons, was not happy about an expanding universe either; but this time he gave in to the arguments and set out to fix the mess. On 10 May 1930 he gave a lecture to the Royal Society on that problem, and in it he reported on Lemaître's work : he referred to the "decidedly original contribution advanced by Lemaître's brilliant solution", saying that it "gives an astonishingly complete answer to the various problems posed by Einstein's and de Sitter's cosmogonies". On 19 May, de Sitter also acknowledged the value of Lemaître's work which was published, translated into English, by the Royal Astronomical Society. Lemaître became famous.

Lemaître's fame was consolidated in 1932. Many astronomers and journalists were present in Cambridge (USA), at the lecture that Eddington gave on 7 September in front of a large crowd, and at that lecture Eddington referred to Lemaître's hypothesis as a fundamental idea for understanding the universe (Lemaître was present at the lecture). On the 9th, at the Harvard Observatory, Eddington and Lemaître were asked to explain their theory.

The primitive atom

If the universe is expanding, it stands to reason that, in the past, it occupied a smaller and smaller space, until, at some original point in time, the entire universe would be concentrated into a kind of "primeval atom". This is what almost all scientists say today, but no one had scientifically elaborated this idea before Lemaître did so, in a article published in the prestigious English journal "Nature" on 9 May 1931.

The article was short, and was entitled "The beginning of the world from the point of view of quantum theory". Lemaître published other articles on the same subject topic in the following years, and went on to publish a book graduate "The hypothesis of the primitive atom".

Nowadays we are used to these issues, but status was very different in 1931. In fact, Lemaître's idea met not only with criticism, but open hostility from scientists who reacted violently at times. Einstein, in particular, found the hypothesis too bold and even tendentious.

This brings us to a status which could be described as the "Galileo syndrome". This syndrome has different manifestations, depending on the case, but it responds to the same state of mind: the fear that religion might interfere with the autonomy of science. Such interference subject is certainly undesirable; but the Galileo syndrome occurs when there is no real interference and yet it is thought to exist.

In our case, there was the Galileo syndrome: several scientists (including Einstein) viewed Lemaître's proposal , which was a serious scientific hypothesis, with suspicion because, in their view, it might favour religious ideas about creation. But before looking more closely at the manifestations of the "Galileo syndrome" in this case, it is worth recording how the relationship between Lemaître and Einstein developed.

Einstein and Lemaître

Lemaître's 1927 article , on the expansion of the universe, did not meet with much response. Of course, Lemaître was not a man to sit back and do nothing. Convinced of the importance of his work, he went to explain it to Einstein himself.

The first meeting was more of a clash. From 24 to 29 October 1927, the famous fifth congress Solvay took place in Brussels, where the great geniuses of physics discussed the new quantum physics. Lemaître sought to talk to Einstein about his article, and succeeded. But Einstein told him: "I have read your article. Your calculations are correct, but your physics is abominable". Lemaître, convinced that Einstein was wrong this time, sought to prolong the conversation, and he too succeeded. Professor Piccard, who was accompanying Einstein to show him his laboratory at the University, invited Lemaître to get into the taxi with them. Once in the car, Lemaître alluded to the speed of nebulae, topic which was at that time the subject of important results that Lemaître knew very well and which is closely related to the expansion of the universe. But the status became rather embarrassing, because Einstein did not seem to be aware of these results. Piccard decided to flee forward: to save the status, he started talking to Einstein in German, language which Lemaître did not understand!

Lemaître's relations with Einstein improved later. The first approach came through the kings of Belgium, who were interested in Lemaître's work and invited him to their court. Einstein passed through Belgium every year to visit Lorentz and de Sitter, and in 1929 he found an invitation from Queen Elisabeth, a German like Einstein, asking him to come to see her with his violon (playing the violon was a common hobby of the queen and Einstein): this invitation was followed by many others, so that Einstein became a friend of the kings. In one conversation, the king asked Einstein about the famous theory of the expansion of the universe, and inevitably Lemaître was mentioned; noting that Einstein felt uncomfortable, the queen invited him to improvise a violin duet with her. It was already raining cats and dogs.

Another rapprochement took place in 1930, at a ceremony in Cambridge, where Einstein met Eddington. Again the Belgian priest's theory came up in conversation, and Eddington defended it enthusiastically.

Einstein had several years to reflect before meeting Lemaître again in person, in the United States. Lemaître had been invited by the famous physicist Robert Millikan, director of the California Institute of Technology. Among his lectures and seminars, on January 11, 1933, he conducted a seminar on cosmic rays, and Einstein was among the attendees. This time, Einstein was very affable and congratulated Lemaître on the quality of his exhibition. Afterwards, the two went off to discuss their views. Einstein already admitted then that the universe is expanding; however, he was not convinced by the theory of the primeval atom, which reminded him too much of creation. Einstein doubted Lemaître's good faith at topic, and Lemaître, for the time being, did not insist.

In May 1933, Einstein conducted some seminars at the Free University of Brussels. When he learned that Hitler had been appointed Chancellor of the German Republic, he went to the German Embassy in Brussels to renounce his German nationality and resign from his posts at the Academy of Sciences and the University of Berlin. Einstein remained in Belgium for several months, preparing his future as an exile. In these circumstances, Lemaître came to see him and organised several seminars for him. In one of them, Einstein announced that the next lecture would be given by Lemaître, adding that he had interesting things to tell them. Poor Lemaître, caught by surprise this time, spent a weekend preparing his lecture, and gave it on 17 May. Einstein interrupted him several times at lecture , expressing his enthusiasm, and then claimed that Lemaître was the person who had best understood his theories of relativity.

From January to June 1935, Lemaître was in the United States as visiting professor for the high school of programs of study at Princeton. He met Einstein for the last time in Princeton.

Science and religion

Let us return to the Galileo syndrome. Einstein found it hard to accept the expansion of the universe, although he finally had to surrender to it, because his religious ideas were on a line that could be somewhat qualified, with all due nuances, as pantheistic. Thus, by somehow granting a divine character to the universe, he found it difficult to admit that the universe as a whole is changing over time. The same reasons led him to reject the theory of the primeval atom. A universe that has a history and begins in a very unique state reminded him too much of the idea of creation.

Einstein was not the only scientist suffering from the effects of the Galileo syndrome. The mere sight of a Catholic priest meddling in scientific matters seemed to suggest that the clergy were meddling in someone else's field. And if this priest proposed, moreover, that the universe had a historical origin, the alleged interference seemed to be confirmed: it would be a priest who wanted to bring divine creation into science. But Lemaître's scientific work was serious, and in the end all scientists, including Einstein, recognised him and gave him all the honours subject .

Lamaître never tried to exploit science for the benefit of religion. He was convinced that science and religion are two different and complementary paths that converge in truth. Over the years, he told the New York Times in an interview: "I was interested in truth from the point of view of salvation and from the point of view of scientific certainty. It seemed to me that both paths lead to truth, and I decided to follow both. Nothing in my professional life, nor in what I have encountered in science and religion, has ever induced me to change my mind".

One event is particularly significant in this context. On 22 November 1951, Pope Pius XII delivered a famous address to the Pontifical Academy of Sciences. Some passages seem to suggest that science, and in particular new knowledge about the origin of the universe, proves the existence of divine creation. Lemaître, who in 1960 was appointed President of the Pontifical Academy of Sciences, thought it advisable to clarify status to avoid misunderstandings, and spoke with Jesuit Daniel O'Connell, director of the Vatican Observatory, and with Monsignors dell'Acqua and Tisserand, about the Pope's forthcoming speech on scientific matters. On 7 September 1952, Pius XII addressed a speech to the general assembly of the International Astronomical Union and, alluding to the scientific knowledge mentioned in the preceding speech , avoided drawing any misleading conclusions.

Lemaître made clear his ideas on the relationship between science and faith. One of his texts is particularly illuminating: "The Christian scientist must master and apply with sagacity the special technique appropriate to his problem. He has the same means as his non-believing colleague. He also has the same freedom of spirit, at least if the idea he has of religious truths is on a par with his scientific training . He knows that everything has been made by God, but he also knows that God does not replace his creatures. The omnipresent divine activity is everywhere essentially hidden. The supreme Being can never be reduced to a scientific hypothesis. Divine revelation has not taught us what we were capable of discovering for ourselves, at least when these natural truths are not indispensable for understanding supernatural truth. Therefore, the Christian scientist goes forward freely, secure in the knowledge that his research cannot conflict with his faith. He has perhaps even a certain advantage over his non-believing colleague; indeed, both are striving to decipher the manifold complexity of nature in which the various stages of the world's long evolution are overlaid and confused, but the believer has the advantage of knowing that the enigma is solvable, that the underlying scripture is after all the work of an intelligent Being, and that therefore the problem posed by nature can be solved and its difficulty is certainly proportionate to the present and future capacity of mankind. This will probably not provide him with new resources for his research, but it will help to foster in him that healthy optimism without which no sustained effort can be maintained over a long period of time. In a certain sense, the scientist dispenses with his faith in his work, not because that faith might hinder his research, but because it is not directly related to his scientific activity". These words, pronounced on 10 September 1936 at a congress in Mechelen, clearly sum up the compatibility between science and faith, in a mutual respect that avoids undue interference, and at the same time show the encouragement that faith gives to the Christian scientist to advance in his arduous work work.

Notes

(1) Valérie de Rath, Georges Lemaître, le Père du big bang. Éditions Labor, Brussels 1994. 159 pages.