Monday, November 07, 2011

Lemaître, Einstein, and the ‘primeval atom’

This is a weekly post by Nidhal Guessoum (see his earlier posts here). Nidhal is an astrophysicist and Professor of Physics at American University of Sharjah and is the author of Islam's Quantum Question: Reconciling Muslim Tradition and Modern Science.


I recently read John Farrell’s ‘The Day Without Yesterday’, which subtitle nicely summarizes the whole book: ‘Lemaître, Einstein, and the birth of modern cosmology’.
Farrell is a writer and produced educated at Harvard in English literature and the history of science. His science and culture blog (at Forbes), Progressive Download, is one I highly recommend.
His book was first published in 2006; I got to read the 2011 edition, where a few corrections were made.
The book focuses on George Lemaître, for two essential reasons: a) few people know much about this great scientist, other than the fact that he was a priest and that he was “the father of the Big Bang” (though this is a bit of a rough short-cut, as will be explained); b) his story parallels the development of modern cosmology in the crucial first half of the 20th century. But the book is not a biography of Lemaître; Einstein figures prominently in the story (for good cause), and others play major roles as well (Eddington, Hubble, and Gamow, in particular).
There is quite a bit of discussion of the idea of a temporal ‘origin’ of the universe, and why Einstein resisted it so much. First, when he tried to rebut Friedman, who had published solutions of Einstein’s general-relativity equations and pointed out that they include possible non-stationary, expanding models, Einstein mistakenly claiming to have found errors in Friedman’s work. Then there is this gem of a quote, Lemaître relating Einstein’s reaction when the cosmologist-priest told the great man about his ideas of a universe with an origin, a quote that is worth reproducing here: “As I spoke with him about my ideas regarding the origin of cosmic rays, he said excitedly, ‘Have you spoken with Millikan?’, but when I spoke to him about the Primeval Atom [Lemaître’s “Big Bang” concept], he interrupted me, ‘No, not that, that suggests too much the creation.’” Elsewhere, Farrell comments on Einstein’s “stubbornness” (his word) concerning a universe with an ‘origin’: “[it] suggest[s] a prejudice, an ingrown view of the cosmos inherited but never really questioned.”
Even the greatest scientists fall prey to their cultural backgrounds and mindsets.
At this point, two important points must be made, and Farrell makes them very clearly in his easy (but informative) book: a) Lemaître’s “primeval atom” cosmological model differs from the Big Bang (an expression which was derisively coined by Hoyle, the leading proponent of the ‘stationary universe’ model) in that Lemaître’s “atom” was supposed to be a cold little ball, from which our universe evolved, an “atom” which physical characteristics and even ontology went unexplained, whereas the Big Bang model, which was developed by Gamow and his two collaborators (Alpher and Herman), was extremely hot and “singular” (with infinite physical parameters, such as the temperature); b) Lemaître never made the philosophical mistake of conflating physical and mathematical ‘origin’ with ‘creation’; in fact, he explicitly stated that the two are not necessarily the same concept, here showing the rigor of his theological training, compared to someone like Hoyle whose confusion of the two was criticized by the Soviet scientists…
One must also mention other great contributions of Lemaître, particularly his insistence until the end of his life that the cosmological constant (Lambda) that Einstein had introduced (to try to get a stationary universe from his equation) then retracted, was not only correct but absolutely needed to explain the expansion of the universe. (Eddington agreed with him.) We now know that a cosmological constant is probably needed to explain the acceleration of the universe. And Lemaître made also seminal contributions to the idea of ‘collapsed objects’, what would later be called “black holes”.
There are a number of gems in this book, but I hesitate to give too much away, as I hope readers of this blog will be enticed to pick up this enjoyable book and find things out for themselves. I will only mention that Friedman and Schwarzschild fought on opposite sides during World War I and both died a few years later from causes that were directly (in one case) and indirectly (in the other) related to the war, and that Lemaître and Eddington had a great friendship perhaps because of their somewhat similar personal philosophies (Lemaître being a priest, who had gone to war before becoming a priest, and Eddington being a Quaker and a pacifist).
Last but not least, there is Lemaître’s ‘science and religion’ philosophy.  Farrell relates to us a story that is so relevant to our experiences today, even/particularly in the Muslim world/culture. One day, as a teenage student, Lemaître went to his teacher (a priest) and excitedly showed him a passage from the Bible that seemed to contain ideas that science had only recently discovered, expecting strong support and approval. Here’s the lesson that Lemaître got, as told by Farrell: “He shrugged at his pupil’s naïve excitement. ‘If there is a connection,’ [the teacher] told his pupil, ‘it’s a coincidence, and of no importance. And if you should prove to me that it exists, I would consider it unfortunate. It will merely encourage more thoughtless people to imagine that the Bible teaches infallible science…”
We cannot say for certain that this incident fully shaped Lemaître’s science-and-religion philosophy; there must have been other, deeper discussions with his masters at the seminary during his training for priesthood (it was there that he was introduced to Einstein’s general relativity). In any case, this is the philosophy that Lemaître carried with him until the end of his life. In particular, that is how he reacted to Pope Pius XII’s 1951 speech in which he equated the Big Bang with the Fiat Lux of the Bible, indeed claiming that science was “bearing witness” to that event. Lemaître was stunned at the theological and philosophical leap, and within a few months he and the director of the Vatican Observatory met with the pope and tried to persuade him that such an approach was neither correct nor useful for the Church and for Science.
Farrell, without referring to NOMA, describes Lemaître as a follower of the philosophy of Non-Overlapping Magisteria, which was simply stated and coined as an acronym many years later by S. J. Gould. Farrell writes: “For Lemaître, religion and science were utterly different paths to truth, and neither should interfere with the other.”
I enjoyed the book greatly, for its simple style, the nice interweaved stories it related, and the various issues (of science, religion, history) it brought up.

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