Only filmed interview with Georges Lemaître, 'father of the Big Bang,' rediscovered after 60 years

The only known video interview with Belgian physicist Georges Lemaître, widely considered the "father of the Big Bang," talking about the birth of the universe has been rediscovered almost 60 years after it was lost.

Lemaître (1894-1966) was a professor of physics at the Catholic University of Louvain in Belgium and  a practicing Catholic priest. In 1927, he was the first person to propose that the movement of galaxies away from Earth was a sign that the universe was expanding, which was later observationally confirmed by the American astronomer Edwin Hubble. 

Lemaître was also the first to derive Hubble's law, which states that galaxies are moving away from Earth at speeds proportional to their distance, even though Hubble received all the credit at the time. (The International Astronomical Union renamed the idea the Hubble-Lemaître law in 2018.) In 1931, Lemaître proposed his "hypothesis of the primeval atom" to account for the universe's expansion, which stated that the universe began from a single point, and later inspired what we now know as the Big Bang theory.

The rediscovered video features Lemaître discussing his ideas with journalist Jérôme Verhaeghe during a Belgian TV interview, which was broadcast on Feb. 14, 1964. A small clip of the interview, around two minutes long, has been widely available for decades, but the full 20-minute video was considered to be lost after the film reel containing the footage disappeared shortly after the interview aired. 

But this reel, it turns out, was simply misplaced.

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On Dec. 29, 2022, Belgium's national service broadcaster for the country's Flemish-speaking community, Vlaamse Radio- en Televisieomroeporganisatie (VRT), rereleased the video after it was discovered in the broadcaster's archives. The film reel had been lost because it was miscategorized and because Lemaître's name was misspelled on the label, which made searching for it like "looking for a needle in a haystack," VRT representatives wrote in a translated statement. (Flemish, also known as Dutch Flemish, is one of the three official languages of Belgium; it is spoken by people living in the Flanders region in the north of the country.)

In the interview, Lemaître speaks in French, with Flemish subtitles added to the video. In a new paper, uploaded Jan. 19 to the preprint server arXiv, a team of researchers translated the interview into English to make it accessible to a wider audience. 

"To our knowledge, it is the only video interview of Georges Lemaître in existence," the researchers wrote in the paper. 

Expansive interview 

The video starts with Lemaître answering an unknown question that was likely asked by Verhaeghe during the interview's introduction. While it's unclear what these opening remarks refer to, Lemaître soon dives into how his hypothesis of the primeval atom differed from the Steady State model — the idea that the universe is always expanding but maintaining a constant average density, with no start or end — which was the preferred view of the cosmos at the time.

Lemaître talks in great length about his rival Sir Fred Hoyle, an English physicist who was one of the best-known and fierce proponents of the Steady State model but who also accidentally coined the term "Big Bang." Although he repeatedly calls out Hoyle for being wrong during the interview, Lemaître remarks that he has the "greatest admiration" for his colleague's work.

Lemaître explains that the Steady State model could work only if the hydrogen required to make stars appeared "like a ghost" from nowhere, which he argued would go against the principle of conservation of energy, the idea that energy is neither created nor destroyed, only transformed from one type to another, which he described as "basically the most secure and solid thing in physics." 

Instead, Lemaître argues in the video, the expansion could be traced back to the "disintegration of all existing matter into an atom," which created "an expanding space filled by a plasma" via a "process that we can vaguely imagine."

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Lemaître also discusses the work and ideas of several renowned academics, including French mathematician Élie Cartan, English astrophysicist Edward Arthur Milne, and Sir James Hopwood Jeans, an English physicist, astronomer and mathematician who was another champion of the Steady State model. 

During the interview, Lemaître notes that detecting cosmic rays — high-energy particles or particle clusters that move through space at nearly the speed of light, which Lemaître poetically described as "rays of the primeval fireworks" — would play an important role in proving his theory. (Lemaître died shortly after learning about the discovery of cosmic microwave background radiation, which occurred two years after the interview and was the first major piece of evidence that he was correct.)

The priest-turned-physicist was also asked whether his theories contradicted his religious views, but he explained that his research involved no "religious ulterior motive" and that "the beginning [of the universe] is so unimaginable" and "so different from the present state of the world" that he saw no reason why it disproved God's involvement in creation. 

The researchers who translated the French transcript to English are pleased to have played a role in making Lemaître's only filmed interview more accessible to the astronomical community and the public.

"Of all the people who came up with the framework of cosmology that we're working with now, there's very few recordings of how they talked about their work," lead study author Satya Gontcho A Gontcho, a physicist at the Department of Energy's Lawrence Berkeley National Laboratory in California, said in a statement. "To hear the turns of phrase and how things were discussed … It feels like peeking through time."