French physicist and media star loses doctorate after plagiarism investigation

One of France’s most famous science communicators has been stripped of his doctor’s title after a 20-month university investigation found evidence that he plagiarized in his Ph.D. thesis. Étienne Klein, a physicist at the Alternative Energies and Atomic Energy Commission (CEA) who has published more than 30 books and hosts a weekly radio show about science, has faced accusations of plagiarism in his popular science writing since 2016. In August 2024, questions arose about his scholarly work as well, when the online outlet Arrêt sur images examined Klein’s doctoral dissertation in philosophy of science, which he defended in 1999 at what is now Paris Cité University. After manually checking and cross-referencing the thesis “line by line,” journalists Loris Guémart and Jean Abbiateci found instances of plagiarism on 20% of its pages, Guémart says, with fragments copied from intellectuals including author Albert Camus, physicist Louis de Broglie, and even some members of his thesis committee. Their article led the university to launch an investigation. On 11 June, Arrêt sur images reported, based on anonymous sources, that Paris Cité had concluded Klein indeed committed plagiarism and the university had revoked his doctorate. (The report, which the university hasn’t made public, found plagiarism in nearly two-thirds of the thesis’ pages, another source told the French newspaper Le Monde.) The university has not confirmed the press reports. “Since this situation involves an individual case, the law does not permit the university to comment on it or disclose any information regarding it,” Paris Cité President Édouard Kaminski wrote in an email to Science. But, he added: “You may note however that the university has not issued any statement refuting the information reported in the press.” Klein did not respond to Science’s repeated requests for comment, but he didn’t dispute that he lost his title in a four-page statement he posted on X on 12 June or in his comments for the story in Le Monde. Klein faced setbacks a decade ago when the French weekly magazine L’Express reported he had plagiarized extensively in his science books, including an Albert Einstein biography, and columns.

After an independent investigation ordered by France’s higher education and research ministry, Klein lost his position as president of the Institute for Advanced Studies for Science and Technology in 2017, but he kept his position at CEA. (CEA told Science on Friday it was aware of the university’s decision and is “considering the consequences.”) Klein’s career in science communication, however, seemed unscathed. He has authored more than a dozen books since 2016 and he went on hosting his radio show on France Culture, a public radio station. In 2020, the French Academy of Moral and Political Sciences awarded Klein a prize for one of his physics essays. The fact that prestigious publishing houses and media outlets in France kept working with Klein despite the revelations “clearly gives a strong impression of cronyism, or at the very least of leniency,” says Olivier Sartenaer, a philosopher of science at the University of Namur who has followed the case. The media and the public continued to regard Klein as a “very respected” figure, Sartenaer says. That may change now: “We have taken note of [the university’s] decision and are reviewing the situation,” France Culture writes in an email to Science. In last week’s letter on X, Klein discussed the accusations at length without using the word plagiarism. Having read many books throughout his career, he may have “assimilated” them and “not always consciously” used them in his own writing, he said. He asked why his dissertation was scrutinized even though others haven’t been and accused “quotation marks zealots” of a double standard by focusing on his writings—which, he says, contain no factual errors and help combat scientific disinformation—instead of pursuing actual disinformation. Sartenaer says Klein’s use of such “fallacious” arguments sends a terrible message to students and researchers. He sees a silver lining, however: The university made a “brave decision” by sanctioning Klein, and it might increase people’s trust in scientific institutions to see that even someone of his fame can be punished for misconduct. “It’s a sign that the institution works.”

Correction, 16 June, 9:45 a.m.: A previous version of this story said Loris Guémart and Jean Abbiateci asked Paris Cité University to launch an investigation. The university took the initiative itself.