A famous science presenter copied his thesis committee — 27 years later, it cost him the PhD

A media physicist loses the title he built a career on

Étienne Klein is about as famous as a physicist gets in France: a researcher at the CEA, author of more than 30 books, host of a weekly radio show on science. In June 2026, Université Paris Cité stripped him of the doctorate he defended in 1999 — a PhD in philosophy of science, not physics — and barred him from re-registering for one.

The trigger was reporting by the outlet Arrêt sur images back in August 2024. Journalists checked the dissertation against prior work line by line and, as Science reported, found plagiarized fragments on 20% of its pages — copied from the writer Albert Camus, the physicist Louis de Broglie, and even members of his own thesis committee. The university's investigation ran 20 months before reaching the same verdict.

"He changed 'En effet' to 'Toutefois'"

The thread's most useful work was nailing down what kind of plagiarism this actually was — because the headline word covers everything from sloppy citation to wholesale theft. The answer that emerged: not verbatim copying, but careful rephrasing.

"In the Arret sur image article you can read a whole sentence plagiarized where the author just changed 'En effet' to 'Toutefois' at the beginning of the quote." — a reader who had gone through the plagiarism report

A reader who'd read the source documents laid out the method: tweak the start of a sentence, copy a chunk word-for-word from one source, splice in another, adjust the ending to lead into the next line. Not "a figure of speech lodged in my subconscious" — whole sentences mashed together from different authors.

That distinction matters, and one commenter drove it home:

"Rephrasing is worse than literal copying from a procedural point of view because it demonstrates intent and obviates a defense of mere incompetence." — a commenter on the procedure of academic fraud

Klein's own defense — used against him

The detail that drew the most reaction was that Klein had borrowed from his own examiners. A Paris-based commenter pointed out that Klein turned this into a defense — the committee didn't object to seeing their own words, so why should anyone now? — and then explained why that defense is hollow:

"The truth is, people on 'thesis committee' don't read thesis. Some do. The director usually does, if he has the time. But many don't; they glance at the intro and conclusion and call it a day." — bambax, writing from Paris

The dissent: is 1990s rephrasing even a crime?

The thread was not a pile-on. A real camp argued the punishment outruns the offense, especially 27 years out and in philosophy rather than experimental science.

"If he's just using phrases / wording from others to get his original points across, it looks bad but I don't see it as a huge deal, especially 30 years out from the phd. A PhD is supposed to be original research" — a commenter weighing letter against substance

Others noted that the technical sections of any thesis force near-identical phrasing to keep concepts precise, and that we're now applying LLM-grade detection to text written when "it was impossible to identify lightly rephrased statements across a wide body of works." One reader compared it to retroactively catching a doping case years later, once the test exists.

The rebuttal was two lines, and it held:

"1. The committee that examined his work in depth didn't reach the same conclusion as you. 2. If you need to use the exact same phrase as someone else, then you should cite them." — a commenter answering the leniency argument

The LLM angle cuts the other way too, and several people said so plainly: the wish to "run plagiarism detection tools on every single doctoral and master's degree thesis ever submitted." Klein's case is less a verdict on one man than a preview — the back catalog of academia is now machine-readable, and a 1999 thesis was never written with that in mind.