The only problem is: Einstein may never have uttered the phrase "biggest blunder."

Astrophysicist and author Mario Livio can find no documentation that puts those words into Einstein's mouth (or, for that matter, his pen). Instead, all references eventually lead back to one man, physicist George Gamow, who reported Einstein's use of the phrase in two sources: his posthumously published autobiography My World Line (1970) and a Scientific American article from September 1956.

Screenshot of the 1956 Scientific American article in which Gamow originally recalled Einstein's claim (Scientific American)

This, for reasons Livio recounts in detail in his new book Brilliant Blunders, is some seriously thin sourcing. For one, Gamow, brilliant physicist though he might have been, had a bit of a reputation for, shall we say, antics. Once, for example, Gamow had teamed up with a student of his named Ralph Alpher to write a paper. "He then realized," Livio told me, "that if he were to add as a co-author another known astrophysicist, whose name was Hans Bethe, then the three names would be Alpher Bethe Gamow, like alpha beta gamma, even though Hans Bethe had nothing to do with that paper." (His first wife, Livio writes, once remarked, "In more than twenty years together, Geo has never been happier than when perpetuating a practical joke.")

Knowing this about Gamow made Livio suspicious. What are the chances that Gamow, this ham, was retelling Einstein's confession with veracity? Not good, Livio found.

Livio looked at almost every single paper that Einstein ever wrote, including making a trip to the Einstein archive in Jerusalem to look at the collection personally. "And nowhere did I ever find the phrase 'biggest blunder', " Livio told me. "I didn't find it -- anywhere."

So he turned his attention to the correspondence between Einstein and Gamow, and it is at this point that Gamow's story begins to look even worse. "When might Einstein have used this expression with Gamow?" Livio writes in the book. As Gamow tells it in his autobiography, he and Einstein were quite close, with Gamow visiting the aging scientist every other Friday as the liaison between the Navy and Einstein during World War II. "He describes what good friends they were, how Einstein would greet him in one of his soft sweaters, and so on," Livio explains.

"Well, guess what," he continues. "I discovered a small article published in some obscure journal of the Navy by somebody named Stephen Brunauer," a scientist who had recruited both Einstein and Gamow to the Navy. In that article, Brunauer wrote, "Gamow, in later years, gave the impression that he was the Navy's liaison man with Einstein, that he visited every two weeks, and the professor 'listened' but made no contribution -- all false [emphasis added]. The greatest frequency of visits was mine, and that was about every two months." Clearly, Livio says, Gamow exaggerated his relationship with the famous physicist.