Exclamation marks and semicolons "have no place in literature", according to Cormac McCarthy, who has emerged as the unlikely copy editor of a biography of the physicist Richard Feynman.

Quantum Man by professor of physics Lawrence M Krauss was positively received when it was published in hardback last spring, but the reclusive Pulitzer prize-winning author of The Road, All the Pretty Horses and No Country for Old Men, who has known Krauss for four years, felt he could make it better yet.

"I was thrilled that Cormac volunteered to do this," Krauss told the Chronicle of Higher Education. "He said he … loved the book so much that he wanted to make better." A paperback edition of Quantum Man, out next month, includes a "discreet note" on the back cover and the title revealing McCarthy's involvement. "Having Cormac's name on the paperback is one of the biggest honours I could imagine," said Krauss.

Although the biography's subject Feynman was a fan of the exclamation mark, titling his own eccentric autobiography Surely You're Joking, Mr Feynman!, McCarthy started out by making Krauss promise that "he could excise all exclamation points and semicolons, both of which he said have no place in literature." The novelist also "went through the book in detail and made suggestions for rephrasing in certain points as well," said Krauss.

McCarthy performed a similar service for the Harvard physicist Lisa Randall in 2005 for her first book, Warped Passages: Unravelling the Mysteries of the Universe's Hidden Dimensions. "He gave it a good copy-edit," Randall told the Radcliffe Quarterly. "He really smoothed the prose." Like Krauss, Randall also found superfluous punctuation removed from her debut. "Cormac isolated all the semicolons in the margin; I then removed them," she told the New York Times. "Apparently exclamation points are only for exclamations! Those were removed too."

McCarthy helped out too on Randall's second book Knocking on Heaven's Door, again attacking the semicolons. "He removed the semicolons the editor added," Randall said. "On a more serious note, we had some nice conversations about the material. In fact, I saw a quote where he used a physics example I had given in response to a question about truth and beauty."

McCarthy has long enjoyed a close interaction with scientists, keeping an office at the Santa Fe Institute, an independent research centre that also houses a host of scientists, founded by the Nobel prize-winning physicist Murray Gell-Mann. (George Johnson's biography of Gell-Mann, Strange Beauty, reveals that McCarthy performed a line-edit on the entire manuscript of his The Quark and the Jaguar, "but Gell-Mann was too rushed and disorganised to take advantage of the suggestions").

McCarthy has written "a few books" at the institute, he told The Daily Beast last week, with his typewriter to be heard echoing through the common areas ("'what is that?'" he says he was asked by a student) and his questions inspiring the scientists. "Cormac is scary," said physicist Luis Bettencourt. "He just asks really good questions." Neuroscientist Chris Wood said the author's knowledge of physics and maths exceeds that of many professionals in the field.

"I'm here because I like science, and this is a fun place to spend time," McCarthy said. "I'm not here because I'm a novelist. I just managed to sneak in. I haven't read a novel in years." The author does, however, believe there are links between great science and great writing. "Both involve curiosity, taking risks, thinking in an adventurous manner, and being willing to say something 9/10ths of people will say is wrong," he said.