Yes, Oppenheimer really left a possibly poisoned apple on his tutor's desk

• J. Robert Oppenheimer (Cillian Murphy) poisons an apple meant for his tutor in "Oppenheimer."
• The scene wasn't simply for dramatic effect. It's based on a real incident.

Early in "Oppenheimer," Christopher Nolan's biopic on the father of the atomic bomb, a slighted, young J. Robert Oppenheimer (Cillian Murphy) injects a green apple with potassium cyanide, leaving it for his university tutor, Patrick Blackett (James D'Arcy).

Tormented by second thoughts, Oppenheimer later tosses it before Niels Bohr (Kenneth Branagh) can take a bite.

It's a bizarre moment, sounding like a scene out of "Snow White," in which the Evil Queen offers a poisoned apple to the fair maiden.

What's wilder is that it's rooted in truth.

According to the biography "Robert Oppenheimer: A Life Inside the Center" by Ray Monk, the incident happened near the end of Oppenheimer's first term studying at Cambridge:

The main difference between the movie and real life is that Blackett discovered the apple.

However, Cambridge didn't press criminal charges, expel, or suspend Oppenheimer, likely because his parents were at the university.

Monk writes, "His father negotiated an agreement with the university authorities, according to which Oppenheimer would be allowed to continue his studies and merely be put on probation, on condition that he agreed to undergo frequent treatment by a Harley Street psychiatrist."

In the same chapter, Monk notes there was some confusion over whether or not Oppenheimer really left a poisoned apple on Blackett's desk or if his claim "should be regarded as metaphorical," quoting a 1979 interview the physicist did where Oppenheimer said he used cyanide "or something somewhere" in the fruit.

According to Monk, the poisoned-apple story had been "told many times in many different versions" by Oppenheimer to his friends that it led some authors of other Oppenheimer texts to wonder if the tale was completely real, a hallucination, or some sort of "mythmaking" on the part of the physicist.