From my biography of Einstein:
"One day at the Institute, Einstein ran into Oppenheimer, who was preparing for the hearings [where the Atomic Energy Commission was deciding whether to revoke his security clearance]. They chatted for a few minutes, and when Oppenheimer got to his car he recounted the conversation to a friend.
“Einstein thinks that the attack on me is so outrageous that I should just resign,” he said. Einstein considered Oppenheimer “a fool” for even answering the charges. Having served his country admirably, he
had no obligations to subject himself to a “witch hunt.”
“The trouble with Oppenheimer," Einstein told Abraham Pais, "is that he loves a woman who doesn’t love him—the United States government. All Oppenheimer had to do, Einstein said, was “go to Washington, tell the officials that they were fools, and
then go home.”
Oppenheimer lost his case. The AEC voted that he was a loyal American but also a security risk and—one day before it would have expired anyway—revoked his clearance. Einstein visited him at the Institute the next day and found him depressed. That evening he told a friend that he did not “understand why Oppenheimer takes the business so seriously.”
When a group of Institute faculty members circulated a petition affirming support for their director, Einstein immediately signed up. Others initially declined, some partly out of fear. This galvanized Einstein. When a group of Institute faculty members circulated a petition affirming support for their director, Einstein immediately signed up. He “put his ‘revolutionary talents’ into action to garner support,” a friend recalled. After a few more meetings, Einstein had helped to convince or shame everyone into signing the statement.
Lewis Strauss, Oppenheimer’s AEC antagonist, was on the board of the Institute, which worried the faculty. Would he try to get Oppenheimer fired? Einstein wrote his friend Senator Herbert Lehman of New York, another trustee, calling Oppenheimer “by far the most capable Director the Institute has ever had.” Dismissing him, he said, “would arouse the justified indignation of all men of learning.”
The trustees voted to keep him.
#ThrowbackThursday: In honor of the new "Oppenheimer" movie, here's a photo of the two physicists, Albert Einstein and J. Robert Oppenheimer.