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Einstein and Oppenheimer: A Friendship That Changed the World


| LAST UPDATE 10/22/2023

By Evelyn Martinez

Einstein and Oppenheimer were two of the most influential scientific minds of the 20th century. But their relationship was heated, driven by admiration and conflict. Why was their bond so complex?

The First Meeting

It was 1932, a year of major changes that were taking place in Germany, and Albert Einstein was visiting the California Institute of Technology (Caltech) to speak about the universe's expansion.

Einstein Oppenheimer First MeetingEinstein Oppenheimer First Meeting
Science History Institute, Public domain, via Wikimedia Commons

In a brief meeting, Einstein was introduced to a Theoretical Physicist, fellow Jew, and professor at the University of California, J Robert Oppenheimer. Even though the brilliant duo did not exchange too many words, this first meeting sparked the beginning of a turbulent relationship.

Agree to Disagree

In the following years, despite having his hands full fleeing Germany, Einstein and Oppenheimer met frequently to debate their differing theories on physics. Eventually, Einstein would take up a position on the opposite side of America at Princeton, while Oppenheimer remained at Berkley.

Einstein Oppenheimer Young StudentEinstein Oppenheimer Young Student
Charlotte Riefenstahl CC, via Wikimedia Commons

Even though both physicists were at the top of their field and the brightest minds alive, the duo disagreed on many theories. While Einstein believed black holes were inconceivable, Oppenheimer used Einstein’s theory to prove that black holes are possible. However, their professional relationship wasn’t harmed by disagreement.

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Could They Be Trusted?

Even by allowing refuge for Einstein as World War II unfolded, the US government did not trust the physicist. As a self-proclaimed pacifist with assumably socialist values, the US feared whatever information Einstein learned from research for America he could share with the Soviet enemy as well.

Einstein Oppenheimer Communist SocialistEinstein Oppenheimer Communist Socialist
Ochoa54, CC via Wikimedia Commons

Not only did the US government not trust Einstein, but they were also slow to trust Oppenheimer. Even though there were suspicions that Oppenheimer could be a Communist Party member with a brother, former partner, and wife with ties to the Party, Oppenheimer was never definitively involved with the Soviets.

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A Simple Signature

Although the US Army denied Einstein security clearance to US Army intelligence, he was still considered an essential voice in the scientific community. In August 1939, a month before the war broke out, Einstein was just one name on a letter that many believe is the reason nuclear power exists at all.

Einstein Oppenheimer Letter FDREinstein Oppenheimer Letter FDR
Albert Einstein PD via Wikimedia Commons

Written by Hungarian scientist Leo Szilard and merely signed by Einstein, the letter was addressed to then-President Franklin Roosevelt and made some substantial warnings. The letter warned that the Germans may be developing a weapon of mass destruction that could destroy the world.

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Regretfully Signed

The letter read, "In view of this situation, you may think it desirable to have some permanent contact maintained between the Administration and the group of physicists working on chain reactions in America." Not long after, they began constructing a team to attempt to create nuclear weapons before the enemy could.

Einstein Oppenheimer FDR LetterEinstein Oppenheimer FDR Letter
National Archives and Records Administration, Public domain, via Wikimedia Commons

At this point, Einstein didn't understand if nuclear power would even work beyond theoretics. Either way, Einstein quickly regretted his involvement in the letter. He told Newsweek, "Had I known that the Germans would not succeed in developing an atomic bomb, I would have done nothing."

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Putting the Plan Into Action

Now that FDR and the US government were aware that a nuclear weapon was in development, given “Germany [had] actually stopped the sale of uranium from the Czechoslovakian mines which she [had] taken over,” it was decided to create a team that would beat the Germans at their own game.

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Unknown navy photographer, Public domain, via Wikimedia Commons

Only two years later, in 1941, following the devastating attack on Pearl Harbour by the Japanese Axis, their plan was put into action, and a team of scientists began to form. A year later, to hide the intention of their mission, it was titled the Manhattan Project under extreme confidentiality and strict privacy.

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Einstein is Left Out

In an article for Kaizō, Einstein wrote, "My participation in the production of the atom bomb consisted in a single act: I signed a letter to President Roosevelt. This letter stressed the necessity of large-scale experimentation to ascertain the possibility of producing an atom bomb."

Einstein Oppenheimer Communist USAEinstein Oppenheimer Communist USA
Donkeyhotey, CC via Wikimedia Commons

Despite his credited rousing of the Manhattan Project, Einstein was actually disallowed information by the US government. Alex Wellerstein told Insider. "They knew each other. They worked in the same place after the war. But Oppenheimer saw Einstein as kind of the old guard."

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Left-Leaning Oppie

Despite many offers to join the Communist Party during the 1930s, Oppenheimer did not officially sign on as a member. However, his mere association with many current and former members was enough to earn suspicion. Namely, he openly campaigned against fascism during the Spanish Civil War.

Einstein Oppenheimer Socialist SovietEinstein Oppenheimer Socialist Soviet
ullstein bild Dtl via Getty Images

General Leslie Groves of the Manhattan Project was initially reluctant to hire Oppenheimer for the nuclear project as he had an “extreme liberal background.” In the end, Oppenheimer’s “overweening ambition” earned him the position as the director of the Los Alamos laboratory.

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Appointing Oppie

Even though they didn't fully trust him, Groves and the U.S. government still chose to bring Oppenheimer to the Manhattan Project. All the while, Einstein was given only what was available to the public, and Oppenheimer was strictly instructed to keep information private to a manageable number of people.

Einstein Oppenheimer Manhattan ProjectEinstein Oppenheimer Manhattan Project
Cedit Line / Digital Photo Archive, Department of Energy, Courtesy of AIP Emilio Segrè Visual Archives, CC0, via Wikimedia Commons

While Oppenheimer generally disobeyed the command, he shared information with many scientific voices but didn't relay anything to Einstein. Chief of Security John Lansdale later said, "I became convinced that not only was he loyal, but that he would let nothing interfere with the successful accomplishment of his task."

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Creating the Weapon

The Manhattan Project was mostly conducted in the U.S., with three top-secret towns serving as significant hubs: Oak Ridge, Tennessee, where uranium was enriched; Hanford, Washington, where uranium was converted into plutonium; and Los Alamos, New Mexico, where the bombs were designed and built.

Einstein Oppenheimer Manhattan ProjectEinstein Oppenheimer Manhattan Project
Ed Westcott (U.S. Government photographer), Public domain, via Wikimedia Commons

Isidor Rabi wrote it was a "real stroke of genius" to hire Oppenheimer. Historian Alexandra Levy told Scientific American, "He contributed to some of the early scientific breakthroughs of the project. His great gift was bringing together scientists, engineers and other technicians to collaborate on and solve problems."

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Cutting Off Friendships

Knowing the US government and General Leslie Groves were watching his every move, Oppenheimer acted to defend himself from any future accusations that could be made against him. Reportedly, he told a close friend, "I'm cutting off every Communist connection." And that he did.

Einstein Oppenheimer Communist ValuesEinstein Oppenheimer Communist Values
Laboratoire national de Los Alamos, PD via Wikimedia Commons

Oppenheimer also allegedly said, "I don't want to let anything interfere with my usefulness to the nation. If I don't take this job, the government will find it difficult to use me." His enthusiasm to work ultimately earned him the coveted position, but it was also the same thing that led to his eventual manhunt.

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Oppenheimer became the scientific director of the Manhattan Project. The lead-up to the Trinity test was a period of intense scientific and engineering activity. Research had been underway for several years, and scientists had made significant progress in understanding and controlling nuclear fission.

Einstein Oppenheimer Trinity TestEinstein Oppenheimer Trinity Test
ENERGY.GOV, Public domain, via Wikimedia Commons

The bomb, codenamed "Gadget," was a complex device that took over two years to build. Even though hundreds of scientists were banned from consulting Einstein, in less than three years, Oppenheimer led the successful test of the first nuclear weapon, the Trinity test, on July 16, 1945.

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And that was it. Oppenheimer had achieved what Einstein advised them to do. Oppenheimer reportedly expressed concern for the Japanese people who were about to be bombed, saying, "Those poor little people, those poor little people." He would later go on to oppose the development of the hydrogen bomb.

Little Man Fat BoyLittle Man Fat Boy
George R. Caron, Public domain, via Wikimedia Commons

On August 6 and 9, 1945, the US dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki. The bombs killed an estimated 210,000 people and contributed to the end of World War II. However, the bombings were a devastating loss of life, and they raised serious ethical questions about using nuclear weapons.

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Death and Woe

When the bomb detonated at Trinity and in the following days, Oppenheimer recalled that the Hindu scripture, "Now I am become Death, the destroyer of worlds," came to mind immediately after the Trinity test. The authors of American Prometheus reported that Oppenheimer was depressed after the detonation.

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Anefo, CC0, via Wikimedia Commons

Similarly, Einstein's reaction was the same horror level as Oppenheimer's. When he learned of the detonation of nuclear bombs, he said, "Woe is me." During a speech for the Nobel Peace Prize in 1962, he said, "It is no longer rational to solve international problems by resorting to war."

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Wipe the Blood Away

Like Einstein had predicted, Oppenheimer was almost instantaneously horrified by his creation. Oppenheimer's guilt over the atomic bombings was evident in his meeting with President Truman in October 1945. He famously told the president, "I feel I have blood on my hands."

Einstein Oppenheimer Truman BloodEinstein Oppenheimer Truman Blood
ENERGY.GOV, Public domain, via Wikimedia Commons

Even with great American success in battle, Oppenheimer felt morally unclean. As reported in the American Prometheus, Truman responded, "I told him the blood was on my hands, to let me worry about that." However, Truman also allegedly offered Oppenheimer a napkin and said, "Well, here, would you like to wipe your hands?"

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Father of Regret

While hailed as the 'father of the atomic bomb,' Oppenheimer later described nuclear weapons as "weapons of aggression, of surprise, and of terror." He warned that if they were ever used again, it would likely be on a massive scale, and millions of lives could be lost from political recklessness.

Einstein Oppenheimer Father AtomicEinstein Oppenheimer Father Atomic
National Archives at College Park, Public domain, via Wikimedia Commons

He also later said, "We have done the Devil's work. Now we have come back to our real job, which is to devote ourselves exclusively to research." Following Japan's surrender, Oppenheimer returned to life as he knew it. In 1947, he became the Institute for Advanced Study director at Princeton, alongside Einstein.

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The New Prince of Princeton

Well before his appointment for the Manhattan Project, Oppenheimer’s future employer at Princeton, Hermann Weyl, had attempted to recruit the scientist to teach at Princeton. However, after an invitation in 1934, Oppenheimer turned him down, stating, “I could be of absolutely no use at such a place.”

Einstein Oppenheimer Princeton PhysicsEinstein Oppenheimer Princeton Physics
National Archives and Records Administration, Public domain, via Wikimedia Commons

Oppenheimer’s appointment at Princeton may have seemed surprising, given his harsh criticism of the university in 1935 in a letter to his brother. He wrote, “Princeton is a madhouse.” He added, “[Princeton] solipsistic luminaries shining in separate & helpless desolation.”

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Smack Talking

However, the scathing comments didn't end there. While fond of Einstein's career and accomplishments, Oppenheimer wrote, "Einstein is completely cuckoo," and he was "not a very good administrator." Einstein also had some negative things to say about Oppenheimer. 

Einstein Oppenheimer Disagree FightEinstein Oppenheimer Disagree Fight
Bundesarchiv Bild, CC-BY-SACC via Wikimedia Commons

In a letter to a friend in 1949, Einstein wrote that Oppenheimer was "a very peculiar fellow" and was "not a very good physicist." Einstein also criticized Oppenheimer for his role in the Manhattan Project, saying he was "not a pacifist" and had "blood on his hands." Despite their respect, it seems the two quarrelled a lot too.

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Not the Biggest Fans

Even with all his strengths, Einstein didn't seem to be a fan of Oppenheimer's physics. He called Oppenheimer "an unusually capable man of many-sided education." Still, in the American Prometheus, the authors wrote, "what [Einstein] admired about Oppenheimer was the man, not his physics." 

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Los Angeles Times, CC via Wikimedia Commons

Familiarly, Oppenheimer struggled to comprehend why Einstein could never accept quantum theory or many of his other backed theoretical claims. Oppenheimer saw Einstein as "a living patron saint of physics, not a working scientist." Oppenheimer believed Einstein represented physics more than he pioneered it.

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Work Buddies; No Less No More

Biographers Bird and Sherwin of the American Prometheus wrote that Einstein didn't consider Oppenheimer a close friend. He said this was partly because [their] scientific opinions are pretty different. Oppenheimer once called Einstein "completely cuckoo" for dismissing quantum theory

Einstein Oppenheimer Princeton FriendsEinstein Oppenheimer Princeton Friends
ASSOCIATED PRESS, CC0, via Wikimedia Commons

Oppenheimer was just as unwillingly fond of Einstein as well. He and his disciples felt that Einstein was wasting time working on a "unified field theory" that would supersede quantum theory. And Einstein knew they saw him "as a heretic and a reactionary who has, as it were, outlived himself."

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Nothing But Respect

Despite their disagreements, Oppenheimer still had a great deal of respect for Einstein. In a 1965 lecture published in The New York Review, Oppenheimer said, "Einstein's extraordinary originality is the true part of the myth." While they bickered behind each other's backs, they mutually respected each other.

Einstein Oppenheimer Nuclear TheoryEinstein Oppenheimer Nuclear Theory
ENERGY.GOV, Public domain, via Wikimedia Commons

Oppenheimer also applauded Einstein's attempts to debunk his theories. He said, "No one could have been more ingenious in thinking up unexpected and clever examples. But it turned out that the inconsistencies were not there; and often their resolution could be found in earlier work of Einstein himself."

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Lovers of the Arts

Despite their disagreements, Oppenheimer and Einstein liked one another. Oppenheimer once hosted a dinner party where he invited legal and scientifc minds; including his professional frenemy. Even with moments of clashing, the two had a great shared appreciation for art and culture.

Einstein Oppenheimer Classical MusicEinstein Oppenheimer Classical Music
https://ufdc.ufl.edu/UF00103013/00006/1x, CC0, via Wikimedia Commons

Aware of Einstein's fondness for classical music, yet knowing his inability to tune in to concerts broadcast from New York, Oppenheimer discreetly arranged for an antenna to be installed on his house prior to Einstein's birthday. Einstein was "delighted" by Oppenheimer's unexpected gift.

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Turning On an Old Pastime

Oppenheimer, haunted by the destructive power of nuclear weapons, called them "weapons of aggression, of surprise, and of terror." He warned that if they were ever used again, it would be on a horrifying scale. "If they are ever used again, it may well be by the thousands, or perhaps by the tens of thousands," he said.

Einstein Oppenheimer Weapons DestructionEinstein Oppenheimer Weapons Destruction
National Nuclear Security Administration / Nevada Site Office, Public domain, via Wikimedia Commons

Consumed by guilt, Oppenheimer lamented, "We have done the Devil's work." He vowed to dedicate himself to research to understand and harness the forces that had unleashed such devastation. Consequently, Oppenheimer joined the Atomic Energy Commission to prevent any more nuclear development.

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Upgrading Old Styles

Oppenheimer’s position on the AEC was always that of a pacifist, as he vowed to prevent further damage through nuclear weapons. To avoid WWIII with the Soviets, Oppenheimer utterly opposed manufacturing the Hydrogen Bomb (H-bomb), a weapon 1000 times more potent than an A-bomb.

Einstein Oppenheimer Hydrogen H-BombEinstein Oppenheimer Hydrogen H-Bomb
Pixabay via Pexels

However, this was not in the interests of many other influential players in the AEC, who believed the Soviet threat and their growing arsenal were too dangerous to ignore. Mainly, fellow Manhattan Project scientist Edward Teller and Princeton Director Lewis Strauss pushed for manufacturing the H-Bomb.

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Confusion from the Older Man

Wishing to weaken Oppenheimer’s public appearance and remove him from the US government, Strauss launched a smear campaign accusing Oppenheimer of Communist sentiments and for revealing government secrets during his management of the Manhattan Project. The trial would determine if his clearance would be revoked.

Einstein Oppenheimer Trial SocialistEinstein Oppenheimer Trial Socialist
Bundesarchiv Bild, CC-BY-SACC via Wikimedia Commons

Wishing to avoid public tarnishing, Oppenheimer went to trial to defend his access to government information. Einstein didn’t understand why Oppenheimer cared. “The older man clearly didn’t understand why he seemed to care so much about maintaining his access to the Washington establishment. Einstein didn’t play that game.”

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Last Sage Words of Advice

Einstein urged Oppenheimer to forgo the ordeal of defending himself against the baseless accusations hurled his way. He argued that Oppenheimer had no obligation to subject himself to the witch-hunt, that he had served his country with distinction, and that if this was the reward America offered, he should turn his back on her.

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Oren Jack Turner, Princeton Public domain, via Wikimedia Commons

Oppenheimer, however, was determined to clear his name. He refused to be silenced or intimidated by the smear campaign. Despite Einstein's sage advice, he chose to face his accusers head-on. Einstein told a friend, "The trouble with Oppenheimer is that he loves a woman who doesn't love him: the United States government."

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Scientific Minded Fool

After Oppenheimer decided to continue with the trial, Einstein remarked to his assistant, "There goes a narr," another word for a fool. Oppenheimer couldn't let the trial go because "he loved America, and this love was as deep as his love of science." As a European native, "Einstein [didn't] understand."

Einstein Oppenheimer Fool EnemiesEinstein Oppenheimer Fool Enemies
MARROS via Pexels

Perhaps Einstein was right, and Oppenheimer should have accepted his fate because the trial falsely branded him a traitor. Oppenheimer's decision to defend himself ultimately proved futile. The security clearance board revoked his access to classified information, effectively ending his career in government service.

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Einstein’s Regret

In the end, it wasn't just Oppenheimer that regretted his part in the deal. Even though the 'father of the atomic bomb' himself never blamed Einstein for leading to the creation of bombs, in the aftermath of World War II, a remorseful Einstein expressed regret for initiating the development of atomic weapons. 

Einstein Oppenheimer Regret JohnsonEinstein Oppenheimer Regret Johnson
Historical via Getty Images

Years later, in 1963, the US government finally apologized to Oppenheimer's social and public manhunt and for depriving him of critical information. Oppenheimer was invited to an event where Lyndon B Johnson awarded him the Enrico Fermi Award for his contributions to theoretical physics.

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Wasn't His Fault

While Oppenheimer blamed himself for beginning the nuclear arms race and triggering the world's potential end, he spent the rest of his life feeling guilty about his creation. However, given Einstein's letter to FDR in 1939, there wouldn't be the Manhattan Project. Well, Oppenheimer never blamed Einstein.

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Harris & Ewing Collection, Public domain, via Wikimedia Commons

Oppenheimer said in a lecture, "Einstein is often blamed or praised or credited with these miserable bombs. It is not, in my opinion, true. This was not what Einstein really was after." He added, "His part was that of creating an intellectual revolution." Oppenheimer didn't even blame Einstein for signing the letter at all.

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Last Decades of Friendship

Despite their differences, Oppenheimer's admiration for Einstein remained steadfast. In a 1966 lecture published in The New York Review, Oppenheimer said, "Indeed, if I had to think of a single word for his attitude towards human problems, I would pick the Sanskrit word ahinsa, not to hurt, harmlessness."

Einstein Oppenheimer Theoretical PhysicsEinstein Oppenheimer Theoretical Physics
Historical via Getty Images

Likewise, a few years before he died, Einstein openly said, "I admire him not only as a scientist but also as a great human being." Even with decades of division and disagreement, two of the most brilliant minds ever to grace theoretical science respected each other until the end and showed that humanity was their priority.

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