Oppenheimer: Designer of the first atomic bomb

It was a sensitive physicist who became the father of the atomic bomb. We examine Oppenheimer's feelings and remorse during the bombing race against Hitler and when the mushroom clouds…

It was a sensitive physicist who became the father of the atomic bomb. We examine Oppenheimer’s feelings and remorse during the bombing race against Hitler and when the mushroom clouds rose into the sky in the post-war years.

The index finger inevitably pointed directly at J. Robert Oppenheimer (1904-1967) when it came to defeating the Nazis in the race for the first atomic bomb.

Oppenheimer became the leader of the American nuclear project, the so-called Manhattan Project, and at the same time the driving force behind the construction of the first atomic bombs.

The next step after the bombs dropped on Hiroshima and Nagasaki was the hydrogen bomb, which was even more terrifying. There, Oppenheimer called it quits and at the same time was put out in the cold and also found himself in the spotlight of contemporary communist hunters.

Here we talk about Oppenheimer, from the elementary school chemistry lab to the atomic bomb, along with how the pacifist in him came to the fore – but also a little about the German Werner Heisenberg and the Dane Niels Bohr.


1. The child prodigy who is fascinated by science and fiction

2. Flirt with a communist

3. Oppenheimer in the spotlight of the FBI

4. That’s why the German energy plan collapsed

5. Niels Bohr paved the way for nuclear power

6. The Manhattan Project in numbers

7. Oppenheimer’s conscience

8. The world never the same

9. This washes off

10. Victim of the witch hunt

In the early morning of July 16, 1945, J. Robert Oppenheimer lay dead in a bunker in the Jornada del Muerto (Journey of the Dead in Spanish) desert in New Mexico.

This one was staring there  A 41-year-old American in anticipation of the test bomb, which stood on a 20-meter high steel tower about 9 km to the southeast.

For the past two years, Oppenheimer had directed a team of about 3,500 scientists at work building the first atomic bomb in history. The headquarters were in the small town of Los Alamos about 330 km north of the test site.

The child prodigy who is fascinated by science and fiction

Oppenheimer was at the very forefront of the field of theoretical physics and there in a group with geniuses such as Albert Einstein, Niels Bohr and then his “colleague” in the Nazi camp, Werner Heisenberg.

Julius Robert Oppenheimer was born on April 22, 1904 into a Jewish family with German roots.

He was an unusually gifted child, who read Plato and Homer in ancient Greek, dabbled in poetry, and started doing physics and chemistry experiments in the school’s chemistry lab when he was only 10 years old.

In 1922, Oppenheimer was admitted to Harvard University. In addition to chemistry, which was his main subject, this inquisitive 17-year-old also studied philosophy, French and English literature and history.

After graduating from Harvard, Oppenheimer threw himself into physics. In 1925, he went to England to study at the prestigious Cambridge University physics institute, the Cavendish Laboratory.

He seemed to excel in his studies, but had a much more difficult time in social life.

“I was constantly unhappy and had no understanding of other people. I had no humility towards reality,” Oppenheimer later said of this 20-something version of himself.

Robert Oppenheimer completed his doctorate in theoretical physics at the University of Göttingen. He spent nine months at this German university, during which time he published seven scientific theses. It took him only three weeks to write his thesis on photoelectron effects on hydrogen and X-rays.

Flirting with a communist

During Oppenheimer’s youth, ideas about a communist society were widely discussed. The world crisis from the 1930s made people sad and the plight of poor people was enormous. Communism was therefore not the distant utopia it became in the days of the Cold War after World War II.

At the age of 23, Oppenheimer returned to the United States in 1928 and received the position of assistant professor at two Californian universities, Caltech in Pasadena and Berkeley in San Francisco.

But he spent his free time on a ranch in New Mexico. On the other hand, he loved the desert and the physics laboratory. “My great loves in life are New Mexico and physics.” It’s a shame that the two can’t be combined,” he said.

In 1936, a third love was added in the form of the beautiful Jean Tatlock. She was a member of the Communist Party of the United States (CPUSA) and it wasn’t long before left-wing politics also became a big part of Oppenheimer’s life.

The relationship with Jean Tatlock did not last long, although they remained friends until 1944 when she took her own life. In 1939, Oppenheimer met the German-American biologist Katherine “Kitty” Vissering Puening, who was also a member of the Communist Party. They married in 1940.

Oppenheimer in the spotlight of the FBI

The first lines of the FBI’s Oppenheimer folder overview go back to the 1940s. Later, the FBI’s surveillance of him became so intense that it could be said that every step was being watched.

According to Oppenheimer himself, his flirtation with a communist was short-lived but very intense, and he never joined the Communist Party of America.

His connections with the left were created both through his wife Kitty and his brother, Frank Oppenheimer, and caused the FBI to closely monitor this physicist, who had now become a professor at the University of Berkeley.

Since 1941, the home was bugged. The FBI file on Oppenheimer ran to many thousands of pages and the conclusion was that he was sympathetic to the communist cause.

However, the contents of the collection folder were not enough to get this clever scientist fired.

A few months after the Japanese attack on Pearl Harbor on December 7, 1941, which led to the entry of the United States into the war, Oppenheimer was appointed as technical director of the largest scientific project ever undertaken.

It was Franklin D. Roosevelt who pushed the so-called Manhattan Project out of his mouth and its coordination took place secretly in Manhattan, New York – that’s how the name came about.

The goal was to develop the first atomic bomb in history before the Germans succeeded.

That’s why the German energy plan collapsed

The Allies take down a German nuclear reactor in 1945. It was hidden in a cave near the town of Haigerloch in southwestern Germany.

The fear of the Germans developing a doomsday bomb was the driving force behind the Manhattan Project in the United States. The American scientists were to reach that goal before the Germans. However, the rumor that the Germans were on the brink of extinction turned out to be very far from the truth.


1. Important structure destroyed

The German scientists – led by Werner Heisenberg – controlled a nuclear reactor, which was preserved in a rock bunker and used heavy water (D 2 O). It was manufactured at the Vemork plant in German-occupied Norway, but on February 28, 1943, Norwegian troops dispatched from Britain managed to sabotage it enough to render it inoperable.


2. The German scientists hesitated

The Germans managed to split atoms as early as 1938, but by 1942 they were far behind the Americans in the race. The German scientists were more interested in using nuclear power for the reconstruction of Germany after the war.


3. Budgets were far too small

The Americans spent billions of dollars in the development of the atomic bomb, and a total of 130,000 people worked on the project. The German scientists were only a little over 100 in number. Budgets were also a pittance compared to the American ones. Calculated in dollars, the Germans provided only about a million dollars for nuclear research during the war.

Niels Bohr paved the way for nuclear power

Oppenheimer with the senior commander of the Manhattan Project, General Leslie Grove. The work weighed heavily on this slender scientist, and for a while he was down to 52 kg.

Theoretically, the origin of the atomic bomb was based on a scientific paper written by the Danish physicist Niels Bohr in 1939.

In his paper, Bohr claimed that it was possible to produce an almost incomprehensible amount of energy with the right amount of the isotope uranium-235, which is a rather rare version of uranium.

The question was how much was needed, and Oppenheimer had calculated that. His conclusion was that 100 kg of uranium-235 was sufficient to cause a chain reaction, which was powerful enough to cause an explosion. Later it was found that to detonate a nuclear bomb with a uranium core only 64 kg is needed.

In the mind of Leslies Grove, the senior officer of the Manhattan Project, there was no doubt. Whether or not Oppenheimer was a communist sympathizer, the Americans could not build an atomic bomb without him.

The Manhattan Project in numbers

The test bomb “The Gagdet” shortly before detonation.

The Manhattan Project lasted from 1942 to 1945 and involved an almost innumerable number of physicists, chemists, engineers and students recruited to secret facilities across the United States.

The best engineers and physicists were holed up in a secret camp outside Los Alamos in the New Mexico desert. There, Oppenheimer directed the dynamics as a scientific leader.

The camp was put into use in March 1943, and in a year and a half the number of employees increased from about 100 to about 3,500.

  • 2.2 billion dollars was the amount that the US federal government put into the development of the atomic bomb.
  • 130,000 people were employed on the Manhattan Project in the years 1942-1945.
  • Three main sites formed the framework for the work on the Manhattan Project: Oak Ridge in Tennessee, Hanford in Washington and Los Alamos in New Mexico.
  • 64 kg of uranium-235 was produced by the giant plants K-25 and Y-12 in Oak Ridge, Tennessee for the atomic bomb “Little Boy”. At the Hanford plant, south of Seattle, Washington, unknown quantities of the test bomb “The Gadget” and the atomic bomb “Fat Man” were produced.
  • The Americans had 18,000 nuclear warheads at the end of the 1960s.

Oppenheimer’s conscience

Oppenheimer’s personality was not such that he could be seen as a self-elected leader. On the contrary, it was said about him that he was not even capable of managing work and the division of labor in a hot dog cart.

Nevertheless, many of the physicists who worked closely with Oppenheimer remembered him fondly and said that he seemed omnipresent and that his mind was extremely fertile and productive.

At the time, Oppenheimer had no doubts about nuclear weapons. During his studies in Göttingen, he had become acquainted with the high level of knowledge and professional ambition of the German scientists. And as a Jew, he did not have to doubt for a moment the bottomless evil of the Nazi regime.

One of Oppenheimer’s old schoolmates, Isidor Rabi, vehemently refused his suggestion to participate in the Manhattan Project. Rabi said that he simply did not want three hundred years of research in the field of physics to end with the creation of weapons of mass destruction. To this Oppenheimer answered without any remorse:

“From my point of view, it’s primarily about being able to develop a new weapon in wartime that can weigh heavily.” It doesn’t seem to me that the Nazis gave us any other option but to follow this trend to the end.”

The world will never be the same

A 1965 television clip in which Oppenheimer describes his feelings and thoughts after the successful 1945 test explosion.

On April 30, 1945, Adolf Hitler committed suicide in his bunker and eight days later the Germans surrendered. But even though there was no longer any doubt that the war would soon be over, the US federal government – now under the leadership of Harry S. Truman – continued work on the atomic bomb.

Two and a half months later, on July 16, 1945, Oppenheimer now lay flat in his bunker in the New Mexico desert, anxiously awaiting whether his test bomb would prove ineffective or blast the world into the nuclear age.

“I have become Death himself, the one who destroys worlds.”
J. Robert Oppenheimer 1965.

At 05:29:45, the two-and-a-half-ton test bomb exploded in a devastating chain reaction.

As a result, a giant fireball rose into the sky and lit the sky bright white. A massive heat storm spread to all eight and 40 seconds after the explosion was followed by a pressure wave and a tremendous bang that could be heard 320 km away.

It was with both pride and terror that Oppenheimer watched a 12 km high mushroom cloud spread over the test site.

Years later, this American physicist recalled thinking, “The world will never be the same again,” in the first moments after the explosion. And immediately an old Hindu text echoed in his head:

“I have become Death himself, the one who destroys worlds.”

This washes off

The Manhattan Project was shrouded in complete secrecy. The woman in the foreground here, Gladys Owens, for example, had no idea that she had worked in uranium enrichment during the war years. It dawned on her half a century later when she went on a tour and recognized herself in this picture.

After this completely successful experiment, Oppenheimer rose to his feet as the father of the atomic bomb. Just three weeks later, on August 6, 1945, an American plane dropped the “Little Boy” bomb on the Japanese city of Hiroshima, and three days later, on August 9, “Fat Man” exploded over Nagasaki.


Nearly 250,000 Japanese lost their lives, and the Second World War thus had the most dire ending of any war, sooner or later.


“I feel like I have blood on my hands,” Oppenheimer told President Harry S. Truman when he visited the White House soon after. The response of the most powerful man in America is said to have been icy cold:


“Just calm down, it will wash off under the tap”.


In his childhood, Oppenheimer had hoped that the atomic bomb would bring peace to the world


But the bomb did not create a new and better world. On the contrary, it became the trigger for a mad arms race between the United States and the Soviet Union and at the same time marked the beginning of a long and exhausting cold war.


Oppenheimer became the chairman of an advisory committee under the Nuclear Energy Agency of the United States, where he lobbied for disarmament as well as for the declassification of the United States’ nuclear weapons program.


He was also a staunch opponent of the hydrogen bomb and became an ardent advocate for international control of nuclear weapons.


“Without international arms control, lasting peace is unthinkable, and without peace there will be nuclear war,” he said.


Oppenheimer died on February 18, 1967, almost 63 years old. His death was throat cancer. More than 600 people followed him to the grave a week later, among them Nobel laureates, politicians, famous generals and world-renowned scientists.


Among those who gave speeches at the ceremony was the American diplomat George Kennan, the main author of the exclusionary policy of the United States towards the Soviet Union and a close friend of Oppenheimer.


“The contradictions that accompanied man’s vastly increased power over nature rested as heavily on no man as he did, a power far beyond man’s mental strength,” Kennan said, adding:


“But no one saw as clearly the dangers that humanity faces as a result of this new imbalance.”


A victim of the witch hunt

Oppenheimer hearings recreated in Christopher Nolan’s film 2023. The security investigation lasted four weeks and was closed to the public. In the main role as Oppenheimer is Cillian Murphy (known from Peaky Blinders, among others).

After the end of World War II, Oppenheimer became chairman of the General Advisory Committee under the AEC.


Oppenheimer was outspoken in his opposition to the development of the hydrogen bomb, which began in 1949 and was tested three years later.


This position earned him many enemies, among them the director of the AEC, Lewis Strauss, who considered the hydrogen bomb to be of paramount importance to the security of the United States.


“I cannot do my job while Oppenheimer is involved with the AEC,” Strauss told President Truman.


In 1954, Strauss and the AEC commissioned a special security investigation of Oppenheimer. Now it was to be ascertained whether he had ever been a member of the Communist Party of the United States.


During interrogations, it was never proven that Oppenheimer had been a member of the party and could thus be considered a threat to the security of the state.


Nevertheless, the father of the atomic bomb was stripped of his security clearance and thus forced to leave the AEC.


The Oppenheimer hearings have later been described as farcical and based on baseless accusations and personal hatred without any basis in reality.


Oppenheimer thus became one of the victims of the witch hunts of the McCarthy era that began before 1950 and lasted until the middle of the decade. The era is attributed to the senator and communist hater Joseph McCarthy. Among the people who had to be interrogated or were blacklisted in some way, no more insignificant names can be mentioned than Charlie Chaplin, Lucy Ball, Leonard Bernstein and Albert Einstein himself.


This taint was not washed from Oppenheimer’s memory until 2022, when the federal government formally reversed the decision to strip him of his security clearance.

Oppenheimer revived in Hollywood bombshell

Christopher Nolan’s movie “Oppenheimer” was released on July 21, 2023.

The film describes Oppenheimer’s race against time to build the first atomic bomb.

Christopher Nolan has made a name for himself with other cinematic masterpieces, such as Dunkirk, Interstellar and The Dark Knight.

Read more about Oppenheimer

Martin J. Sherwin & Kai Bird: American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer , Vintage Books, 2006

Cynthia C. Kelly: Remembering the Manhattan Project , World Scientific, 2005

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