Biography of J. Robert Oppenheimer, Director of the Manhattan Project

J. Robert Oppenheimer, right
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J. Robert Oppenheimer (April 22, 1904–February 18, 1967) was a physicist and the director of the Manhattan Project, the United States' effort during World War II to create an atomic bomb. Oppenheimer's struggle after the war with the morality of building such a destructive weapon epitomized the moral dilemma that faced scientists who worked to create the atomic and hydrogen bombs.

Fast Facts: Robert J. Oppenheimer

  • Known For: Leader of the Manhattan Project, which developed the atomic bomb
  • Also Known As: Father of the Atomic Bomb
  • Born: April 22, 1904 in New York City, New York
  • Parents: Julius Oppenheimer, Ella Friedman
  • Died: February 18, 1967 in Princeton, New Jersey
  • Education: Harvard College, Christ's College, Cambridge, University of Göttingen
  • Published WorksScience and the Common Understanding, The Open Mind, The Flying Trapeze: Three Crises for Physicists
  • Awards and Honors: Enrico Fermi Award 
  • Spouse: Katherine "Kitty" Puening
  • Children: Peter, Katherine
  • Notable Quote: "If atomic bombs are to be added as new weapons to the arsenals of a warring world, or to the arsenals of the nations preparing for war, then the time will come when mankind will curse the names of Los Alamos and Hiroshima. The people of this world must unite or they will perish."

Early Life

Julius Robert Oppenheimer was born in New York City on April 22, 1904, to Ella Friedman, an artist, and Julius S. Oppenheimer, a textile merchant. The Oppenheimers were German-Jewish immigrants but did not keep religious traditions.

Oppenheimer attended the Ethical Culture School in New York. Although J. Robert Oppenheimer easily grasped both the sciences and humanities (and was especially good at languages), he graduated from Harvard in 1925 with a degree in chemistry.

Oppenheimer continued his studies and graduated from the University of Gottingen in Germany with a Ph.D. After earning his doctorate, Oppenheimer traveled back to the U.S. and taught physics at the University of California at Berkeley. He became well known for being both a well-regarded teacher and a research physicist—not a common combination.

In 1940, Oppenheimer married Katherine Peuning Harrison and their eldest child was born. Harrison, a radical student at Berkeley, was one of many communists in Oppenheimer's circle of friends.

The Manhattan Project

During the beginning of World War II, news arrived in the U.S. that the Nazis were progressing toward the creation of an atomic bomb. Though the Americans were already behind, they believed they could not allow the Nazis to build such a powerful weapon first.

In June 1942, Oppenheimer was appointed the director of the Manhattan Project, America's team of scientists that would work to create an atomic bomb.

Oppenheimer threw himself into the project and proved himself not only a brilliant scientist but also an exceptional administrator. He brought the best scientists in the country together at the research facility at Los Alamos, New Mexico.

After three years of research, problem-solving, and original ideas, the first small atomic device was exploded on July 16, 1945, in the lab at Los Alamos. Having proved their concept worked, a larger scale bomb was built and exploded at the Trinity site. Less than a month later, atomic bombs were dropped on Hiroshima and Nagasaki in Japan.

A Problem With His Conscience

The massive destruction the bombs inflicted troubled Oppenheimer. He had been so caught up in the challenge of creating something new and the competition between the U.S. and Germany that he—and many of the other scientists working on the project—had not considered the human toll that would be caused by these bombs.

After the end of World War II, Oppenheimer began to voice his opposition to creating more atomic bombs and specifically opposed developing a more powerful bomb using hydrogen, known as a hydrogen bomb.

Unfortunately, his opposition to the development of these bombs caused the United States Atomic Energy Commission to examine his loyalty and questioned his ties to the Communist Party in the 1930s. The Commission decided to revoke Oppenheimer's security clearance in 1954.


From 1947 to 1966, Oppenheimer worked as the director of the Institute for Advanced Study in Princeton, New Jersey. In 1963, the Atomic Energy Commission recognized Oppenheimer's role in the development of atomic research and awarded him the prestigious Enrico Fermi Award.


Oppenheimer spent his remaining years researching physics and examining the moral dilemmas related to scientists. Oppenheimer died in 1967 at age 62 from throat cancer.


The invention of the atomic bomb had a profound impact on the outcome of World War II and on the ensuing Cold War and arms race. Oppenheimer's personal ethical dilemma has become the focus of myriad books and several plays, including In the Matter of J. Robert Oppenheimer.


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Rosenberg, Jennifer. "Biography of J. Robert Oppenheimer, Director of the Manhattan Project." ThoughtCo, Aug. 28, 2020, Rosenberg, Jennifer. (2020, August 28). Biography of J. Robert Oppenheimer, Director of the Manhattan Project. Retrieved from Rosenberg, Jennifer. "Biography of J. Robert Oppenheimer, Director of the Manhattan Project." ThoughtCo. (accessed April 2, 2023).

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