Robert Oppenheimer and Albert Einstein had a professional relationship and shared mutual respect for each other's work, but they were not particularly close friends. Their connection primarily stemmed from their involvement in the development of nuclear weapons and their shared concern about the potential consequences of their creation.
Einstein, a theoretical physicist, played a crucial role in the early understanding of nuclear fission and the concept of mass-energy equivalence, which would later contribute to the development of atomic weapons. Oppenheimer, a theoretical physicist and scientific administrator, was the scientific director of the Manhattan Project, which was responsible for developing the first atomic bombs during World War II.
Although Einstein initially signed a letter to President Franklin D. Roosevelt, urging the United States to research atomic weapons due to fears that Nazi Germany might develop them first, he became more vocal about his opposition to the use of nuclear weapons later on. Oppenheimer, on the other hand, led the scientific efforts to develop these weapons but became deeply concerned about their destructive power after witnessing the successful test of the first atomic bomb.
Their paths crossed during their involvement in the Manhattan Project, and they likely had conversations and correspondence related to the project and its implications. However, there is no evidence to suggest that they had a close personal friendship beyond their shared professional concerns.