Julius Robert Oppenheimer or J. Robert Oppenheimer was an American theoretical physicist and nuclear physicist who has been credited as the “father of the atomic bomb” and has also be described as “the destroyer of worlds” due to his role in organizing the Manhattan Project that resulted in the development and deployment of the first nuclear weapons. He specifically designed the atomic bombs that were dropped on Hiroshima and Nagasaki in Japan during the Second World War. However, besides his accomplishments in the field of nuclear physics, he also made significant contributions in the different areas of theoretical physics, including significant achievements in quantum mechanics. He has been regarded as one of the most influential scientists of the 20th century.
Who Was J. Robert Oppenheimer? What Were His Contributions? How Did His Accomplishments Advance the Field of Physics and Science?
1. Father of the Atomic Bomb: Development of the First Nuclear Weapons and Contributions in the World War II
Oppenheimer had a notable contribution to the outcomes of the Second World War and the specific victory of the United States and the Allied forces against Japan and the Axis forces. To be specific, on 13 August 1942, the Manhattan Project was officially created. Albert Einstein and Leo Szilard wrote a letter to U.S. President Theodore Roosevelt warning him that Germany might be developing nuclear weapons.
Roosevelt responded with the creation of numerous offices and undertakings aimed at researching nuclear chain reactions and developing relevant nuclear-based weapons. The Manhattan Project was a specific pursuit aimed at developing an atomic bomb before Germany could do so. American Lieutenant General Leslie R. Groves was named its military director and he selected J. Robert Oppenheimer as the scientific director.
The task of developing an atomic bomb was under the purview of the Los Alamos Laboratory. It was a secret laboratory operated by the University of California and was located in Los Alamos County in New Mexico. Oppenheimer was the lab director. He headed a team of scientists and engineers that designed and developed the gun-type fission weapon using plutonium called Thin Man and the variant Little Boy based on uranium-235.
Nevertheless, under the directorship of Oppenheimer, the Manhattan Project and the specific Los Alamos Laboratory had produced ready-to-deploy atomic bombs by July 1945. These were the uranium-enriched gun-type nuclear weapon called Little Boy and the plutonium implosion-type nuclear weapon called the Fat Man. Little Boy was dropped in Hiroshima on August 6 while Fat Man was dropped in Nagasaki on August 9.
2. Other Accomplishments in Theoretical Physics: Remarkable Works and Important Contributions in the Field
It is important to reiterate the fact that Oppenheimer was one of the most brilliant theoretical physicists of his generation and remains one of the most influential scientists in history. His leading contributions to the design and development of the first nuclear weapons marked his acumen in nuclear physics. Take note that he was specifically chosen to lead the Manhattan Project because of his scientific capabilities and professional shrewdness.
Furthermore, apart from his monumental contribution during the Second World War, the entire legacy of Oppenheimer also includes other remarkable works and important contributions in the field of theoretical physics. Take note that he co-introduced the Born-Oppenheimer approximation in 1927 with his teacher Max Born that simplified the Schrödinger equation for molecules and helped in advancing the field of quantum mechanics.
Oppenheimer also made important contributions to the theory of cosmic ray showers and his work led to descriptions of quantum tunneling. He also wrote the paper “On the Theory of Electrons and Positrons” in 1931. It described the characteristics of the positron. The existence of positron was hypothetical at that time. American physicist Carl Anderson eventually discovered the positron in 1932 and won the Noble Prize in Physics in 1937.
He worked on a theory together with American physicist Melba Philipps in 1938 to explain a phenomenon in a deuteron-induced nuclear reaction. It was called the Oppenheimer-Philipps Process or strip reaction. The process is a type of nuclear reaction that can occur when a deuteron collides with a nucleus. This results in the nucleus capturing the neutron in the deuteron and ejecting the proton in the same deuteron.
Oppenheimer became interested in astrophysics. The Tolman–Oppenheimer–Volkoff limit introduced in 1939 in the paper “On Massive Neutron Cores” explained that there was a limit to the mass of stars beyond which they would not remain stable as neutron stars and would undergo gravitational collapse. He also wrote the paper “On Continued Gravitational Contraction” with Hartland Snyder in 1939 which predicted the existence of black holes.
3. Institute for Advance Studies: Leading a Research Center to Guide Established and Emerging Intellectuals
Oppenheimer left Los Alamos Laboratory in 1945. American naval officer and businessman Lewis Strauss offered him a directorship position at the Institute for Advanced Studies in 1947. This organization is an independent center for theoretical research and intellectual inquiry located in New Jersey. It has served as the academic home of prominent scientists like Albert Einstein, John von Neumann, Hermann Weyl, and Oswan Veblen.
Nonetheless, after assuming the new role, Oppenheimer brought together numerous established intellectuals from various disciplines. The goal was to answer pertinent questions of the age. He was responsible for directing and encouraging the works of several well-known scientists. These included British-American theoretical physicist Freeman Dyson and physicist duo and Nobel Prize winners Yang Cheng-Ning and Tsung-Dao Lee.
He also attempted to bring together intellectuals outside the realms of the natural sciences. He specifically also instituted temporary memberships for scholars from the humanities. These included poet and essayist T. S. Elliot and diplomat and historian George F. Kennan. Some faculty members opposed this directive because they believed that the Institute for Advanced Studies should remain exclusive to pure scientific research.
Oppenheimer also directed others to revisit outstanding pre-war problems. These included inquiries about infinite, divergent, and nonsensical expressions in the quantum electrodynamics of elementary particles. Julian Schwinger, Richard Feynman, and Shin’ichiro Tomonaga tackled the problem of regularization while Robert Marshak posited the two-meson hypothesis. Cecil Frank Powell won the Nobel Prize for his discovery of the pion.
4. Opposition to Nuclear Weapon Proliferation: Controversial Scientific and Political Stance After World War II
Remember that one of the key legacies of Oppenheimer was the development of the first nuclear weapons. The deployment of the atomic bombs in Japan was a significant career milestone. He was even responsible for blocking a petition from his colleagues that opposed the use of nuclear weapons during the Second World War. However, after the war, his stance on nuclear weapons and their proliferation changed.
Oppenheimer wrote a letter to U.S. President Harry S. Truman warning him of the dangers of nuclear proliferation. He also opposed the development of the hydrogen bomb and specifically argued that it would be a weapon of genocide. He also influenced the Acheson–Lilienthal Report which advocated the creation of an international Atomic Development Authority tasked to own all fissionable material and the means of its production.
The Atomic Energy Commission was established in 1947 and Oppenheimer served as the chairperson of its General Advisory Committee. He was responsible for providing advisories on several nuclear-related issues. Hence, using his position and influence, he lobbied for international arms control and attempted to stir policies away from a heated arms race. He also opposed the development of the hydrogen bomb called “Super” in 1949.
Oppenheimer explained that global nuclear weapons proliferation would increase the risk of nuclear war and that these weapons pose a threat to human survival. Nevertheless, because of his stance and allegations of security risk, he was stripped of his security clearance in 1954 and was banned from working on government projects after a four-week hearing by the Atomic Energy Commission. This decision damaged his reputation and career.
In 2014, six decades after the hearing that ended his career and political influence, the U.S. Department of Energy released the declassified transcripts of the proceedings. The document reaffirmed what most people have believed. Oppenheimer was loyal to the United States and his prosecution was motivated by politics and personal enmities. The biased and flawed handling of his case demonstrated the problems of American bureaucracy.