Atomic Bomb’s Invention And Its Influence On Science: Welcome back to “Science For Everyone”, ABP Live’s weekly science column. Last week, we discussed what matter and antimatter are, and what a CERN physicist says about the matter-antimatter asymmetry. This week, we explain how the project for the invention of the atomic bomb brought together extraordinary scientific minds from across the world, and how the development of the first nuclear weapons shaped scientific discoveries over the years.
The invention of the atomic bomb is a quintessence of scientific triumph that introduced the world to the marvels of particle physics. The atomic bomb was developed as part of the Manhattan Project, under the leadership of American theoretical physicist Julius Robert Oppenheimer, on whose life Christopher Nolan's latest masterpiece, Oppenheimer, is based.
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The scientific discoveries that made the invention of the atomic bomb possible
The creation of these nuclear weapons was a great scientific breakthrough and helped end World War II, the first and only time such destructive munitions were used in conflict.
In order to develop the atomic bomb, leaders and scientists from all scientific fields and engineering disciplines came together, explored the fields of nuclear physics and chemistry, and used the concepts of practical engineering to process radioactive materials uranium-235 and plutonium-239. The scientists leveraged nuclear fission of uranium-235 and plutonium-239, and the chain reactions that can liberate colossal amounts of destructive heat energy, in order to produce nuclear weapons.
Before understanding the significance of the invention of the atomic bomb, let us understand the events that led to the development of the first nuclear weapons.
Fission is a form of chemical interaction between subatomic particles, and nuclear fission is the process in which an atom is split by bombarding the nucleus with neutrons, a type of subatomic particle carrying no charge. The other subatomic particles in an atom are protons and electrons, which are positively- and negatively-charged particles respectively. An atomic nucleus has both protons and neutrons, but no electrons, because of which the core of an atom is positively-charged. The electrons revolve around the nucleus in shells. It is the collision of atomic particles that leads to different chemical reactions.
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When neutrons collide with the nucleus of another atom, a tremendous amount of energy is released. Since protons as well as the nucleus of an atom are positively-charged, they will repel each other, and hence, protons cannot be used in nuclear bombardment.
Therefore, in nuclear fission, neutrons are used, and are fired towards an atom with the aim of making the neutrons fuse with the nucleus. After this, a less-stable isotope is produced. Since the isotope is less stable than the original element, it is chemically volatile, splits into two stable atoms, releases neutrons, and generates energy in the form of Gamma radiation.
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However, this is not the end of the reaction. The newly released neutrons fuse with the nuclei of other atoms, causing them as well to release neutrons. In this way, a chain reaction begins, and not only are neutrons released, but also large amounts of heat radiation. The chain reaction, if left unchecked, can create an atomic bomb.
Not every atom is fissionable, because if that were the case, there would have been no stability to matter, and chaotic energy transformations would have ensued in the world.
The isotopes of only a few elements can undergo a fissile chain reaction.
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German scientists Otto Hahn and Fritz Strassman conducted an experiment in 1939, as part of which they added non-radioactive barium to uranium, and fired neutrons at the latter. At the conclusion of the experiment, they observed some barium atoms had radioactivity. This was surprising because they had used non-radioactive barium in the reaction.
Austrian-Swedish physicist Lise Meitner said that when uranium was bombarded with neutrons, each atom was split into two, forming two elements, one of which was barium. The barium atoms formed as a result of the splitting of uranium were radioactive.
After learning about the theory that uranium is a fissionable element, Danish physicist Neils Bohr told the entire world about the important discovery at an international conference in Washington.
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In the early 20th century, fission was a newly recognised process, and in order to make the most of it, American scientists, many of whom were refugees from fascist regimes in Europe, took steps in 1939 to organise a project.
The need to create nuclear weapons before enemy nations, including Nazi Germany, produced such devastating bombs themselves, and the newfound knowledge of nuclear fission culminated in the Manhattan Project in 1942, and subsequently, the development of the atomic bomb in 1945.
The invention of the atomic bomb, and how it shaped scientific discoveries
The Manhattan Project was a success due to several factors, including scientific intellect, and communication between scientific minds.
On the sidelines of a physics conclave held at Shiv Nadar School, Gurgaon, ABP Live spoke to Dr Archana Sharma, a principal scientist at CERN, and the head of the engagement office for the Compact Muon Solenoid; and Jahnavi Phalkey, a filmmaker and historian of science and technology, and the Founding Director of Science Gallery, Bengaluru, and asked them about how the invention of the atomic bomb has shaped scientific discoveries over the years.
Dr Sharma explained that the invention of the atomic bomb “accelerated” the development of advanced scientific and engineering technologies. She also said that since the development of the atomic bomb required a deep understanding of nuclear physics, it led to significant advancements in the field of nuclear research. The atomic bomb was invented because scientists had unravelled interesting mysteries of the atom, and after it was developed, a multitude of interesting phenomena occurring at the subatomic level was unravelled.
“The invention of the atomic bomb has had a profound impact on scientific discoveries and the course of history in several ways. The development of the atomic bomb required a deep understanding of nuclear physics, leading to significant advancements in this field. Researchers gained valuable insights into the behaviour of atomic nuclei, radioactive decay, and nuclear reactions laying the foundation for subsequent research in nuclear physics and helped unravel the mysteries of the atom. This accelerated the development of advanced scientific and engineering technologies leading to cutting-edge equipment, materials, and manufacturing processes,” Dr Sharma explained.
She also said that the technological innovations resulting from the invention of the atomic bomb proved to be useful for civilians. Some of these applications include the use of nuclear energy for generating electricity.
“Many of these technological innovations found civilian applications, contributing to advancements in various industries. Exploration of nuclear energy for peaceful purposes, such as electricity generation, and the discovery of controlled nuclear fission paved the way for the construction of nuclear power plants worldwide,” Dr Sharma said.
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Explaining how a lot of investment went into particle physics after the atomic bomb helped end World War II, Phalkey said: “The making of the atomic bomb was accelerated largely after the discovery of nuclear fission. The construction of the bomb was accelerated because it happened during World War II. A lot of investment went into physics after the War. So, at least for the first 30 years after World War II, a lot of investment went into high energy and particle physics, into building massive accelerators, into nuclear chemistry, nuclear medicine, nuclear engineering and nuclear physics. Therefore, it pulled out large-scale physics, or big sciences out of the universities and into centralised institutions across the world, including in India.”
However, branches of physics apart from nuclear physics got less funding, Phalkey said. “Thus, in a way, the invention of the atomic bomb slowed down the growth of other branches of physics. At some point, the saturation began. There was an anti-nuclear movement. There were some countries' decisions to divest from arms.”
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A remarkable benefit of nuclear physics is that it indirectly gave birth to molecular biology.
“Nuclear physics indirectly led to the beginnings of molecular biology. So, physicists started doing bioinformatics and biology. Today, we would not have had biotechnology if it was not for an excessive amount of physicists trained after the War who then found their way into molecular biology,” Phalkey said.
Without the invention of the atomic bomb, the world would have been oblivious to the treasure trove of secrets hidden within an atom.
“The atomic bomb continues to be an essential chapter in the history of science with a lasting impact on the trajectory of scientific research,” Dr Sharma concluded.