In 1938, Italian physicist Enrico Fermi, who fled to New York to escape fascism, discovered material in which a process of this type took place: uranium. Fearing that the Nazis could also discover the ability of this element to produce a chain reaction, the Manhattan project Born in 1940, a secret program for the development of nuclear weapons led by Arthur Compton. Compton formed a research group, which also included Close and Szilard, which would continue to conduct experiments on nuclear chain reactions. Theoretical physicist Julius Robert Oppenheimer was also part of the team.
On December 2, 1942, the first actual experiment took place under the football field of the University of Chicago; In Squash court, physicists built a reactor nicknamed “Chicago Mass 1” This achieved the first ever lasting nuclear reaction created by humans, providing confirmation of Szilard’s idea. In 1943, Oppenheimer became project manager at the Los Alamos Laboratories in New -Mexico, where the first true nuclear device in history would be projected and built. On July 16, 1945, the United States detonated it in the New -Mexican Desert. Twenty days later, on August 6, a similar bomb fell on the Japanese city of Hiroshima, and on 9 August in the city of Nagasaki, causing the surrender of Japan a few days later and the end of World War II.
A thing of kernels
As we all learn in school, atoms are composed of a core of neutrons and protons, around which electrons orbit. Atomic nuclei can unite to form larger atoms, or fragment to form smaller atoms. The first case is called nuclear fusion, and it is the process taking place in stars, and which researchers today try to recreate in the lab as a means of producing energy. Under hell heat and pressure, atoms merge to form heavier atoms. For example, in a star like the sun, hydrogen nuclei merge to form helium nuclei. This process releases energy that radiates in the solar system, creating deliverable conditions on Earth.
However, when a core dissipates, we call it a nuclear fission, which we exploit in a controlled manner in nuclear power plants and an intentionally uncontrolled way in nuclear bombs. In this case, heavier unstable atoms are fragmented into lighter atoms, a process that also releases energy. In addition to energy, excess neutrons are also released, triggering precisely the fission chain reaction conceptualized by Szilard. To maintain a chain reaction, however, the crack material must achieve criticism – a state where enough neutrons are released and other atoms are hit to continue triggering further atoms to split. In a nuclear reactor, achieving criticism is the goal; In a nuclear bomb, it must be exceeded, with one reaction triggers multiple more reactions and causes the process to escalate.
From fission to fusion
These weapons discussed so far are “classic” atomic bombs, based on fission. Typically, a bomb is triggered by a chemical explosion that compresses a mass of uranium or plutonium until it exceeds criticism. Subsequent developments in this field of research, however, have led to another type of nuclear device, called a fusion bomb. These are called thermonuclear bombs, in which there is a sequence of two explosions. The primary explosion is equivalent to a fission bomb, with the aforementioned sequence of chemical explosion and fission chain. The energy released from the primary explosion then leads to a secondary explosion, used to trigger the melting of hydrogen atoms. The most powerful device of this type ever projected and tested is the famous TSAR -Bomb, which was detonated in the Arctic in 1961 by the Soviet Union.
As the explosion occurs
We all have the image of a fungal cloud in our minds. But how does it originate? As soon as a bomb explodes, within the first second, there is a sudden release of energy in the form of free neutrons and gamma radii. The explosion appears as a fiery sphere, which expands to tens of kilometers from the trigger point. This fire explosion, rising into the atmosphere, creates the typical fungal shape. Thermal flash occurs; The heat emitted can ignite fires and cause burns even miles away from the center of the blast (depending on the power of the bomb).
Expanding so fast, the explosion creates a shocking wave, a sudden change in atmospheric pressure, which creates much of the destruction associated with atomic bombs. The peculiarity of atomic bombs, however, is the radioactive fall: a shower of physio products that spread across the area surrounding the explosion and which can contaminate it with radioactive elements for decades.
This story originally appeared in Wired Italy and was translated from Italian.
