To understand the development of nuclear weapons, we must first come to understand the development of the science behind them. By the latter third of the 1800s, science had made such strives forward that many people were beginning to believe that there was little if anything left to learn about the nature of the universe. There were, however still some major problems which science could not explain. Scientists still could not successfully explain the process that fueled the sun or the fundamental reasons behind chemical reactions1.
The first two clues into these secrets which the universe still held came in 1895 with the discovery of "X-Ray" radiation by Konrad Roentgen, and a year later when Henri Becquerel discovered the radioactivity of Uranium Salt. Roentgen had been conducting experiments involving passing an electric current through a sealed cylinder of a gas at low pressure. He discovered that if he was in a dark room all light was kept from the tube, he could leave images on photographic plates of different objects in varying degrees of transparency using the radiation produced. Since he did not know what the rays were, he named them “X-Rays”2. Becquerel had been trying to find a connection between Roentgen’s new “x-rays” and natural phosphorescence (the emission of light without heat or burning). He discovered that when he put uranium salts (which phosphoresce when exposed to light) on a sheet of paper on a photographic plate, that the entire plate would appear foggy. In short, He discovered naturally occurring radiation3.
Following these two discoveries more discoveries were made very quickly. In 1896 Plutonium was discovered, in 1897 Radium. The effect of these discoveries and others led to the development of a unified Quantum theory by 1905, the year in which Einstein began to explore his theory of relativity, which explained the origin of these atomic energies. Many other theories and discoveries were made about the nature of atoms and the universe that are important to the technical aspect of making the nuclear bomb but will not be discussed further here4.
Science continued to advance, despite being slightly hampered by the emergence of the First World War. And so it came about on September 12th in 1933 that a Hungarian scientist by the name of Leo Szilard made the idea of harnessing this “nuclear power” when he had the idea that it could be released using a chain reaction of neutron collisions. His theory about using chain reactions came more than six years before the discovery of an actual chain reaction process5.
Leo Szilard both conceived the idea for a chain reaction and its use as a bomb in 1933. On the fourth of July in 1934 he filed and was awarded a patent for the plans to this bomb which were extremely detailed and contained the concept of critical mass, which is necessary to create an atomic weapon. After creating this patent, rather than selling it and trying to use it for personal gain, he – realizing its great danger – took it immediately to the British government so that it would be classified and protected. They refused his offer, however in February of 1936 the British Navy took him up on his offer. Ironically, the bomb’s inventor was also the first to realize its dangers and attempting to control it. Later in his life Szilard fought against the use of the bomb and was instrumental in the founding of The Bulletin of Atomic Scientists and also of The Council for a Livable World6.
The discovery of nuclear fission – the splitting of larger atoms into smaller ones – was key in the making of the nuclear bomb. The development of this idea was sparked when a team of Roman scientists headed by Enrico Fermi bombarded every known type of element with neutrons and observed the effects. The results of this when it came to Uranium boggled scientists. The uranium, when it was bombarded, created several radioactive products which could not be identified7.
It is first proposed by Ida Noddack that the uranium atom is actually splitting apart and becoming smaller particles. This theory was later proven correct by Otto Hahn and Lise Meitner, who showed one of the particles conclusively to be a radioactive barium isotope8.
By January 29th of 1939, fission is discovered and the bomb finally becomes a very real possibility9.
In that same year Niels Bohr discovered that the two isotopes of Uranium – U-235 and U-238 – have different properties in fission. U-238 could undergo fission by bombardment with fast neutrons, while U-235 underwent fission slowly. But even with this discovery there were many things that scientists did not know that would be instrumental in developing the bomb. Scientists were still uncertain in how many neutrons an atom undergoing fission released and much more vital information besides10.
In March, 1939 Enrico Fermi and Herbert Anderson discover that two neutrons are emitted per atom having undergone fission, thus clearing one of the major uncertainties in the creation process. In July, Szilard and Fermi discuss the possibility of using a graphite lattice to hold the uranium in the reactor, and was a better moderator than the previously used water, which would not allow a self-sustaining reaction to occur. On the last day of August in 1939 Niels Bohr and John Wheeler publish a paper discussing fission; they decide that U-235will undergo fission more easily than U-238, and that another element that was not discovered but which was theorized and called 94-239 would be extremely fissile as well. We have come to know element 94-239 as Plutonium. The day after this paper was published Germany invades Poland, igniting the Second World War11.
While these advances were being made, things on the political front were not advancing, but were devolving into a state of repression, violence perpetrated by governments and their militaries and general instabilities. In Europe there was a rise in fascism and dictatorship, while in the Far East Japan was pushing outward starting with an invasion of Manchuria and pushing onward into China. With all of this going on international tension was very high, and it is easy to see why Szilard was so worried about the weapon he had conceived. And so it was that World War II entered the scene right as the idea of a nuclear weapon left the realm of possibility and passed into that of probability near certainty12.
Seeing all of this happening, Szilard and Einstein write a letter to then-president F.D. Roosevelt to warn him about the possible dangers of nuclear weaponry. A mere ten days after receiving the letter Roosevelt ordered the first meeting of the Advisory Committee on Uranium to convene in Washington DC to study fission. However, because the administration in the United States was skeptical and somewhat short-sighted, the project never received sufficient funding or attention. For this reason many of the following developments took place in the United Kingdoms13.
In early 1940 a report was made by physicists Otto Frisch and Rudolf Peierls containing an analysis of the fission of U-235, an estimate of the critical mass needed and bomb designs that were practical and became the blueprints, with some alterations and refinements, are still sound and used in the making of nuclear weapons. In response to this report, a committee called the MAUD Committee is formed in the British government and later in the year the committee had found the best method for enriching uranium14.
In 1940 and 1941 development in the United States made significant progress while still lacking support and funding. Philip Abelson began to actually make a system by which he could enrich uranium, Glenn Seaborg and Arthur Wahl discover plutonium, and experiments allow an actual critical mass to be calculated. In July of 1941 Plutonium is proven to be the best material for fission15.
In September Britain begins to develop an atomic bomb. In December, after the United States entered the war, a US project to develop a bomb is made. This project is a forerunner of the Manhattan Project and is named the S-1 project. In the first month of 1942 Enrico Fermi’s work concerning graphite is moved to the University of Chicago, and is called the Metallurgical Laboratory, or Met Lab. It is there that he began to build the first man made nuclear reactor16.
A picture of the people in the S-1 Committee. This picture was found on the United States Government Department of Energy Office of History & Heritage's "The Manhattan Project" Site.
A picture of the people who worked at the Met Lab. This picture was found on the United States Government Department of Energy Office of History & Heritage's "The Manhattan Project" Site.
On June 18 General Steyr had James Marshall make an Army Corps of Engineers District take over the nuclear bomb project. This was originally called the Manhattan Engineer District, which became known as the Manhattan Project17.
Sources for this Page
1. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/
2. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
3. Encyclopedia Britannica. 15th ed. Vol. 2. Chicago: Encyclopedia Britannica Inc., 2003.
4. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
5. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
6. Encyclopedia Britannica. 15th ed. Vol. 10. Chicago: Encyclopedia Britannica Inc., 2003.
7. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
8. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
9. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
10. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
11. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
12. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
13. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
14. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
15. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
16. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.
17. The Nuclear Weapon Archive. http://nuclearweaponarchive.org/.