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| Fig. 1: Mock-up of Little Boy. (Source: Wikimedia Commons) |
Uranium-235 (U-235) is an isotope of the element uranium which allows for fission reactions. Although the naturally occurring uranium is Uranium-238, it does not allow for fission reactions. [1] With the ability to perform fission reactions, U-235 was used to construct the first uranium-based nuclear bomb used in World War II known as Little Boy.
Little Boy was 10 feet long and 28 inches in diameter and weighed 9,700 pounds. In terms of its power, the Little Boy had an explosive force of 15,000 tons of TNT. [2] To note, 1 ton of TNT is equivalent to 4.184 × 109 Joules and is a conventional way of measuring energy. With this amount of energy and force, the outcomes of the use of the Little Boy on Hiroshima was catastrophic. In detail:
Hiroshima was a city of nearly 300,000 with an important military and communications center [3]
The Little Boy was dropped from the Enola Gay piloted by Colonel Paul Tibbets at 8:15 a.m. of August 6, 1945 [3]
43 seconds after the Little Boy was dropped from Enola Gay, the bomb detonated 1900 feet above Hiroshima [3]
The Enola Gay was rocked by the detonation despite it being 11.5 miles away from where the Little Boy was dropped [3]
The Little Boy killed 70,000 people and injured another 70,000 [3]
By end of 1945, the Hiroshima death toll grew to 140,000 from radiation sickness; and ultimately, five years later, the death toll reached about 200,000. [3]
President Truman's decision to drop the bomb on Hiroshima was controversial without a doubt. From Truman's perspective, he believed that a regular invasion in Japan by the US military "would cost at a minimum one quarter of a million casualties, and might cost as much as a million on the American side alone, with an equal number of the enemy". [4] However, from the side of the people of Japan, it was a much different story. The atomic bomb used on Japan was recognized as "a new and most cruel bomb" by the then-Japanese Emperor Hirohito. [5] In fact, on February 27, 1963, the Tokyo District Court ruled that the use of weapons at the scale of nuclear bombs on undefended cities (i.e. Hiroshima) was "an illegal act under the current international law." The Tokyo District Court believed that there should be limits to weapons used during war. More specifically, the Court believed weapons like Little Boy which entailed unnecessary suffering on large numbers of noncombatants and regular citizens should be a violation against international law. [6] Overall, the thought of the use or disuse of nuclear weapons hinging on politics and the lives of millions being on the line is frightening. With advancements in nuclear technology having grown much more since the end of World War II, it is eye-opening to grasp how far we have come and how far we can still go.
© William Park. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] T. G. Spiro and W. M. Stigliani, Environmental Science in Perspective (State University of New York Press, 1985).
[2] J. T. Correll, "The Smithsonian and the Enola Gay," Aerospace Education Foundation, April 2004.
[3] F. G. Gosling, "The Manhattan Project: Making the Atomic Bomb," U.S. Department of Energy, DOE/MA-0002, January 2010.
[4] D. D. Wainstock, The Decision to Drop the Atomic Bomb (Praeger, 1996).
[5] F. Pike, Hirohito's War: The Pacific War, 1941-1945 (Bloomsbury Academic, 2015).
[6] S. Ienaga, Japan's Last War (Wiley-Blackwell, 1979).
