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The History of the Atomic Bomb

Development and History of the Atomic Bomb and The Manhattan Project

"My God, what have we done?" - Robert Lewis, the co-pilot of the Enola Gay, the B-29 that dropped the first atomic bomb.

Atomic Bomb picture
On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then President Franklin D. Roosevelt. Einstein and several other scientists told Roosevelt of efforts in Nazi Germany to purify uranium-235, which could be used to build an atomic bomb. It was shortly thereafter that the United States Government began the serious undertaking known then only as "The Manhattan Project." Simply put, the Manhattan Project was committed to expediting research that would produce a viable atomic bomb.

The most complicated issue to be addressed in making of an atomic bomb was the production of ample amounts of "enriched" uranium to sustain a chain reaction. At the time, uranium-235 was very hard to extract. In fact, the ratio of conversion from uranium ore to uranium metal is 500:1. Compounding this, the one part of uranium that is finally refined from the ore is over 99% uranium-238, which is practically useless for an atomic bomb. To make the task even more difficult, the useful U-235 and nearly useless U-238 are isotopes, nearly identical in their chemical makeup. No ordinary chemical extraction method could separate them; only mechanical methods could work.

A massive enrichment laboratory/plant was constructed at Oak Ridge, Tennessee. Harold C. Urey and his colleagues at Columbia University devised an extraction system that worked on the principle of gaseous diffusion, and Ernest O. Lawrence (inventor of the Cyclotron) at the University of California in Berkeley implemented a process involving magnetic separation of the two isotopes.

Next, a gas centrifuge was used to further separate the lighter U-235 from the heavier, non-fissionable U-238. Once all of these procedures had been completed, all that needed to be done was to put to the test the entire concept behind atomic fission ("splitting the atom," in layman's terms).

Over the course of six years, from 1939 to 1945, more than $2 billion was spent during the history of the Manhattan Project. The formulas for refining uranium and putting together a working atomic bomb were created and seen to their logical ends by some of the greatest minds of our time. Chief among the people who unleashed the power of the atom was J. Robert Oppenheimer, who oversaw the project from conception to completion.

Finally, the day came when all at Los Alamos would find out if "The Gadget" (code-named as such during its development) was going to be the colossal dud of the century or perhaps an end to the war. It all came down to a fateful morning in midsummer, 1945.

At 5:29:45 (Mountain War Time) on July 16, 1945, in a white blaze that stretched from the basin of the Jemez Mountains in northern New Mexico to the still-dark skies, "The Gadget" ushered in the Atomic Age. The light of the explosion then turned orange as the atomic fireball began shooting upwards at 360 feet per second, reddening and pulsing as it cooled. The characteristic mushroom cloud of radioactive vapor materialized at 30,000 feet. Beneath the cloud, all that remained of the soil at the blast site were fragments of jade green radioactive glass created by the heat of the reaction.

The brilliant light from the detonation pierced the early morning skies with such intensity that residents from a faraway neighboring community would swear that the sun came up twice that day. Even more astonishing is that a blind girl saw the flash 120 miles away.

Upon witnessing the explosion, its creators had mixed reactions. Isidor Rabi felt that the equilibrium in nature had been upset -- as if humankind had become a threat to the world it inhabited. J. Robert Oppenheimer, though ecstatic about the success of the project, quoted a remembered fragment from the Bhagavad Gita. "I am become Death," he said, "the destroyer of worlds." Ken Bainbridge, the test director, told Oppenheimer, "Now we're all sons of bitches."

After viewing the results several participants signed petitions against loosing the monster they had created, but their protests fell on deaf ears. The Jornada del Muerto of New Mexico would not be the last site on planet Earth to experience an atomic explosion.

Scientists Who Invented the Atomic Bomb under the Manhattan Project: Robert Oppenheimer, David Bohm, Leo Szilard, Eugene Wigner, Otto Frisch, Rudolf Peierls, Felix Bloch, Niels Bohr, Emilio Segre, James Franck, Enrico Fermi, Klaus Fuchs and Edward Teller. View a copy of the letter Einstein wrote Roosevelt that prompted the Manhattan Project.

atomic bomb pictureAtomic Bomb Detonation at Hiroshima

As many know, the atomic bomb has been used only twice in warfare. The first was at Hiroshima. A uranium bomb nicknamed "Little Boy" (despite weighing in at over four and a half tons) was dropped on Hiroshima August 6, 1945. The Aioi Bridge, one of 81 bridges connecting the seven-branched delta of the Ota River, was the target; ground zero was set at 1,980 feet. At 0815 hours, the bomb was dropped from the Enola Gay. It missed by only 800 feet. At 0816 hours, in an instant, 66,000 people were killed and 69,000 injured by a 10-kiloton atomic explosion.

The area of total vaporization from the atomic bomb blast measured one half mile in diameter; total destruction one mile in diameter; severe blast damage as much as two miles in diameter. Within a diameter of two and a half miles, everything flammable burned. The remaining area of the blast zone was riddled with serious blazes that stretched out to the final edge at a little over three miles in diameter.


On August 9, 1945, Nagasaki fell to the same treatment. This time a Plutonium bomb nicknamed "Fat Man" was dropped on the city. Though "Fat Man" missed its target by over a mile and a half, it still leveled nearly half the city. In a split second, Nagasaki's population dropped from 422,000 to 383,000. Over 25,000 people were injured.

Japan offered to surrender on August 10, 1945.

NOTE: Physicists who have studied these two atomic explosions estimate that the bombs utilized only 1/10th of 1 percent of their respective explosive capabilities.

Byproducts of Atomic Bomb Detonations

While the explosion from an atomic bomb is deadly enough, its destructive ability doesn't stop there. Atomic bomb fallout creates another hazard as well. The rain that follows any atomic detonation is laden with radioactive particles, and many survivors of the Hiroshima and Nagasaki blasts succumbed to radiation poisoning.

The atomic bomb detonation also has the hidden lethal surprise of affecting the future generations of those who live through it. Leukemia is among the greatest of afflictions that are passed on to the offspring of survivors.

While the main purpose behind the atomic bomb is obvious, there are other by-products of the use of atomic weapons. While high-altitude atomic detonations are hardly lethal, one small, high-altitude detonation can deliver a serious enough EMP (Electro-Magnetic Pulse) to scramble all things electronic, from copper wires to a computer's CPU, within a 50-mile radius.

During the early history of The Atomic Age, it was a popular notion that one day atomic bombs would be used in mining operations and perhaps aid in the construction of another Panama Canal. Needless to say, it never came about. Instead, the military applications of atomic destruction increased. Atomic bomb tests off of the Bikini Atoll and several other sites were common until the Nuclear Test Ban Treaty was introduced.

Part Two: Nuclear Fission/Nuclear Fusion

Mary Bellis

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