Development & Use of the Atomic Bomb during WWII

Why build a bomb? Albert Einstein wrote to President Franklin D. Roosevelt on August 2, Albert Einstein wrote to President Franklin D. Roosevelt on August 2, Einstein and several other scientists explained that Nazi Germany was working on a way to purify uranium-235, which could be used to build an atomic bomb. Einstein and several other scientists explained that Nazi Germany was working on a way to purify uranium-235, which could be used to build an atomic bomb. The Manhattan Project began shortly after this letter. The Manhattan Project began shortly after this letter.

Portion of the letter from Albert Einstein to President Roosevelt August 2,

The Manhattan Project Goal: begin research that would produce a viable atomic bomb. Goal: begin research that would produce a viable atomic bomb. Project Chief: Brigadier General L. Groves Project Chief: Brigadier General L. Groves Head Physicist: J.R. Oppenheimer, oversaw the entire project from start to finish. Head Physicist: J.R. Oppenheimer, oversaw the entire project from start to finish. More than $2 billion was spent during the project. More than $2 billion was spent during the project.

Manhattan Project Cont. In 1942, Enrico Fermi produced the first controlled chain reaction in a laboratory at the University of Chicago. Scientists worked to design a bomb that could store the raw materials and trigger a much more powerful chain reaction on demand. In 1942, Enrico Fermi produced the first controlled chain reaction in a laboratory at the University of Chicago. Scientists worked to design a bomb that could store the raw materials and trigger a much more powerful chain reaction on demand.

Portion of a Memo to the Secretary of War From V. Bush and J. B. Conant September 30, 1944

The Test “The Gadget” (code-name for the bomb) was tested on July 16, 1945 in the desert of New Mexico at 5:30 in the morning. “The Gadget” (code-name for the bomb) was tested on July 16, 1945 in the desert of New Mexico at 5:30 in the morning. J.R. Oppenheimer was thrilled with the success of the bomb, but at the same time concerned about the threat it posed for mankind. J.R. Oppenheimer was thrilled with the success of the bomb, but at the same time concerned about the threat it posed for mankind.

The Test Cont. After the blast Oppenheimer is remembered to have quoted a portion of the Bhagavad Gita. “I am become Death,” he said, “the destroyer of the worlds.” After the blast Oppenheimer is remembered to have quoted a portion of the Bhagavad Gita. “I am become Death,” he said, “the destroyer of the worlds.” After viewing the test several of the participants signed petitions against dropping the bomb. It was suggested that it be held in control by the international community. After viewing the test several of the participants signed petitions against dropping the bomb. It was suggested that it be held in control by the international community.

Dropping the bomb The atomic bomb has only been used twice in warfare. The atomic bomb has only been used twice in warfare. The first bomb was dropped on Hiroshima August 6, It was a uranium bomb nicknamed “Little Boy”, even though it weighed over four and half tons. The first bomb was dropped on Hiroshima August 6, It was a uranium bomb nicknamed “Little Boy”, even though it weighed over four and half tons. The bomb was dropped from the Enola Gay. It killed 66,000 people instantly. The bomb was dropped from the Enola Gay. It killed 66,000 people instantly.

This shows the "Little Boy" weapon in the pit ready for loading into the bomb bay of Enola Gay. (Photo from U.S. National Archives, RG 77-BT)

A nuclear weapon of the "Little Boy" type, the uranium gun-type detonated over Hiroshima. It is 28 inches in diameter and 120 inches long. "Little Boy" weighed about 9,000 pounds and had a yield approximating 15,000 tons of high explosives. (Copy from U.S. National Archives, RG 77-AEC)

The mushroom cloud billowing up 20,000 feet over Hiroshima on the morning of August 6, 1945 (Photo from U.S. National Archives, RG 77- AEC)

Dropping the bomb cont. The second bomb was dropped on August 9, 1945 on Nagasaki. The second bomb was dropped on August 9, 1945 on Nagasaki. It was a Plutonium bomb nicknamed “Fat Man”. It was a Plutonium bomb nicknamed “Fat Man”. It missed its target by over a mile and a half, but still leveled nearly half the city. It missed its target by over a mile and a half, but still leveled nearly half the city.

The polar cap of the "Fat Man" weapon being sprayed with plastic spray paint in front of Assembly Building Number 2. (Photo from U.S. National Archives, RG 77-BT)

The mushroom cloud over Nagasaki shortly after the bombing on August 9. (Photo from U.S. National Archives, RG 77- AEC)

After the Bomb The dropping of the bomb itself was not the only thing that killed people. The dropping of the bomb itself was not the only thing that killed people. The rain that falls after an atomic detonation is full of radioactive particles. The rain that falls after an atomic detonation is full of radioactive particles. Many survivors of Hiroshima and Nagasaki succumbed to radiation poisoning. Many survivors of Hiroshima and Nagasaki succumbed to radiation poisoning.

After the Bomb cont. Survivors of the blast have had lasting implications. Survivors of the blast have had lasting implications. Leukemia is commonly passed on to the offspring of survivors. Leukemia is commonly passed on to the offspring of survivors.

Questions Were atomic strikes necessary primarily to avert an invasion of Japan in November 1945? Were atomic strikes necessary primarily to avert an invasion of Japan in November 1945? Did Truman authorize the use of atomic bombs for diplomatic-political reasons-- to intimidate the Soviets--or was his major goal to force Japan to surrender and bring the war to an early end? Did Truman authorize the use of atomic bombs for diplomatic-political reasons-- to intimidate the Soviets--or was his major goal to force Japan to surrender and bring the war to an early end?

Questions Cont. Were there alternatives to the use of the weapons? If there were, what were they and how plausible are they in retrospect? Why were alternatives not pursued? Were there alternatives to the use of the weapons? If there were, what were they and how plausible are they in retrospect? Why were alternatives not pursued? How greatly did the atomic bombings affect the Japanese decision to surrender? How greatly did the atomic bombings affect the Japanese decision to surrender? Was the dropping of the atomic bombs morally justifiable? Was the dropping of the atomic bombs morally justifiable?

Sources NSAEBB162/index.htm NSAEBB162/index.htm NSAEBB162/index.htm NSAEBB162/index.htm America: Pathways to the Present, Prentice Hall America: Pathways to the Present, Prentice Hall NSAEBB162/index.htm NSAEBB162/index.htm NSAEBB162/index.htm NSAEBB162/index.htm uOifg4kCFQ2uSAod7irfAA uOifg4kCFQ2uSAod7irfAA