Atomic Bombs

Leo Szilard, a Hungarian Jew living in London at the time, in 1933. He patented it in 1934, the patent GB630726 was granted in 1936 and immediately classified to prevent Nazi Germany from using it. It took 12 more years before the US was able to build the first ones, after an enormous investment in industrial infrastructure. Szilard's patent was not made public until 1949. During WW2 this was done under the Manhattan Project. There was a large team of scientists, the chief one was Dr Robert Oppenheimer.

Professor Rudolph Peierls and Otto Frisch were also involved.

The atomic bomb was originally invented in 1940 by German scientists, Professor Rudolph Peierls and Otto Frisch who were both working for Britain at the time.
During World War II, the United States, with the assistance (collaboration) of physicists, mathematicians, and engineers from the U.S., Britain, Canada and Europe, completed the Manhattan Project to produce the first atomic bomb.

(The project started as the "Manhattan District Engineers" and only became "The Manhattan Project" some time later).

There was some early speculation about the possibility of what could be done if a nuclear chain reaction was unleashed in a way that would allow it to build without control. For a roll call, consider that Robert Oppenheimer was the head of "science" for the Manhattan Project, and (in alphabetical order) Felix Block, David Bohm, Niels Bohr, Enrico Fermi, James Franck, Otto Frisch, Klaus Fuchs, Rudolf Peierls, Emilio Segre, Leo Szilard, Edward Teller and Eugene Wigner all played crucial roles in getting the weapon designed and built.

The physicist Albert Einstein did not participate directly in the invention of the atomic bomb-but was instrumental in facilitating its development. His Special Theory of Relativity emphasized that a large amount of energy could be released from a small amount of matter. This was expressed by the equation E=mc2 (energy = mass times the speed of light squared). The atomic bomb would clearly illustrate this principle.

The first demonstration of "the gadget" (the code name for the first atomic bomb) was at Trinity site in Alamogordo, New Mexico, and it proved that the weapon would detonate and that the chain would build as predicted. The second and third demonstrations were conducted in Japan, which brought a quick end to the Second World War. Just up to and during World War 2, Germany was also working to develop atomic weapons, but was hampered by many technical and political problems (including sabotage and Allied bombings) which prevented their successfully completing their work. This left the U.S. as the only nation to ever unleash nuclear weapons in an attack.
The first fission weapons, also known as "atomic bombs," were developed jointly by the United States, Britain and Canada during World War II in what was called the Manhattan Project. (Wikipedia)

Leo Szilard invented the atomic bomb in 1933 while crossing a London street. He patented it in 1934. (British patent 630,726)

The Manhattan Project built the first one in 1945.
Robert oppenheimer
the united states made the atomic bomb

The original reason that the US began the project to build the atomic bomb was fear. Fear that Nazi Germany would build one first and use it to take over the world.

After the war ended the US and USSR built them out of fear of each other.

No, it started formally when Hitler ordered a faked Polish attack (by German soldiers wearing Polish uniforms) on a German radio station on September 1, 1939 (although fighting had been going on for several years before that between Italy & Ethiopia and Japan & China). In "retaliation" for this faked attack, Hitler declared war on Poland and invaded.

The war was ended by the first use of atomic bombs ever in combat when two bombs were dropped on Japanese cities: Hiroshima on August 6, 1945 & Nagasaki on August 9, 1945.

Yes, a third atomic bomb (a MK-III plutonium implosion assembly atomic bomb) kit had been built by Los Alamos during WW2. It had been shipped to San Francisco to be flown across the Pacific to Tinian for assembly and delivery to another Japanese city in late August. (Note: this kit was probably just the plutonium core, the polonium/beryllium initiator neutron source, and the uranium tamper as Tinian already seems to have had a dozen or more MK-III casings and explosive lens assembly kits stockpiled)

However as the Japanese had announced their intent to surrender on August 14 (while this bomb was still in transit), causing Truman to declare the end of the bombing of Japan, when this bomb arrived in San Francisco on August 18 it was immediately shipped back to Los Alamos, becoming the first atomic bomb in the US nuclear stockpile.

Had Japan not surrendered, the US had plans and the industrial capacity to produce and deliver 20 more MK-III type atomic bombs on Japan before the end of 1945:

1. 3 in September
2. 3 in October
3. 7 in November
4. 7 in December

All of the nuclear weapons available in WW2 were owned by the US and were pure fission atomic bombs:

1. 'Gadget', MK-III prototype plutonium implosion assembly design, tested on a 100 foot tower at Trinity site, NM on July 16, 1945
2. 'Little Boy', MK-I uranium gun assembly design, dropped by the B-29 Enola Gay on Hiroshima on August 6, 1945
3. 'Fatman', MK-III plutonium implosion assembly design, dropped by the B-29 Bockscar on Nagasaki on August 9, 1945
4. unnamed, MK-III plutonium implosion assembly design, arrived in San Francisco on August 18, 1945 to be flown to Tinian then dropped on Japan in late August 1945 but was returned to Los Alamos

Had the war not ended the US had plans and the industrial capacity to make 20 more atomic bombs and drop them on Japan:

• 3 MK-III plutonium implosion assembly design for September 1945
• 3 MK-III plutonium implosion assembly design for October 1945
• 7 modified MK-III composite plutonium/uranium implosion assembly design for November 1945
• 7 modified MK-III composite plutonium/uranium implosion assembly design for December 1945

Early planning had proposed additional production of the MK-I uranium gun assembly design, but after the successful July 16, 1945 Trinity test shot this was canceled, as it was decided the uranium could be used more efficiently in the modified MK-III composite plutonium/uranium core design. The 'Little Boy' was already in transit to Tinian aboard the Indianapolis at the time of this test, so it was used.

Yes and we were committed to carrying out all of them, but the atomic bomb was used first and Japan surrendered so none of the other choices were needed, thus saving many millions of lives on both sides and ending the war at least a year sooner than anyone expected.

• a Japanese D-Day invasion landing
• chemical weapons attacks on Japan
• continued 1000 plane firebombing raids
• etc.

The first authoritative explanation of how and why it was decided to use the bomb came in February 1947 from Henry L. Stimson, wartime Secretary of War and the man who more than any other was responsible for advising the President in this matter. [3] This explana-

• invasion - already planned
• chemical weapons - already planned, if Japan resisted as they had in last islands
• firebombing - already in progress
• let Japan keep everything they conquered - unacceptable

With what was planned the war would have lasted over a year longer (Japan actually had plans to try to stretch it out ten years and keep everything they had conquered even though they would have to ultimately surrender). Had chemical weapons been used against Japan this would have been the first time the US broke the Geneva Convention.