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This week’s podcast tells the story of Operation Crossroads, the first nuclear weapons tests after the end of World War II. During much of the ensuing cold war, a lot of physics research was dominated by the need to develop new and better nuclear weapons for the military. Physicists at the Manhattan Project in New Mexico built and tested the first atom bomb in 1945. Today nine nations possess nuclear weapons and collectively have conducted 2,083 tests since that first early morning explosion. 
To put that in perspective, artist Isao Hashimoto made this short video of all atomic weapons tests up until 1998. It doesn’t include the most recent member of the nuclear weapons club, North Korea, but you get the idea.

July 16, 9145 "Trinity" became the world's first atomic bomb test. This footage shows technicians prepping the bomb (which they referred to as “the gadget”) and moving it into place. The detonation happens at 8:28.
On August 6, 1945 the Enola Gay dropped the atom bomb “Little boy” over the Japanese city of Hiroshima. Three days later, the plane Bockscar dropped “Fat Man” over Nagasaki.
July of 1946, Operation Crossroads were the first atomic tests after the war.
On August 29, 1949 the Soviet Union surprised the United States with the detonation of “Joe One.”
November 1, 1951, the United States detonated “Ivy Mike,” the first thermonuclear weapon, often referred to as the H-Bomb. It’s a whole new class of nuclear weapons, ones that utilized fusion to explode, and were an order of magnitude more powerful than the fissioning A-bombs.
August 12 1953, the Soviet Union responded with their own thermonuclear bomb, “Joe 4.”
March 1, 1954, the United States detonates “Castle Bravo.” At 15 megatons, it was the biggest atomic bomb the United States ever tested.
October 30, 1961, the Soviets detonated “Tsar Bomba,” a 52-megaton bomb, the biggest detonation in history.
July 9, 1962, the United States detonated “Starfish Prime” 250 miles above the Pacific Ocean. The weapon exploded in space, creating an electromagnetic pulse that damaged power grids as far distant as Hawaii, 900 miles away.
In 1963, the PartialTest Ban Treaty was signed by the US and USSR, outlawing the testing of nukes in the atmosphere, underwater and in space, pushing all tests underground for decades.
In 1996, the Comprehensive Nuclear Test Ban Treaty, outlawing all nuclear tests, was signed by 71 nations. Today it has been ratified by almost all countries around the world.
For a more complete history of Operation Crossroads, check out James Delgado, Daniel J. Lenihan and Larry E. Murphy’s report TheArcheology of the Atomic Bomb.


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