An American physicist stands next to the world's first atomic bomb

The New York Roots of The Manhattan Project

On July 16, 1945 at exactly 5:29:45 a.m., the world entered the unprecedented atomic age with the successful testing of the most powerful weapon known to man.

"Gadget," the first atomic bomb, was born out of the Einstein-inspired Manhattan Project, and was detonated in the desert near Alamogordo, New Mexico.

Overseeing the project was US Brigadier-General Leslie Groves and Los Alamos director and American physicist Robert Oppenheimer.

Designed and launched under Oppenheimer's chosen codename "Trinity" — inspired by a poem by John Donne — the original $6,ooo program budget skyrocketed to a cool $2 billion after Einstein raised multiple concerns that the Nazi's were close to perfecting their own game-changing weapon.

gadgetUS Department of Energy

The explosion vaporized the steel tower, sent a massive shockwave across the desert sand, and produced a mushroom cloud soaring 40,000 feet into the air, according to the Department of Energy.

Immediately after the blast, Oppenheimer reportedly exclaimed, "it worked!"

On August 6, 1945, the US dropped a 5-ton atomic bomb on the Japanese city of Hiroshima. The blast killed 80,000 people immediately and leveled four square miles of the city.

Related: Look back at the effects of the atomic bomb dropped on Hiroshima:

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Looking back: Atomic bomb dropped on Hiroshima
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An American physicist stands next to the world's first atomic bomb
UNSPECIFIED - CIRCA 1754: Hiroshima after the dropping of the atom bomb in August 1945. USAF photograph. (Photo by Universal History Archive/Getty Images)
UNSPECIFIED - CIRCA 1754: Survivors of the explosion of the Atom bomb at Hiroshima 1945 suffering the effects of radiation. ICRC photograph. (Photo by Universal History Archive/Getty Images)
World War II, after the explosion of the atom bomb in August 1945, Hiroshima, Japan. (Photo by: Universal History Archive/UIG via Getty Images)
World War II, after the explosion of the atom bomb in August 1945, Hiroshima, Japan. (Photo by: Universal History Archive/UIG via Getty Images)
World War II, firestorms after the explosion of the atom bomb in August 1945, Hiroshima, Japan. (Photo by: Universal History Archive/UIG via Getty Images)
1945: Atomic bomb damage at Hiroshima with a burnt out fire engine amidst the rubble. (Photo by Keystone/Getty Images)
World War II, Human shadow on bank steps, in Hiroshima after the explosion of the atom bomb in August 1945, Japan. (Photo by: Universal History Archive/UIG via Getty Images)
World War II, after the explosion of the atom bomb in August 1945 Hiroshima, Japan. (Photo by: Universal History Archive/UIG via Getty Images)
World War II, shadow of a tap on a pipeline at Hiroshima after the explosion of the atom bomb in August 1945, Japan. (Photo by: Universal History Archive/UIG via Getty Images)
6th August 1945: The twisted wreckage of a theatre, located 800 metres from the epicentre of the atomic explosion at Hiroshima. (Photo by Keystone/Getty Images)
HIROSHIMA, JAPAN: This September 1945 file picture shows the remaining of the Hiroshima Prefectural Industry Promotion Building, known as the Atomic-Bomb Dome, which was later preserved as a monument. (Photo credit should read AFP/Getty Images)
HIROSHIMA, JAPAN - NOVEMBER 26: Atomic Bomb Dome stands among fallen autumn leaves at the Hiroshima Peace Memorial Park on November 26, 2014 in Hiroshima, Japan. (Photo by Yuriko Nakao/Getty Images)
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Three days later, the US dropped another bomb on Japan's Nagasaki, killing about 40,000 people instantly; thousands more would die of radiation poisoning.

Eight days later, Japan informally surrendered to the Allied forces, effectively ending World War II.

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