Associated Press file photo
A mushroom cloud rises 20,000 feet over Nagasaki, Japan on Aug. 9, 1945, moments after an atomic bomb was dropped on the city by U.S. forces.

The world became a lot more complicated on July 16, 1945, when the first atomic bomb was successfully test detonated in the New Mexico desert.

Physicist J. Robert Oppenheimer led the program that developed the weapon, and upon witnessing its tremendous destructive power recalled the words of the Bhagavad Gita, the Hindu holy book: “Now, I am become death, the destroyer of worlds.”

Another physicist who worked on the bomb, I. I. Rabi, later wrote of that first explosion, dubbed the Trinity test: “Suddenly there was an enormous flash of light, the brightest light I have ever seen or that I think anyone has ever seen. It blasted; it pounced; it bored its way right through you. It was a vision which was seen with more than the eye... Finally it was over, diminishing, and we looked toward the place where the bomb had been; there was an enormous ball of fire which grew and grew and it rolled as it grew; it went up into the air, in yellow flashes and into scarlet and green. It looked menacing. ... A new thing had just been born...a new understanding of man, which man had acquired over nature.”

The successful test detonation of the atomic bomb was the culmination of more than three years of intensive government research and development. In October 1941, American physicist Vannevar Bush wrote a memorandum to President Franklin D. Roosevelt, urging him to begin research on an atomic bomb. It was not until January 1942, while America was reeling from Pearl Harbor, that Roosevelt agreed.

Historian Jean Edward Smith writes in his presidential biography “FDR”: “Roosevelt's OK galvanized American efforts. Secretary of War (Henry) Stimson went to Capitol Hill for the money. 'I don't want to know why,' said (Speaker of the House) Sam Rayburn, who arranged with the Appropriations Committee chairman Clarence Cannon to conceal the funds in the War Department budget.”

With that, the Manhattan Project was born. Under the direction of Oppenheimer and Army Gen. Leslie R. Groves, the project was tasked with developing an atomic bomb before the Germans. The German war production minister, Albert Speer, had no passion for the project, believing it would rob material from more vital research, and Hitler had also written off the idea as “Jewish physics.”

The Soviet Union, an American ally against Nazi Germany, took a keen interest in the Manhattan Project, however. One of the physicists who worked on the project was German-British Klaus Fuchs. A convinced anti-Nazi, Fuchs began to spy for the Soviet Union in 1941 and began sending the Soviets secret information as soon as he started working on the project.

Just over a month before the Trinity test, Soviet intelligence revived information detailing the specifications of the weapon. The information most likely came from Fuchs, who also noted: “The first test explosion of an atomic bomb is anticipated in July of this year.”

President Harry Truman succeeded Roosevelt, who died on April 12, 1945, and was in Potsdam, Germany, meeting with Winston Churchill and Joseph Stalin when he received news of the successful Trinity test. He decided the time had come to tell his Soviet ally the truth about the Manhattan Project.

In his biography “Stalin,” Robert Service writes: “Both Truman and Stalin knew that the American A-bomb was ready for use, but Truman did not know that Stalin knew. In fact Soviet espionage had reported accurately to Moscow. ... When Truman informed him about the American technological advance, Stalin had prepared himself to be unperturbed — and Truman was astounded by his sangfroid.”

Two atomic bombs were used against Japan the following month at Hiroshima and Nagasaki, with a total death count perhaps exceeding 200,000. That same month, Japan sued for surrender. The decision to drop the atomic bombs remains controversial to this day.

It is ironic that the most destructive weapon ever created has never been used against human targets since World War II, and that its existence almost certainly played a part in preventing a conventional third world war in the 20th century.

Cody K. Carlson holds a master's degree in history from the University of Utah and currently teaches at Salt Lake Community College. He is also the codeveloper of the popular History Challenge iPhone/iPad apps. Email: [email protected]