Exactly fifty summers ago, scientists gathered in the New Mexico desert to preside over a seismic shift in humanity's relationship to the universe.

On the day of the first atomic bomb test in July 1945, no one knew what would happen. About half the scientists didn't think it would explode at all. Enrico Fermi was taking bets that it would burn off the earth's atmosphere.

It did explode, with such brightness that a woman blind from birth traveling in a car some distance away saw it. "A colony on Mars, had such a thing existed, could have seen the flash," writes Gerard J. DeGroot in his new book, '>The Bomb: A Life. "All living things within a mile were killed, including all insects."

The Bomb was more than the most powerful weapon in history, although the fact that it was, led to much that happened later that summer and in the years afterwards. Scientists like Leo Leo Szilard (motivated in part by what he remembered from the H.G. Wells novel that predicted-and named-the atom bomb in 1914) had urged the U.S. to develop the Bomb because they feared that Germany might build it first.

But Germany hadn't, and was now defeated. Japan's defeat was all but inevitable by the spring of 1945. So the day after the first test, Szilard sent government officials a petition signed by 69 project scientists arguing that to use the bomb would ignite a dangerous arms race and damage America's post-war moral position, especially its ability to bring "the unloosed forces of destruction under control."

But the momentum was all towards using the Bomb, not just demonstrating it. The second atomic bomb was already on its way to the Pacific, and General Leslie Groves, the senior military official in charge of the Bomb project, began making a case that Szilard was a security risk.

Some believe that the Bomb was dropped on Hiroshima as much to impress the Soviet Union as to defeat Japan. The arms race between the Soviets and U.S. dominated the next 40 years. In the U.S., to criticize the Bomb became unpatriotic, an act of disloyalty that only helped the Communist enemy. And so people were silent and compliant, and streamed into air-conditioned theatres to see movies that expressed the doubts and fears they were not allowed to articulate openly.

These movies expressed all kinds of suppressed and repressed emotions, including forbidden sex and hidden violence, so these films of varying quality could be lurid-and especially advertised as lurid-- in many different ways.

Many of these films also tapped into the feeling that with the Bomb, humanity had committed sacrilege, had transgressed by learning secrets of power that man was not meant to know.

But there are several different ways that various movies relate to the Bomb and the Cold War.