Here’s a gloomy proposition: Eventually, a nuclear exchange is inevitable. The atomic genie was released from the bottle at Hiroshima on Aug. 6, 1945. The city was destroyed, and more than 200,000 civilians were killed, instantly or within a few days, or years later from the effects of radiation. But the world was not as horrified as we might now imagine. Many were simply relieved that World War II was finally over, and the ghastly carnage at Hiroshima and Nagasaki was quietly folded into the suffering and deaths of millions during the war. Some, however, recognized that the atomic bomb repres…