Seventy-five years ago, at 8:16 on the clear morning of August 6, the world changed forever. A blast equivalent to more than 12,000 tons of TNT, unimaginably larger than that of any previous weapon, blew apart the Japanese city of Hiroshima, igniting a massive firestorm. Within minutes, between 70,000 and 80,000 died and as many were injured. Hospitals were destroyed or badly damaged, and more than 90 percent of the city’s doctors and nurses were killed or wounded. By the end of the year, thousands more had died from burns and radiation poisoning—a total of 40 percent of the city’s population.