When it comes to the atomic bomb and its use, Albert Einstein is the person most look to as its progenitor. After all, he was the one behind the science and mathematics that made it possible.
After the war, he even expressed deep regret for encouraging President Roosevelt to pursue atomic and nuclear weapons. He stated that he would never have done so had he realized the Germans were nowhere close to successfully developing their own (via Time).
Yet, Einstein did not have a hand in designing and building the first atomic weapons, though. That responsibility was instead given to J. Robert Oppenheimer of the Manhattan Project (via Britannica).
While he did his work to beat the supposedly comparable Axis atomic programs as well, seeing the destruction that his own weapons not only brought to Japan, but could in theory bring to the world, left him with exceptional regret. It not only followed him into death, but may have helped accelerate his demise.
OPPENHEIMER’S HABITS WERE LIKELY EXACERBATED BY REMORSE
Possible regret over his scientific research was just one thing Oppenheimer had to deal with in the immediate post-war years. His possible communist sympathies led to his being ostracized by the government despite many of Oppenheimer’s Allied and former Axis peers, including rocket scientist and former Nazi party member Wernher von Braun, lauding his character (via Atomic Heritage).
The scientist was, by 1944 and 1945, already described as a heavy chain smoker who could burn through 100 cigarettes in a day, as well as consume excessive amounts of alcohol (via Farbound).
His overall health was reportedly abysmal, and he had a dangerously low BMI. The cumulative stresses of his purported personal guilt and public humiliation likely did nothing to curb his habits, especially in the case of the former, since he lived to see the potential nuclear exchange that was the Cuban Missile Crisis. In 1965, Oppenheimer was unfortunately, but unsurprisingly, diagnosed with throat cancer, and he died in 1967 at the age of 62 (via Biography).