It's also possible that if it wasn't for the Manhattan project, there would have been nuclear armageddon in the 50s or 60s.
The bomb arrived at a time when the US and Russia were allies. They were focused on winning the war. By the time they started snarling at each other in earnest, the Russians had the bomb (1949) and detente had been established. WWII gave us a smooth glide path to both superpowers having the bomb and MAD doctrine was established.
If instead the bomb had arrived say in the 60s, there would have been an entirely different political landscape. Perhaps even more bitter than the cold war. If one side had then got the bomb, just when they were at each other's throats, they could well have used it.
The bomb arrived at a time when the US and Russia were allies. They were focused on winning the war. By the time they started snarling at each other in earnest, the Russians had the bomb (1949) and detente had been established. WWII gave us a smooth glide path to both superpowers having the bomb and MAD doctrine was established.
If instead the bomb had arrived say in the 60s, there would have been an entirely different political landscape. Perhaps even more bitter than the cold war. If one side had then got the bomb, just when they were at each other's throats, they could well have used it.