What would have happened to A-bomb development if Japan had surrendered before 07/16/45?

Would the U.S. have tested the bomb? Would the Soviets have tested their own bomb? I saw a film about the development of the bomb which contained a scene where Leo Szilard went to see the Secretary of State as the head of a delegation of bomb scientists to urge that a bomb not even be tested. He pointed out that to test it would give away the greatest secret of all: that it can be done. In the film (no idea if this really happened), he claimed that Stalin would not proceed with a Soviet project unless he thought success was likely. Dr. Szilard didn’t know about Fuchs or Hiss though.

FWIW,
Rob

I have no doubt the bomb would have been tested. By the spring of '45 the momentum was way too strong, the investment too great, to stop without testing. Without a live test there would have been major doubts about the viability of the implosion plutonium design. As to mantaining the secret, the generally accepted belief that the Manhatten Project was totally secure and Alamogordo Bombing Range was as remote as it could be.

Once the United States had a working bomb the Soviet Union would, without doubt, have rushed to develop their own - just as in this timeline.

The more interesting question is what would post war history of been like? Without the lesson of Hiroshima and Nagaski would there have been the same constraint on politicians and the military using A weapons in the post war conflicts? How about Korea? Would MacArthur have been allowed to use the bomb on China?

I don’t think the actual use of the bombs in Japan made that much difference. There would have been the same postwar testing with various simulated targets that would have made clear that having a nuke go off anywhere near you is Not Good. What really scared the bejeezus out of people was when the comparitively tiny yields of the first generation fission weapons were multiplied literally a thousand times by high-yield fusion bombs. Add to that the expansion of arsenal sizes from scores to thousands of weapons, and what happened to Hiroshima and Nagasaki seems trivial by comparison.

Suppose the Axis powers capitulated in, say, August of '44 which was well before the bombs were ready. Do you think development would have proceeded? I tend to think that it would have, although at a much slower pace, partially because the pressure was off and partially because at least some of the scientists working on the bomb would have quit.