It always amazes me how seemingly careless they were with these nuclear devices back then. To know that such a devestating bomb was handled by a sultry, shirtless youngster, in a shed on a small island in the Pacific... It reminds me of the Slotin Incident ( http://www.damninteresting.com/bitten-by-the-nuclear-dragon/ ) where dr. Louis Slotin accidently slipped the screwdriver he used to separate two plutonium/uraniu…
Also note that the design tested at Trinity was not the design used on Hiroshima. The Little Boy design used on Hiroshima was a gun-type design that was so obvious it would work that it wasn't felt that any testing was required. The Fat Man design used on Nagasaki was vastly more complex (but much more efficient and scalable) that it was felt best to validate it before using it in war.
I occasionally wonder about the atomic bombings and the timing of everything. If the project had been delayed by a year or so, the war would have ended without them. But the development would continue, and the Cold War would no doubt kick off something like it did in reality. But without two examples of the horrors of nuclear war, would the superpowers have been as restrained as they were in reality? Rather than the first (and so far, only) use of nuclear weapons in war being two primitive bombs, it could have been hundreds or thousands, in a war run by people thinking that they were just doing a scaled up version of the city bombing of WWII. It seems like the timing ended up being extremely lucky.