At a first glance I feel like most people, certainly myself, would immediately be repulsed at the idea of killing a ridiculous amount of people with a bomb. However, context and circumstance can change everything, so it's only fair to give a more in-depth look at the situation.
In "Fat Man and Little Boy", the scientists are tasked with making an incredibly powerful bomb to aid the US in a war. In short, simple terms: they need to make a powerful weapon to stop a force that threatens them. Initially I would say I'm against the creation and use of such a weapon, but then I considered the scenario in "Gojira".
In "Gojira", a rampaging monster must be stopped in order to save as many people as possible. In short, simple terms: they need to make a powerful weapon to stop a force that threatens them.
The scenarios of "Fat Man and Little Boy" and "Gojira" are surprisingly similar when thought of like this, but there is, of course, one striking difference between to two: In one a literal monster is slain, in the other human beings are killed.
One can argue that both are in self defense: a weapon to stop a threat. However, that argument essentially equates human beings to the monster that is Godzilla. Godzilla is undeniably at fault for the destruction it causes, but could every corpse created by the bomb be held accountable for their country's actions? Furthermore, does dropping a bomb on thousands of people not make us the monster?
That being said, if I were a scientist offered to do research with weapon applications, I would hesitate to either accept or decline. It is hard to say whether or not I would be okay with my research leading to the deaths of a human, let alone thousands. Perhaps if my country were in undeniable danger I would, but I would not be proud of it. Eventually I would have to consider what was at stake. It is really selfish to want to protect yourself and your loved ones? But what right do I have to take other lives, aren't they just trying to do the same? I would not try to distance myself as the creator from the "droppers" of the bomb. I was a cog in the process, and at least some fault would fall to me.
Maybe if it were the only option to save my country and me, and maybe if I had nowhere else to bring my science I would do it. That isn't to say, however, that I would have a peaceful sleep for the rest of my nights.
Perhaps sometimes we humans have to do things we may not think is right just for the sake of survival. Perhaps it is wrong for us to consider our survival more important than others', but perhaps we shouldn't ignore that most basic human instincts.
It's easy to say "I'm above killing others" and move on, but, unfortunately, sometimes the situation is a bit more complex.