You have to look at these things in the context of the war that had been going on for years at the time. Imperial Japan had attacked, invaded, and occupied any neighbors who had resources they might need or who otherwise might oppose them. That occupation often came with brutality and oppression at a scale that would make the Nazis blush.
When the US entered the war, one of their first moves was unrestricted submarine warfare, meaning any Japanese ship is sunk on sight, regardless of who or what is onboard or where it is heading. It continued with sinking many naval fleets, re-invading many islands, generally resulting in the death of basically everyone in the Japanese garrison, as it was part of their code to kill themselves or carry out suicide attacks rather than surrender.
Continuing on, we have the unrestricted aerial bombing of basically every city in Japan. The only reason Hiroshima and Nagasaki were relatively untouched so late in the war was that they were exempted from conventional bombing for the purpose of evaluating the effectiveness of the atomic bombs when they were ready. Many of the conventional bombing raids caused greater death and destruction than the atomic bombings.
In light of all of this, suggesting a demonstration of the bomb seems kinda pointless. The Imperial Japanese administration would probably interpret such an act as saying that America didn't have the courage to carry out major attacks, thus encouraging them to hold out longer and requiring more destruction in the end to force a surrender. The bombings were terrible, but the real suffering was the war itself, and the only way to stop it was to force the surrender of Imperial Japan as quickly as possible. Against such an enemy, the best way to end the war with as much of Japanese society as possible still intact was to demonstrate total ruthlessness in doing anything in our power to destroy Japanese infrastructure and kill Japanese citizens as quickly as possible.
> It strikes me as pure evil that the very first use of nuclear energy was to drop a massive bomb over a bunch of fellow humans.
Atomic weapons are a natural evolutionary step up from conventional explosives, which are a natural evolutionary step up from clubs and rocks. All this talk about atomic weapons being qualitatively different (as opposed to quantitatively different) is mostly hyperbole, with one exception -- only wealthy industrial powers can create them ... so far.
> Surely the force of nuclear weapons could have been demonstrated without actually dropping it on a concentration of living, healthy people.
The people in charge decided that a demonstration wouldn't stop the war or the need to use the new weapons, and later events proved them right. Contrary to what many Americans believe, the Japanese didn't surrender because of the atomic bombings, but because Russia invaded Manchuria, a development the Japanese saw as much more dangerous than atomic bombs.
>The people in charge decided that a demonstration wouldn't stop the war or the need to use the new weapons, and later events proved them right. Contrary to what many Americans believe, the Japanese didn't surrender because of the atomic bombings, but because Russia invaded Manchuria, a development the Japanese saw as much more dangerous than atomic bombs.
If that is the case, then that proves they were dead wrong about their justification for the necessity of dropping those bombs in the first place. Why tell everyone "we need to bomb" in order for Japan to surrender when you knew it wouldn't stop the war?
> Why tell everyone "we need to bomb" in order for Japan to surrender when you knew it wouldn't stop the war?
For various political reasons (I'm not justifying this, only explaining it). The Manhattan Project began in response to the perceived threat that Germany might create an atomic weapon. In 1945, with Germany out of the picture, and with no alternative, people began to talk about using it against Japan. It was realized that, if we didn't force Japan to surrender to us, they would surrender to the Russians, with unimaginable postwar consequences.
Again, I'm only explaining the thinking of the time, not justifying it.
After the war, it was discovered that Germany was nowhere near creating an atomic bomb, but it came out that Japan was actively pursuing this class of weapon and was technically farther ahead, lacking only the raw materials. In the closing days of the war, a German submarine was intercepted trying to deliver uranium to Japan for use in a nuclear weapon they planned to build and use against the U.S. :
Surely the force of nuclear weapons could have been demonstrated without actually dropping it on a concentration of living, healthy people.