"They gave out dark glasses that you could watch it with. Dark glasses! Twenty miles away, you couldn't see a damn thing through dark glasses. So I figured the only thing that could really hurt your eyes (bright light can never hurt your eyes) is ultraviolet light. I got behind a truck windshield, because ultraviolet can't go through glass, so that would be safe, and so I could see the damn thing.

Time comes, and this tremendous flash out there is so bright that I duck, and I see this purple splotch on the floor of the truck. I said, "That's not it. That's an after-image". So I look back up and I see this white light changing into yellow and then into orange. Clouds form and disappear again - from compression and expansion of the shock wave.

Finally, a big ball of orange, the center that was so bright, becomes a ball of orange that starts to rise and billow a little bit and get a little black around the edges, and then you see it's a big ball of smoke with flashes on the inside of the fire going out, the heat.

All this took about one minute. It was a series from bright to dark, and I had seen it. I am about the only guy who actually looked at the damn thing - the first Trinity test. Everybody else had dark glasses, and the people at six miles, couldn't see it because they were all told to lie on the floor. I'm probably the only guy who saw it with the human eye.

Finally, after about a minute and a half, there's suddenly a tremendous noise - BANG, and then a rumble, like thunder - and that's what convinced me. Nobody had said a word during this whole thing. We were all just watching quietly. But this sound released everybody - released me particularly because the solidity of the sound at that distance meant that it had really worked.

The man standing next to me said, "What's that?"

I said, "That was the Bomb.

<....>

After the thing went off, there was tremendous excitement at Los Alamos. Everybody had parties, we all ran around. I sat on the end of a jeep and beat drums and so on. But one man, I remember, Bob Wilson, was just sitting there moping.

I said, "What are you moping about?"

He said, "It's a terrible thing that we made."

I said, "But you started it. You got us into it."

You see, what happened to me - what happened to the rest of us - is we started for a good reason, then you're working very hard to accomplish something and it's pleasure, it's excitement. And you stop thinking, you know; you just stop. Bob Wilson was the only one who was still thinking about it, at that moment."

"Surely you're joking Mr. Feynman" by Richard P. Feynman, 1985.