I've never really understood this story. Feynman wasn't wrong, but UV-A and even sufficiently-bright visible light also cause eye damage.
Did he know the main visual hazard from the bomb was UV-B? Did he just get lucky?
Did he know the main visual hazard from the bomb was UV-B? Did he just get lucky?
Lasers didn't exist yet to force us to study retinal exposure to bright non-UV light and the flash from the bomb didn't last that long, nor were the first few bombs that bright, so he may have been fine... but obviously if you stare at the sun through three inches of glass you're still going to burn your retinas.
He says "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 the ultraviolet can’t go through glass, so that would be safe, and so I could see the damn thing."
What we know from later laser research is that unless you have a comprehensive visual field test, it's often hard to identify that part of your retina has been scorched. Your brain just filters it out as a blind-spot and you don't realize what you're failing to see.
There's every chance that Feynman totally burned a section of his retina and never realized it, and there's every chance that he was fine because the exposure at his distance wasn't that bad, but at the end of the day he was more reckless than insightful in this situation.
FYI vacuum exposure can cause blindness, visual impairment, and death.
Before y'all criticize that statement, keep in mind it's coming from one of the best scientists of the 20th century.
He was talking before lasers. For a purely thermal source to hurt the eyes, it would have to be:
1. insanely hot
2. quite close to the observer
First condition is met by the nuke, but the second one, obviously, is not, unless you're a victim of the explosion.
Source: Am experimental physicist; do dumb things. Sometimes my colleagues do too, even the best ones.