Its been years since I visited the museum in Hiroshima, but one of the exhibits still haunts me.
There are some stairs that seem to be made of concrete that were cut out from in front of a building and brought to the museum. On these stairs there appear to be shadows of 2 or 3 people that are some how burned into the concrete. The actual stairs are there, not just photos.
What exactly are these dark areas? Are we looking at super heated human flesh that was somehow embedded into the stairs?
Yahoo Answers says the images were burned by the sharp, short, very bright burst of radiation from the bomb.
I had thought they were caused by “beta burn,” by the exposure to beta rays, but this does not seem to be the case, so I learned (or “unlearned”) something from doing some quick Googling.
From memory, I believe there were people sitting there and that is all that was left after the blast, the heat disintegrated everything else.
Basically, the flash (bright light ) from the bomb bleached the concrete of the steps, except for the places where people were. So the ‘shadows’ are the unbleached, aged concrete color, while the rest of the steps was bleached to a whiter color.
It is a bleaching effect. It really is a shadow. The individual at the bank cast a shadow and everything in the area was bleached by the intense light. By the time he (or she) was burned up, the first few seconds of extreme flash were already passing. So the area behind him was protected from the bleaching effect.
If you search online, you can find many pictures of such shadows - the earliest researchers entering the city after the bombing actually used the shadows to triangulate the exact center of the blast.