Vanilla 1.1.2 is a product of Lussumo. More Information: Documentation, Community Support.
I remember seeing a photograph of a shadow imprinted on the cement belonging to a man sitting on the steps of his local bank. Apparantly he was facing in the direction where the nuclear bomb dropped and instantly incinirated. I am curious why the shadow imprinted on the cement?
From what I understand it is caused by thermal radiation from the flash of the initial explosion. Since the light travels from a central point it burns everything directly in its path but if its path is interrupted by something (a person/object) the area shielded from the light will be left relatively untouched. Kinda like a sunburn.
I guess these burns can happen miles and miles away from the explosion in areas otherwise unaffected by the bomb.
There are similar photos showing shadows cast by plants and wooden objects which are still intact.
Someone else could probably give a better explanation but thats all I know.
URLs for some images
----------------------
mans shadow on steps
http://history.independence.co.jp/ww2/raid/h01.jpg
--------------------
pipes
http://www.richard-seaman.com/Travel/Japan/Hiroshima/AtomicBombMuseum/IndividualArtifacts/LargeValveHandleShadow.jpg
----------------
ladder and man
http://history.independence.co.jp/ww2/raid/h02.jpg
--------------------
plant shadow
http://e3.uci.edu/clients/bjbecker/SpinningWeb/bombshadowleaf.jpg
-------------------
fence
http://www.atomicarchive.com/Photos/Hiroshima/images/HR43.jpg
----------------------
The shadows are exactly that, shadows. Nuclear bombs emit electromagnetic radiation, as does a light bulb. If a EM radiation source has an object(x) placed in front of it with another(y) beyond that then (x) will absorb some of the photons. A solid object such as a person will absorb almost if not all of these photons. If you think of the bomb as a giant light bulb then you see why a shadow occurs during the event.
When photons interact with matter they can have a bleaching effect . This is easily seen with compound such as those used in camera film, and is the reason curtains fade. The more photons that interact (and I guess the more energy they have) the greater the bleaching effect. the gamma photons emitted by a nuclear fission event have a far greater frequency than the photons emitted by a light bulb, meaning they have a far higher energy. Indeed they are energetic enough to vaporize matter as we experience it every day. Think of water evaporating when the sun shines on it. Now replace the puddle with a human body. Same effect really, the matter rapidly gains energy (gets hotter in effect), and converts from solid to gas. The energy supplied is also great enough to break most of the chemical bonds in the body. Hence the incineration.
If you consider that fission events are highly energetic, a nuclear bomb produces huge amounts of energy then things become clearer. The bomb in question, Little boy, emitted around 8.4 x 10^13 joules. A large amount of this energy was emitted as electro magnetic radiation, over a period of a few millionths of a second. Assuming 100 millionths of a second (an approximation of the most it could be to be in the range of millionths of a second) that gives about 840000000000000000Watts. That's about 7000000000000000 120W light bulbs. Bright.
This explains the shadowing, the areas behind solid bodies were exposed to less bleaching radiation. The magnitude of the difference was sufficient that a visible difference in bleaching is clear.
I think some of this makes sense. Sorry, I'm tired, and I'm only an A-level physicist
1 to 3 of 3