in ww2 when America dropped the atomic bombs on Japan, there are images after of shadows of people being left on the street. What is the science behind that?
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Original comment from u/verylittle
**Disclaimer: Reader discretion is advised. Before you click any links, know that you cannot unsee this.**
The shadows of Hiroshima are probably the second most *haunting* thing I can tell you about the nuclear attacks on Japan during WWII. Please know that I am not being hyperbolic with that disclaimer.
The detonations over Hiroshima and Nagasaki created a ball of plasma that plowed out through everything around it, like a mosh pit starting in a concert crowd, which pushed outward until atmospheric pressure could stop it. The nuclear fission chain reaction releases its heat in a fraction of a second, meaning the surface of this plasma ball releases a flash of light as if the sun was suddenly hovering a few hundred meters over the city. This wall of photons is called ‘the flash,’ and is a wall of heat at a temperature of thousands of degrees. The time from chain reaction to plasma-ball-expansion to wall-of-heat is faster than human reflexes can register. When a nuclear bomb goes off, the world instantly goes from normal to *on fire.*
The photons of the flash span infrared through *literally blinding* visible light through ultraviolet and X-rays, and it scorches *everything*. In the case of wood and carbon based materials, they can be turned black by the heat- burnt. In the case of many other noncombustible surfaces, like stone and some paint, they can be bleached by the intense UV. Have you’ve left a piece of plastic for a long time in a window, or in your car, and noticed it lost its color after lying in sunlight? This is the same thing, but happening in a seconds instead of months.
And if there was something in the way of this light, it left a shadow. A shadow meant that the scorching or bleaching was interrupted, the flash blocked. For example, [by a ladder.](https://www.thesun.co.uk/wp-content/uploads/2016/03/2440067.main_image.jpg) Next to that ladder you can see the silhouette of a person- they would have been covered in third degree burns instantly, unable to comprehend what had happened or why.
The Hiroshima bomb exploded at 8:15 am- we know the exact time because many clocks stopped. [Is this the shadow of a man, not too different from you or me, who was waiting for his bank to open? Was he wearing a hat to help stay cool in the hot August sun?](https://allthatsinteresting.com/wordpress/wp-content/uploads/2018/03/running-Hiroshima-shadows.jpg) We’ll never be able to ask him about his choice of hat that morning, but we do know the bombing was only possible because of the clear weather on August 6, 1945.
Many of those shadows were present for *years* before rain and weathering finally washed them away. In the case of the man at the bank, we will never know who he was, but those stones were removed and are preserved at the [Hiroshima Peace Memorial.](http://hpmmuseum.jp/modules/exhibition/index.php?action=ItemView&item_id=112&lang=eng) You can see them in person if you like.
If you haven’t lost your appetite, I do encourage you to learn more about the effects of nuclear weapons. Maybe starting with [this video.](https://www.youtube.com/watch?v=5iPH-br_eJQ) Even though the people killed by the bombs can’t speak to us to warn us of the horrors of nuclear weapons, maybe their shadows can.
Original comment from u/verylittle
**Disclaimer: Reader discretion is advised. Before you click any links, know that you cannot unsee this.**
The shadows of Hiroshima are probably the second most *haunting* thing I can tell you about the nuclear attacks on Japan during WWII. Please know that I am not being hyperbolic with that disclaimer.
The detonations over Hiroshima and Nagasaki created a ball of plasma that plowed out through everything around it, like a mosh pit starting in a concert crowd, which pushed outward until atmospheric pressure could stop it. The nuclear fission chain reaction releases its heat in a fraction of a second, meaning the surface of this plasma ball releases a flash of light as if the sun was suddenly hovering a few hundred meters over the city. This wall of photons is called ‘the flash,’ and is a wall of heat at a temperature of thousands of degrees. The time from chain reaction to plasma-ball-expansion to wall-of-heat is faster than human reflexes can register. When a nuclear bomb goes off, the world instantly goes from normal to *on fire.*
The photons of the flash span infrared through *literally blinding* visible light through ultraviolet and X-rays, and it scorches *everything*. In the case of wood and carbon based materials, they can be turned black by the heat- burnt. In the case of many other noncombustible surfaces, like stone and some paint, they can be bleached by the intense UV. Have you’ve left a piece of plastic for a long time in a window, or in your car, and noticed it lost its color after lying in sunlight? This is the same thing, but happening in a seconds instead of months.
And if there was something in the way of this light, it left a shadow. A shadow meant that the scorching or bleaching was interrupted, the flash blocked. For example, [by a ladder.](https://www.thesun.co.uk/wp-content/uploads/2016/03/2440067.main_image.jpg) Next to that ladder you can see the silhouette of a person- they would have been covered in third degree burns instantly, unable to comprehend what had happened or why.
The Hiroshima bomb exploded at 8:15 am- we know the exact time because many clocks stopped. [Is this the shadow of a man, not too different from you or me, who was waiting for his bank to open? Was he wearing a hat to help stay cool in the hot August sun?](https://allthatsinteresting.com/wordpress/wp-content/uploads/2018/03/running-Hiroshima-shadows.jpg) We’ll never be able to ask him about his choice of hat that morning, but we do know the bombing was only possible because of the clear weather on August 6, 1945.
Many of those shadows were present for *years* before rain and weathering finally washed them away. In the case of the man at the bank, we will never know who he was, but those stones were removed and are preserved at the [Hiroshima Peace Memorial.](http://hpmmuseum.jp/modules/exhibition/index.php?action=ItemView&item_id=112&lang=eng) You can see them in person if you like.
If you haven’t lost your appetite, I do encourage you to learn more about the effects of nuclear weapons. Maybe starting with [this video.](https://www.youtube.com/watch?v=5iPH-br_eJQ) Even though the people killed by the bombs can’t speak to us to warn us of the horrors of nuclear weapons, maybe their shadows can.
It also left “dodge and burn” shadows (like on photographic film) on the skin of people who were in the path of the flash…I remember pics of people where you could see the pattern of the print on their clothing, I guess different dyes/pigments were more effective at blocking the radiation than others.
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It also left “dodge and burn” shadows (like on photographic film) on the skin of people who were in the path of the flash…I remember pics of people where you could see the pattern of the print on their clothing, I guess different dyes/pigments were more effective at blocking the radiation than others.
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Simply put, the bright flash from the explosion bleached the walls and sidewalks. The person’s body created a shadow area that blocked the light radiation from bleaching a portion of the wall or sidewalk.
Simply put, the bright flash from the explosion bleached the walls and sidewalks. The person’s body created a shadow area that blocked the light radiation from bleaching a portion of the wall or sidewalk.
WAIT someone explain why we were even allowed to do that… like could the US just do something like that again if they wanted to ? drop a fucking atomic bomb on a country?
WAIT someone explain why we were even allowed to do that… like could the US just do something like that again if they wanted to ? drop a fucking atomic bomb on a country?
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