system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can an atomic bomb cause a shadow to forever burned into a surface, like what can be seen at Hiroshima?
gpt
Basically, the people/objects absorbed some of the radiation and acted as a shield. The 'shadow' is the part of the surface behind them that was shielded by the body/object and not burned as much as the rest of the surface.