How is the "light" trap at the beginning supposed to work?
In the opening scene of Raiders of the Lost Ark, Indiana Jones encounters a trap where blocking a shaft of light with his hand causes spikes to shoot out of the wall next to him:
This always bugged me, as such a trap would probably require some kind of light sensor, which would be far too advanced for an ancient civilization to create.
Is there any plausible explanation for how this trap could work?
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How to Set up a Light Trap
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