

Why do Mirrors Reverse Left and Right (but not Up and Down)? - jankassens
http://math.ucr.edu/home/baez/physics/General/mirrors.html

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elmindreda
They don't; they "reverse" along the mirror's surface normal.

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phlux
Didn't Feynman do a talk on this, that mirrors are actually reflecting from
inside out thus the reversal. The basically show you the inverse projection of
rays of photons, so it is impossible for them to turn it upside down.

