From: Eliezer S. Yudkowsky (sentience@pobox.com)
Date: Wed Dec 27 2000 - 19:35:35 MST
Spike Jones wrote:
>
> Emlyn wrote:
>
> > My daughter (5 yo) just asked me a question which I can't answer...
>
> Emlyn, Ive also been stumped by a 5 year old girl, altho I suspect
> her father mighta put her up to asking this one.
>
> She said: if things in a mirror appear reversed, why dont they
> also appear upside down?
Mirrors do not reverse right and left. They reverse front and back. When
you raise your right hand, the image in the mirror does not raise a "left"
hand; it raises a right hand with front and back reversed, so that you see
the front of the hand instead of the back.
It so happens that, because humans are roughly symmetrical in the
right/left plane, it is possible to take an image that with front and back
reversed and mentally imagine that it is actually a nonreversed human who
has been rotated 180 degrees around a vertical axis. If humans had two
arms on the right and one arm on the left, but two heads, we would
mentally visualize ourselves as rotating around a horizontal axis and we
would say that a mirror reverses up and down.
-- -- -- -- --
Eliezer S. Yudkowsky http://singinst.org/
Research Fellow, Singularity Institute for Artificial Intelligence
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