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From: ags@pucc-i (Seaman)
Newsgroups: net.philosophy
Subject: Re: Why do mirrors reverse left & right, not up & down?
Message-ID: <180@pucc-i>
Date: Fri, 3-Feb-84 12:20:05 EST
Article-I.D.: pucc-i.180
Posted: Fri Feb  3 12:20:05 1984
Date-Received: Wed, 8-Feb-84 05:32:21 EST
References: <537@bbncca.ARPA> <2471@rabbit.UUCP>
Organization: Purdue University Computing Center
Lines: 22

If you face north and look into a mirror, you see your image facing south.
If you raise your east hand, your image also raises its east hand. This
shows that the mirror reverses only back-front, not up-down or left-right.

The confusion comes when you try to mentally superimpose your real self
on your mirror image.  You do this by a rotation instead of a reflection.
This has the effect of reversing BOTH left-right and up-down AT THE SAME
TIME.  The disparity between the rotation and the reflection is what causes
people to think that left and right are reversed, when in fact they are
EXPECTING to see left-right reversed and find that it ISN'T.

Try the two-mirror experiment which I suggested before to see the difference.
This allows you to simulate a true rotation with mirrors, rather than a
simple reflection.

-- 

Dave Seaman
..!pur-ee!pucc-i:ags

"Against people who give vent to their loquacity 
by extraneous bombastic circumlocution."