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From: scent@sask.UUCP (Scent Project)
Newsgroups: net.physics
Subject: Left, Right, and Mirrors
Message-ID: <235@sask.UUCP>
Date: Thu, 6-Jun-85 13:37:22 EDT
Article-I.D.: sask.235
Posted: Thu Jun  6 13:37:22 1985
Date-Received: Fri, 7-Jun-85 03:24:55 EDT
Distribution: net
Organization: University of Saskatchewan, CANADA
Lines: 23

Mirrors flip images back to front, but not in the plane of the mirror.
We think of mirrors as inverting left-to-right because we project our-
selves into the scene or person we see in the mirror, and from that
vantage point, left and right are flipped.  (If you stand facing a
friend, your left is their right, and vice-versa.)

An interesting, related bit of trivia is the fact that "left" and
"right" are concepts which can only be communicated among two
parties if both parties can "see" each other.  In other words, if
we ever contact an alien civilization which is so far away that we
can communicate with them only by radio, and there is no astronomical
object which both we and they can view, then we would have no way to
tell them what we mean by "left" as opposed to "right"--or, for that
matter, how to tell the north pole of a magnet from the south pole.
For those interested, Martin Gardner, of "mathematical recreations"
fame (I THINK it was Martin Gardner) wrote a very interesting book
about the handedness of the universe.  You'll have to find the
title yourself.

					Ken McDonald

"Recent research indicates that 90% of all statistics are
 completely unreliable" :-)