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From: dgary@ecsvax.UUCP (D Gary Grady)
Newsgroups: net.physics
Subject: Re: Yet Another Flaky Paradox
Message-ID: <1385@ecsvax.UUCP>
Date: Mon, 3-Jun-85 16:59:28 EDT
Article-I.D.: ecsvax.1385
Posted: Mon Jun  3 16:59:28 1985
Date-Received: Thu, 6-Jun-85 20:41:12 EDT
References: <5377@tektronix.UUCP>
Organization: Duke U Comp Ctr
Lines: 33

carlc@tektronix.UUCP (Carl Clawson) asks... (knowing the answer)
> When you look in a mirror, the image you see is reversed left to right.
> Why is it not also reversed in the vertical direction?

But it DOES reverse in the vertical direction, if the mirror is on the
ceiling.  I'm sure because I just went into the bedroom and checked.
Anyway...

Mirrors do NOT in fact reverse left for right.  They only reverse fore
and aft.  Stand in front of a mirror and raise your right hand.  The
mirror image on the same side of your body (east, say), will go up.  If
it doesn't, see if the mirror is under warranty.  Now note which
direction you're facing.  If you're facing north, say, your mirror image
will be looking southward, and no doubt dreaming of mint julips.

The reason text (and people) in a mirror look "backwards" is that it is
not normally possible to reverse in only one direction.  If you are
facing north and you want to face south, you must either rotate about a
vertical axis (which means your right arm now points west instead of
east) or about a horizontal one (so that you are standing on your head).
There is nothing wrong with your body; you are just constrained by the
laws of normal space.  If you hop up a dimension and turn around with
respect to the appropriate axis you can come down a mirror image of your
old self and eat and eat and not gain weight.

Come to think of it, a mirror CAN reverse right and left if you stand
with your side to it...

-- 
D Gary Grady
Duke U Comp Center, Durham, NC  27706
(919) 684-3695
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