[extropy-chat] Mirrors (was: against ID)

[Herb Martin]

> "spike" <spike66 at comcast.net>
> 
> > My mind boggles as I try to understand: why
> > is it that the mirror reverses left to right but not
> > top to bottom?
> 
> A mirror doesn't reverse left and right, it reverses front 
> from back. Face 
> north and move your east hand, the east hand in the mirror 
> moves too, move 
> your west hand, the west hand in the mirror moves too, but 
> point to the 
> front and the mirror man points to the back.
> 
>   John K Clark

Correct.  And although John explained it nicely, it might
be useful to note that "left-right" are terms relative to
the point of view of someone (or something). Thus when
you look in a mirror, your left hand image is still on YOUR
LEFT.

We just unconsciously assume that the image in the mirror
is to be treated like we normally treat a real person; in
the case of a real person (not a front/back reversed image)
we change the point of reference (implicitly) when speaking
of "left hand" or "right hand" even though we also know 
implicitly that the person we are facing has the "left hand" 
on OUR own right side due to the difference in orientation.

This is also the reason that sailors and aviators use 
Port and Starboard to fix the concept of 'sides'.  By
using common reference (the vessel or aircraft), rather
than the direction some particular person is facing, or
even the particular direction traveling from moment in
regards to another particular time. (I.E., a ship might
turn around but the reference is still to the bow-stern
line rather than direction of travel, e.g., north-south.)


--
Herb Martin