Upside down E--another argument

[Baker, John]

        It's not surprising that, in this context, we need disambiguation of "upside-down" but not of "backwards."  Humans live in three spatial dimensions but tend to think in two, although not always the same two.  (Eyesight presents a two-dimensional field of vision, we move around on a two-dimensional landscape.)  That means that there will be one dimension that we find confusing.

        Compare the so-called mirror paradox:  Why do mirrors reverse left-right but not up-down?  Actually, mirrors always reverse in one direction.  If you positioned yourself with a mirror for each dimension, the mirror in front of you would reverse left-right, the mirror to your side would reverse front-back, and the mirror below you would reverse up-down.

John Baker


-----Original Message-----
From: Tom Kysilko [mailto:pds at VISI.COM]
Sent: Thursday, February 20, 2003 2:06 PM
To: ADS-L at LISTSERV.UGA.EDU
Subject: Re: Upside down E--another argument


But if you want to get technical.  In transformational geometry it is recognized
that transformations in a plane that preserve congruence must be some
combination of:
1. translation (think of dragging an icon around on a computer desktop)
2. rotation about a point
3. reflection across a line

"Upside-down" is disambiguated by distinguishing between 2 and 3.  Curiously,
"backwards" doesn't have this problem.

--Tom Kysilko