Re: Are EM fields "real," or are they abstract concepts?

[William Beaty <billb@ESKIMO.COM>]

On Wed, 31 Jan 2001, Mark Sylvester wrote:

> If I may, I'd like to post Bill's account on our school Theory of Knowledge
> site, as a physicist's view of the problem.

Sure!

> What I would add is the
> evolutionary angle - the idea that our mental model-forming apparatus must
> be "good" in the sense that it has been selected by interaction with the
> reality that it models. Sometimes philosophical accounts seem to imply that
> there is only an arbitrary connection between our mental models and the way
> things are.

Good point.  We don't get into much trouble when we mistake our mental
model of the rubber ball in our hand for the "real" ball which is out
there.  Over time we've evolved a very good internal representation.  Only
when we try to discuss things like color (as opposed to reflected
frequency spectrum) are we forced to realize that the "ball" that we
perceive is being assembled in our minds.

Suppose we could interface TV cameras to our brains.  Rather than using a
3-channel color camera, lets use a camera which slices the spectrum into
thousands of frequency bins.  Include everything from thermal IR to
shortwave UV.  A person who saw the world through that sort of TV camera
would see a very different rubber ball than a normal person.  Now mess
with their 3D perception by connecting ten TV cameras to one brain, rather
than two-eyed stereo vision of normal humans.  That person could see the
back and front of the ball at the same time.  Now give those cameras a
zoom-microscope setting, say 1200x max. magnification.  That person could
be simultaneously looking at microscopic surface details at the same time
as looking at the wide angle view.  What does such a ball look like?  It
would be totally alien!  Now for good measure throw in an MRI scanner
which can look at all parts of the INTERIOR structure of the ball and also
be able to "see" chemical compounds in the paint and rubber.

For a person equipped with all this "cyborg" equipment, the reality of a
rubber ball would be nothing like the reality humans normally experience.
So, who sees the "real" ball, the human or the cyborg?  Ah, but the cyborg
is very limited.  She is unable to directly perceive vibrating chemical
bonds, or count all the quarks in all the nuclei at a glance, or feel the
spacetime warp caused by the ball's mass, or feel the 3D resistivity of
different parts of the rubber, or...

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