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From: gwyn%brl-vld@sri-unix.UUCP
Newsgroups: net.physics
Subject: Re:  Re: eV Revisited - (nf)
Message-ID: <16831@sri-arpa.UUCP>
Date: Sat, 18-Feb-84 20:13:08 EST
Article-I.D.: sri-arpa.16831
Posted: Sat Feb 18 20:13:08 1984
Date-Received: Tue, 21-Feb-84 04:04:59 EST
Lines: 36

From:      Doug Gwyn (VLD/VMB) 

The reason you don't get the same conversion factor for mass<->distance
working it out two ways is that in one of them you have tried to mix a
relativistic fundamental equivalence (E=mc^2) with a Newtonian formula
(E=Fs) that is not appropriate.  One should not just toss a bunch of
formulas together at random; your equations should be describing some
single THING or SITUATION in order for them all to apply at once.

It is true that if sufficient care is taken one can reduce the number
of "fundamental" physical units (standards of measurement).  Instead of
separate time and space units, one can use the fundamentals of special
relativity to relate the units to each other via the speed of light.
(A careful treatment of this would require discussion of canonical
forms of the metric tensor and their physical interpretation.)

Similarly, other types of physical quantity have fundamental relations
that let one interconvert what appear to be different aspects of an
object or situation.  The interesting question is, how FEW independent
standards of physical measurement are there?  From the standpoint of
geometrical theories of physics such as relativity, there would appear
to be only one basic unit (could measure any non-pure-number attribute,
e.g. unit of length, or of mass, or of time, ...).

Amazingly, according to Einstein-Schr"odinger unified field theory, there
are NO inpendendent measurement standards.  This is a consequence of the
closure of the theory; it is sometimes phrased "the universe is self-
gauging".  A more usual way of looking at this would be to allow one
unit (say length) in terms of which the natural curvature of the
universe would be expressed (the reciprocal of a very large number,
using "laboratory size" units), instead of the theoretically preferable
approach of using the inherent curvature as a "natural" unit.  (In this
theory, the local metric is intimately related to the large-scale
structure of space-time via a non-zero CONSTANT that spontaneously
occurs in the development of the theory [think of it as a constant of
integration if you wish].)