N. 3 - 21 aprile 2001 - Giano Bifronte

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(C) The sum of all forces of any nature (gravitational, electric,
magnetic, elastic, nuclear, etc.) acting on any body is always zero in all
frames of reference" (p. 164).
The main result reached by this approach is that the so-called
'fictitious forces' can be seen as the effect of the matter at large in the
universe (described, as far as the derivation of the inertial forces is
concerned, as a spherically isotropic matter shell). The proportionality
between inertial and gravitational mass need not be postulated
independently on experimental grounds, but can be seen as a
consequence of interpreting Newton's second law in terms of relational
mechanics. More strikingly, three basic constants of physics, namely,
Newton's gravitational constant, Hubble constant and the average
density of the universe turn out to be linked by an equation which was
noticed as a numerical coincidence (and then expanded in a wider
theoretical hypothesis) in the 1930's by Dirac.
I find these results (which in different forms have been found also by
other authors - see chapter 11) fascinating, and I think that they should
be more widely known. They do not involve mathematics beyond the
level of a (good) first degree in physics or applied mathematics, so an
attempt might be done to introduce them at a fairly basic stage.
In order to make his proposal more plausible than what is its main
competitor, Assis advances several criticisms against both special and
general relativity. I do not know how much weight he places on this
pars destruens, but in my opinion the relativists will hardly be
convinced by it.
For instance, as regards the twin paradox Assis does not deal with
Hafele and Keating's celebrated experiment (the replication of which is,
in my opinion, much overdue), and for the mesons he favours the
hypothesis that "the half-lives of the mesons depend on their high
velocity relative to the distant material universe" (p. 133). However,
should Hafele and Keating type experiments be confirmed, it would not
be clear how to make room for the concept of 'proper time' in relational
mechanics. Against the constancy of the velocity of light, he contrasts
Einstein's postulate with the fact that all velocities we know depend on
the relative motion of the observer either to the source (like bulletts) or
to the medium (like ordinary sound waves). Indeed, the speed of light is
an anomaly in Einstein's universe, and Assis is right in insisting that
"light is a physical entity which carries momentum and energy [...] is