Einsteinians shift allegiance, very carefully:

http://www.sps.ch/artikel/geschichte...physicist_ 2/
Jan Lacki: "Indeed, in his activity, Ritz persisted to build classical
models of the atom and confronted Einstein over relativity and more
generally over the foundations of electrodynamics. Today, the
necessity of the departure from the classical scheme operated by
quantum theory and relativity appears, with hindsight, as evident. But
there were at the time brilliant minds who thought differently. Driven
by the same dissatisfaction with received schemes, they chose a
different road, in a sense equally revolutionary, so it is fair to say
that they too broke with 19th century classicism. Ritz stands high
among them. (...) In the short span of his life, Ritz found also time
to propose his own views on the problems faced then by
electrodynamics. In his last months, he even confronted his
conceptions with Einsteins, and their exchange is very instructive to
anyone willing to penetrate deeply in the roots of our present
physics. (...) Ritz expressed his dissatisfaction with Maxwell-Lorentz
electrodynamics using still other arguments such as those related to
the ambiguity in the definition of the e. m. energy density present in
the ether and also to the difficulty to secure the action-reaction
principle between the latter and matter. I shall not report them here.
Suffice it to say that to Ritz eyes, all these problems were
symptomatic of the basic insufficiency of the field formulation which,
while possibly computationally a handy fiction, had to be given up as
far as foundations and true physical description were concerned.
Rejecting the fields together with the ether, Ritz sketched instead,
in a radical move, an alternative theory where charges were postulated
ab initio to interact through a retarded force. The latter was
conceptually shaped using as guideline the picture of charges emitting
light particles at constant speed, responsible for the interaction.
Since the velocity of these particles depended on that of the emitting
charge, Ritz could preserve Galilean kinematics in opposition to
Einstein who preferred to keep the equations of field electrodynamics
and introduce instead relativized kinematics and relativistic
transformations. By a careful tuning of his force expression (but also
some ad hoc assumptions) Ritz could account for most of the
phenomenology known then. The emissionist stance of Ritz theory should
not be considered as indicating that Ritz was trying to rehabilitate
for real the Newtonian corpuscular view on electromagnetic processes.
His writings show that he was just using emission theory as a
framework where to think an alternative to the received
electrodynamics of his time. Even if his theory was still in a
preliminary stage, Ritz was convinced that it showed that alternative
ways of thinking of electrodynamic processes were possible and well
worth investigating. Ritz confronted his views with Einstein sometimes
in 1909 with the ensuing result that none convinced the other."

Pentcho Valev