EINSTEIN'S VISION 461
From this lecture as well as from discussions with him on the foundations of
quantum physics, I have gained the following impression. Einstein tended to com-
pare the successes of classical mechanics with those of quantum mechanics. In his
view both were on a par, being successful but incomplete. For more than a decade,
Einstein had pondered the single question of how to extend the invariance under
uniform translations to general motions. His resulting theory, general relativity,
had led to only small deviations from Newton's theory. (Instances where these
deviations are large were discussed only much later.) He was likewise prepared
for the survival of the practical successes of quantum mechanics, with perhaps
only small modifications. He was also prepared to undertake his own search for
objective reality, fearless of how long it would take. It is quite plausible that the
very success of his highest achievement, general relativity, was an added spur to
Einstein's apartness. Yet it should not be forgotten that this trait characterized his
entire oeuvre and style.
The crux of Einstein's thinking on the quantum theory was not his negative
position in regard to what others had done, but rather his deep faith in his own
distinct approach to the quantum problems. His beliefs may be summarized as
follows:
(1) Quantum mechanics represents a major advance, and yet it is only a limiting
case of a theory which remains to be discovered:
There is no doubt that quantum mechanics has seized hold of a beautiful ele-
ment of truth and that it will be a touchstone for a future theoretical basis in
that it must be deducible as a limiting case from that basis, just as electrostatics
is deducible from the Maxwell equations of the electromagnetic field or as ther-
modynamics is deducible from statistical mechanics. [E2]
(2) One should not try to find the new theory by beginning with quantum
mechanics and trying to refine or reinterpret it:
I do not believe that quantum mechanics will be the starting point in the search
for this basis, just as one cannot arrive at the foundations of mechanics from
thermodynamics or statistical mechanics. [E2]
(3) Instead—and this was Einstein's main point—one should start all over
again, as it were, and endeavor to obtain the quantum theory as a by-product of
a general relativistic theory or a generalization thereof. Starting all over again had
never daunted him. That is the single most important link between the early and
the late Einstein. His reverence for Lorentz had not held him back from rejecting
the latter's dynamic views on the contraction of rods and on the interpretation of
Fizeau's experiment. His reverence for Newton had not prevented him from
rejecting absolute space. The relativity theories, his own greatest successes, his
theories of principle, had been arrived at by making fresh starts. He was going to
do that again for the quantum theory, and never mind the time it might take. In
1950 he wrote to Born, 'I am convinced of [objective reality] although, up to now,
success is against it' [E5].