RELATIVITY THEORY AND QUANTUM THEORY 31the Planck medal from Planck's own hands. By then the revolutionary period of
the old quantum theory—which coincided exactly with the years of Einstein's
highest creativity!—had made way for nonrelativistic quantum mechanics (and
the beginning of its relativistic extension), a theory which by 1929 was recognized
by nearly everyone as a new theory of principle.
Einstein dissented. To him, who considered relativity theory no revolution at
all, the quantum theory was still in a state of revolution and—as he saw it—
remained so for the rest of his life; according to him the old did not yet fit in
properly. That is the briefest characterization of Einstein's scientific philosophy.
He was more deeply commited to orderly transition than to revolution. He could
be radical but never was a rebel.
In the same speech in 1929, he also said, 'I admire to the highest degree the
achievements of the younger generation of physicists which goes by the name
quantum mechanics and believe in the deep level of truth of that theory; but I
believe that the restriction to statistical laws will be a passing one.' The parting
of ways had begun. Einstein had started his solitary search for a theory of prin-
ciple that would maintain classical causality in an orderly way and from which
quantum mechanics should be derivable as a constructive theory.
Far more fascinating to me than the substance of Einstein's critique of quantum
mechanics—to be discussed in detail in (26)—is the question of motivation. What
drove Einstein to this search which he himself called 'quite bizarre as seen from
the outside' [E5]? Why would he continue 'to sing my solitary little old song' [E6]
for the rest of his life? As I shall discuss in (27), the answer has to do with a grand
design which Einstein conceived early, before the discovery of quantum mechanics,
for a synthetic physical theory. It was to be a theory of particles and fields in
which general relativity and quantum theory would be synthesized. This he failed
to achieve.
So to date have we all.
The phenomena to be explained by a theory of principle have become enor-
mously richer since the days when Einstein made the first beginnings with his
program. Theoretical progress has been very impressive, but an all-embracing the-
ory does not exist. The need for a new synthesis is felt more keenly as the phe-
nomena grow more complex.
Therefore any assessment of Einstein's visions can be made only from a vantage
point that is necessarily tentative. It may be useful to record ever so briefly what
this vantage point appears to be to at least one physicist. This is done in the fol-
lowing 'time capsule,' which is dedicated to generations of physicists yet unborn.*
2b. A Time Capsule
When Einstein and others embarked on their programs of unification, three par-
ticles (in the modern sense) were known to exist, the electron, the proton, and the
"The following section is meant to provide a brief record without any attempt at further explanation
or reference to literature. It can be skipped without loss of continuity.