8
The Edge of History
- A New Way of Thinking. On April 6, 1922, the Societe Francaise de Phi-
losophic (which Henri Poincare had helped found) convened for a discussion of
the special and the general theories of relativity. Among those in attendance were
the mathematicians Elie Cartan, Jacques Hadamard, and Paul Painleve, the
physicists Jean Becquerel, Albert Einstein, and Paul Langevin, and the philoso-
phers Henri Bergson, Leon Brunschvicg, Edouard LeRoy, and Emile Meyerson.
In the course of the discussions, Bergson expressed his admiration for Einstein's
work: 'I see [in this work] not only a new physics, but also, in certain respects, a
new way of thinking' [Bl].
Special relativity led to new modes of philosophical reflection. It also gave rise
to new limericks, such as the one about the young lady from Wight. However,
first and foremost this theory brought forth a new way of thinking in physics itself,
new because it called for a revision of concepts long entrenched in the physics and
chemistry of the classical period. In physics the great novelties were, first, that the
recording of measurements of space intervals and time durations demanded more
detailed specifications than were held necessary theretofore and, second, that the
lessons of classical mechanics are correct only in the limit v/c <K. 1. In chemistry
the great novelty was that Lavoisier's law of mass conservation and Dalton's rule
of simply proportionate weights were only approximate but nevertheless so good
that no perceptible changes in conventional chemistry were called for. Thus rel-
ativity turned Newtonian mechanics and classical chemistry into approximate sci-
ences, not diminished but better defined in the process.
Today these revisions seem harmless and are easy to teach. To Einstein they
came rather abruptly, but only after years of unsuccessful thinking. His postulates
were obvious to him once he had conceived them. When I talked with him about
those times of transition, he expressed himself in a curiously impersonal way. He
would refer to the birth of special relativity as 'den Schritt,' the step.
It was otherwise in the case of Lorentz and Poincare. Each of them had strug-
gled hard with these same problems, made important steps toward their solution,
and garnered deep insights along the way. But neither of them had quite made
the final transitional steps. In later years all three men, Einstein, Lorentz, and
Poincare, reacted to the special theory of relativity in ways which arouse curiosity.
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