THE EDGE OF HISTORY 167imagining arbitrarily large velocities. In that way, one comes very close to the
concept of absolute simultaneity.
'Finally, it should be noted that the daring assertion that one can never observe
velocities larger than the velocity of light contains a hypothetical restriction of
what is accessible to us, [a restriction] which cannot be accepted without some
reservation.'
It is clear beyond doubt that Lorentz's imagination was the classical imagina-
tion. Light moves with a velocity c km/s. There is no difficulty in imagining a
velocity equal to c + 1 km/s. The classical mind asserts, the relativistic mind
denies, that a velocity which can be imagined mathematically can necessarily be
reached physically.
As I understand Lorentz, he was a leader in theoretical physics who fully
grasped all the physical and mathematical aspects of the special theory of relativity
but who nevertheless could not quite take leave of a beloved classical past. This
attitude has nothing to do with personality conflicts. Those were alien to him.
Einstein and Poincare always spoke in praise of him, Lorentz always reciprocated.
Nor did he hesitate to make clear where he had been in error: 'The chief cause of
my failure [in discovering special relativity] was my clinging to the idea that only
the variable t can be considered as the true time and that my local time t' must
be regarded as no more than an auxiliary mathematical quantity,' he wrote in a
note added to the second edition of his Columbia lectures [L4]. In a draft* of a
letter to Einstein, written in January 1915 [L5], Lorentz wrote the following
about the FitzGerald-Lorentz contraction: 'I added the remark that one arrives
at this hypothesis if one extends to other forces what one can already say about
the influence of a translation on electrostatic forces. If I had stressed this more,
then the hypothesis would have given much less of an impression of having been
invented ad hoc.' Lorentz never fully made the transition from the old dynamics
to the new kinematics.**
- Poincare and the Third Hypothesis. In April 1909 Poincare gave a series
of six lectures [P3] in Goettingen. In the last of these, entitled 'La Mecanique
Nouvelle,' the lecturer dealt with questions bearing on relativity. At first glance
the reader of this text may experience surprise at not finding any mention of Ein-
stein, whose theory was four years old by then. On closer scrutiny, he will find
that this absence is justified. Poincare does not describe Einstein's theory.
The new mechanics, Poincare said, is based on three hypotheses. The first of
these is that bodies cannot attain velocities larger than the velocity of light. The
second is (I use modern language) that the laws of physics shall be the same in all
inertial frames. So far so good. Then Poincare introduces a third hypothesis: 'One
'This draft was discovered in 1979 by A. Kox in one of Lorentz's notebooks. I am grateful to Dr
Kox for drawings my attention to this text.
"'According to Born, 'Lorentz... probably never became a relativist at all, and only paid lip service
to Einstein at times, to avoid arguments' [B2].