42 FOUNDATIONS OF
STATISTICAL PHYSICS
papers
on
Brownian motion and
on
the
quantum
hypothesis;[8]
the
proof
of
the
equiparti-
tion
theorem
for canonical
ensembles, a
result crucial to
Einstein's
dispute
with
Planck
over
the
interpretation
of
the
quantum hypothesis;[9]
and
the
definition
of
probabilities
as
time
averages, along
with their
equation
to ensemble
averages,
which
lies
behind
Ein-
stein's
conflict with Planck and others
over
the
manner
in
which
probabilities are
intro-
duced in
physics.[10]
II
Einstein
probably
first read about the
theory
of
heat in the
popular-scientific
literature
and
textbooks that he read
as an
adolescent.[11] But his formal introduction
to the
subject came
in his
fourth-year physics
class at the
Aargau Kantonsschule,
and
above all in H. F.
Weber's
physics
lectures at the
ETH.[12]
In this
respect,
as
in
others, however,
Einstein's
ETH
physics
education failed to
acquaint
him with
recent
developments
in the
field.[13]
Weber's
lectures
presented
a survey
of
the
theory
of
heat in the form in which it had
been
developed by
Clausius.[14]
The
only
more
recent
developments
covered
were
experimental
studies
of
topics
such
as
diffusion,
specific
heats,
thermal
conductivity,
and
black-body
radiation-all
of
them research interests
of
Weber.[15]
The
course
included
nothing
about
developments
in
kinetic
theory
in the last third
of
the nineteenth
century owing
to Max-
well, Boltzmann, Helmholtz,
and
others,[16] nor
about the controversies
surrounding
this
theory.[17]
[8]
See
Einstein
1905k
(Doc. 16),
p.
551,
and
the editorial
note,
"Einstein
on
Brownian Mo-
tion,"
pp.
206-222;
see
also Einstein
1906d
(Doc. 34),
p.
201,
and the editorial
note,
"Ein-
stein's
Early
Work
on
the
Quantum Hypothe-
sis,"
pp.
134-148.
[9]
See
especially
Einstein 1909b
(Doc. 56),
p.
186.
[10]
For
Einstein's
comments
on
Planck, see
the
papers
cited in
note
63.
[11]
Einstein's
early readings
included Büch-
ner 1855,
Bernstein 1853-1857,
Krist
1891,
and
Violle
1892, 1893 (see
Vol.
1,
the editorial
note,
"Einstein's
First Scientific
Essay,"
pp.
5-6).
[12]
For evidence that Einstein studied the the-
ory
of
heat at the
Aargau Kantonsschule, see
his
Aargau
Kantonsschule Record
(Vol. 1,
Doc.
10)
and his
Aargau
Kantonsschule Curriculum
(Vol.
1,
Appendix D, p. 361).
For his notes
on
We-
ber's
lectures
on
heat, see
H. F.
Weber's
Lec-
tures
on Physics,
Vol.
1,
Doc.
37, pp.
63-147.
[13]
For
shortcomings
in
Einstein's
physics
ed-
ucation at the
ETH,
in
particular
the absence of
a course on
Maxwell's
electrodynamics,
see
Vol.
1,
the editorial
note,
"Einstein
as a
Student
of
Physics,
and His Notes
on
H. F.
Weber's
Course,"
pp.
60-62.
[14]
See Clausius
1879-1891.
Einstein
may
have studied Clausius sometime before 1905.
Asked about relevant
readings
prior
to his work
on
Brownian motion
(see
Carl
Seelig
to
Ein-
stein,
11 September
1952),
Einstein wrote:
"Naturally I
was
familiar with
Clausius's
gen-
eral
investigations
of
kinetic
theory"
("Clau-
sius'
allgemeine Untersuchungen
über Kinetik
kannte ich
natürlich")
(Einstein
to
Carl
Seelig,
15
September
1952).
[15]
See Vol.
1,
the editorial note,
"Einstein
as
a
Student
of
Physics,
and His Notes
on
H. F.
Weber's
Course,"
pp.
60-62, and the editorial
note
in
this
volume,
"Einstein's
Early
Work
on
the
Quantum
Hypothesis,"
p.
135.
[16]
See Maxwell
1871, 1877, 1878;
Boltz-
mann
1896, 1898a;
Helmholtz
1903;
Kirchhoff
1894;
and
Meyer,
O. E.
1877, 1895,
1899. For
a
survey
of
the
history
of
kinetic
theory
in the
nineteenth
century, see
Brush 1976.
[17]
The earliest evidence
of Einstein's
ac-
quaintance
with
any
of these controversies
is
a
discussion
of
Poincare
cycles
in
Einstein's
notes
for
his lectures
on
the kinetic
theory
of
heat at
the
University
of
Zurich, summer
semester of
1910. See also Discussion/Einstein
1911,
pp.
436-439.