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.