EINSTEIN ON BROWNIAN

MOTION

I

Einstein's

study

of

Brownian motion constitutes

one

of

the

high points

in

the

long

tradition

of

research

on

the kinetic

theory

of

heat and

of

his

own

contributions to this

field.[1]

Some

of

the

consequences

of

his

work

were

of

great

significance

for

the

development

of

physics

in the twentieth

century.

Einstein's

derivation

of

the laws

governing

Brownian

motion,

and

their

subsequent experimental

verification

by

Perrin and others,

contributed

signifi-

cantly

to the

acknowledgment

of

the

physical reality

of

atoms

by

the

then

still

numerous

skeptics.

His

papers on

Brownian motion

helped

to establish the

study

of

fluctuation

phe-

nomena as a new

branch

of

physics.

The methods he created in the

course

of

his

research

prepared

the

way

for statistical

thermodynamics,

later

developed

by

Szilard and

others,

and

for

a general theory

of

stochastic

processes.

Einstein

published

four

major

articles

on

Brownian motion in

liquids

between

1905

and 1908: Einstein 1905k

(Doc. 16),

Einstein 1906b

(Doc. 32),

Einstein

1907c

(Doc. 40),

and

Einstein

1908c

(Doc. 50).

His

own summary

of

a

lecture to the

Naturforschende

Gesellschaft

Bern,

Einstein

1907f,

is

presented

as

Doc. 43. He also

published

three

papers

on

related

topics during

this

period:

the

first, originally

published

as

Einstein's

disserta-

tion,

Einstein

1905j (Doc. 15),

deals with

the determination

of

molecular

dimensions;[2]

the two others

concern

Brownian motion in condensers and its measurement,

Einstein

1907b

(Doc. 39),

and Einstein

1908a

(Doc. 48).

Finally,

a

remark

by

Einstein

on

the

measurement

of

Brownian motion made after

a

talk

that

was

given

at the 1909

Salzburg

meeting

of

the Gesellschaft Deutscher Naturforscher und Arzte

is reproduced, together

with

other

discussion

contributions,

as

Einstein

et

al.

1909a

(Doc. 58).

In

1920, Wolfgang Ostwald,

editor

of

Ostwald's Klassiker der

exakten

Wissenschaften,

proposed

to

Einstein

an

edition

of

his

papers on

Brownian motion and diffusion.[3]

The

resulting

volume,

Einstein

1922,

reprints

most

of

these

papers.[4]

An

English

translation

appeared as

Einstein 1926.

[1]

For studies

of Einstein's

work

on

Brownian

motion,

see,

e.g.,

Brush

1968,

and

Pais

1982,

chap.

2,

§

5.

[2]

For

a

discussion

of

this

paper, see

the edi-

torial note,

"Einstein's

Dissertation

on

the

De-

termination

of

Molecular Dimensions,"

pp.

170-182.

[3]

Wolfgang

Ostwald to

Einstein,

22

Novem-

ber

1920. Einstein

immediately agreed, leaving

to

Ostwald the decision about which

of

his arti-

cles should be

reprinted

(Einstein

to

Wolfgang

Ostwald,

22

November-20

December

1920).

In

his

reply,

Ostwald

informed Einstein that he in-

tended

to

appoint

Reinhold Fürth

as

co-editor

(Wolfgang

Ostwald

to

Einstein, 20 December

1920).

See

Fürth

1980,

for evidence that Fürth

wrote Einstein,

asking

for his consent to the

preparation

of

the edition.

[4]

The

reprinted papers are

Einstein 1905k

(Doc. 16);

Einstein 1906b

(Doc. 32);

Einstein

1906a,

incorporating

the correction

of

a

calcu-

lational

error

and 1906c

(Doc. 33);

Einstein

1907c

(Doc. 40);

and Einstein

1908c

(Doc. 50).

Some

of Fürth's

annotations

for the 1922 edition

(Fürth

1922)

have been utilized in these editorial

notes.