144 EARLY WORK ON

QUANTUM

HYPOTHESIS

V

Einstein maintained that his

analysis

of Planck's

law showed the need to

modify

the foun-

dations

of

both

electrodynamics

and mechanics. In

early

1908 he wrote:

"I

believe

more-

over

that

we are

still far from

having satisfactory elementary

foundations for electrical and

mechanical

processes"

("Ich

glaube übrigens,

dass wir noch weit davon

entfernt

sind,

befriedigende

elementare

Grundlagen

für die elektrischen und mechanischen

Vorgänge

zu

besitzen").[66]

Most

leading

theoreticians, however, were

still

not

even

convinced

of

the

need

to intro-

duce

energy

quanta.[67]

Doubts about the

validity

of

the

equipartition

theorem

were

still

expressed.[68]

In

1906 Planck

attempted

to invalidate

the

ergodic assumption underlying

the

equipartition

theorem

by introducing

a

lower

limit to

the size

of

phase space

cells

of

equal

probability,

their size

being

fixed

by

the

quantum

of action

h.[69]

Another obstacle

to

acceptance

of

the

quantum hypothesis was

the

attempt

to

defend the

validity

of

the

Rayleigh-Jeans

law.[70]

H. A.

Lorentz,

universally recognized as an authority on

theoreti-

cal issues,

originally hoped

to

prove

that the

equipartition

theorem

simply

does not

apply

to matter-free

radiation.[71]

He demonstrated

just

the

opposite,

however, in

Lorentz 1908a,

arriving

at the

Rayleigh-Jeans

law and

calling

for

new experiments

to decide

between

it

and

Planck's

law. His

paper prompted a vigorous

discussion

of

the radiation

problem

in

the

pages

of

the

Physikalische Zeitschrift.

Lummer and

Pringsheim emphatically

reiterated

that

experiment

had

already

decided in

Planck's

favor,[72]

Jeans defended his

position on

equipartition,[73]

and Walter Ritz asserted that the exclusive

use

of

retarded

potentials

would

restrict

the

equipartition

of

energy.[74]

Lorentz 1908b

accepts

the

criticism of

the

experimentalists,

admitting

"that

a

derivation

of

the radiation laws from the electron the-

ory

will

hardly

be

possible

without

a profound

modification

in

the foundations

of

the lat-

ter"

("daß

eine

Ableitung

der

Strahlungsgesetze aus

der

Elektronentheorie

schwerlich

ohne

tiefgehende Änderung

ihrer

Grundlagen möglich

sein

wird").[75]

Lorentz's

statement

sion

of Einstein's

work

on specific

heats and its

reception,

see

Klein

1965;

Kuhn

1978,

pp.

210-

220;

Pais

1982, chap.

20; and

Mehra and

Re-

chenberg

1982,

pp.

113-136.

[66]

Einstein

to

Arnold

Sommerfeld, 14

Janu-

ary

1908. See the

Introduction,

pp.

xxi-xxix,

for

further

discussion

of Einstein's

search for

"satisfactory

elementary

foundations."

[67]

Ehrenfest

is

a noteworthy exception.

See,

e.g., Ehrenfest

1906.

[68] See,

e.g.,

Rayleigh

1905a,

1905b. For

a

discussion

of

earlier doubts,

see

Brush 1976,

vol.

2,

pp.

356-363.

[69]

See

Planck

1906c,

pp.

154-156, 178.

Planck's

attempt

is discussed in the editorial

note,

"Einstein

on

the Foundations

of

Statistical

Physics,"

p.

49. Planck 1906c

is

further

discussed

in Kuhn 1978,

pp.

114-134, and

Jungnickel

and

McCormmach

1986b,

pp.

265-

268.

[70]

For

example,

Jeans

argued

that the law

does

not

hold

for

laboratory black-body

radia-

tion because such radiation has

not

yet

reached

thermal

equilibrium

(see

Jeans

1905c, p. 293).

Rayleigh

had stated

in

1900 that "although

for

some

reason

not

yet explained

the doctrine

[of

equipartition]

fails in

general,

it

seems

possible

that it

may

apply to

the

graver

modes

[long

wavelengths]" (Rayleigh 1900, p. 540).

For

a

discussion

of

attempts

to account

for the failure

to obtain

Planck's

law from the

equipartition

theorem, see

Garber

1976.

[71]

Lorentz stated this

hope

in Lorentz

1908a,

p.

19,

and Lorentz

1908b,

p.

562.

[72]

See Lummer

and

Pringsheim

1908.

[73]

See

Jeans

1908.

[74]

See Ritz 1908b.

[75]

Lorentz

1908b, p.

562. See also Hendrik