DOC.

400

MAY

1912 301

opinion

that

among

the

country's

own

theoretical

physicists

there

are

several

individuals

of such

ability,

so

that

it

seemed natural

to

include

only

Austrians

in

the

proposal.

It

turned

out

that,

among

those

who should be considered,

two men, namely

Paul

Ehrenfest and

Philipp

Frank,

both

from Vienna,

are

to be

proposed first,

owing

to

their

outstanding

scientific

accomplishments.

Further, the commission believes

that

it should

propose

Mr. E.

Kohl,

who had

already

been

included in

the

proposal

at

the time of the

last

vacancy.[3]

All

three of the candidates named here

are

of German

nationality.

Paul Ehrenfest

was

born

in

1880

in Vienna,

where

he also

attended

and

completed

the

Gymnasium.

He studied

mainly

at

the

universities in

Vienna

and

Göttingen.

On the

basis

of

a

work

on

hydrodynamics

he

was

awarded the doctoral

degree

in 1904 in

Vienna.[4]

After that

he moved

to St. Petersburg,

where

he lives

for

his studies, and

privately

leads

a

seminar,

unattached

to

the

university

there.

Ehrenfest's

papers

deal

mainly

with

the

kinetic

theory

of heat and the

statistical

theory

of radiation.

Owing

to his

outstanding

critical

abilities,

several of these

papers

made essential contributions

to

clarifying

the

problems

considered. From

among

his

numerous

publications,

we are

singling

out the

following

ones as

especially

important:

"Uber

die

physikalischen

Voraussetzungen

der Planck'schen Theorie der

irreversiblen

Strahlungsvorgänge"

["On

the

Physical Assumptions

of

Planck's

Theory

of

Irreversible Radiation

Processes"].[5]

"Uber

zwei

bekannte Einwände

gegen

das

Boltzmann'sche H-Theorem"

[On

Two

Familiar

Objections

against

Boltzmann's

H-Theorem"]

(1907).[6]

"Gleichförmige

Rotation

starrer

Körper

und

Relativitäts-theorie"

["Uniform

Rotation of

Rigid

Bodies and the

Theory

of

Relativity"]

(1909).[7]

"Welche

Züge

der

Lichtquantenhypothese spielen

in

der Theorie der

Wärmestrahlung

eine wesentliche Rolle?"

[Which

Traits

of

the

Light

Quantum

Hypothesis Play

an

Essential Role

in

the

Theory

of Thermal

Radiation?"]

(1911).[8]

In

the

first of

these

papers

it

is

demonstrated that

in

Planck's

theory

of radiation

a

role

is

played

not

only by

those

assumptions

that

have

been

postulated at

the

beginning

of

the

investigation

and

are

taken

from

electrodynamics

and

mechanics,

but

that

Planck's

theory

also has

hidden

within it

a new

physical assumption,

which

is

in

need of

physical

interpretation.

The

second

of

the cited

papers

rebuts

with

great

acumen

the

objection

often raised

against

the

kinetic

theory

of

heat,

namely

that

it

is

impossible

to trace

irreversible

thermal

processes

to

(friction-free)

motions

because the

latter

are

always

reversible.

The

third of

the cited

publications

demonstrates

in

a

vivid

manner

the

difficulties

occasioned

by

the

introduction of

rigid

bodies in the

theory

of

relativity.

The

fourth

paper is

a

thorough

and

ingenious study

of

the

question:

What

statistical

properties

must

we

attribute

to

radiation

in

order

to

satisfy

the radiation

formula,

insofar

as

the

latter

is

confirmed

by

experience.