DOC.

23

MAX

PLANCK AS SCIENTIST

271

Doc.

23

Max Planck

as

Scientist

by

A.

Einstein

[Naturwissenschaften

1

(1913):

1077-79]

For the

academic

year

1913-14, the

rectorship

of the

University

of

Berlin has been

bestowed

upon

the theoretical

physicist

Max Planck.

We,

his close and his distant

[2]

colleagues,

wish

joyfully

to

take this

opportunity

to

celebrate with

gratitude

the

achievements that

science

owes

to

his creative

activity.

Max Planck's first

independent

work

was

his

inaugural

dissertation,

"Über den

zweiten

Hauptsatz

der mechanischen Wärmetheorie"

["About

the Second Law

of

the

Mechanical

Theory

of

Heat]"

which he

presented

at

the

age

of

21 to

the

University [3]

of Munich in

1879.

It

is characteristic

that

Planck

started his

publishing

activity

with

the

treatment

of

a

topic

of

such

generality, only

to

turn,

in

subsequent years,

to

the

treatment

of

more specific problems

that

were

naturally

connected with those first

investigations.

This is characteristic of his

way

of

working,

perhaps

of the method of

the

pure

theoretician in

general.

He

always

starts out

from

a

proposition

of

the

greatest possible generality

and deduces

from

it individual

special results,

which he

then

compares

with

experience.

Planck's first

great

scientific

accomplishment

is

the third

of

his

papers,

entitled

"Uber das

Prinzip

von

der

Vermehrung

der

Entropie"

["About

the

Principle

of

Entropy

Increase"]

(Wied.

Ann. 32

(1887): 462),

which deals with the

general theory

[4]

of chemical

equilibrium,

with

special

attention

given

to

dilute solutions. To be

sure,

the

general

results of this

paper

had

already

been derived

more

than

10

years

earlier

by

Gibbs,

and those

concerning

dilute solutions

partly by

van't Hoff. But Gibbs's

[5]

papers

were

little

known and

not

easily

accessible;

even

just

to

recognize

their value

[6]

was

already

an

accomplishment, and,

in

fact,

I

believe that Planck would have

passed

over

Gibbs's

papers uncomprehendingly,

like almost

everyone else,

had he

not

independently

embarked

upon

a

similar road. The

great

value

of

Planck's aforemen-

tioned work lies in the fact that

he established

a

few formulas

regarding

the

equilibrium

of dilute solutions of

a generality so great

that all of the

thermodynami-

cally

derivable laws

on

dilute solutions

are

contained

in

them.

On

the basis

of

his

general formulas,

Planck

was

the

first,

and thus ahead of

Arrhenius, to

conclude that

[8]

in

aqueous

solutions with

"abnormally high" vapor pressure

reduction

(resp.

lowered

freezing point

or

raised

boiling point)

the dissolved substance

must

be dissociated.

Planck's

general

formulas include the so-called Ostwald law of dilution for

binary

electrolytes as a completely special

case.

[9]

[7]

We

are

not

going

to

speak

here about Planck's

papers

that

deal with

more

[1]