374

THE

RADIATION

PROBLEM

to prevent

the

electron's

electrical

masses

from flying apart

under

the

influ-

ence

of

their electric interaction.

The

relation

h

=

e2/c

seems

to

me

to

indicate

that

the

same

modification

of

the

theory

that

will

contain the ele-

mentary quantum

e as a

consequence

will also contain the

quantum

structure

of radiation

as

a

consequence.

The

fundamental

equation

of

optics

1

O2~

___

__

- =0

will

have to

be

replaced

by an

equation

in which

the universal

constant

e

(probably its square)

also

appears

in

a

coefficient.

The equation

sought

(or

the

system

of

equations sought) must

be

homogeneous

in its dimensions. It

must

remain

unchanged upon

application

of

the Lorentz transformation. It

[70]

cannot be

linear

and

homogeneous.

It

must-at

least if Jeans'

law

is really

valid in the limit

of

small

v/T

-lead

to

the

form

D(q)

=

0

for

large

amplitudes

in

the limit.

I have not

yet

succeeded

in

finding

a

system

of

equations

fulfilling

these conditions

which would have looked

to

me

suitable for the construction

[71]

of the

elementary

electrical

quantum

and the light

quanta.

The

variety of

possibilities

does not

seem so

great,

however,

for

one

to have to

shrink

from

this task.

Addendum

From

what

has

been

said

above

under 4.

in

this

paper,

the

reader could

easily

get

an

incorrect

impression

about the

standpoint

taken

by

Mr.

Planck

with

regard

to

his

own

theory of

thermal radiation.

I

therefore

deem

it

appropriate

to

note

the

following.

In

his

book,

Mr.

Planck

emphasized

in several places that his

theory

should

not

yet be viewed

as

something complete and

final.

At

the

end

of

his

introduction, for

example,

he

says

verbatim: "I find it

important,

however,