

DOC.

14 87

light,

and

other

groups

of

phenomena

associated with the

production

or con-

version of light

can

be

understood better if

one

assumes

that the

energy

of

[5]

light

is discontinuously

distributed in

space. According

to

the

assumption

to

be contemplated

here,

when

a

light

ray

is

spreading

from

a

point,

the

energy

is

not

distributed

continuously

over

ever-increasing

spaces,

but consists

of

a

finite

number of

energy quanta

that

are

localized in

points

in

space, move

without dividing,

and

can

be

absorbed

or

generated only

as a

whole.

In this

paper

I wish to communicate

my

train of

thought

and

present the

facts that led

me

to

this

course,

in the

hope

that the

point

of

view to be

elaborated

may

prove

of

use

to

some

researchers in

their

investigations.

§1.

On a

difficulty encountered

in the

theory of "black-body

radiation"

We

shall

begin

by

taking

the

standpoint

of

Maxwell's

theory and

the

electron

theory

and

consider the

following

case.

Consider

a

space

enclosed

by

completely

reflecting walls

containing

a

number

of

gas

molecules

and

electrons

that

move

freely

and

exert

conservative forces

on

each

other

when they

come

very

close

to each other,

i.e.,

they

can

collide like

gas

molecules

according

to

the kinetic

theory

of

gases.1

Suppose,

further,

that

a

number

of electrons

are

bound

to

points

in

space

which

are

very

far

from each

other,

by

forces

that

are

directed

toward

these

points and

are

proportional

to

the

elongations

from

the

points. These

electrons,

too, shall

enter

into conservative

interactions with the free

molecules

and

electrons

when

the latter

come very

close

to them.

We

call the electrons

bound

to

the

points

in

space

"resonators";

they emit and

absorb

electromagnetic

waves

of definite

periods.

[7]

According

to

the

present view

about the

origin

of light,

the radiation

in the

space

considered, found

for the

case

of

dynamic

equilibrium

on

the

basis

of

Maxwell's

theory,

must be

identical with

"black-body

radiation"

-

at

[8]

least if

one assumes

that

resonators

of all the relevant

frequencies

are

present.

[9]

1This assumption

is

equivalent

to

the

assumption

that the

mean

kinetic

energies

of

gas

molecules

and electrons

are

equal

to each

other

at thermal

equilibrium.

As

we

know,

Mr.

Drude

used

the latter

assumption

to

derive

the

ratio of

thermal

and

electric conductivities

of

the

metals

theoretically.

[6]