DOCS.

195,

196

DECEMBER

1909

145

I

haven't

discovered much.

The

most interesting

discovery

is

that

one can

specify

an

infinite manifold of

energy

distributions that

are

compatible

with Maxwell's

equations.

Perhaps

the solution of the

quantum question

lies

therein after

all. For,

if

u,

v,

w

=

current

density

p

is

el.

density

Tx,

Ty, Tz,

p

are

potentials,

then

one can assume

the

energy

density[3]

pp

+ (Txu +

·

+

. )

+

P

a2(p

__

dp2

\

\

P

dt

+

/

a

_

*n x

\

\

dt x

_

2 dt

+

·

+

/

This

expression

can

be

generalized

by

replacing

(p

with

P

d\|j

dt

with

P

+

at

'

dx

etc.,

where

\|/

is

an

arbitrary

solution of

the

diff.

eq.[4]

A\|j

Maxwell's

eq.

I hope

this

is not

a

mock-window.

Cordial

greetings

from

your

dt

=

0.

This

is

compatible

with

Albert

[...][5]

196.

To Jakob

Laub

Zurich, 31

December

1909

Dear

Mr.

Laub,

I

was

delighted

with

your postcard,

even

if it

aroused terrible

pangs

of

conscience in

me

because

I have

not

written

to

you

for such

a

long

time. But

I

have not

done

so

for

the

simple reason

that

I

am

very

busy.

I

take

my

lectures

very

seriously,[1]

so

that

I must

spend

much

time

on

their

preparation.

6

hours

a

week and

an

evening

seminar does

not

seem

like

much,

but

it

is.[2]

The

only reason why

I

did not send

you

the

Salzburg

talk[3]

was

that

it

does

not

contain

anything new.

But

I

am sending

it

to

you now.

Have

you

seen

Coehn's

paper

on

current

flows and electro-osmosis[4] This

is

most

interesting