DOC.

596

AUGUST

1918 621

596. From Friedrich Adler

Stein-on-the-Danube,

9 August 1918

Dear

Friend,

Cordial

thanks

for

your

letter, postcard,

and

the

book

by

Weyl.[1]

I have

looked

through

the

book and

it

appears

to

me

to

be

very good

as

an

introduction

to

the mathematical

problems.

However,

he

brushes off

what

seems

to

me

to be

the

main

physical question, namely,

the

time

concept,

just

as

lightly

as

do

other

explanations.

You

will

see

what

I

mean

when

you

read

my paper,

which

was

sent

out to

you

last

week and which

you probably already

received in

the meantime.[2]

In

the

copy

I prepared

for

you,

a

small emendation

is

still

missing, as

I

see

in

retrospect.

Namely,

if

the

value

for

x

from formula

(77b)[3]

is

introduced

into

(48),

the

generally

valid formula for the

“starting

time”

results:[4]

ta

=

X

V

and there

(~Ti~:

71 1

us

applies;

so

this

starting

time is

always only a

function

of

u,

and

the

relation[5]

t'a=ru's

ta

Us

between

the

starting

times

corres[pondingly]

results;

hence

a

dependence

on

7.

When

you emphasize

the limitation

of

theoretical

possibilities

as an

advantage

of

the

theory

of

relativity,

I

think that this limitation

is not

weakened

by

the

proof

of

the

necessity

for

the

assumption

of

a

preferred

reference

system.

But

I

hope

we

shall

understand

each

other

more

quickly

on

all these

questions

when

you

have read

my

work.

For

today I

just

want to

say

that

my

admiration

for

your

achievement

grew

proportionately

as

I penetrated

into

the

problem

and

as

the

immense amount

of

difficulties

you

were

facing

became clearer

to

me.

And

this

admiration

did

not

diminish

in

the

least

by

the

fact

that

it

simultaneously

became

increasingly

clear to

me

that

your

solution

is

an

inadmissible

generalization

of

a

special case.

What

a

pity

that

we

cannot discuss this

question orally,

but

I

hope

I

have worked

it

out

clearly enough

in

the

book.

A

note

was

inside

the

book

by

Weyl

that

you

sent

me,

which

you

had

forgotten

to

remove.

As

you may possibly

be

looking

for

it,

I

am sending

it back to

you

herewith

by

return

post.