282 DOC.

25

FOUNDATIONS OF GENERAL THEORY

Doc.

25

On

the Foundations of the Generalized

Theory

of

Relativity

and

the

Theory

of

Gravitation

by

A. Einstein

[Physikalische Zeitschrift

15 (1914):

176-180]

[1]

The

arguments

in what follows have been

prompted by

a

critique, published

in this

journal,1

which

Mr.

Mie

devoted

to

the

theory

that

I

worked

out

in collaboration with

[3]

Mr.

Grossmann.

I

do

not

agree

with the conclusion of this

critique,

and

I cannot

escape

the

impression

that Mr. Mie has

not

correctly

understood

my

theoretical

intentions.

But at

the

same

time

I

believe that the

incompleteness

of

my previous

presentation

of the main ideas of the

theory

is

to

be blamed for this misunderstand-

ing.

This

incompleteness

derives from the fact

that,

in

many respects, I

had

not

yet

achieved

complete clarity myself.

For that

reason

I

will

briefly go through

the

fundamental

questions

here

one

by one,

but in

doing

so

I

assume

that

the

reader is

already

familiar with the

theory

as

far

as

its formal

content is

concerned.

1.

The

theory presently

called "the

theory

of

relativity"

is based

on

the

assumption

that

there

are

somehow

preexisting "privileged"

reference

systems

K with

respect

to

which the laws of

nature

take

on

an

especially

simple

form,

even though

one

raises

in

vain the

question

of what could

bring

about the

privilegings

of

these

reference

systems

K

as compared

with other

(e.g., "rotating")

reference

systems

K'.

This

constitutes,

in

my opinion,

a

serious

deficiency

of

this

theory.

These

privileged

reference

systems

are

postulated

as

those with

respect

to

which the

principle

of

the

constancy

of

the

velocity

of

light

in

a

vacuum

is to

be valid. There

can

be

no

doubt

that this

principle

is

of

far-reaching

significance;

and

yet, I cannot

believe in its

exact

validity.

It

seems

to

me

unbelievable that the

course

of

any process (e.g.,

that of the

propagation

of

light

in

a

vacuum)

could be conceived of

as

independent

of

all other

[4]

events

in the world. But whatever

one may

think of

such

arguments,

it

is in

any

case

interesting

to

pose

the

question:

To what

extent is

it

possible

to

build

a

theory

of

[5]

relativity

that does

not

have the

constancy

of

the

velocity

of

light

as

its foundation?

2.

The old

theory

of

relativity

follows

formally

from

the

assumption

that,

for

every justified

substitution of the

space-time variables,

ds2

= Edx2v

(1)

is

an

invariant,

which

assumption

derives from the

principle

of

the

constancy

of the

velocity

of

light. Accordingly, only

linear

orthogonal

substitutions

appear as justified

[2]

115

(1914):

115,

169.