DOC.

30 FOUNDATION OF GENERAL RELATIVITY

147

THE FOUNDATION OF

THE GENERAL

THEORY

OF RELATIVITY

By

A.

EINSTEIN

A.

Fundamental Considebations

on

the

Postulate

of

Relativity

§

1.

Observations

on

the

Special

Theory

of

Relativity

THE

special

theory

of

relativity

is based

on

the

following

postulate,

which

is also

satisfied

by

the

mechanics

of

Galileo

and Newton.

If

a

system of

co-ordinates

K

is chosen

so

that,

in

re-

lation

to it,

physical

laws

hold

good

in their

simplest

form,

the

same

laws also hold

good

in relation

to

any

other

system

of co-ordinates K'

moving

in uniform translation

relatively

to K.

This

postulate

we

call

the

"special principle

of

relativity."

The

word

"special"

is

meant to intimate

that the

principle

is

restricted

to

the

case

when

K'

has

a

motion

of

uniform

translation

relatively

to

K,

but

that the

equivalence

of K' and K does not

extend

to

the

case

of

non-

uniform motion

of

K'

relatively

to K.

Thus the

special

theory

of

relativity

does

not

depart

from

classical

mechanics

through

the

postulate of

relativity,

but

through

the

postulate

of

the

constancy

of

the

velocity

of

light

in

vacuo,

from

which,

in combination

with

the

special

prin-

ciple

of

relativity,

there

follow,

in the

well-known

way,

the

relativity

of

simultaneity,

the Lorentzian

transformation,

and

the related

laws for

the behaviour

of

moving

bodies

and

clocks.

The

modification to

which the

special

theory

of

relativity

has

subjected

the

theory

of

space

and time

is

indeed

far-

reaching,

but

one

important

point

has remained

unaffected.

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