178 DOC.

38 ETHER AND RELATIVITY

20

SIDELIGHTS

ON

RELATIVITY

former,

disregarding

the

causes

which

con-

dition

its

state.

Thus

we

may

also

say,

I

think,

that the ether

of

the

general

theory

of

relativity

is

the

outcome

of

the

Lorent-

zian ether,

through

relativation.

As

to

the

part

which the

new

ether

is

to

play

in

the

physics

of

the future

we are

not

yet

clear.

We know

that it

determines

the

metrical relations in

the

space-time

[24]

continuum,

e.g.

the

configurative possi-

bilities

of

solid bodies

as

well

as

the

gravita-

tional

fields;

but

we

do

not

know whether

it

has

an

essential share in

the

structure of

[25]

the

electrical

elementary

particles

consti-

tuting

matter. Nor do

we

know whether

it is

only

in

the

proximity

of

ponderable

masses

that its

structure differs

essentially

from

that

of

the Lorentzian

ether;

whether

[26]

the

geometry

of

spaces

of

cosmic extent

is

approximately

Euclidean.

But

we can

assert

by

reason

of

the relativistic

equations

of

gravitation

that there

must be

a

depart-

ure

from Euclidean

relations,

with

spaces

of

cosmic order

of

magnitude,

if

there

exists

a positive mean density, no

matter

[27]

how

small, of

the

matter in

the

universe.