176 DOC. 38 ETHER AND RELATIVITY
18
SIDELIGHTS
ON
RELATIVITY
follows
Mach,
to
the
ether,
which has
to
serve as
medium for
the
effects of
inertia. But this
conception
of
the ether
to which
we are
led
by
Mach’s
way
of
thinking
differs
essentially
from
the ether
as
conceived
by Newton, by Fresnel,
and
by
Lorentz.
Mach’s
ether
not
only con-
ditions
the behaviour
of
inert
masses,
but
is
also
conditioned
in
its
state
by
them.
Mach’s
idea finds
its
full
development
in
[19]
the
ether
of
the
general
theory
of
relativity.
According
to
this
theory
the metrical
qualities
of
the continuum
of
space-time
differ in
the
environment
of
different
points
[20]
of
space-time,
and
are
partly
conditioned
by
the
matter
existing
outside of
the
territory
under
consideration. This
space-
time
variability
of
the
reciprocal
relations
of
the standards
of
space
and
time,
or,
perhaps,
the
recognition
of
the fact
that
“empty space”
in
its
physical
relation
is
neither
homogeneous
nor
isotropic, compel-
ling us
to
describe
its
state
by
ten functions
(the
gravitation potentials
guv),
has,
I
think,
finally disposed
of
the
view
that