DOC. 38
ETHER AND RELATIVITY 169
ETHER
AND
RELATIVITY
11
Lorentzian
ether,
it
may
be said
of
it,
in
a
somewhat
playful spirit,
that
im-
mobility
is
the
only
mechanical
property
of
which
it
has not been
deprived
by
H.
A.
Lorentz.
It
may
be
added that the
whole
change
in
the
conception
of
the
ether
which
the
special
theory
of
relativity
brought
about,
consisted in
taking
away
from
the ether its last
mechanical
quality,
namely,
its
immobility.
How
this
is
to
be
understood
will forthwith
be
expounded.
The
space-time
theory
and the
kine-
matics
of
the
special
theory of relativity
were
modelled
on
the
Maxwell-Lorentz
theory
of
the
electromagnetic
field. This
theory
therefore satisfies
the
conditions
of
the
special
theory
of
relativity,
but
when viewed from
the latter it
acquires
a
novel
aspect.
For if
K be
a
system
of
co-ordinates
relatively
to which
the
Lorentzian
ether
is at
rest,
the
Maxwell-
Lorentz
equations
are
valid
primarily
with
reference to K.
But
by
the
special theory
of
relativity
the
same equations
with-
out
any change
of
meaning
also hold in
relation to
any
new system
of co-ordinates