DOC. 38 ETHER AND RELATIVITY 167
ETHER
AND
RELATIVITY
9
mechanics
was
shaken
by
the
experi-
ments
with
B-rays
and
rapid
kathode
rays.
[8]
This dualism
still
confronts
us
in
unex-
tenuated
form in
the
theory
of Hertz,
where matter
appears
not
only as
the
bearer
of
velocities,
kinetic
energy,
and
mechanical
pressures,
but
also
as
the
bearer
of
electromagnetic
fields.
Since
such
fields
also
occur
in
vacuo-i.e.
in free
ether-the ether
also
appears
as
bearer
of
electromagnetic
fields.
The
ether
appears
indistinguishable
in
its
functions from
ordinary
matter.
Within
matter
it
takes
part in
the
motion
of
matter
and in
empty
space
it
has
everywhere a
velocity;
so
that the ether has
a definitely assigned
velocity
throughout
the
whole
of
space.
There is
no
fundamental
difference between
Hertz’s
ether and
ponderable
matter
(which
in
part subsists
in the
ether).
The
Hertz
theory
suffered not
only
from
the
defect of
ascribing
to
matter and
ether,
on
the
one
hand
mechanical states,
and
on
the other hand
electrical states,
which do not
stand
in
any
conceivable