170 DOC. 38 ETHER
AND RELATIVITY
12
SIDELIGHTS
ON
RELATIVITY
[11]
K'
which is
moving
in uniform trans-
lation
relatively
to
K. Now
comes
the
anxious question:-Why must
I
in
the
theory
distinguish
the
K
system
above all
K'
systems,
which
are physically
equivalent
to
it
in all
respects, by
assuming
that the
ether
is
at rest relatively
to
the
K
system?
For the
theoretician
such
an
asymmetry
in the theoretical
structure,
with
no cor-
responding
asymmetry
in
the
system
of
experience,
is
intolerable.
If
we assume
the ether
to be
at
rest
relatively
to
K,
but
in
motion
relatively
to K',
the
physical
[12]
equivalence
of
K
and
K'
seems
to
me
from
the
logical standpoint,
not indeed
downright
incorrect,
but
nevertheless
[13]
inacceptable.
The
next
position
which
it
was possible
to
take
up
in face
of
this
state of
things
appeared
to be
the
following.
The
ether
does not exist
at all.
The
electromag-
netic
fields
are
not states of
a
medium,
and
are
not
bound
down to
any bearer,
but
they
are
independent
realities which
are
not reducible to
anything
else, exactly
like
the
atoms
of
ponderable
matter. This