354 DOC.
364
JULY
1917
of
1914
about
Friedrich Adler’s
idea,
to
which he himself attached
such
great
significance.
The
former did
not
find it
noteworthy,
and
so
I
did not
concern
myself
with it
further.
I
am
not
a physicist,
rather
a
philosopher,
but
frequently
study
physical
problems. Upon
discussing
this
with Professor
Frank,
he
now con-
firmed to
me
that
my proposal
of
that
time
coincides with Adler’s
idea,
which
I
am
familiar with
only
through
newpaper reports; yet,
he
continues
as
before not
to consider
the
matter worth
notice.[2] I
would
like
to
present
in
the
following
my
current
conception
of
that
idea,
which
I
have
now
taken
up again
and
which
in
my
view contradicts
neither
the
special
nor
the
general principle
of
relativity,
since different issues
are
involved here. The
principle
of
relativity is
concerned
with the
formulation of
differential equations
through
which the natural
laws
are
expressed;
the latter
observations of
mine,
on
the
other
hand,
concern
the
description
of real
processes
in
nature.
In
describing
these
processes
with the
given
constants,
obviously
not
all
possible systems are equally suited;
certain
ones
portray
the
phenomena
more simply.
The
general principle
of
relativity,
in
particular,
compels
us
to
give
due consideration
to
this
drawback in
general
relativity
as
well.
Although
the
general principle
of
relativity
allows
the
depic-
tion of the
phenomena
in
the
Ptolemaic
system
as well,
there
is
no
doubt that
despite
the
general
covariance of
the
differential
equations,
the
real
phenomena,
which
are
described
by doubly
integrated
equations,
are
presented
more
simply
in the
Copernican system
than
in
a
system
in
which
the
geometry
deviates
so
enormously
from
the
Euclidean and in which
the
light
ray
of
a
star
comes
to
us
along
a
spiral
path
that
revolves
around the Earth
in
24
hours.[3]
I
often
try to
imagine
as
intuitively
as
possible
the Ptolemaic
system according
to
the
general
theory
of
relativity,
with all
the
peculiarities
that
result from it.
How
ought
one
to
imagine a
world
system
in
which
a
billiard
ball, brought
into
rotation
through
an
eccentrical
stroke,
is
viewed
as
at
rest? In
general,
it
can
be said
(if
all
sys-
tems, moving uniformly
and in
a
straight
line with reference
to
one
another,
are
initially regarded
as one
system)
that the
phenomena
are
most
simply
described
in
a
system
whose
geometry
is most
nearly
Euclidean. After
having
chosen
the
three
spatial
axes
in accordance with these
aspects,
we
must
now
determine
the
time
axis,
that
is,
the
spatial
coordinate
system’s
state of motion.
First
of
all,
concerning
the
relative rotation, could
the
most
simple system
not
be defined
by
having
its total
angular
momentum
equal
to zero? If
we
place
the coordinate
system’s origin
at
the Earth’s
center,
this would most
closely
approximate
the
Copernican
system
(with an
infinitesimal rotation
of
this
system).
This
system
would
probably
also be
one
in which Foucault’s
pendulum
is
at rest.
I
state these
considerations
only
with
reservations,
since
I cannot
judge
whether,
after
more
precise calculation,
they
can
still be
seen
as
correct.
Concerning
its
rotation,
the