DOC. 42 SPECIAL AND GENERAL
RELATIVITY
361
Part III
Considerations
on
the Universe
as a
Whole
[71]
THIRTY
Cosmological Difficulties
of
Newton's
Theory
Apart
from the
difficulty
discussed in Section
21,
there
is
a
second fundamental
difficulty attending
classical
celestial
mechanics, which, to
the best of
my
knowl-
edge,
was
first discussed in detail
by
the
astronomer Seeliger.
If
we
ponder
over
the
questions
as
to
how the
universe,
con-
sidered
as a
whole, is
to
be
regarded,
the
first
answer
that
suggests
itself
to
us
is
surely
this:
As
regards space
(and time)
the universe
is
infinite.
There
are
stars everywhere,
so
that
the
density
of
matter,
although very
variable
in
detail, is
never-
theless
on
the
average everywhere
the
same.
In
other
words:
However far
we might
travel
through space,
we
should find
everywhere
an
attenuated
swarm
of
fixed
stars
of
approxi-
mately
the
same
kind and
density.
This
view
is
not
in
harmony
with the
theory
of Newton.
The
latter
theory
rather
requires
that
the
universe should
have
a
kind
of
centre
in which the
density
of
the
stars
is
a
maximum,
and
that
as we
proceed
outwards from this
centre
the
group-density
of the
stars
should
diminish,
until
finally,
at
great
distances,
it
is
succeeded
by
an
infinite
region
of
emp-