DOCS.
299,
300
FEBRUARY
1917 287
better).
In
the
spring
or
In
the
summer
I
shall
definitely
come
to
see
you
in
Switzerland; traveling
is too repugnant
now,
especially
for
a
rickety
old
fellow.[7]
300. To
Erwin Freundlich
[Berlin,]
Sunday.
[18
February
1917
or later][1]
Dear
Freundlich,
I
have been
turning
the
elliptic space problem
over
in
my
mind and
understand
it
completely. My
calculation remains
correct,
in
particular,
the
relation between
A,
p,
and
R; only,
the total
volume is half
as
large
as
for the
originally spherical
space.[2]
The
elliptic space
is
simply
a
spherical one
in which
points
that
are
symmetric
with
respect
to
the
center
are
identical
(not distinguishable).
Put
another
way,
G
P
P'
Let G
and
G'
be
two
geodetic
lines
that
start
at
P.
These
same
lines intersect
each
other
at
P'.
According
to
spherical geometry,
P
and
P'
are
opposing points;
according
to
the
elliptic one, they
are
identical. An
elliptic space
can
aptly
be
described
as
“hemispherical.”
The star
statistics
question
has become
a
burning
issue to be addressed
now.[3]
I
suggest
that
we
discuss
the
problem
in
a
joint
paper.
If it
is
necessary
or
beneficial,
I shall seek to
have
you
granted
time
off
from
your
duties
for
a
specified
period.
We
must act
cautiously
in
doing this, though,
so
that
your
position
is
not
jeopardized.[4]
The
matter of great
interest here
is
that
not
only
R
but
also
p
must be indi-
vidually
determinable
astronomically,
the
latter
quantity at
least to
a
very rough
approximation,
and
that
then
my
relation between them
ought
to hold.
Maybe
the
chasm between
the
104
and
107 light years
can
be
bridged
after
all![5]
That
would
mean
the
beginning
of
an
epoch
in
astronomy.
The
paper by
Harzer
is
very
interesting.
If
only
it
were
known what should be done with
the
loathsome ab-
sorption;
it
is
so
abominably up
in
the
air.[6]
But
managing
without this
quantity
is
unfortunately
impossible.
Best
regards,
yours,
A. Einstein.