492
DOCS. 476-478
MARCH
1918
P. S.
The naturalness
of
the
hypothesis
of the
world’s spatial
closure
can
proba-
bly
best
be
demonstrated
in this
way:[6]
The
boundary conditions
must
also be
expressed covariantly,
in
keeping
with
the
nature
of
the
thing.
The
differential
equations
(ik,
lm)
=
0
(at
infinity)
must
take the
place
of
the
conditions
guv
=
const. at
infinity.
These
are
evidently
far less
natural than the
closure condition.
It
is
clear
that
the latter
is
not
attainable with the
original
field
equations.
I
am
already
looking
forward to
presenting your paper
to the
Academy.
Do
send
it
to
me
soon!
May
I
see
to
the
corrections,
or
is
it
necessary
that
they be
sent to
you?
The Berichte
the
things upon receipt.
477. From Arnold Sommerfeld
[Munich,
8
March
1918]
Dear
Einstein,
I
am
very glad
that,
gradually, you
are
recovering.
As I
hear,
Lenz has also
provided
a
small
contribution
to
your
nutrition.[1]
Lenz
is particularly close to
me
profession[ally]
and
personally.
In
re
the
Planck
celebration,
the
following suggestion,
which
comes
from Laue
and
which
I support
as
plainly
serviceable:[2]
Take
the
order
Warburg, Laue,
Sommerfeld,
Einstein.
Thermodynamics precedes
the
quanta for Planck tempo-
rally
and
practically.[3]
I
do
not
know in
the
least
yet
what
I
am
going
to
say,
though.-
At
the
moment I
am
busy
constructing
the
Lothar
Meyer
curve
for
atomic volumes
from Bohr’s
model.[4]
Kindest
regards, yours,
A. Sommerfeld.
478. From
Karl
Scheel
Berlin,
9
March
1918
Dear
Colleague,
Today
I
finally
come
back
to
your
last letter
after
having
discussed
the Planck
issue
with
a
few
interested
parties, particularly
with
Mr. Jahnke.[1]
The
unani-
mous
view
is
that
it
is not
necessary
to
convene a meeting
of
the
board;
further-
more, your suggestion
of
fixing
the
festive
meeting
earlier for
April
19th has been