DOCS.
200,
201
MARCH
1916
201
So
you really
can
be content and have
some
peace
of mind in
looking
to
the
future.
When
you
have informed
me
of
your opinion,
I
shall entrust
the
matter
to
an
attorney-at-law
who must
see
to it
that
everything
is put
nicely
in order.
In
14
days
I’ll
set
off
and
try
to travel to Zurich.
I
am going
to
stay
at
an
inn there.
But
if
mortal
providence
does not
allow
me
to
cross,
I
shall
stay
in
Singen[9]
and
request
that Albert
travel
the
couple
of
stations
across
to
me.
He
will not
encounter
any
difficulties. I’ll write to him
very
soon.
Greetings
to
you
and kisses for
the
boys,
y[ours],
Albert.
201. From Otto Stern
Lomscha
[Poland],
13
March
1916
Dear Prof.
Einstein,
I
measure
the
specif.
heat
(and entropy)
of
the
model:
Gaseous molecules
in
gravity,
where I cool
it
down to
T
=
0.[1]
Question.
What
do
I
measure
in
case
(1)
and in
case (2)?
Case
(1)
Transition
from
one
chamber to
another
very rare
(in
my
view
also, always
realized
at
sufficiently
low
temperatures).
Answer
Initially I
measure no
quantity at
all with which
I
can
do
anything
as a
thermodynamics expert.
Only
from
that
moment
on
when
the
molecule
is
located
in
the
chamber
(e.g.,
2)
from which it
can no longer
escape any
more
do
I
measure
the
spec.
heat
of
the
system
in
this
state
(2),
that
is,
the
spec.
heat
of
a
specific
chemical bond.
Case
(2)
Transition
frequent (practically, never
realizable at
sufficiently
low
temperatures;
in
principle,
always
[realizable]
through sufficiently gradual
cooling).