298
DOCS. 395-397 MAY
1912
have
to
expect
here,
by necessity,
behavior
(b)?
But if
the
absorption is
an
eventlike
thing,
such
as,
say,
the
elementary
chemical
process
caused
by a
molecular
collision,
then
case
(a)
would have
to
ensue.
Thus,
an experimentum
crucis
seems
to
be
possible
here,
at
least
if
one
does
not want to
take
the
point
of
view
that different carriers
correspond
to
the
frequencies
v1
&
v2,
which in the
case
of
a
selective effect looks
rather
improbable
indeed.
I
do
not know
what
criticism of
Ehrenfest's
you're
talking
about
in
your postcard.
Ehrenfest
visited
me as
well,[6]
and he has
changed
his views
considerably.
He
said
that
he must tell
you
about
it.
Our conversation
revolved
mainly
around fluctuations.
E.
concedes their
existence and also the
impossibility
of
explaining
them
by
means
of
the
undulation
theory.
One
cannot
seriously
believe in the existence
of countable
quanta,
since
the interference
properties
of
light
emitted
by
a
luminous
point
in
different
directions
are
not
compatible
with
it. Nevertheless,
I
still
prefer
the "honest"
theory
of
quanta to
the
hitherto
found
compromises
meant
as
its
replacements.-
It
is
a
great
pity
that
the
theory
of
gravitation
leads
to
so
little
that
is
observable.
But it
must
be
taken
seriously
all
the
same,
because
the
theory
of
relativity insistently
demands
such
a
further
development,
for
the
gravitation
vector cannot be
made
to
fit
into the
relativity
theory
with
a
constant
c
if
one
requires
the
gravitational
mass
of the
energy.[7]
Abraham informed
me
that
he has
"converted"
to
my
equations
of motion of
the material
point
in the
gravitational
field.[8]
With best
regards,
I
remain
yours very truly,
A.
Einstein
396.
To
Marian
von
Smoluchowski
[Prague,
20
May
1912]
Very
welcome
anytime
when
will
you
arrive
Einstein
397. To
Marian
von
Smoluchowski
Prague,
20
May [1912]
Highly
esteemed
Colleague,
I
just
sent
you a
telegram[1]
because it
occurred
to me, to
my
great
horror,
that
I
have
not
yet
answered
your
letter.
I cannot
permit
myself
to
invite
you
and
your
wife[2]
to
stay
with
us,
because
we are
not
adequately
set
up
for
that.
But I
hope
that
we
will be able
to spend
much time
together
all the
same.
With
kindest
regards
to
you
and
your
wife, I
remain
yours,
A.
Einstein