42
DOCS.
57,
58
SEPTEMBER
1907
As for
the
rest,
it
seems
to
me
that
the
question
as
to
what
happens
with
these
small
energy
quanta
in the
absorbing
body
is not
yet
ripe
for
an answer.
If
one
takes the
theory
of
light
quanta
as a
basis and
assumes
that
only
finite
energy quantities
can
be
absorbed,
then
one
must
regard
the
exponential
law
of
absorption
as
approximately
valid
only
for
relatively large energies,
and
abstain
from
any answer
to
the
question
as
to what
happens
with
the
small
ones.
Finally,
I
wish also
to
tell
you
that
I cannot uphold
§7
of
my
paper,[3]
at
least
not
the second
part
of
it.
It
contains
an error
that
is
closely
linked
with
some
ideas about
Planck's
hypothesis
of natural
radiation,[4]
which
I
will describe to
you
one
of
these
days.
Upon
my
return
I
came
across an
article in
the
Annalen
by
J. Laub,
"Optics
of
Moving
Media,"[5]
which derives
the
dragging
coefficients[6]
from
the
relativity principle.
The
paper
has
a
very
neat basic
idea, but, unfortunately,
it
later
on
contains
two
direct
errors
and
one inconsistency
in
the
reasoning,
namely an
interchanging
of
group
and
phase
velocity.[7]
Even
so, I
did
not
withdraw
my derivation;
rather,
it will
appear
in
one
of
the
next
issues.[8]
I have
communicated
my objections
to
the
author.[9]
At
the
moment I
am
absorbed
with
a new
article
by
J. J.
Thomson,
"On
the
Electrical
Origin
of
the
Radiation
from
Hot
Bodies"
(Phil.
Mag.
14:
217),[10]
which
is
very
interesting,
even
though I
disagree
with
it,
because for
the
time
being I
cannot
believe
that the
manner
in which
electrons
get
accelerated
in collisions with atoms
is
the
same
for all bodies.
Rest assured that
I
will
take
advantage
of
the
next
opportunity
that leads
me
to
the
vicinity
of Bern
to
look
you up.
The
stimulating suggestions
that
I
got
from
my
conversation
with
you
are so
valuable
that
I would like to have
more
of
them.[11]
Please
mention
me
to Mrs.
Einstein.
With
kindest
regards,
your
M.
Laue
58. To Johannes
Stark
Bern, 25 September
1907
Highly
esteemed Professor
Stark:
I will be
glad
to
furnish
the
report
for
the Jahrbuch that
you
requested,
only
please
apprise
me
of the
approximate
date
you
would like
to
get
it.[1]
I must
also note
that
I
am
not
in
a
position
to
acquaint
myself
with
everything
published
on
this
topic,
because
the
library
is
closed
during
my
free
time.[2]
In
addition
to
my own
works,
I
am
acquainted
with
one
paper
by
H. A.
Lorentz
(1904),[3] one by
E.
Kohn,[4]
one by
Mosengeil,[5]
and
two
by
Planck.[6] I
do not know
of
any
other theoretical
papers
on
the