DOCS. 55-57
AUGUST-SEPTEMBER
1907 41
I
do
not
assert
that,
no
matter
how
one might
make these
stipulations, superluminal
propagation
cannot exist. I
assert
only
the
following as a
consequence
of the
argument
given
earlier: If the
above
stipulations
are so
formulated that
an
electric
current
can
be
induced
at
a
given
location
only
by
the
electromagnetic field
at
the
same
spatial location,
then
no signal can possess
superluminal
velocity.
Thus,
the
pure
Maxwell
theory
does not
rule
out
propagation
with
superluminal
velocity
(Sommerfeld,
rigid electron);[5]
here the
above
condition
is
simply
not fulfilled.
But
the
theory
of
dispersion
does fulfill the
mentioned condition.
Thus,
my
argument
can
be
applied here,
and
the
impossibility
of
superluminal signals
follows with
certainty.
Respectfully,
A.
Einstein
56.
To
Conrad and Paul Habicht
[Bern,
2
September
1907]
Dear
Habichts:
I
am
driven
by
murderous
curiosity
to ask
what
you're up
to.
Since
then
I
have
found
nothing
more
of
significance
with
regard to
the
Maschinchen.[1]
Best
regards
from the
news-thirsty
A. E.
57.
From
Max
Laue
Berlin,
W.
15
Pariserstr. 47.
4 September
1907
Esteemed
Mr.
Einstein:
Thank
you
so
much for
your
kind
letter.
As
regards
your
objection,
I
do
not
understand
how much
of
an
objection
it
really
is.
After
all,
I conclude:
If the
energy
in
the
stage
under
discussion
were
not immeasurably small,
then there
would be
a
conflict
with
the second
law. On the
contrary,
your
remark refutes
an
old
objection
that
has
been raised
from time
to
time
by
Geheimrat
Voigt,[1] one
that
I could
never
really
put
out
of
my
mind.
He
said
that
light energy
that
is
not
perceptible
in
itself
might
nevertheless
be
detected
through accumulation,
by way
of
photography,
for
example.
I
only
replied
that
no one
knows how
non-natural
radiation[2] affects
the
plate,
but
I
was
not
really
satisfied with this
answer.
Because
I
am
not
sure
that
the
disorderliness of
radiation
is
essential
to photochemical
processes.
Your remark reminds
me
that
such
an
accumulation of
quantities
of molecular
energy
need
not
be
admitted
as possible.