632
DOCS.
605,
606
AUGUST
1918
luminescence in
the
gases proves
to
me
that
the
molecular structures
are
sharply
defined and do
not
vary
with
the
individual
mass
limits. Your
comparison
of the
theoretical
arguments
to the
bundle
of
brushwood from
the
familiar fable
is
a
good
one![13]
Your
way
of
extricating
the
individual
twig, however,
and of
showing
that
it
can
be
snapped
seems misleading
to
me.
The
value of
a hypothesis
lies in
the
multiplicity
of its results.
A
hypothesis
belonging
within
a
theoretical
complex
can never
be
proven.
Your
experiments
also
are
theoretically explained.
You also
recognize
the
admissibility
of
individual
methods
of
determining
B
just
by
the
fact
that
they
provide
concurring
results:[14]
hence
along an
indirect
path.
On
the
whole,
it
is
thus
with electrons
as
well.
One
more
thing. Negative
radiation
pressures
are
impossible
for substances
that
absorb
light
because such
pressures
would
contradict the
principle
of reaction.
Consider the
following rigid system.
If
the
metal did
not
experience
the
same
forces of
pressure
as
the
sulfur,
the
system
would have
to set
itself
into
motion,
if
it
was
suspended
in
a vacuum.
sulfur
screen
light
source
metal
screen
Whatever
may
be
the
final result of
your fascinating investigations,
one
thing is
certain;
none
of
your
critics has offered
anything
convincing
against
your analyses.
With best
regards, yours,
A.
Einstein
m[anu]
p[ropria]
606. To Hermann Anschutz-Kaempfe
Ahrenshoop, 22 August 1918
Esteemed Dr.
Anschütz,
I
read
your explanations
about the
book
by
Usener with interest.[1]
Now I
really
know
why
Usener sent
me
the little
book
a
while
ago![2]
I
do
not
doubt
the
dishonest
intent
of its author, who
uses
such
sophisticated
tactics,
and
I
can
imagine
how
offensive
such conduct
is.
But
everyone
knows
that it
was you
who
first
brought
the
gyrocompass
into
being.
You arrived
at
this
goal
by
reducing
the
horizontal
stability.
How
obvious
this
solution
was
is
a
moot
question;
the
point
is
to
hit
upon
it!
In
wishing
that, from
now
on, you
will
not be
plagued
and
injured
anymore
either
by
the
mala
fides
of
interested
parties
or
by
the
limited
understanding
of
impartial experts
in
the
field,
I
am yours
truly,
sig.
A.
Einstein.
(from
the
day
after
tomorrow,
back at
5
Haberland
St.,
Berlin)