158
DOC.
160 DECEMBER
1915
A
more
stringent
test of this
prediction
of the
theory
could be
performed
on a
binary
star
composed
of
two
stars
of substantially
different
sizes.
We
would
then
no longer
be
dependent
on
establishing
a mean
value,
but
could test
the
theory
directly
from
the
observational
data
gained
from
a
single
binary
star of
that
type.
This
is
one
of
the
projects Mr. Freundlich aims to
carry
out.[4]
2.
The
theory
provides
that
(owing
to
the imprecise validity of Newton's theory)
the
elliptic
orbits
of
the planets
rotate
slowly
around the Sun (in the
orbital
direction)
instead
of
being
fixed in
space. This consequence
of
the theory
has
been verified brilliantly with
the
planet
Mercury.[5]
3.
The
theory
provides
that
a
light ray passing
by
a celestial body
is
deflected
by it.
light ray
star
Now,
this
consequence
is
the
most
interesting
and
astonishing
of
all,
and
prob-
ably
also
undoubtedly
the
theory’s
most characteristic
one;
and
precisely
this
consequence
has not
yet
been
subjected
to
any
test.
It
is
true
that
our Academy
has
sent
an
expedition
to
Russia,
led and
organized by
Mr. Freundlich for
the
observation of
the latest
solar
eclipse
in order
to study
the
effect produced
by
the
Sun.
But
unfortunately
war
(and weather) deprived
this
expedition
of
success.[6]
Through close
examination
of
the available observational
material,
Mr.
Freundlich
now
arrives
at
the result that
the
light-deflection
effect
could be
demonstrated
also
with the
planet Jupiter,
although
only
with
the subtlest
of
photographic
measurements
and
through
an
increased number of observations.
The
most
im-
portant
specialists
in
the
pertinent field
of
precision technology
confirm
that
the
observational
method
conceived
of
by
Mr. Freundlich
ought
to
lead
to
the
objective.[7]
This
is
the
most
important project
for Dr. Freundlich.
It
could be carried out
at
the
observatory
in
Neubabelsberg
without
any
substantial
cost.
It
would
just
be
necessary
that
Mr. Freundlich be released for
a
few
years
from
the routine
duties
of
measuring
star
positions
so
that
he could devote himself in
peace
to
the
projects
indicated
here.[8]
If Your
Excellency
wishes
more
detailed information
on
this
or
that
point, I
am
naturally
gladly
prepared
to
provide
them
for
you personally.
I
preferred
to
remain
a
bit
unspecific
here
so as
not to tax
your patience
excessively!
(sig.)
A.
Einstein.
Telephone
Pfalzburg 7273.