442
DOCS.
435,
436
JANUARY
1918
Only by again having
staff members with not
only
practical
but
also
theoret-
ical
training
at
the
large
observatories at New
Babelsberg
and Potsdam and
by
also
granting
them the
necessary
freedom of
action,
can an
improvement
in
the
current conditions be
brought
about.
Among
the
younger
astronomers at New
Babelsberg
and
Potsdam,
to
my knowledge,
Mr. Freundlich
is
the
only
one
with
a
solid
knowledge
of
mathematics,
celestial
mechanics,
and
gravitation
theory.
Although
considerably
less
talented than
Schwarzschild,
he nevertheless
recog-
nized
the
importance
of modern
gravitation
theories to
astronomy many years
before
the latter did and has worked
fervently
toward
verifying
the
theory
along
astronomical
or
astrophysical
lines.[5]
His director’s
negative stance, however, pre-
vented him
seven
years long
from
carrying
out his research
plans
to test
the
theory.
Instead,
year
after
year,
Freundlich
was
forced to
perform
a
task that
any
nor-
mally gifted 18 year-old boy
could be
assigned
to
do after brief
training.[6]
In
the
interest
of science and
equity
it would be
very
desirable if he could be
employed
at
one
of
the
two
large
institutes in such
a
way
that
he
could,
within
certain lim-
its, freely
choose
the
topic
of his research. The fact
that Mr.
Freundlich
has not
yet
had the
opportunity
to
acquire
practical
skills in
certain
areas
of
astrophysics
is
infinitely
less
significant
compared
to
the
favorable
qualifications
mentioned.
This
deficiency can
be offset within
a
short time.
It
is
quite inconsequential
to
the issue whether Mr. Freundlich
ought
to be
employed
at New
Babelsberg or
at
Potsdam;
formally speaking,
Potsdam
would be most
suitable,
because testing
gravitational
theory
must be
seen as an
astrophysical
task.
Very respectfully,
A.
Einstein.
436. From
Rudolf Humm[1]
Göttingen,
14
Planck
St.,
15
January 1918
Esteemed
Professor,
While
preparing
a
talk
on
your
and de Sitter’s
boundary
conditions at
infinity,[2]
I
noticed
the
following,
which relates to
your
new
gravitation
equations.
These
equations
are:
A"fiv
^-9-
k
29pvT^
dxß
dxy
= p-
ds
ds
(1)