DOCUMENT 361 JULY 1917
483
der
Aufpunkt
hat die Koordinaten:
r
=
b,
cp
=
0,
u
=
u.
b
» a
höhere
Potenzen als
a2/b2
und
w2
werden
vernachlässigt.
Der
Einfluß der Rotation
besteht
für sehr
entfernt
gelegene
Punkte
nur aus
einer
Vergrößerung
der scheinbaren
Masse;
bei
Aufpunkten,
für
welche
a2/b2
nicht
mehr
vernachlässigt
werden
kann,
tritt
ein Glied
hinzu,
welches dem
Felde
seine
Zentralsymmetrie
raubt. Halten Sie
es
für
möglich,
daß
man
einen
Einfluß
auf
den
innersten
Juppitermond
beobachten
könnte.
Der
Jupiter
hat
von
allen
Planeten
das
größte
co
und das
größte
a-ich
fürchte,
daß
aber trotzdem
der Effekt
gegenüber
den
Störungen
der Monde
untereinander
und
gegenüber
der
Perihelbewegung zu
klein ist.
Am
Schlüße eine kleine
Bemerkung zu
Ihrer
kosmologischen
Arbeit:[16] Das
"mittlere“ Linienelement
der
sphärischen
Welt
(Gl. (12)
S.
150)
läßt sich
ganz
schön in Polarkoordinaten
ausdrücken,
welche für diesen Raum
orthogonale
Koor-
dinaten
sind. Es heißt
dann:[17]
ds2
=
-
^1
- ~
r2^2
-
r2sin2$Ap2
+
dt2.
ADft
(AVZB, Thirring Nachlaß). [84 047.1].
At the
head of
the
draft,
which
is
on
pp.
49-51 of
a
Thirring
notebook entitled
“Wirkung
rotierender
Massen”,
the author noted: “Brief
an
Einstein
11.
7.
1917." The number “17” has
been
superimposed on
“11” in the date.
Thirring
noted “12. VII.
17.”
at the head
of
p.
50. The
designations
“Brief
an
Einstein
Forts.” at the head
of
pp.
50
and
of
51
are
omitted.
[1]Thirring
(1888-1976)
was
Privatdozent
in
physics
at
the
University
of
Vienna.
[2]Philipp
Frank.
[3]Karl
Ludwig
Flamm (1885-1964)
was
Assistent
at
the
Physical
Institute
of
the
Technical
Uni-
versity
of
Vienna and Privatdozent in
physics
at the
University
of
Vienna. His
published
paper
is
Flamm
1916;
he
was working on
Flamm
1917,
which he
submitted
two
months later.
[4]A
volunteer
in
the Austrian
Army, Thirring
had been
assigned to
construct
photoelectric
devices
for
military application
(see
Zimmel
and
Kerber
1992,
p.
18).
Thirring’s
calculations
are preserved
in
a
notebook
on rotating
masses,
with
entries from 1917
to
1922,
which also contains this document
and drafts
of
the
publications,
to which this work would lead
(Thirring
1918, on
the metric field
inside
a rotating
hollow
sphere,
and Lense
and
Thirring
1918,
on
the metric field outside
a
rotating solid
sphere).
For
a
discussion of
the
first
publication,
see
Peixoto and
Rosa 1994.
[5]Friedrich
Hasenöhrl
was
Ludwig
Boltzmann’s
successor
as
Professor
of
Physics
at the Univer-
sity
of
Vienna. At the outbreak
of
the
war,
he
joined
the
Austrian
army
and
was
killed in
October
1915, defending
the Isonzo salient.
Thirring,
who had
been
Hasenöhrl’s
Assistent,
assumed
responsi-
bility
for
his
courses
in
mechanics.
[6]Even
before Einstein found
generally
covariant field
equations,
he had
argued,
in the introduc-
tion
of
Einstein 1914o
(Vol. 6,
Doc.
9),
that his
new
theory
of
gravitation
relativizes
rotation
along
Machian
lines because it
establishes
the
equivalence
of
situations
“(I)”
and
“(II)”
mentioned
by
Thirring.
This
passage
from
Einstein’s
1914
paper
is
quoted
in the introduction to
Thirring
1918.
[7]In 1913,
Einstein had
already
calculated the metric field inside
a rotating
hollow
sphere on
the
basis
of
the “Entwurf”
theory
(see
Doc.
245,
note
4,
for
more
details).
[8]Einstein
1916g
(Vol. 6,
Doc.
32).
[9]The
following expression
is the
special case
rf
=
tt/2
(where
0
is the azimuth
angle)
of
the
expression
for g44
given
at
the
end of
this
paragraph.
The
latter
is identical to the
44-component
of
eq.
(13)
in
Thirring
1918. The
square
brackets here and in the
following are
in the text.