144
DOC.
3
STATICS OF
GRAVITATIONAL
FIELD
Lichtgeschwindigkeit
und
Statik
des
Gravitationsfeldes.
369
tationspotential,
so
werden die
Naturgesetze
von
ausgezeichnet
einfacher und invarianter
Form,
wenn man
sie
auf ein Raum-
Zeitsystem
derjenigen Mannigfaltigkeit bezieht,
welche
durch
die
Lorentztransformationen mit konstantem
c
miteinander
ver-
knüpft
sind.
Beschränkt
man
sich
nicht auf Gebiete
von
kon-
stantem
c, so
wird die
Mannigfaltigkeit
der
äquivalenten
Systeme,
sowie
die
Mannigfaltigkeit
der die
Naturgesetze
un-
geändert
lassenden Transformationen eine
größere
werden,
aber
es
werden dafür
die
Gesetze
komplizierter
werden.
Prag,
Februar
1912.
(Eingegangen 26.
Februar
1912.)
Published
in
Annalen der
Physik
38 (1912):
355-369. Dated
Prague, February 1912,
received
26
February 1912, published
23
May
1912.
[1]Einstein 1911h
(Vol. 3,
Doc.
23).
[2]Although the
hypothesis
of the
equivalence
of
(uniformly)
accelerated reference frames
and
gravitational
fields
was
earlier formulated
in
Einstein
1907j (Vol. 2,
Doc.
47)
and
in
Einstein 1911h
(Vol.
3,
Doc.
23),
this
is
the
first
time Einstein
uses
the
term
"equivalence
hypothesis"
("Äquivalenzhypothese").
Later
in
this
paper
the
term
"equivalence principle"
("Aquivalenzprinzip")
is
used
(pp.
360, 366).
[3]Abraham
1912a.
For
an
account
of the debate between Einstein and Abraham
on
the
problem
of
gravitation,
see
the editorial
note,
"Einstein
on
Gravitation and
Relativity:
The
Static
Field,"
pp.
124-127.
[4]For this
definition of what
is
now
often called
proper
acceleration,
see
Born
1909, §5.
The
problem
of
defining
acceleration
was
earlier discussed
by
Einstein
in
Einstein 1908b
(Vol. 2,
Doc.
49).
[5]This is
one
of
the
earliest indications that the
problem
of the
rotating
disk
played
an
important
role
in
the
development
of
general relativity;
for another
early
indication,
see
Einstein
to
Arnold
Sommerfeld, 29
September
1909
(Vol. 5,
Doc.
179).
In
Einstein
1916a,
pp.
774-
775,
the
rotating
disk
is
cited
as an
argument against
the direct metrical
meaning
of coordinates
and for the
necessity
of
introducing a
non-Euclidean metric. For
an
extensive historical dis-
cussion,
see
Stachel
1980.
[6]Laue
1911b shows that
any
definition of
a
rigid body
would
be in
conflict with the
impli-
cation of the
special theory
of
relativity
that
no
signal velocity
can
exceed the
velocity
of
light.
For further discussion of this
problem, see
Vol.
3,
the editorial
note,
"Einstein
on Length
Contraction
in
the
Theory
of
Relativity,"
pp.
478-480.
[7]"Fortsetzung" should be
"Festsetzung."
The condition
given
here
is
weaker than the
ones
Einstein
had formulated
in
earlier discussions of the definition of
simultaneity
(see,
e.g.,
Ein-
stein 1905r
[Vol.
2,
Doc.
23],
§1,
and Einstein
1907j [Vol. 2,
Doc.
47],
§1).
[8]This
equation
should have
no
number.