INTRODUCTION
TO
VOLUME
6
xix
in the third and
final
paper. Interestingly,
none
of
the
papers
contains
any
ref-
erence
to
the "hole
argument"
which had
played
such
a
crucial role
in
Ein-
stein's earlier
thinking.
It
is
only through
Einstein's
correspondence
that
we
know that
he
came
to
reject
it when he realized that
not
the metric
field,
but
only
the
totality
of
space-time
coincidences has
physical meaning.[19]
Even before the last of the three
papers
of November
1915
had been
pub-
lished,
Einstein
used his
generally
covariant
field
equations
to
calculate the
perihelion
motion of
Mercury, arriving
at
the
result
of
43
seconds
of
arc per
century,
in
very satisfactory agreement
with
observations.[20]
When he
saw
the
result,
Einstein later told
his former
collaborator Adriaan
Fokker,
he
was
so
excited that he had heart
palpitations.[21]
A
few months after the
final
papers
had
appeared,
Einstein
was
ready
to
spend
some
time
writing
a
review
paper
in which the whole
theory
was
pre-
sented and
explained
in
a
consistent and accessible
way.
The
paper appeared
in the Annalen
der
Physik
(Einstein
1916e
[Doc. 30]),
but
was
also
widely
sold
as a
separate
booklet
(Einstein 1916f).
It
gives
an
excellent overview of
the
theory.
In the
same
year
Einstein also
completed
a
book-length popular
exposition
of
both the
special
and the
general theory,
Einstein 1917a
(Doc.
42).
It
was an
instant
success
and remains
a
classic
to
this
day.[22]
The
new
theory
also
gave
rise
to
other elaborations and
consequences: a paper on
the
Hamiltonian
formulation
of the
theory
(Einstein
1916o
[Doc.
41]),
an
earlier
manuscript
version of which
is
presented
in this volume
as
Doc.
31,
and
a pa-
per on
gravitational
waves
(Einstein 1916g
[Doc.
32]),
which had
to be
re-
tracted in
1918 because
of
a
serious
error.
III
In
the
spring
of
1917
Einstein
published
his first
paper on cosmology,
Ein-
stein 1917b
(Doc.
43).
It
may
be said
to
mark the birth
of
modern
cosmology.
Einstein's interest in
cosmology
derived from his
conviction,
already
men-
tioned
above,
that
a
theory
of
gravitation
should include in
some way or an-
[19]See
Einstein
to
Paul
Ehrenfest,
26 December
1915,
and Einstein
to
Michele
Besso,
3
Jan-
uary
1916.
[20]See
Einstein 1915h
(Doc. 24),
submitted
18
November
1915.
The
speed
with which
Ein-
stein
performed
the calculations and
developed
the
approximation procedure
he
employed in
this
paper
has become less
surprising
now
that
we
know
that he could draw
on
his earlier work
with Besso.
[21]See
Fokker
1955,
p.
126.
[22]See
the editorial
note,
"Einstein's
Popular
Book
on Relativity," pp.
417-419
,
for
more
details.