DOCUMENT
357
JUNE
1917
477
[5]In
the
equation
below,
h2 should be
1
-
|iA2
(see
Kerszberg
1989b,
p.
186,
for
a diagram,
and
Doc. 321,
note
9,
for
a
discussion
of
De Sitter’s comments
on
this
hyper-surface).
Einstein
made the
same error
in Doc. 325.
[6]See
De Sitter’s correction to Einstein’s calculation
of
late March
(see
Doc.
317,
in
particular,
note
6),
which
was
conveyed
to Einstein in
mid-April (see
Doc.
327).
[7]The
light cone
of the
origin
of
the coordinate
system
used is
given by
h2
=
0,
which
is
asymp-
totic to the
hyper-hyperboloid 1
-
\th2
=
0
.
[8]The origin
in
the
coordinate
system
used
is the
point
where the
stereographic
hyperplane
touch-
es
the
hyper-hyperboloid
representing
the
De Sitter
solution
in
a
4+1-dimensional Minkowski
space-
time. Since this
point can
be
chosen
arbitrarily,
it is
clear
that its
apparently privileged
status
is,
in
fact,
an
artifact
of
the chosen coordinates.
[9]When
he first
presented
his
new
solution
to
the field
equations
with
cosmological
term,
De Sitter
emphasized
the
danger
of
extrapolation
beyond
the visible part
of
the universe
(see,
for
instance,
Doc. 321 and De Sitter
1917a).
In
the
subsequent
closer
examination
of
his solution,
De
Sitter
became
more
willing
to
consider
questions
about the
global
geometry
of
the universe
(as
is
evident
especially
from
the
preceding
document
and
from
De
Sitter
1917b, 1917c).
[10]De
Sitter
was
recuperating
from tuberculosis in
a
Doorn sanatorium
(see
Doc.
321).
Paul
Ehrenfest had noted
a
marked
improvement
in his
condition
a
week earlier
(see
Doc.
352).
357. To Michele
Besso
[Berlin,]
24. VI.
[1917][1]
Lieber
Michele!
Zwischen
5.
& 7. Juli hoffe ich in Zürich eintreffen
zu
können. Ich
freue
mich
unbeschreiblich, wenn
auch die Reise selbst
jetzt
eine
grosse Strapaze
sein
soll.[2]
In Zürich bleibe ich
nur wenige
Tage,
weil dies
zu
strapaziös
ist für meinen kräche-
ligen
Leichnam.[3] Dann
gehe
ich
mit Albert
nach
Arosa,
hierauf
nach Luzern
zu
meiner
Schwester, wo
ich
mich
mehrere Wochen
aufhalte.[4]
Ich freue mich
sehr,
auf
unsere Gespräche,
auch
auf
Dällenbach, wenn er
da ist.
Hoffentlich sehe ich auch Weiss
wieder,
der wieder in Zürich sein
soll.[5]
Sei nicht
bös,
dass ich Dir
so wenig
schreibe;
das
geht
wies
scheint nicht anders! Gute Vor-
sätze nützen nicht
für
die Dauer!
Sei mit Anna und Vero bestens
gegrüsst von
Deinem
Albert.
Ich verreise
Freitag
&
bin
bis
zu
meiner
Abreise
in die Schweiz bei
meiner
Mut-
ter.[6]
AKS
(SzGB).
Einstein/Besso 1972,37
(E. 29).
[7
309].
The
verso
is addressed
“Herrn M. Besso Uni-
versitätsstr. 33
Zürich.,”
with
return address “Abs. A.
Einstein
Wittelsbacherstr 13 Berlin.,”
and
post-
marked
“Berlin-Wilmersdorf
1
[25.6.17.
-].”
The
postmark
in the
photocopy
available to the editors
is obscured.
[1]The
year
is
provided by
the reference to Arosa.
[2]Presumably
because
of
the
delays
at the
German-Swiss border
(see,
e.g.,
Doc.
178).
[3]Einstein’s
planned trip
to
Frankfurt
at the end
of
the
month
was
also
to
be kept
short
on
doctor’s
orders
(see
Doc.
354).
[4]With
Hans
Albert,
Einstein
planned
to visit Eduard in
Arosa
(see
Doc.
344).
The
subsequent
stay
with
Maja
Winteler-Einstein in Lucerne
was
in lieu
of
a
proposed
rest-cure in the
mountains,
which