DOCUMENT 19 JULY 1914 41
of Sciences
to
Einstein,
22
November
1913
[Vol.
5,
Doc.
485]). Payment was
to be
on a quarterly
basis.
In
mid-May
a
ministerial decree
formalizing
these terms
was
drafted
(see
Friedrich
Schmidt
(-Ott)
to
Königliche
Akademie
der
Wissenschaften, 12
May
1914,
GyBAW,
II-III, Vol. 36,
p. 101).
[3]Two
days
later,
Planck
recommended
that Einstein’s
special personal
income
as a
member of
the
Academy
be reinstated should he be forced to
give up
the
directorship
of
the Kaiser Wilhelm Institute
or a
similar office
(see
the minutes
of
the
meeting
of
the
Secretariat of
the
Academy,
9
July 1914,
GyBAW,
II-V, Vol. 176).
The
entire
Academy expressed
its
agreement
shortly
thereafter
(see
Wilhelm
Waldeyer
draft to
Einstein,
20
July 1914,
and
preceding
text,
GyBAW,
II-III, Vol. 36, p. 105).
[4]In
his
response
(Planck
1914) to
Einstein 1914k
(Vol. 6,
Doc.
3),
Einstein’s
inaugural
lecture at
the
Academy
five
days
earlier,
Planck
had
argued
that the
restricted
covariance
of
the “Entwurf” the-
ory
implied
that this
theory was
not
a
true
generalization
of
special relativity.
He had also
expressed
skepticism
about the need
to
generalize special relativity
to include accelerated motion.
[5]In
Einstein
and
Grossmann 1914b
(Vol.
6,
Doc.
2),
pp.
220-225, and in Einstein 1914o
(Vol.
6,
Doc.
9), pp.
1067-1074,
the
covariance
properties
of
the “Entwurf”
theory are
discussed
in terms
of
“justified”
(“berechtigte”)
transformations
between
“adapted” (“angepasste”)
coordinate
systems.
A
coordinate
system
is
adapted
to
a
particular
metric field
if
the metric field
expressed
in
those
coordi-
nates is
a
solution
of
the field equations
of
the “Entwurf”
theory.
Given
a
metric field
in
adapted
co-
ordinates,
a
transformation to
a new
coordinate
system
is
justified
if
the
new
coordinates
are
also
adapted
to that metric field. It is
not
necessary
that all solutions
in
the old coordinates
are
also solu-
tions in the
new
coordinates.
Earlier,
Einstein had considered
analyzing
the covariance properties
of
the
“Entwurf”
theory
in terms
of
what he called
“dependent” (“unselbständige”)
transformations,
in
which the
new
coordinates
depend
both
on
the old
coordinates
and
on
the metric field
(see
Einstein
to H. A.
Lorentz, 14
August
1913
[Vol.
5,
Doc.
467]).
19. To
Paul
Ehrenfest
[Berlin,]
8.
VII.
[1914][1]
Lieber
Ehrenfest!
Nun
ist
es
mir leider trotz aller
Beteuerungen
von
neulich
unmöglich,
die Reise
mit Euch
zu
machen.[2]
Meine Mutter hat
dieser
Tage
eine schwere
Operation
durchzumachen
(Krebs),[3]
die
[al]le
meine
Pläne
umgeworfen
hat.
Aber
wenn es
auch
heuer
nicht
geht:
Ich
hoffe,
meine nächste
Wanderung
mit Euch
zu
machen.
Die Geschichte
vom
Wasserstoff ist sehr interessant. Aus ihr scheint
endgültig
hervorzugehen,
dass
Quanten
ohne
Nullpunktsenergie
mit der
Erfahrung
unverein-
bar
sind.[4]
Nun aber
muss [m]ans
mit
Quanten
und
Nullp
Energie probieren:[5]
h2
w=(y+1)e ;~=
IG+-I1~22jI
32ir4J\.
ë =
KT2~{1g~(G+1)e1(T}
Die Ausdrucke unterscheiden sich ja nur durch das
1/2
in (a+1/2)2 in
ea