370 DOCUMENT
281 NOVEMBER 1916
die
ja
nichts
neues
enthält.-
Hoffentlich
können
Sie
aus
dieser
kurzen
Resumé
se-
hen, wovon
die Sache sich handelt. Ich
habe darüber
eine kleine
Mitteilung zusam-
mengeschrieben
und
werde dieselbe
hier
in Holland veröffentlichen.[10]
Vom Hause erfahre
ich,
dass als
Sachverständige,
die sich
über
das Besetzen des
Professorats
an
der techn. Hochschule äussern
sollen, folgende
vier
Personen
aus-
gesehen
sind: zwei
Helsingforserprofessoren
Sundell und
Melander,
Bjerkén an
der
techn.
Hochschule Stockholm
und
Birkeland in
Norwegen.[11]
Ich
hoffe,
dass
mein
Vetter Carl
Hirn bei Ihnen
gewesen
ist.
Sende Ihnen die herzlichsten
Grüsse,
und
hoffe,
dass wir
uns
im nächsten Jahre
wieder sehen werden.
Ihr
Gunnar
Nordstrom.
ALS.
[18 427].
[1]Einstein had renewed his
acquaintance
with Nordstrom
two
months
earlier
in
Leyden,
where
Nordstrom
was
boarding
with the Ehrenfest
family,
in
whose home Einstein also
lodged (see
Doc.
263).
[2]The
question
of
the
boundary
conditions at
infinity
had been
a topic
of
discussion
during
Ein-
stein’s recent visit to
Leyden.
The discussion
was
continued
in
correspondence
between
Einstein and
Willem de Sitter and in
papers
by
De Sitter
(see
Docs. 272 and 273
for
more
details).
[3]See
Droste 1916a.
[4]Herglotz
1911.
[5]The
“rest deformations”
are
found
by
considering
a
deformed volume
element
in
a moving body
and
performing a
Lorentz transformation that
brings
the
volume element to rest. In this
way,
the effect
of
the Lorentz
contraction
is
separated
from the
actual deformation.
Herglotz’s equations
(16')
express
the coefficients
eij
characterizing
the
rest deformations in the coefficients
Aij,
which
are
defined
as
in
eq. (1)
of this
document,
with
guv
replaced
by
the Minkowski tensor. The coefficients
aij
are
defined
through dxi
= aijdEj,
where
xi are
the coordinates
of
a
moving
point
that has
coordinates
Ei
before
deformation.
[6]P
is the
Lagrangian
for the motion
of
the
body; £2
is
a
function
of the
deformations and the
entropy
e.
[7]Herglotz’s eq.
(68)
is:
DFij
=
a
a®
jhda:ih ,
with
Fij,
the
energy-momentum
tensor.
[8]Nordström
refers
to
eq. (19)
in Einstein
1916o
(Vol.
6,
Doc.
41),
which
gives
the
energy-
momentum tensor
of
matter
as a
derivative
of
the
material
part
ül
of
the
Lagrangian.
[9]The
following equation,
the
energy-momentum
conservation
law,
is identical to
eq. (22)
of
Einstein 1916o
(Vol.
6,
Doc.
41).
[10]Nordström’s
paper
had been communicated
by
Hendrik
A. Lorentz to the Amsterdam
Academy
on
25 November 1916 and
was published as
Nordstrom
1917.
[11]Nordstrom,
who had
a
three-year fellowship
in the Netherlands
(see
Doc.
112,
note
3), was
looking
for
a
permanent
position, preferably
in
his
native Finland. One such
possibility was
a profes-
sorship
in
physics
at the Technical
University
of
Helsingfors (Helsinki) (see
Isaksson 1985,
p. 49),
for
which the
following
four
referees
were
chosen:
August
Fredrik Sundell (1843-1924),
Emeritus
Professor
of
Physics
at the
University
of
Helsingfors;
Gustaf
Melander (1861-1938),
Professor and
Director of
the Central
Meteorological
Station in
Helsingfors;
Pehr Constantin Bjerkén (1859-1919),
Professor
of
Physics
at the Technical
University
of
Stockholm;
and Kristian
Birkeland
(1867-1917),
Professor
of
Physics
at
the
University
of Kristiania
(Oslo).
For Nordstrom’s
candidacy
more
than
a year
earlier
at the
University
of
Berlin,
see
Doc. 112.