176 DOCUMENT 122 SEPTEMBER
1915
einer
wirklichen
Lichtabsorption (Verwandlung
in
Wärme)
entsprechen.[8]
Sie
sa-
gen
aber nichts
darüber,
inwiefern wir
wissen,
dass eine
derartige
wirkliche Ab-
sorption
nicht
stattfinde.-
Wahrscheinlich habe ich Sie missverstanden.
Über Ihre
Abhandlung
habe ich mich sehr
gefreut.[9]
Ich habe auch einen Beweis
für
die
Gültigkeit
des
Impuls Energ[ie]satzes
des
elektromagnet.
Feldes mit Be-
rücksichtigung
der
Gravitation
gefunden
sowie eine kovariantentheoretisch verein-
fachte
Darstellung
der
Vakuumgleichungen,
indem sich
der
Begriff
des
"dualen“
Sechservektors als entbehrlich
erweist.[10]
Ich bin
gerade
mit
dem
Studium Ihrer
Arbeit
beschäftigt.
Ferner
lese ich mit
Bewunderung
die
geistreiche
Broschüre No
3
Nico Van Suchtelens.[11] Eine förmliche
Revokation des
berüchtigten
Manifestes
werde ich wohl
kaum
herbeiführen
können,[12]
trotzdem die Erkenntnis sich Bahn
gebrochen
hat,
dass
es
sich
hier
um
einen recht
unglücklichen
und
schlecht
erwo-
genen
Schritt
gehandelt
hat.[13]
Ich halte
es
für noch
wichtiger,
dass die
Gutgesinn-
ten in den
Dingen Zusammengehen,
die
für
die Zukunft
von
realer
Bedeutung
sind.
Man erkennt den
Reuigen
nicht in erster
Linie
am
Revozieren.-
Es
grüsst
Sie
herzlich
Ihr
A. Einstein
Ich bitte
Sie,
den
Grass
Ihrer Frau freundlich
zu
erwidern.
ALS
(NeHR,
Archief
H. A.
Lorentz). [16 440].
There
are perforations
for
a
loose-leaf
binder at the
head
of
the
page. Cropped.
[1]Einstein
was
in Switzerland from
5
until
21
September.
[2]The
deletion
was presumably
suggested by
Lorentz
in connection with his
editing
of
the
discus-
sion remarks made
at
the second
Solvay Congress
in October 1913
(see
Doc.
103,
note
5).
Eduard
Grüneisen
(1877-1949)
was
Professor
of
Experimental Physics
at
the
University
of
Berlin. Einstein
made
a lengthy
comment
after his
Solvay
lecture
(see
Vol. 4,
Doc.
22,
pp.
555-559).
[3]Wander
de Haas had carried
out
a new
series
of
experiments
on
molecular
currents
in
Teyler’s
Institute in
Haarlem,
of
which Lorentz
was
Curator.
Employing a new
method
to
eliminate
disturbing
effects,
he found
good agreement
with
theory.
The
results
were published
in De Haas 1915. See
also
Vol.
6, the editorial note, “Einstein
on Ampère’s
Molecular
Currents,” pp.
145-149.
[4]The same
idea
is mentioned
in
Doc. 61.
[5]The experiment
was
described the
next year
in Einstein 1916d
(Vol. 6,
Doc.
28).
[6]The
De Haas family had moved to the country town
of
Deventer
(see
Doc.
107,
note
3).
[7]The
“Delbrück-Demburg petition,” urging
abandonment of
annexationist
policies
and
signed by
Einstein,
Max
Planck,
David
Hilbert,
Heinrich Rubens (1865-1922),
Professor of
Experimental
Physics
at the
University
of
Berlin,
and
more
than
one
hundred others in
July,
had received wide-
spread
attention in
Germany, appearing even
in
right-wing
journals
such
as
the Rheinisch-West-
fälische
Zeitung
(see
Die Friedens-Warte
17
(October
1915),
no.
8,
p. 298).
[8]See
Lorentz
1914b,
in which
a theory
of
the width
of
spectral
lines is
developed,
based
on
the
assumption
that the lines
are produced by
damped
electronic vibrations
within
the individual atoms.
Lorentz considered two
damping
mechanisms:
radiation
damping
and
damping as a consequence
of
atomic collisions.
Both
mechanisms
give
rise
to
friction terms
proportional
to the
velocity
in the
equa-
tion of motion for
a vibrating
electron,
with friction constants
g1
and
g2, respectively.
A
calculation
of
the ratio
of
these two coefficients for sodium
based
on a simple
model leads to the result that col-
lisions would
cause
an absorption
172 times
as strong as
that caused
by
radiation. Because radiation
damping by
itself
gives
rise
to
the well-established
Rayleigh scattering
formula,
Lorentz concluded
that
in
reality
the
effect of
collisions
was
much
smaller
than his model
predicted.