DOCUMENTS
147,
148 APRIL 1909 167
ALS (NeHR,
Archief
H. A. Lorentz).
[16
413].
There
are
perforations
for
a
loose-leaf binder
at
the head of the document.
[1]Hendrik
Antoon Lorentz
was
Professor of Theoretical
Physics
at
the
University
of
Leyden.
[2]Einstein
1909b
(Vol. 2,
Doc.
56).
[3]In §7
of Einstein 1909b
(Vol. 2,
Doc.
56)
the fluctuations of the
radiation-pressure
are
calculated with the
help
of Planck's
law.
The result
turns out to
be
incompatible
with
a
theory
based
on
electrodynamics
and molecular mechanics
only.
[4]James
Jeans;
see
Jeans 1905e for his derivation
of
the displacement
law
using
dimension-
al
considerations.
[5]In §10
of Einstein 1909b
(Vol. 2,
Doc.
56)
Einstein
uses a
generalization
of Jeans's
ap-
proach
to
derive
a
general
form for the radiation
formula,
which includes both the
Rayleigh-
Jeans law and Planck's law
and
contains
an
unspecified
scalar function.
Comparison
with
Planck's law leads
to
the conclusion that Planck's
constant
h is
determined
by
the
quotient
Ģ2/c (with
e
the
elementary charge
and
c
the
speed
of
light),
up
to
a
numerical factor with the
approximate
value of
900.
147.
To
Johannes Stark
Bern, 6
April
1909.
Einstein
expresses pleasure
"that
you
have
achieved
an
external
position commensurate
with
your outstanding capacity
for work. But
I
am
also rather
pleased
that
you
hit
upon
the idea of
choosing
me
to
assist
you,
even
if
I
am
not
in
a
position
to
accept your friendly
offer.
As
I
am
married,
the income from
such
a
position
would
not
be
sufficient"
("daß
Sie
nun
eine äußere
Stellung erlangt haben,
die Ihrer eminenten Arbeitskraft
entspricht.
Nicht
wenig
freut
es
mich
aber
auch,
daß Sie darauf verfallen
sind,
mich
zu
Ihrem Mitarbeiter
zu
wählen,
wenn
ich auch
nicht
in
der
Lage
bin,
Ihr freundliches Anerbieten anzunehmen. Da ich verheiratet
bin, wären
die Einnahmen
jener
Stelle nicht
groß genug").
Stark
was
appointed
Professor of
Experimental
Physics
at
the Technical
University
of Aachen
on
1
April
(see
Aachen
Programm
1909,
p.
166).
Einstein's
salary
at
the Swiss Patent Office
was
4500 francs
(see
Doc.
34).
Einstein sends him his "most
recent
paper,
which
is
primarily
critical,
but also contains the
reasons
which
cause me
to
ascribe
a
kind of molecular constitution
to
radiation"
("neueste
Ar-
beit,
die
hauptsächlich
Kritisches
enthält,
aber auch die
Gründe,
die mich dazu
bewegen,
der
Strahlung
eine Art molekularer Konstitution
zuzuschreiben").
The
paper
is
Einstein 1909b
(Vol.
2,
Doc.
56).
The
source
of this document
is
the
description
of
an
ALS in
the Karl und Faber dealer
cat-
alogue
89
(spring 1964),
lot 2657.
[22
357].
148.
From Johannes Stark
Aachen,
Lütticherstr.
189.
8.
IV. 09.
Sehr
geehrter
Herr
Kollege!
Ich danke Ihnen für Ihren freundlichen
Brief.[1] Wenn
es
mich auch sehr
ge-
freut
hätte,
Sie
zu
gewinnen,
so
mußte ich doch eine
Ablehnung
von
Ihrer
Seite
erwarten.[2]
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