582 DOC. 60
CONSTITUTION
OF
RADIATION
500
Verhandlungen
der Deutschen
Physikalischen
Gesellschaft.
[Nr.
20.
Singularitäten
viele
in Abständen
vorhanden,
die klein sind
gegen-
über
den
Abmessungen
des
Kraftfeldes eines
singulären
Punktes,
so
werden die Kraftfelder sich
übereinanderlagern
und
in
ihrer
Gesamtheit ein undulatorisches Kraftfeld
ergeben,
das sich
von
einem undulatorischen Felde im
Sinne
der
gegenwärtigen
elektro-
magnetischen
Lichttheorie vielleicht
nur
wenig
unterscheidet. Daß
einem
derartigen Bilde, solange
dasselbe nicht
zu
einer exakten
Theorie
führt,
kein
Wert beizumessen
ist,
braucht
wohl
nicht
be-
sonders
hervorgehoben
zu
werden. Ich wollte durch dasselbe
nur
kurz
veranschaulichen,
daß die beiden
Struktureigenschaften
(Undulationsstruktur
und
Quantenstruktur),
welche
gemäß
der
Planckschen
Formel beide
der
Strahlung
zukommen
sollen,
nicht
als miteinander unvereinbar anzusehen sind.
P.825[/ein-
ander-
lagern]
Published
in
Deutsche
Physikalische
Gesell-
schaft, Verhandlungen
7
(1909):
482-500.
Lec-
ture,
held
on
21
September
1909,
published
30
October
1909.
[1]
The
session
was
chaired
by
Woldemar
Voigt
(see Versammlung 1909a,
p.
417,
and
1909b, p. 778).
A list
of
some
of
those in
atten-
dance
is
given
in
Mehra and
Rechenberg
1982,
p.
121.
[2]
Khvolson
1902,
p.
9.
[3]
See, e.g.,
Einstein 1905i
(Doc. 14).
[4]
See,
e.g., Lorentz
1895.
[5]
See,
e.g., Wiener 1890 and
Drude
1891.
[6]
The
expression
for
the
pressure
exerted
by
light was
first derived in Maxwell
1873,
§
792.
It
was
experimentally
confirmed in Lebedev
1901 and Nichols
and
Hull 1903.
[7]
See
Fizeau 1851.
[8]
Fizeau
actually
considered three
possibili-
ties: the ether
is
totally dragged
by
the
moving
body;
it
is not dragged
at
all; or,
in
accord
with
Fresnel's
hypothesis,
it
is partially dragged.
His
results
are
in accord with
Fresnel's
hypothesis.
[9]
In this
equation, n
is
the index of refraction
of
the
body through
which
light
is
propagating.
[10]
For
a
discussion
of
this
problem, see
Hi-
rosige
1976 and Swenson 1972.
[11]
Lorentz 1895.
[12]
Michelson
and
Morley
1887.
[13]
See Lorentz
1892b;
FitzGerald
1889.
[14]
See Einstein
1905r
(Doc. 23)
and the edi-
torial note,
"Einstein
on
the
Theory
of
Relativ-
ity,"
pp.
253-274.
For details
of
the follow-
ing summary
of
the
nature
of
light
in the
relativity theory, see
Einstein
1905r
(Doc. 23)
and
Einstein
1905s
(Doc. 24).
[15]
For
a
discussion
of
the connection between
Einstein's work
on relativity
and
on light
quanta, see
the Introduction,
pp.
xvii-xviii.
[16]
See Einstein 1905s
(Doc. 24).
[17]
See Einstein 1905i
(Doc. 14),
Einstein
1907a
(Doc. 38),
and Einstein 1909b
(Doc. 56),
p.
191.
[18]
See Lenard
1902, pp.
166-168.
[19]
This
hypothesis, now
known
as
the
"trig-
gering
hypothesis,"
appeared
in
Lenard
1902,
pp.
150 and 170. It is also used in
Thomson,
J. J.
1905,
pp.
588-589; Wien
1905;
Ladenburg
1907; and
in
a
postscript
to Hendrik
Lorentz to
Einstein,
6
May
1909. In his
reply
to the
last,
Einstein
to
Hendrik
Lorentz,
23
May
1909,
Ein-
stein refuted
Lorentz's
version
of
the
hypothe-
sis,
whereby
the electrons
are
ejected
with
ve-
locities
equal
to their thermal motions in the