370
DOC. 34
EMISSION
&
ABSORPTION
OF
RADIATION
Published
in
Deutsche
Physikalische Gesellschaft. Verhandlungen
18
(1916):
318-323.
Re-
ceived
17 July
1916, published
30
July
1916.
[1]See
Planck
1900b.
[2]See
Planck
1900a, in particular
the discussion
leading to eq.
(34).
[3]Einstein refers
to
Max Planck's calculation of the basic units of
charge
and
mass:
the
electron's
charge and
the
mass
of the
hydrogen atom
(see
especially
Planck
1901b).
[4]See
in particular
Einstein 1907a
(Vol. 2,
Doc.
38);
see
also the reviews of the work
on
specific
heats
by
Einstein and Walther Nernst
at
the first
Solvay Congress,
Einstein 1914a
(Vol. 3,
Doc.
26),
and Nernst
1914 (or
the French
version,
Nernst
1912).
[5]See
Einstein
1909b,
1909c
(Vol. 2,
Docs.
56 and 60)
for Einstein's
analysis
of the incom-
patibility
of the
quantum hypothesis
and classical
electromagnetism.
[6]For
Planck's
attempts to
revise his
theory,
see
his
Solvay report,
Planck 1914a
(or
the
French
version,
Planck
1912b),
and Planck
1914c.
[7]See
Bohr
1913.
[8]Einstein
expressed
his enthusiasm for the work
presented
in
this
paper
more
strongly
in
a
letter
to
Michele Besso of
11
August 1916,
when he
wrote:
"A
splendid
idea
on
the
absorp-
tion and
emission
of
radiation has dawned
on
me"
("Es
ist mir ein
prächtiges
Licht über die
Absorption
und Emission der
Strahlung
aufgegangen").
He
called his derivation of Planck's
law
"amazingly simple" ("verblüffend einfach"),
characterizing
it
as
"the derivation"
("die
Ableitung").
The letter
was
written while Einstein
was
working
on
Einstein 1916n
(Doc. 38),
which
repeats
the
argument
of
§2
of this
paper
and adds
important
new
results
as
well.
[9]See
Einstein
1905k.
[10]See,
e.g.,
Planck 1900a.
[11]Ernest Rutherford had described radioactive
decay
by
the
equation representing
such
a
"monomolecular"
process
as
early
as
1900 (see
Rutherford
1900).
[12]Such
calculations
were
indeed made
as soon as
both classical mechanics
and
classical
electrodynamics
had been
put
in
quantal
form
(see
Dirac
1927).
[13]For
the Wien
displacement
law in
appropriate
form,
see
Planck
1901a,
sec.
2.
[14]For
Einstein's earlier work
on
the law of
photochemical equivalence,
see
Einstein 1912b
(Vol. 4,
Doc.
2), 1912f (Vol. 4,
Doc.
5),
and 1913a
(Vol. 4,
Doc.
12);
see
also
Vol.
4,
the edi-
torial
note,
"Einstein
on
the Law of Photochemical
Equivalence,"
pp.
109-113,
for
a
discus-
sion.