546
DOC.
26
THE
PROBLEM OF SPECIFIC HEATS
Erklärung von
Euckens Resultaten nichts
beiträgt").
The
following argument may provide
the
justification
Einstein had
in
mind.
[31]Eucken
1911b,
the
printed
version of Eucken's lecture
to
the
83d
meeting
of the
Gesellschaft Deutscher Naturforscher und Ärzte
in 1911
in
Karlsruhe,
which
was
attended
by
Einstein,
had
appeared
in
time
to
be cited
in
the
present
document but
not in its earlier
versions,
the German
manuscript
and the French version Einstein
1912a.
[32]The
sign
of
the
exponent
in
the first
expression on
the
right-hand
side
should
be
negative.
It
appears correctly
in
the German
typescript
and
in
the French
version,
Einstein
1912a, p.
421.
[33]For
a
derivation of
this formula,
see
Einstein
1911g
(Doc. 21),
pp.
690-691.
[34]The
following
calculations of
energy
fluctuations
in
a
solid
body
and their
interpretation
are
here
published
for the first
time;
they
closely
follow
Einstein's
previous
considerations of
fluctuations of
black-body radiation;
see,
e.g.,
Einstein
1909b
(Vol.
2,
Doc.
56),
pp.
188-189.
Einstein
first
sketched these calculations
in
a
letter
to H.
A.
Lorentz,
characterizing
them
as
supplementing
his
talks with Lorentz
on
the
subject; see
Einstein
to
H.
A.
Lorentz, 15 February
1911.
Einstein later commented
on
the
impact
of
his
theory
of fluctuations
at
the
Solvay
Congress: "Nobody was
able
to
object
to
the
theory
of fluctuations. Planck
defended himself
but
was very
much
pushed
into
a
corner"
("Gegen
die Theorie der
Schwankungen
hat
niemand
was
vorbringen
können. Planck wehrte
sich zwar,
wurde aber sehr
in
die
Enge getrieben"),
Einstein
to
Ludwig Hopf,
after
20
February 1912;
for
a
similar
comment,
see
Einstein
to
Michele
Besso,
26
December
1911.
For
Planck's criticism of Einstein's
treatment
of
fluctua-
tions,
see
Einstein
et
al. 1914
(Doc.
27).
[35]For
an
account
of
Einstein's earlier
attempts to
understand the
nature
of
radiation,
including
references
to
secondary literature,
see
Vol.
2,
the editorial
note,
"Einstein's
Early
Work
on
the
Quantum Hypothesis,"
pp.
134-148. In the German
typescript,
the
following
passage
is
accompanied by
a
diagram:
[36]Einstein had inferred the absence of
an
intensity
threshold for
photoluminescence
as
a
consequence
of the
quantum hypothesis
in
Einstein
1905i
(Vol. 2,
Doc.
14),
p. 144.
In
1909,
however, he
recognized
that
photochemical processes
might not be
suitable for
testing
the
quantum hypothesis
because
they
seemed to have
an
excitation
threshold,
a
phenomenon
that
he thought might
be due
to
the
occurrence
of
inverse
processes.
See
Einstein to
Edgar Meyer,
28
October
1909,
and Einstein
to
Michele
Besso,
17
November
1909.
At
the
Solvay
Congress
already,
Einstein
apparently
had
a
controversy
with Emil
Warburg
about the existence of such
a
threshold,
a
controversy
that led
to
Einstein's derivation of
the law of
photochemical equivalence (Einstein 1912b); see
Einstein
to
Heinrich
Zangger, 20
November
1911,
and Einstein
to
Michele
Besso,
4 February 1912.
[37]Einstein had
explained
the
photoelectric effect
on
the basis of
his light quantum hypothe-
sis in
Einstein
1905i
(Vol.
2,
Doc.
14),
§8.
In
a
lecture that Einstein
attended,
Sommerfeld
provided
an
alternative
explanation
of
the
photoelectric effect, according
to
which
a resonance
effect
between
a
molecular oscillation of the
absorbing
material and the
frequency
of the
incident radiation leads
to
a
nonlinear
dependence
of the electron
energy
on
the
frequency
of
the
radiation;
see Sommerfeld
1911b, §§9-10,
and Einstein's
comments in
Sommerfeld
et
al.
1911
(Doc.
24).
For
a
brief
overview
of
the contemporary experimental
evidence
relating to
this