22.
Discussion remarks
following
lectures
delivered
at
second
Solvay
Congress
[27-31
October
1913]
I.
Thomson
In his
lecture
(Thomson 1921),
J.
J.
Thomson reviewed
current
theories of atomic
structure.
Einstein's remark
is part
of
a
discussion
on
the
origin
of
the
energy
of
the
electrons that
are
emitted
during
ionization
or
photoelectric processes.
In
response to
Einstein's
remark,
Wilhelm Wien commented
that it
would take
too
long
to
separate
the
ionized
atoms
since
the rate
of
production
of
ions
is
very
low.
No. 28
(PSSC,
p.
67;
Thomson
et
al.
1921,
p.
52)
Nach der
"Ansammlungstheorie"
des
photoelektrischen
Effektes
muss man
annehmen, dass ein
Atom,
unmittelbar nachdem
es
ein
Elektron emittiert
hat,
wieder
längere
Zeit
braucht,
bis
es
wieder
emittieren
kann.
Wäre
es
also
mög-
lich,
Atome, die
soeben emittiert
haben,
aus
dem
bestrahlten Raume
zu
ent-
fernen
und
in einem
andern Raumteil
anzureichern,
so
müsste die in diesem
Raumteil befindliche Substanz eine verminderte lichtelektrische
Empfind-
lichkeit
zeigen.
Eine
derartige Anreicherung
wäre
aber
(in
einem
Gase)
prin-
zipiell möglich
mittelst eines elektrischen
Feldes,
das die
Atome
unmittelbar
nach der
Aussendung
des
Elektrons beiseite schafft.
II. Laue
Max Laue discussed
X-ray
diffraction
by
crystals (see
Laue
1921).
In
a
section added
to
his
lecture in
proof
he
briefly
reviewed Peter
Debye's
work
on
the
influence of
the
thermal motion of
crystal
atoms
on
the
intensities of interference
spots (see Debye
1913a,
1913b).
In the
ensuing
discussion Walther Nernst raised
the
question
whether
the
existence of
a
zero-point energy might
be
established
from the
observed
intensities
of interference
spots.
Arnold Sommerfeld
pointed
out that
experimental
data
were
inconclusive,
a
conclusion that
had
also been drawn
by Debye.
Einstein's
first
two
discussion remarks
were
made
in this
context.
The
paper
with Stern to
which
he refers
is
Einstein and Stern
1913
(Doc. 11); see
also the
editorial
note,
"Einstein
and
Stern
on
Zero-Point
Energy,"
pp.
270-273,
for
a
discussion. After
the
Solvay meeting
Ein-
stein expressed
the
hope
that
Debye
would
soon
demonstrate
the
invalidity
of
the
hypothesis
of
the
existence of
a
zero-point energy
(see
Einstein
to
Ludwig Hopf,
2
November
1913
[Vol.
5,
Doc.
480]).
Einstein's third remark
is
a
reply to
a
direct