264
DOC.
22
SOLVAY DISCUSSION
REMARKS
Doc.
22
Discussion
Remarks
Following
Lectures Delivered
at Second
Solvay
Congress
[Based
on manuscripts,
an
unpublished printed
version
of
the
proceedings
of
the
second
Solvay Congress
(PSSC),
and the
published
version
(Rapports
1921)]
[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)
According
to
the
"accumulation
theory"
of
the
photoelectric
effect,
one
must
assume
that
right
after
it
has emitted
an
electron,
an
atom
needs
quite
a long
time before it
can
emit
again. Thus,
if
it
were
possible
to
remove
from the radiated
space
atoms that
had
just
emitted and increase their number in another
part
of
the
space,
then the
substance
present
in this
part
of the
space
would have
to
evince diminished
photoelectric sensitivity.
But such
an
enrichment would be
possible
in
principle (in
a gas)
with
the
help
of
an
electric field that
moves
the
atoms
aside
immediately
after
the emission
of
the electron.
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
dicussion 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,
Einstein
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
question by
Nernst whether Einstein's
rejection
of
a
zero-point
energy implied
that he also retracted the
explanation, published
in Einstein
and
Stern 1913
(Doc.
11),
of Arnold
Eucken's measurements of the
specific
heat of
hydrogen
(see
Euchen
1912).