DOC.
24
DISCUSSION OF GDNA LECTURES
389
Sommerfeld:
I
hope
so.
Koenigsberger:
In
several metallic elements,
the
specific
heat
at constant
volume
exceeds
the
value
6
at
high
temperatures.
The
specific
heat of
metals cannot
be
represented
by
Einstein's
original
formula
either,
though
the formula
holds
much better
for
an
insulator
such
as
diamond.
Perhaps
the
free
electrons in
metals
do
have
to
be
taken into
account
after
all.
It
seems
to
me
therefore that the behavior of
specific
heat
supports
the
quantum
theory
more
in
a
qualitative
than
in
a
quantitative
way.
Rubens:
But Nernst's
experiments
on specific
heats
at low
temperatures
can
be
completely represented by
Einstein's formula if
one
does not
stop
at
a single
oscillation
but
assumes many proper
frequencies
instead, just
as
Einstein's formula
also
presupposes.
*****
[1]
Einstein: I would like
to
ask
whether
the
speaker
does not
think
it
possible
that the
conductivity
of
pure
metals
becomes infinite
as
the
temperature approaches
the absolute
zero.
After
all,
Kamerlingh
Onnes
has
found that
even
the
slightest
impurities
have
a
very
great
effect,
and that the
purest
metals
have
an extremely
small
resistance.
Were
[2]
there,
by any
chance,
different
samples
of aluminum
available,
and
were they
tested
for
this?
Nernst: I
believe, too,
that the
high
value
for aluminum
is
due
to
impurities.
After
all,
pure
aluminum
is currently
very
difficult
to produce.
Certainly,
one
could
assume
the
value
zero
for
the
resistance of
absolutely
pure metals,
but
I believe
that
it will have
a
finite
characteristic
value
for
each metal.
Sommerfeld:
How does
the
quantum theory
envision
the
influence
of
small amounts
of
impurities?
*****
Einstein:
We
are
indeed
facing
a
certain
difficulty,
because
we
do not know how to
understand luminescence radiation. The
more a system
deviates
from the
state
of
thermodynamic
equilibrium,
the
more
blurred become the differences between thermal
radiation and
luminescence
radiation,
because the
concept
of
temperature
loses its
meaning.
In the
case
of
a
mercury
lamp, we
cannot
say
what
the
temperature
in
the
[1]
lamp
is.
Surely,
there
will exist
a
certain
temperature
with
respect
to
the molecules
undergoing translatory motion,
but
not
so
with
respect
to
the
ions.
In
this
sense
the
radiation of
the
mercury
lamp
is
surely
luminescence
radiation,
since at
the
temperature
a
termometer
inside
the
lamp
would
indicate,
the
lamp
would not
emit radiation without
current.
But
it
does
not
seem
out
of
the
question
that
such
a
radiation
might
be emitted
without
a
current at
a
higher temperature,
i.e.,
that the radiation of the
mercury
lamp
is