DOC.
16
FUNDAMENTAL DIFFICULTY IN
PHYSICS
339
Doc.
16
Comment
on a
Fundamental
Difficulty
in Theoretical
Physics
Zurich,
2
January 1911
Our
present
physical
world
picture
rests
on
the fundamental
equations
of
point
mechanics
and
on
Maxwell's
equations
for the
electromagnetic
field in
a vacuum.
It becomes
more
and
more
apparent
that
all
those
consequences
of
this
foundation that refer
to
slow,
i.e.,
not
rapid periodical
processes,
are
in excellent
agreement
with
experience.
We
have
[1]
succeeded
in
arriving
at
a general
formulation
of
the limits
of
validity
of
thermodynamics
with
the
help
of
point mechanics,
and
in
deriving
from the latter the fundamental
laws
of
thermodynamics.
We
have
succeeded
in
entirely
different
ways
in
determining
the
absolute
sizes
of
atoms
and molecules
with
undreamed-of
accuracy.
We
have also
been
able to derive
the
law
of thermal radiation for
long wavelengths
and
high
temperatures
from
statistical mechanics
and
electrodynamics.
But
the foundations of
the
theory
leave
[2]
us
in
the
lurch
when
it
comes
to all
those
phenomena
that
involve
the transformation of
energy
of
rapid
periodical
processes.
We
know
of
no
flawless
derivation of the
law
of
radiant heat for short
wavelengths
and
low
temperatures.
We
do not know
the
reason
[3]
why high
molecular
temperatures
are
needed
for
the
generation
of
short-wave
radiation,
and
why
the
absorption
of
the
latter
can produce elementary
processes
of
relatively
great
energy.
We
do not know
why
the
specific
heat
at low
temperatures is
smaller than
predicted
by
the
Dulong-Petit
law. We know
just
as
little
about
why
those
mechanical
degrees
of freedom of
matter
that
must
be
postulated
in
order
to
comprehend
the
optical
properties
of
transparent
bodies
make
no
contribution
to
the
specific
heats of these
bodies.
[4]
But
one
thing
has
been done.
M. Planck has shown
that
one
arrives at
a
radiation
formula that
is in
agreement
with
experience
if
one
modifies
the formulas
resulting
from
our
theoretical foundations
as though
the
energy
of
oscillations
of
frequency v
could
only
occur
in
integral
multiples
of the
quantity
hv.
This modification also leads to
a
[5]
modification
of the
consequences
of
mechanics
that
has
thus far
proved
useful if
rapid
oscillations
are
involved.
A
proper theory
has not
yet come
into
being,
but
it
can
be said
[6]
with
certainty:
point
mechanics
is
not valid
for
rapid periodic processes,
and the
customary conception
of the distribution of radiant
energy
in
space can
also not
be
maintained.
[7]
A.
Einstein
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