274 DOC.
23
MAX PLANCK AS SCIENTIST
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which has been
consistently
confirmed
by experiment so
far. The latter
gives
the
numerical values
of
the
constants h
and
k.
The
great
triumph
that this
analysis
immediately brought
about consists in the
following.
The
constant k
has been taken
from the above-mentioned Boltzmann
principle,
where it is defined
as
k
= R/N =
universal
gas
constant
number of
molecules
in
one
gram-molecule
Thus,
the
quantity
k,
which is determined from radiation
measurements, yields
with
complete accuracy N,
i.e.,
the absolute size of the
molecules,
and the molecular size
obtained in this
way
turned out to be
in
satisfactory agreement
with the results
of
the
determinations
of
this
quantity
based
on
the
theory
of
gases.
Since that
time,
exact
determinations
of
N
have become known that
rest
on
totally
different foundations and
they
confirmed Planck’s result
brilliantly.
But what is the
meaning
of
the other constant
of
nature
h that
appears
in the
Planck radiation formula? To arrive
at
a
usable radiation
formula,
Planck had
to treat
the
energy
of
the
system
of
resonators
as
if
it consisted of discrete
energy quanta
of
the
magnitude
hv0,
an assumption
that
is
not consonant
with
electrodynamics,
and
thus neither with the first
part
of
Planck’s
investigation.
Therein lies the
great
difficulty
that has been
occupyinig
the theoreticians for the last
8
years
or so.
Planck
modified his
theory during
the
past
few
years
so as
to
resolve this
contradiction;
it
remains for the future
to
decide whether his efforts
resulted
in the
right
solution.
In
any
case,
it turned out that the Planck formula is
not
only
useful
as such,
but
that
a
physical
reality
also attaches
to
the
auxiliary quantities appearing
in the
theoretical deduction. On the
one hand,
the
photoelectric
effect
and
the cathode
rays
generated by Röntgen rays
impinging on
matter
have shown that
energy
quanta
of
the
order
of
magnitude
hv indeed
appear
when radiation is absorbed. On the other
hand,
it turned
out
that the decrease of the
specific
heat
of
solids
at
low
temperatures
can
be attributed
to
the fact
that, contrary
to
statistical
mechanics,
the thermal
energy
of
every
structure
depends
on
the
temperature
in the
same
way
as
that
of
the resonators
in Planck’s
theory
does.
Finally,
a
third
area
in which
we
are greatly
indebted to Planck is that
of
the
theory
of
relativity.
It is in
great measure
due
to
the decisiveness and warmth with
which he
championed
this
theory
that fellow
physicists began so quickly
to
pay
attention to
it.
Planck
was
the first
to establish the
equations
of motion
of
the
material
1
c
denotes the
velocity
of
light
in
vacuum.