DOC.
26
THE PROBLEM OF SPECIFIC HEATS
421
a
particular
density
of the
acting
radiation,
then
it must
induce the
same
effect at
any
lesser radiation
density as
well,
no
matter how
small this
density may
be.
[36]
These
consequences seem
to be
confirmed
in
every particular,
in which
regard
it must
be noted that
according to
our
conventional theoretical
conceptions
we
would have
expected
a totally
different behavior. One
would have
thought
that
a
certain
minimal
density
of
electromagnetic oscillatory energy
is
necessary
to
induce,
for
example,
the
photochemical decomposition
of
a molecule;
the
electromagnetic
vibration
brought
about
in
a
molecule at
a
smaller radiation
density
should not
be
capable
of
causing
the
molecule's breakdown. On the other
hand,
our
prevailing
conceptions
cannot
explain
why
radiation of
higher frequency
should
produce elementary
processes
of
greater
energy
than radiation
of
lower
frequency.
In
brief, we
neither understand the
specific
effect
of
frequency
nor
the
lack
of
a
specific
effect
of
intensity.
Further,
it has
been
pointed out
in
many
a
discussion
that
according
to
our
theoretical
conceptions
it
is
inconceivable
that
light,
and
even
more so
Roentgen
rays
and
y-rays,
no
matter how low
their
intensities,
should
be
able to
accelerate electrons
with such violence
that
they
would
fly
out from
bodies
with
their
well-known
high
velocities.
In the
photoelectric
effect,
in
particular,
the
kinetic
energy
of the
ejected
electrons
is
of the
same
order of
magnitude as
the
product
hv of the
acting
radiation,
and
it
even
turns out
that
this
kinetic
energy
increases
approximately
as
hv and
v
in
ranges
devoid
of
resonance
effects.
In the
face
of
this
[37]
experience, one
cannot
easily
close
one's
mind to
the
conception
(especially
if
one
keeps
in mind
the
great
fluctuations
in the
conductivity
of
air
that
is
irradiated with
y-rays)
that
energy
appears
in
the
form
of
large
quanta
in
the
course
of
absorption
of
radiation,
and
[38]
also
that the formation of
secondary energy is
in
no way spatially
and
temporally
somewhat uniform.
These
discontinuities,
which
we
find
so
off-putting
in
Planck's
theory,
[39]
seem really
to exist in nature.
The
difficulties which
stand
in
the
way
of
formulating
a
satisfactory
theory
of these
fundamental
processes
seem
insurmountable
at
this time.
From where
does
an
electron
in
a
piece
of metal that
is
struck
by
Roentgen
rays
take the
great
kinetic
energy
we
are
seeing
in
secondary
cathode
rays?
After
all,
the
field
of
the
Roentgen
rays impinges
on
all
of the
metal;
why
does
only a
small
portion
of electrons attain the
velocity
of those
cathode
rays?
How
is
it
that the
absorbed
energy
shows
up
only
in
relatively exceedingly
few
places?
What
distinguishes
these
places
from
other
places?
These and
many
other
questions are being
asked in vain.
[40]
An
interesting question is
whether
absorption
has
the character of
a
random
event
also when viewed
from the
standpoint
of the absorbed radiation.
This amounts to
the
question as
to
whether
two
coherent
ray
bundles remain
completely
coherent
if
each of
them
is
weakened
to
the
same
fraction of
its
value
by
absorption.
No doubt,
everybody
presumes
that the
coherence
will
be
completely
maintained;
still,
it would
be
nice if
we
knew this
for
sure.
[41]