124 DOC. 163 MAY 1909
present
before
the
reflection
or
refraction.
By
the
way,
the essential
thing seems
to
me
to
be not
the
assumption
of
singular points
but
the
assumption
of
field
equations
of
a
kind that
permit
solutions
in which finite
quantities
of
energy
propagate
with
velocity c
in
a specific
direction without
dispersion.
One
would
think that
this
goal
could be achieved
through
a
slight
modification of
Maxwell's
theory.
But
my
search
for such
a
modification has
been
futile
so
far.
An
attempt
in this
direction
is
outlined
at
the
end of
this
letter.

The idea of
reducing
the
available
degrees
of freedom
by
introducing
couplings
does
not
seem
to
me
appealing
insofar
as
this
expedient
is
in
a way
tailored
too
much to the
case
of the radiation
cavity.
If the mathematical formulation
were
to succeed,
the
general
physical
interpretation
would
probably
not be less difficult
than
with
Planck's
modus procedendi.
Contrary
to
the
opinion I
advanced in
my
last
publication,[9]
it
seems
possible
to
me
that the differential
equations
that
are
to be
sought
are
linear
& homogeneous.
To
be
sure,
it follows from
the
statistical
properties
of radiation that
when
one
starts out from
one
radiation
process,
one
does
not
arrive
at
a
new
one by
multiplying
all
amplitudes
(field
strengths)
by
the
same
arbitrary
constant[s].
But
one can
take
care
of
this
requirement
by merely introducing
singularities,
without
choosing
the
equations
to
be
nonlinear
or
inhomogeneous. However,
one
would be forced to do
the
latter,
in
my
opinion,
if
one
wished
to
manage
without
introducing
singular points,
which
certainly
would be
the
most
satisfactory
thing
to
do.
Neither
do I like
the
remaining
factor of
900 in the
questionable
relation between
h and
e, even
though
the
occurrence
of
a
factor
such
as 6.(4tt)2
is
not
so very
extraordinary.
But
the
fact
that
a
dimensional
argument
leads
one
to
Wien's
displace
ment
law and to
Planck's
determination of the
elementary quantum,
where
the
latter
is
surely
correct
in
the order of
magnitude,
seems
to
me
nonetheless
quite
significant.
Also,
in
my
opinion,
one
should
keep
in mind
the
possibility
of
conceiving
of
light
quanta
and
electrons
as
mathematically
identically
defined
singularities,
all the
more so
since
nature
seems
to
stint
with universal
constants (measures).
I eagerly
look
forward
to
your
comprehensive
article in the Annalen.
Of
course
I
will
be
happy
to
comply
with
your request
to
convey
to
you my
views
on
it.
In
fact,
I
consider
it
a
great
blessing
to be able to enter into
a
closer
relationship
with
you.
In
my
opinion,
no
importance
can
be
attached
to
the fact
that the electrons released
by
ultraviolet
rays
have
a
kinetic
energy
that
is
not
so
very
different
(although
about
50
times
larger)
from
that of
an
electron
at
the
temperature
of the
metal.
For the
velocity
of the emitted electrons increases
with
v
and
reaches
extraordinary
values in
the
case
of
hard
Roentgen
rays,
which,
certainly
in
principle,
are
constituted
in
the
same
way
as
light.
The
thought
that
(even
without the
light
quantum
hypothesis)
the
kinetic
energy
of the
emitted
electrons
should be
expected
to
correspond
to the
temperature
of
the
incident
pencil
of
light
occurred
to
me
too. This
conception
becomes
especially plausible