DOC. 42 SPECIAL AND GENERAL RELATIVITY 417
178
Relativity
natural form
for
this
generalisation,
but
I have
not
yet
been
able
to
find
out
whether this
generalised
law
can
stand
up
against
the
facts
of
experience.
The
question
of
the
particular
field
law is
secondary
in
the
preceding general
considerations. At the
present
time,
the
main
question
is
whether
a
field
theory
of the kind here
con-
templated can
lead
to
the
goal
at
all.
By
this
is
meant
a
theory
which describes
exhaustively physical
reality,
including
four-
dimensional
space, by a
field.
The
present-day generation
of
physicists
is
inclined
to
answer
this
question
in
the
negative.
In
conformity
with the
present
form of the
quantum theory,
it
believes
that
the
state
of
a
system cannot
be
specified directly,
but
only
in
an
indirect
way by
a
statement
of the statistics
of
the
results of
measurement
attainable
on
the
system.
The
conviction
prevails
that the
experimentally
assured
duality
of
nature (corpuscular
and
wave
structure)
can
be realised
only
by
such
a
weakening
of
the
concept
of
reality.
I
think that
such
a
far-reaching
theoretical renunciation
is
not
for
the
present justified by
our
actual
knowledge,
and
that
one
should
not
desist from
pursuing to
the
end the
path
of the relativistic
field
theory.