DOC.
532 MAY 1918 553
condition
plainly
leads to
the natural
coordinate
system,
in
the
case
of
spherical
symmetry,
if
one
also chooses
p
=
0
in addition.
But
now comes
the
question[20]
I
would have liked most
to
have discussed
more
with
you:
What
sense
does
the
whole wonderful
theory
have
if the
general
transformability
of
the fundamental
equations
really
is
removed
again
in
the
end
by
other
additions,
namely,
the
choice of
a
preferred
natural
coordinate
system?
This
question was
actually
the
topic
of
my Göttingen lectures,
and
I
must
admit
that
it
has often saddened
me
that
you
have not
yet
uttered
a
word in reaction
to
the
positive
answer
I
gave
to
this
question,
with which I
hoped
on
my
part
to
make
a
modest
contribution
to
your
wonderful
theory.[21]
My
criticism of
“general
relativity”
was
only supposed
to clear
the
way
for
new
positive results,
and
I
am
convinced
that
I
have arrived at
some. (The
most
important
result of
my
considerations
is,
in
my judgment,
that the
assertion
of
the
transformability
of
the
equations
can
be carried
further
along
the
same
lines: (that
the fundamental
equations
physical
laws
essentially
retain their
form
unchanged,
also
in
non-
Minkowskian
regions,
thus
where
a
transformation
is
no longer
at
issue).
It
is
precisely
this
very general validity
of
the
fundamental
laws,
which
they
can
have,
however, only
if
general transformability
also
exists,
which
actually
seems
to
me
to
be
the
very
core
of
the
theory.
I
have been
thinking
a
great
deal
recently
about
attacking
a
specific problem
that
attracts
me
very
much with
the
aid of
this
“extended
principle
of
the
relativity
of
gravitational
effects.”
I
shall
give
it
a
try,
even
though
it
will
not be
easy mathematically.
Should
my
attempt
succeed,
I shall
be
able to show
you
more
clearly
with
it than
with words
what
I
mean.
But
maybe
this letter
already
will result
in
some
possibilities
for
us
to
discuss
this
further
as
well.
This
much
I
would still
like
to
remark,
that
the
plain
coordinate
transformations,
as
studied
first
by
Mr.
Born in his
doctoral
thesis[22]
and later
in
more
detail
by
Mr.
Kottler,[23]
can
certainly
be
very amusing
mathematically,
but the
problems
themselves
can never
be
probed,
one
is
only
beating
around
the
bush. Mr.
Kretschmann,
I
find,
has
given
a
very
nice
explanation
for
this.[24]
Perhaps you
will
see
from
this
what
I
am
driving
at
now.
With
kind
regards,
yours truly,
Gustav
Mie.
[2]Deleted
text
in draft:
“individual
points actually
do
exist,
where
a
clarification
of
the
views
can
promote
our
knowledge.
I
am
generally
of
the
opinion
that
a
physicist
does not
need to
be
very
familiar
with
epistemology;
when
a
scientist
is
too
critically
epistemological,
it
can even
be
an
obstacle to free and
original
research.”
[13]Deleted
passage
in
draft:
“If
experimental
physics
were
to
adopt
the mathemat-
ical
standpoint
of
complete
freedom in
making definitions,
then it
would be
thoroughly
unproductive.
The
nicest
test
case
is
Faraday,
who
liberated
us
from
the
exclusively