Symposium on unidentified flying objects: hearings before the Committee on Science and Astronautics, U.S. House of Representatives, Ninetieth Congress, second session, July 29, 1968.

118
the
glasses.
Likewise,
for
light
that
had had
its
plane
of
polarization
turned
through
90
plus
180
degrees
90
plus
360
degrees,
and
so
on,
there
would
be
a
partial extinction
oilight.
On
this
basis,
the
outer
dark
ring
was
due
to
the
rejection
by
the
polarizing
filter
of
the
glasses
of
light
which
had had
its
plane
of
polar-
ization
turned
through
90
degrees,
the
next outermost
band
by
light
that
had
been
turned
through
270
degrees,
et
cetera.
This
interpretation
is
strengthened
by
Webb's
observation
that the
dark
rings
were narrower than
the
brighter
areas
between
them;
this
is
what
should be
expected
on
the
basis
of
the
above
explanation.
What
hypotheses
can
be
constructed
that
might
account
for
this
unusual
observation?
There
are
at
least
two
that
have
interesting
implications
for the
propulsion
problem.
First
by
the
Faraday
effect,
a
magnetic
field
parallel
to
the
path of the
light
could
so
rotate
theplane
of
polarization.
A
quick
calculation
using
the
properties
of
the
atmosphere
shows
that
a
field
of
200,000 gauss, operating
over
a
dis-
tance
of 130
feet
-40
meters—could
turn the plane
90
degrees;
this
is
indeed
a
very
intense
and
extensive
magnetic
field
and, of
course,
would
only account for
one
ring.
Three
rings
would
require
a
million
gauss over
the
same
distance.
We
have
been
able
to
achieve
these
field
strengths in
the
laboratory
for only
fractions
of
seconds over very small
distances.
However,
the
principal
argument
against
this
hypothesis
is
the
conclusion
that
were
such
a
field
brought
at
all
close
to the
surface
of
the
earth
its
effect
would
be
to
induce very strong
remnant
magnetism
in nearly
every
piece
of
iron within
several
hundred
yards.
This has not
been
found.
We
have
been
able
to achieve that
kind of
field
strength
for
frac-tions
of
seconds only over
short
distances
on
earth,
or
at
least
we,
on
earth.
However,
there
has been
a
suggestion
made
earlier
that
a
very strong
magnetic
field
might
so
saturate
certain
iron
cores
of
electrical
ma-
chinery as
to explain
some
of
the observed
phenomena
of
electrical
malfunctioning.
Despite the above
-described observation, there
is
little
reason to
be-
lieve
that
magnetic
fields
of
themselves, could be of
much
use in pro-
pelling
a
spacecraft,
although
there
has
been
much
uninformed
specu-
lation
about
this
in
popular
UFO
publications.
The
simple reason
is
that
we
cannot produce
a
north
pole
without
at the
same
time produc-
ing
a
south
pole.
This
is
a
consequence
of fundamental
theory.
Such a
dipole
cannot
exert
a
force in conjunction
with
a
uniform magnetic
field,
such as the earth
may
be assumed
to
have
in
a
given
locality,
though
it
can produce
a
force in
a
nonuniform
field.
To
go
beyond
the above
discussion
would be
rather
speculative,
but
it
is
just
here that
we
find
a
stimulus
and
challenge to
scientific
theory.
It
is
almost
circular
to say that
when we
find
a phenomenon
we
under-
stand but vaguely
we
have
also
found a means
of advancing our un-derstanding;
this
has been
particularly true in astronomy.
Concerning the propulsion of
UFO's, a
tentative hypothesis
wouldbe that
it is
connected with
an
application
of
gravitational
fields
that
we do not understand.
Gravitation remains one of the enigmas of modern
science,
although
there have been some advances in
its
understanding, beyond general