Evening star., 1930-12-11
Mount Wilson Observatory
Staff Member Tells of
Recent Discoveries.
REFLECTOR TELESCOPE
USED TO EXPLORE SPACE
Most Powerful instruments Reveal
Transparency in All
Directions.
BY THOMAS r. HENRY.

! 6OUUUU,UUU ,UOU,OUO,O ,OOO, 900 miles in
every direction.
| So far as the most powerful instru-
ment now available can detect, space
| is transparent throughout. with matter
! in the form of millions of universes,
each composed of millions of stars, dis
trlbuted through it in relatively uniform
! density, which is about the same for all
| directions.
These are the latest conclusions
reached in the exploration of space by
means of the 100-inch reflector tele-
scope of the Carnegie Institution of
Washington on Mount Wilson. Calf
| described last night by Dr. Edwin P.
| Hubble of the observatory staff. DR..
Hubble's work has been with the spiral
nebulae, or island universes, of which
several millions have been detected by
long exposure of Photographic plates.
Range of Island Universes.
Each of these he described as a uni
verse of stars comparable in size to the
Milky Way galaxy of which the sun
with its planetary system is one of the
millions of members. The island uni
verses range from the Magellanic clouds
IN the Southern Hemisphere from which
light, moving at approximately 100 900
miles a second, reaches the earth in
only 100000 years, to tiny dots Of
luminosity which appear on the. photo
graphic plate only after several nights
of exposure and from which light travels
for 300,000,000 years.
DIR. Hubble described the methods of
observation and statistical calculation
by which the probable distance of these
universes is determined. BY means of
the 100-inch telescope certain stars of
known types, and hence of known
brightness. were found in the arms Of
some of the nearer nebulae.
The distance of these objects was
then determined by comparison of their
brightness, which diminished for the
observer according to known ratio
with distance with the brightness Of
similar veriable stars in the local"
galaxy. BY this means was established
approximately 100,000,000 times that of
the sun. Only ''neighbors" could be
calculated in this way because no stars
could be isolated in the distant nebulae.
But once the average brightness criteria
was applied to the great numbers found,
the comparative method could be ap-
piled to all of them and their approx
innate distance determined by statistical
formulae.
The spectra of the nebulae have re-
vealed a strange situation, DR.. Hubble
said, which throws light on the Struc-
ture of space itself The visible spec
trum of an island universe, he pointed
out, ranges from violet lines produced
by the shortest visible light waves to
the red lines produced by the longest.
as is the case with all luminous bodies
whose light is split up through prism.
Now If a source of light is moving rap
idly toward an observer, the waves will
be crowding upon each other and con-
sequently producing a shortening effect
shown by a shift toward the violet
end of the spectrum. If the light source
is moving away rapidly, the waves are
being drawn out and produce a shift
toward the red.
Appear to Move Faster.
BY means Of microscopic comparison
OF the lines in the spectrum of NOV
ing body to those in the spectrum of
2 luminescent body ct rest the direc-
ton and speed OF the movement can
be determined. And the spectra of the
spiral nebulae, except for few nearer
ones which appear to be moving in the
direction of the earth, show shifts
toward the red end, which increase
in proportion to the calculated distance.
Thus the further away they are the
faster they appear to be moving away
from the earth This increase in speed
is approximately 100 miles second for
each million light years.
Thirty Velocities for distant nebulae
have been determined during the year,
Dr. Hubble said. The most distant, u.s.
100000 light years away. was moving
out at the rate of $500 miles a second,
thus verifying the formula established
for nearer objects. The speed of the
fight of univerSes apparently is new
valid measure of their distances.
But, DR.. Hubble said, this strange
acceleration of velocity with distance
probably is an illusion due to the
structure of space rather than an actual
movement Of the bodies themselves. He
compared it to the distortion that is
inevitable in trying to put map of the
earth with its three dimensions on
fiat surface. For short distances it
can be done easily, but eventually con-
tinentS and oceans lose their true shape
IL the two-dimensional picture.
Something similar, although difficult
to comprehend, takes place in observa-
tions of the spirals where the observer
is trying to fit a -dimensional
cosmos into a three -dimensional con-
ception of things, which is all that is
possible to the human senses. The
time dimension comes in and distorts
the picture with this appearance of in
creasing speed.
Actual Physical Facts.
This all points, he said, to the Elm
steinian concept of curved space, al
though the observations do not entirely
fit the EinStein formula. But DR. Hub
BILE pointed out, these discoveries are
actual physical facts observed in a field
where hitherto all has been philosophi-
cal conjecture.
The 100-inch telescope, he said. is
far from having penetrated to the ulti-
mate borders of space. Thus far the
further the eye of the telescope goes
in every direction-either by the use
of more powerful instruments or longer
camera eXposures-the greater becomes
| the number of island universes. Some
of them appear grouped in clusters, but
on the whole, there seems to be uni
form distribution, the star systems be-
ing about 100,000,000 light years apart.
The increase in number, according to
the cube of the distance, he pointed
out, would be expected because of the
greater extent of space included in the
observations.
But, he said, the concept of a space
extending infinitely outward is incon-
sistent with such facts as the blackness
of the night sky between the clouds.
If luminous matter extended to infinity
the sky could be nothing except a
dome of light. The conclusion must
be, he said, that space is infinite and
yet bounded, curving back upon itself.
In only one direction, he pointed out,
are there few island universes revealed
Inv tha teIaccOpn- -IoOrirp toWard the