Evening star., 1932-04-18
BY THOMAS r. HENRY.
Light is never tired.

LIBnI Is never JIeu
Without any change Of pace 1t races
through space for approximately Ao
billion billion miles, it is demonstrated py
measurements reported by the Carnegie
Institution of Washington.
A highly technical method was de-
vised at the Mount Wilson Observatory
Of the Carnegie Institution for compar-
ing the speed of light from spiral nebu-
lac 10000 900 light years away from the
earth-a light year is the distance Gov
cred in a year by light travelling stead
lily at 1876, 900 miles a second-With that
from stars in the same general region
of the Heavens, but distant only lew
thousand light years.
Two VeIocities Same,
1t was found that the two velocities
were the same, within the limits OF tne
probable error of measurement. Llgnt
from the most inconceivably distant OBJ
ject was reaching the earth at the same
constant 10000 miles second as IS
light from the nearby sun. The posi-
bility that light coming over a vast dis
tance might undergo some sort OF
fatigue which would invalidate deduc-
tions concerning the behavior OF the
spiral nebulae-far away aggregatlons
galactic system of which the sun and
its planetary system is a minute past
was considered by the Carnegie lnveSt1-
gators.
Within q very small area Of the
heavens, according to statement Is
sued from the Carnegie Institution
today, cluster Of more than 400 OF
these spiral nebulae has been recorded
on Photographic plates at mean dis
tance of 45,000,000 light years. Every
one of these may approach in size the
galactic system itself, estimated in the
Carnegie statement to consist OF about
80 600, 900 900 stars. This, 1t is stated,
leads to a conception OF numbers,
dimensions and masses which is beyond
all imagination The fainteSt nebula SO
far photographed with the l00-lnch
telescope is at a distance of 300, 100000
light years. This represents the pres
ent limit of observable space with ex-
isting telescopes"
Star Aggregations Cornted.
Approximately 10000 of t.4ese enor-
nous star aggregationS lying far out
side the galactic system have been
counted on the Mount Wilson photo
graphic plates. Calculations lead to
the conclusion that these nebulae are
distributed through space with density
of about l to every 10 trillion billion
billion cubic miles. Following out these
calculations. the distribution of a mass
S billion times that of the sun through
observable space would be almost in
conceivably tenuous, so great is space
itself in comparison with the objects
within it. The calculation of the Car
negie astronomers shows that there is
only approximately one 500 quatrillionth
of a Quatrillionth of a gram of matter
in q cubic centimeter of space That
Is, while observable space contains
many thousands of aggregations of
billions of stars, space, nevertheless, is
almost empty.
Investigations of the nebulae, says
the Carnegie statement, indicate a dis
tance Of approximately 800,0 light
years for the nearest Of them. "At
such enormous distances" continues
the statement, these objects whose ap-
parent size in the sky is not very much
larger than that of the moon would
have linear diameters at least compa-
rable to our stellar system. The diam
eter of the Andromeda nebula. one of
the nearest, is about $1,000 light years
as against value of perhaps five or six
times this amount for our galaxy. Its
mass Is estimated at about 1000, 100000
times that of our sun and its intrinsic
brightness at not far from one-hun-
dredth that of our entire stellar SyS-
tenn. II formed on the same pattern
as our galaxy, and numerous types Of
observations show close analogy, this
nebula must be system smaller than
our own, but containing hundreds of
millions Of suns comparable in bright
ness with any that We know in the