The Washington herald. [volume] (Washington, D.C.) 1906-1939, 1922-02-07
BLUE And YELLOW |.
LIGHT HESAhIE j
SPEED IN SPACE
Astronomers at Harvard
Study Light 10000
Years Old.
TUESDAY. FEBRUAHY :. rszz.

TUESDAY. PEBnUAHY :. 1870.
on the Orient win be the sub
3ect OF the principal Illustrated
address. by DR.. A. s. Hitchcock.
OF the National Museum. al IN.
meeting. Of the Botanical Society
OF Washington. Cosmos Club, to-
night. at o'clock. DIR. Hitch
cock has just returned from an
eight months trip TO the Philip-s
pines. Japan. Central and South
China and Indo-China. Thers
will also be a discussion Of the
Toronto meeting Of the Ameri-l
can Association for the A.
vancement Of Science. led by Or
G. r. Lyman on 'Phyiopathoi-
ogy."
National Capital Dental Society.
George Washington University
Medical School. tonight, 8 o'clock.
DR.. Allen Scott Wolf. OF this city,
will read an illustrated paper on
photographic Diagnosis and
Surgical Elimination" and DEM
onstrate his new hypodermic
point which is a new departure
in syringe needles
The chances are Eve 10 one that
the difference in the time Of pas
rase Of blue light and yellow light
through empty space is less than
one second in 800 years. according
TO a result just announced by the
Harvard Spllege Observatory. =,
is inferred from this result that
there may be no difference IN
velocity whatever.
The new and extremely sensitive
test Of the relative velocity Of light
Of different wave-lengths is made
possible. IL is stated. by the recent
determination Of the distance Of a
remote globular star cluster named
Messier 5, and by the completion
at Harvard Of long study Of the
variations affecting the light OF
some OF the clusters brighter stars
The distance OF Messier is lss
kiloparsecs. which Is the equivalent
Of two hundred million billion
miles; IL takes light nearly 10000
years to travel across the space be-
tween the star cluster and the earth
From a study OF photographs
made at the Harvard astronomical
station at Arequips. Peru. a large
number of variable stars have been
found in this remote star swarm.
The changes in the lights Of these
variables have been studied at Har-
ward, and more recently several Sc
ries of photographs OF the cluster
were made with a big reflector at
Mount Wilson. California. using
plates sensitive TO blue light and TO
yellow light. The time Of the
Frightening Of tho variable stars
was then determined separately for
the two colors: but no difference in
the time Of arrival Of the blue and
yellow pulses of light was found at
the md OF the journey across empty
space journey that has taken the
lsst 400 centuries
The uncertainty Of the measured
result is so small, according 90 nr.
! Harlow Shapley. director Of the
Harvard Observatory. that he finds
rrs chances are twenty 90 one that
blue and yellow pays differ in We
locity by less than two inches IN a
second while travelling through
space At the rate OF $4,000 miles a
second
Blue light IS closer to the N-rays
and radium emanations in fire.
Iquency or wave length than yellow
light. which approaches more close
] ly the electrical waves. whether the
velocity Of light changes with the
color. that is with its frequency or
wave length, has been a disputed
question among physicists and as
tronomers. although most OF them
believe that the velocity is con-
slant. The velocity of-light is 1885,
$50 miles per second.