Evening star., 1937-05-27
STARS, MEN AND ATOMS
Notebook of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY.

Tentative evidence that the speed of
light may vary according to wave length
has just been communicated to the Ma
tional Academy of Sciences here by DR..
F. ZWicky. physicist of the California
Institute of Technology.
The hypothesis, if sustained by actual
observations which DR.. Zwicky proposes,
might have far-reaching consequences
to current theories of the structure of
the universe.
Light of the entire spectrum, from
the infra-red through the ultra violet,
so far as it ever has been possible to
observe hitherto, moves at a constant
speed very close to 186,324 miles per sec
ond-the ultimate speed in creation.
This speed, it has been assumed, never
varies regardless of the intensity or the
distance covered.
Now probably the greatest puzzle of
modern astronomy has been the red
Shift first observed at the Mount Will
son Observatory of the Carnegie 1nstitu-
ton of Washington. All the lines in
the spectrum Of luminous object NOV
ing away from an observer, it long has
been known and can be calculated from
physical formulae, will be shifted Slight
ly towards the red end Conversely, all
the lines of an object moving towards
the observer will be shifted slightly
towards the violet. The speed of motion
OF the object can be determined from
the extent Of this spectrum shift. 1t
was found by the Carnegie astronomers,
observing the spectra of island uni
verses" millions of light years distant
from the Milky Way Galaxy, that the
more distant the object the greater the
red shift. In other words, the farther
away galaxy the faster it was moving
away from this region of space. An ex-
act ratio of speed to distance was OBJ
tanned, so that it was possible to CAL
culate the distance from the extent of
the shift. This has constituted the
chief physical evidence in favor of the
hypothesis of the expanding universe"
in which all things are flying fragments
from the explosion of an original coSmic
atom.
But the red shift, DR.. Zwicky empha-
sizes in his report to the National
Academy. can also be explained in
another way which may be expert
mentally verified. Supposing that red
light actually moves trif1e faster-say
a hundredth or a thousandth of kill
ometer second-than violet light.
There is way of measuring this, says
DR.. Zwicky, IF we knew of any light
signals of different frequency which have
started simultaneously from a very dis
tant source. The dependence of velocity
on frequency could perhaps be demon
strated by checking up on the times of
arrival of these signals. A unique case
to perform this test is afforded by the
observation of distant nova outbursts.
For such an outburst we may safely as
sumo that photons in the various ennis
sion lines of hydrogen have started out
simultaneously on their long journey.
We must therefore attempt to determine
whether or not the intervals in which
the different hydrogen lines flare up in
the spectrum Of a distant super-nova are
zero or not. With the present telescope
equipment it is probably possible to find
super-nova to distances as great as 100,-
100000 light years. With reasonable
luck it should be possible to detect diff
ferences in the time Of arrival Of vari-
Gus emission lines amounting to as little
as q few days"
But this Is little more than an hy-
pothesis DR.. Zwicky stresses. Nova, or
new stars, Hash up occasionally not only
in the Milky Way galaxy, but in the far
distant island universes. Presumably
these star explosions are identical phe-