The Indianapolis times. [volume] (Indianapolis [Ind.]) 1922-1965, 1933-09-14
-Dietz on Science
SCIENCES join
TO BRIDGE CAP
IN LIGHT STUDY
Astronomy, Physics United
to AnaIyze Rays,
WaveIenqthS.
BY DAVID DIETZ
Scripps- Howard Science Editor

Most of the newer knowledge OF
the sun and the stars has been the
offspring of a union of two sciences,
astronomy and physics.
Scientists call this union by the
rather formidable name Of astro-
physics. This is not done with a
diabolic desire to confuse the lay
man, but to supply scientists with
a definite name for the interesting
and exceedingly fruitful territory
which has grown up on the border
between astronomy and physics.
To grasp fully the work which is
going on in this field, it is necessary
to have an understanding Of the
knowledge which has been amassed
in recent years about the nature
and behavior of light. For light is
the only means by which the sun
and the stars can be studied.
Originally, the astronomer could
do no more than gaze at the celes-
tial objects. Then he learned how
to analyze their light by means OF
the spectroscope and allied 1nstru-
mentS.
Once Laboratory Marvel
Within recent years he not only
studies their visible light but their
invisible light as well, analyzing the
infra-red rays and the ultraviolet
rays which penetrate the earths
atmosphere.
He interprets conditions and &C
tivities within the sun and the stars
on the basis of what is known about
the origin and behavior Of these
various kinds of light.
Visible light is only one form
of what the scientist has named
electromagnetic radiation. The
longest electromagnetic waves are
the ones used in radio, sometimes
called Hertzian waves in honor OF
Professor Heinrich Hertz, their dis
coverer. Once upon a time they
constituted a laboratory marvel. To-
day, they are familiar to every one
under the name of radio waves.
Radio waves range in length from
those more than a mile long to
those a few inches long. The very
long ones are used in transoceanlc
radio biography.
Waves Serve No Purpose
The short ones for the so-called
shortwave radio. The radio waves
trail off into extremely short ones
which can be studied in the laoora-
tory, but as yet serve no CONNER
cial purpose.
Just a bit shorter than these eX-
tremely short electric waves are the
infra-red rays. Every one is ia
miliar with them under another
name. Their more popular name is
that of heat rays. The heat wnlch
is radiated from an electric heater,
for example. is in the form OF IN
fra-red rays.
Next come the rays of visible light,
the longest of which give us the
sensation of red and the shortest
of which give us the sensation OF
violet. Our eye is like radio re-
ceiver which can only tune in a
limited band of wavelengthS. The
longest wavelength to which it Will
respond is that which gives us the
red sensation. The shortest to which
it will respond is that which gives
us the sensation of violet.
X-Ray Pierces Matter
The scale of electromagnetic ra-
diation does not stop with visible
light. Every one knows of ultra
violet light. It is so named because
it is composed of waves shorter than
the waves of visible light. Your
ewes can not see ultra violet light
But your skin responds to it by
tanning.
Still shorter than ultra violet light
are the waves which comprise X
rays. X-rays are so short that they
can find their ways between the
molecules Of matter. That is why
X-rays will furnish a photo, for ex-
ample, of the bones within per-
sons hand. The gamma rays OF
radium are still shorter than X-rays
At one. time, scientists imagined
that the electromagnetic scale ended
with the gamma rays. But within
recent years, Professor r. A. Mill
kan has verified the existence Of the
so-called cosnic rays, waves shorter
than the gamma rays Of radium
These cosmic rays appear to enter
the earth's atmosphere generally
from outer space.