The Indianapolis times., 1924-04-18
ALL LIGHT
rs FORMED
OF WA YES
Old Theory Concerning Minute
Particles Is Disputed by T.,
Scientists.
BY DAVID DIETZ
Science Editor of The Times


HE nature and cause of light
form one of the :. great mys-
1J Jeries which was solved by the
modern physicist when he discovered
the inner structure of matter.
For nearly 300 years there were
two conflicting theories among physi
eists.
One theory was that light consist
ed of myriads of minute particles shot
out in all directions from the s.urce
of light. This was called the corpus
cular theory.
The other theory was that light con-
sisted of waves.
Every one has seen waves upon a
lake or the ocean. Most people also
know that sound consists of waves
Of a somewhat similar nature travel
ing upon the air.
Opposition at First
But the theory that light consisted
of waves met with great opposition at
first.
The natural question every one
asked was: What do the waves travel
on?
So scientists that held to the wave
theory of light said that all space was
filled with a medium which they
named the ether. The ether, they
said. could not be felt or seen or
weighed or measured or identified in
any other way.
One experiment to prove the exist
ence of the ether led to Prof Albert
Einstein's famous theory Of relativity.
But we must reserve that for discus.
sion little later.
At the close Of the nineteenth CEN
tury a British physicist. Thomas
Young. proved conclusively that light
Consisted of wave motion In empty
space, or on the ether. If you wish
to believe the ether exists.
Does Ether Exist?
Some Of the followers Of Einstein's
theory Of relativity say, as we shall
see later. that his theory does away
with the necessity Of imagining an
ether i
But Sir Oliver Lodge. one of the
leading English scientists says that
there is nothing In the theory Of rela-
tivity which conflicts with belief in
the existence of the ether.
Young not only proved conclusively
that light consisted OF wave motion
in space, but he measured the length
of the different colored lights
AS any one can prove for himself.
white sunlight is a combination Of a
number of Colors. A prism held in the
sunlight proves that by dividing the
the rainbow. or the physicist would
say. into the visual spectrum
Wave Lengths Vary
Young showed that violet light con-
sisted OF the shortest waves. the
length incr easingly progressivly
through the, blue, green, yellow and
orange. the red waves being the long
est.
Yellow light, situated in the middle
OF the visual spectrum. consists Of
waves about one ffty-thousandth Of
an inch long
Fifteen years after Young's expert
ments, an English mathematician
James Clark Maxwell. astonished the
scientifis world Of his day by proclaim
ing that light waves were really cleo
tro-magnetic waves. Maxwell was the
Einstein of his day The majority Of
people didn't know what he was talk
ing about. Mainly, because no one
knew what an electro-magneucw wave
wac.
But ten years later German phys
icist, Heinrich Hertz, cleared up the
mystery by proving the existence o.
electro magnetic waves IN space. All
Of us are familiar with them today
Only instead Of calling them electro
magnetic waves. we call them radio
waves.
Next article in series: The Com.
plete Spectrum.
Copyright, 1924, by David Dietz)