The Indianapolis times. [volume] (Indianapolis [Ind.]) 1922-1965, 1926-01-06

around the exlItn more ttdil ScNCh
times. Indeed. so fast does light
travel that until $50 years ago the
best Of scholars thought it went
instantly from place to place. And,
compared to most other moving
agents about us. light does travel
INSTANTLY" Sound travels through
the air at about 1,100 feet a second,
more than ten times the speed OF
the fastest railroad trains; and yet
sound seems to stand still when
light goes by You see the distant
lightning several seconds before you
hear the thunder; the sound started
at the same time as the light, but
the light came Instantly" as we
say
But light does not really come in
stantly The first person to show
that light actually takes time to so
across space was a Danish astron-
omer, Ole Roemer. In 1876 he
showed, from the motion of the lit
tie moons that revolve about the
planet Jupiter. that it takes a longer
time for light tc come from Jupiter
at the season of the year when the
earth Is further away from Jupiter
than at the season when the earth
is nearer to Jupiter. 1t was not,
however, until 1S49 that a method
was found to measure the time That
| light takes to travel distance ON
the earth. This was done at Paris
by Frerah professor, Armand
Fizeau. He chose two high towers
or stations something more than
five miles apart. At the Grst he had
bright light ard at the second he
placed mirror, which reflected the
beam Of light directly back TO the
first station. Then he put at the
first station a revolving toothed
wheel SO arranged that the beam OF
light went out through the open
ings between two teeth. 1t was re-
f1ected back through the same open
ing when the wheel was at rest. But
when the wheel was revolved rapid
ly enough the light that came back
found that tooth nf the wheel had
moved into the place of the opening;
thus NJ, light could be seen reflected
from tSs second station. The time
which the light took to travel from
the first station to the second and
back again to the first station was
thus the time that 1t took a tooth
OF the wheel to move to the place
of the opening. BY doubling the
speed Of the wheel, Fizeau could
again SEQ the reflected light, because
second opening had now moved
into the line Of sight. From a
speedometer he could get the num-
Der of revolutions of this toothed
wheel and thus calculate the time
that it takes the light to travel be-
tween stations and back. BY this
and similar methods the velocity Of
light has been determined with great
accuracy. The best measurement is
that made by an American profess
sor. A. A. Nicholson of the Univer-
sity Of Chicago. He found the ve-
locity Of light to be 1864 miles a
second.
Eight Minutes From Sun
Speedy as light is, the distance in
the heavens are so great than even
to get from the sun, lights needs
eight minutes, for the sun is $4,000
600 miles away. To come from the
nearest fixed stars, light takes more
than four years: and many stars are
so distant, that the light that we
saw last night started hundreds of
years ago.
And what is light, this swiftest of
ali messengers? We can think Of
only two things that can travel
across space, either matter or mo
ton. That is, we must think Of
light as some fine material substance
thrown of by bodies; or we must
think Of light as a motion set up in
some medium. Sir Isaac Newton,
the greatest scientist of his day. be-
lieved that light was material sub
stance, and that beam of light was
a stream Of fine particles. These
particles OF light, he knew, must
be of so much smaller and lighter
than any known Of matter, that he
called them ''corpuscles. Hence his
material theory Of light was called
"corpuscular theory of light" We
now know that Newton was wrong,
and that light is not matter
Then how are we to explain light?
Let us so back for an idea to the
sport Of our childhood. The boy
throws stone into a smooth pond
or pool to watch the waves it makes
on the surface of the water. These
waves go out in circles, and these
circles travel outward until. they
are DETECTED by some, floating plank
or perhaps until they reach the
shore. In Holland $50 years ago there
was great mathematician and
scientist, who found In water waves
a suggestio NOT what light is. This
great man was Christian Huygens,
who in 1890 published a book in
which we find the wave theory Of
light which scientific men hold to-
day.
Ether Explained
OF course light cannot be q wave
motion in a heavy substance like
WdloE. huyBcnS SeIu CHero uluSt DC
a substance which is far thinner than
the lightest gas. a substance which
has no conceivable weight, and so
fine that It penetrates between the
smallest molecules and atoms, and
that spreads through all space to the
farthest star and beyond that. The
substance is the ether: The only
way we can know ether is by the