Omaha daily bee. (Omaha [Neb.]) 187?-1922, 1915-02-03

thermometric zero IA
Of the centigrade n
scale and about 461
degrees below the thermometric zero of
the Fahrenheit scale.
Absolute zero might, imaginatively, be
defined as molecular death, because n
substance which has lost all temperature
has necessarily lost all molecular, or in
ternal, energy, and has become entirely
inert.
Both light and heat are effects pro-
duced by motion of the molecules and
atoms Of which all matter consists. A
molecule is the smallest quantity of a
compound substance which can exhibit
the properties by which that substance is
identified" An atom is one of the con-
stituent parts Of molecule and may be
defined as the smallest quantity of sim
pie matter which can enter into the COM
position OF the molecule." Thus a MOLE
cule OF water consists Of two atoms of
hydrogen and one atom of oxygen. We
need not here consider the recent dis
covery that atoms themselves are divisi-
BILE into yet smaller particles.
Except when in a state of absolute
zero. the molecules of all substances are
in continual motion among themselves.
We can see neither the molecules nor
their motion, but we can feel the molecu-
lar motion, or vibration in the sensation
that we call heat To satisfy yourself
that heat" is an internal motion among
the particles, OF molecules of a body,
take a hammer and pound upon a piece
OF iron. After a time both the hammer
and the iron will become warm. They
do so because their molecules have been
set into greater vibration than before.
There are many sources of heat on the
earth. but all Of them are insignificant
in comparison with the sun, which sup
plies nearly all the heat and light that
the earth. as a whole. enjoys. This sup
ply is furnished by vibrations. originating
in the motions of the atoms and mole
clles composing the sun, and transmitted
through the "ether" across space to the
Garth. The ether is a theoretical medium
Cof which we have no knowledge except
by its effects that is believed to extend
through all space. and to pentrate freely
through all forms of matter.
The vibrations that the ether receives
from the sun and pc sses on to the earth |
and the other planets are called radiant |
energy. and two Of the most familiar |
forms in which this energy is manifested |
We know as light and heat.
Now. you ask: at what distsnce from |
The earth do light and heat ceaseT'
Evidently, from what has been said |
above. distance from the earth has Moth |
ing to do with the cessation or with the |
existence of the rays of energy from the |
sun. They will continue to pass farther |
and farther away into space. on all |
sides. their intensity within q given area |
varying inversely as the square of the |
distance. until they have become so |
widely dispersed as to be insensible II
they hit the earth, that is the earth's
good luck.
Yet these rays are neither light nor
heat, in our sense of those words, as
long as they are simply borne onward
through the ether. 1t is only when they
strike some material substance, like the
earth. that they give rise to molecular
vibrations producing the sensation of
Tight In the eye. and of heat in the or
gans OF touch or feeling. The form that
the radtations take is that OF minute
waves in the ether, and there is an i'm
mense variety in the length and the
rapidity OF vibration of these waves. |
Those whose length falls between about
one 40,00otb and one 6O.OOOth of an inch
produce the sensation of light in the eye. !
Those that are shorter or longer than
these produce no effect upon the nerve
OF vision, but we are beginning to find
out that some of them have other effects,
for the recognition of which we seem 70
possess no special senses. Some Of these
invisible waves produce heat on striking
the earth. but most OF the heat-produc-
ing waves appear 10 be at the same time
producers Of light.
The Their itself is not rendered lumin-
GUS and is not heated. by the passage
or the suns rays. Consequently il you
could place yourself out in open space,
beyond our atmosphere. you would find
no diffused light around you. You would
see no luminous rays. You would sec
the sun and the stars, but the former
would appear as a brilliant round disk
set in a perfectly black sky. and the
stars would be points Of piercing bright
ness, with no flicker or halo OF light
about them. The suns rays falling upon
your head might produce a sensation OF
heat, for its molecules would be set into
vibration; yet the intense cold about YOU
and the absence OF any absorbing medium
10 retain the heat. might. at the same
time, result in your being frozen solid 10
the center with the suddenness Of an ex-
plosion.