<h2><SPAN name="CHAPTER_XV" id="CHAPTER_XV"></SPAN>CHAPTER XV</h2>
<h2>WE SEND MESSAGES FROM THE STARS</h2>
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<div><span class="pagenum"><SPAN name="Page_144" id="Page_144"></SPAN></span></div>
<h3><i>THE SCRIBE'S NOTE ON CHAPTER FIFTEEN</i></h3>
<div class="blockquot"><p>It is remarkable that man has been able to
discover what the distant stars are made of.</p>
<p>Our knowledge concerning the chemistry
of the stars has been obtained by means of
the spectroscope, in which a beam of light
from the star is passed through a glass
prism.</p>
<p>The result is the well-known image of the
coloured spectrum, in which certain well-defined
lines appear, according to the distant
elements originating the æther waves.</p>
<p>The electron explains the whole subject
from its own point of view.</p>
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<p><span class="pagenum"><SPAN name="Page_145" id="Page_145"></SPAN></span>
It is only within recent times that man has
observed that we send messages from the distant
stars to this planet. But there is nothing
new to us in this proceeding; we have
been busy sending these messages ever since
the solar system was formed. Through all
those ages we have kept on sending these
messages, knowing that in time man must
come to take notice of them.</p>
<p>If the subject should happen to be new to
you, you will be anxious to know to what
kind of messages I refer. Needless to say,
they are wireless messages—waves in the
great æther ocean. The waves, to which I
refer specially, fall within that small range
of which I told you something in the preceding
chapter. In other words, they are
those waves to which man has given the
<span class="pagenum"><SPAN name="Page_146" id="Page_146"></SPAN></span>
name <i>light</i>. But what special information do
these waves, coming from the stars, convey
to man? They tell him of what materials
these distant stars are made. Needless to
say, it is we electrons who produce those
informative waves.</p>
<p>You are familiar with our method of producing
waves. You know that we whirl
around the atoms of matter at prodigious
speeds, and that according to the number of
revolutions we make per second, we produce
waves of corresponding frequencies.</p>
<p>In an earlier chapter I have hinted that the
speed of the revolving electron is determined
by the kind of atom to which it acts as a
satellite. For instance, when electrons revolve
around iron atoms they produce certain
wave-lengths, while those moving around
hydrogen atoms produce an entirely different
series of waves. But how is man to recognise
these?</p>
<p>It is quite evident that man may gaze at a
distant star and be little the wiser concerning
the different lengths of the waves which
impinge upon his eyes. He may observe
that the sensation is inclined to red, from
which he may infer that the waves are long
<span class="pagenum"><SPAN name="Page_147" id="Page_147"></SPAN></span>
ones—that they are farther apart than some
of the waves produced by a white-hot body.
But had man been content to try and decipher
our wireless messages in this rough-and-ready
manner, he would never have
gained the interesting information which we
have now placed in his hands. How, then, did
we enable man to read our messages?</p>
<p>Our plan may seem to be somewhat mysterious,
but I assure you that it is really very
simple. When these æther waves of light
fall upon a triangular prism of glass, the
waves are bent out of their normally straight
path. But the point that may seem strange
to you, is that those waves which produce the
sensation of red are not bent so much as the
others. The more rapidly the waves follow
one another, the greater is the bending of
such a ray from its original direction. In
this way the various wave-lengths are all
spread out, so that they form an image like
a coloured ribbon, red at one end, being followed
by orange, yellow, green, blue, and
violet. Every man must be familiar with
this coloured spectrum. When some of my
fellows are enclosed in drops of water in the
air they produce a great rainbow spectrum
<span class="pagenum"><SPAN name="Page_148" id="Page_148"></SPAN></span>
across the heavens. But I must tell you how
we electrons succeed in bending these rays of
light.</p>
<p>I have told you already how we either
absorb or reflect the æther waves which
happen to fall upon us. In most substances
it is only those electrons very near the surface
that are disturbed. They succeed in stopping
the waves. They may do this in either of two
different ways. If the satellite electrons are
attracted strongly by their atoms, the electrons
will spin around the atoms keeping time
to the movements of the incoming waves, and
in this way the electrons take up the energy
of the waves. In doing this, the electrons
send out fresh waves in the æther. This is
the real explanation of what man calls <i>reflection</i>
of light.</p>
<div class="figcenter"> <span class="pagenum"><SPAN name="Page_149" id="Page_149"></SPAN></span> <SPAN href="images/figp149-800.jpg"> <ANTIMG src="images/figp149-400.jpg" width-obs="351" height-obs="400" alt="" title="" /></SPAN> <p class="smcap bold center">The Spectroscope and the Electrons' Wireless Messages</p> <p>The spectroscope is seen in the extreme left of No. 1 photograph.
The instrument is explained at <SPAN href="#Page_207">page 207</SPAN>.</p>
<p>The operator is passing an electric current through a glass tube
containing a rarefied gas, causing the gas to become luminous.
When he examines its light through the spectroscope he sees
bright lines as shown in photograph No. 2, and from the position
of these lines he can tell what substance is producing the light.
No. 2 is the spectrum of mercury vapour. No. 3 is part of the
spectrum of the sun. Note the dark lines, as explained in the
text.</p>
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<p>In the second case, the electrons are not so
firmly attached to their atoms, so that the
incoming waves dislodge them, and they are
knocked about from atom to atom, and in
this way the energy of the waves is frittered
away. Man speaks of the light having been
<i>absorbed</i> by the substance upon which it fell.
In both cases the only electrons which take
part in these actions are those electrons who
<span class="pagenum"><SPAN name="Page_151" id="Page_151"></SPAN></span>
can move in sympathy with the incoming
waves.</p>
<p>It will be clear to you that only those of us
who are near the surface of a substance know
anything about these incoming waves. The
electrons attached to atoms in the interior of
the substance are left in peace, owing to the
defensive actions of our fellows on the outside.
But this is not the case with all substances.
There are some congregations of
atoms through which the æther waves can
make their way. Man calls such materials
<i>transparent</i>; for example, glass and water
are transparent substances. The fact of the
matter is that in such substances none of us
are able to respond to the incoming waves, and
so we cannot stop them. I should say almost
none of us, for there are always a few electrons
present who happen to be in sympathy with
the incoming waves. That is why no substance
is perfectly transparent.</p>
<p>The point concerning which I wish to speak
in particular is this. Although we allow the
æther waves to pass through such substances,
we do offer some slight resistance to the passage
of the waves; the faster the to-and-fro
motion of the waves, the more resistance do
<span class="pagenum"><SPAN name="Page_152" id="Page_152"></SPAN></span>
we offer. That is why the waves of highest
frequency are bent farthest from the straight
line when passed through a glass prism.
We actually force the æther waves to travel
slower through a piece of glass than through
the air.</p>
<p>Now there should be no mystery concerning
our action in a triangular piece of glass.
Whatever combination of æther waves falls
upon it, the different trains of waves are
sorted out according to their frequencies.
Suppose, for instance, that æther waves
emitted from some incandescent sodium are
passed through a glass prism. The bulk of
the electrons attached to the sodium atoms
are capable of revolving at speeds which produce
waves causing the sensation of yellow.
Hence there will appear a very distinct line of
yellow light in the spectrum. But why
should the light be in the form of a line?
Simply because our æther waves are passed
through a narrow slit in a shutter. But I
need not trouble you with further details of
our actions, which, although very simple to
us, may seem somewhat strange to you.</p>
<p>You will understand, however, that we
form bright lines in different parts of the
<span class="pagenum"><SPAN name="Page_153" id="Page_153"></SPAN></span>
spectrum, according to the kinds of atoms to
which we are attached. It was this fact
which attracted man's attention to our wireless
messages. He soon discovered the meaning
of these lines, for he commenced to take
exact notes of the different positions in which
we placed these lines. He saw that when we
were attached to hydrogen atoms we always
produced three prominent lines; a very distinct
line in the red section, another in the
blue part, and a third one somewhat fainter
and farther along in the blue. On the other
hand, when attached to sodium atoms, we
produced two very distinct lines in the yellow.
When attached to iron atoms we produced a
great variety of lines in the spectrum. Of
course these substances have to be incandescent
to enable us to produce the æther
waves.</p>
<p>Now it will be clear to you how we send
wireless messages from the distant stars.
These stars are great masses of flaming gases,
so that the satellite electrons are kept busy
dancing attendance to excited atoms. The
electrons are constantly sending out æther
waves, which reach this planet. We sort out
these waves when man passes them through a
<span class="pagenum"><SPAN name="Page_154" id="Page_154"></SPAN></span>
glass prism, mounted in a telescope arrangement
which he calls a <i>spectroscope</i>. He then
examines the positions of the lines we produce
in the resulting spectrum, and from these he
knows what kinds of atoms are present in the
distant star. It is we who have informed
man that there are forty different materials
in the sun, the most common of which are
hydrogen, sodium, iron, copper, nickel, and
zinc. Of course these all exist in a gaseous
form.</p>
<p>There is one point about which I need
hardly trouble you, although it is worth
mentioning in passing. While we produce
bright lines in the spectrum of any incandescent
substance on this planet, our messages
from the stars appear as dark lines. The
reason for this is that there are cooler masses
of the gases surrounding the incandescent
masses forming the stars, and these cooler
gases completely absorb the waves we produce.
So completely are these waves absorbed
that blank spaces are left in the
spectrum, and these are the dark lines to
which I refer. As they are in the same positions
that the bright lines would have occupied
had the waves reached the earth, it
<span class="pagenum"><SPAN name="Page_155" id="Page_155"></SPAN></span>
makes no difference to the reading of our
messages.</p>
<p>Curiously enough, some of our actions in
forming lines in the spectrum led to our
actual discovery by man; but I shall tell you
of this in the following chapter.</p>
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