Kitabı oku: «The Autobiography of an Electron», sayfa 5

CHAPTER XIV
HOW WE PRODUCE COLOUR

THE SCRIBE'S NOTE ON CHAPTER FOURTEEN

Colour is merely a sensation in the brain.

What the electrons really produce are æther waves, and these give rise to the sensations of colour.

However, the electrons may claim to produce colour in the same sense as we savages produce pain in fellow-men by firing rifle-bullets at them.

The electron explains how some objects appear white, while others are red, and so forth.

It explains also how electrons produce artificial light.

The electron twits man upon his ridiculously wasteful processes of obtaining artificial light.

In the preceding chapter I have been telling you how we electrons produce waves in the æther ocean. I pointed out that if we make the waves follow each other at too slow or too fast a rate they fail to affect man's eyes.

It may seem strange to you that only a very small range of our æther waves should affect man's visionary apparatus. Of course this limitation lies beyond our province; we can produce endless variety of æther waves – it is man's organs which fail to appreciate the bulk of these. However, there is plenty of variety in the sensations which we can produce in man. If we make the waves follow each other at a certain speed, man says he has the sensation of red. If we move faster, he speaks of orange-colour, and as we increase our speed he names his further sensations as yellow, green, blue, and violet. Then if we combine all these waves – that is, if we produce them all at one time – he says he has the sensation of white. If we produce none of these waves, he calls the result black.

While we electrons are very versatile, our actions are dependent in a great measure upon circumstances. For instance, if an electron is acting as a satellite to one particular kind of atom, its rate of revolution around that atom may be very different from that of an electron similarly attached to another kind of atom. We electrons are all identical, but the speed of revolution is determined by the kind of atom. The reason is very simple; electrons revolve around some atoms at a much greater distance than they would around other atoms. Those making only the smaller orbits not only get around their atoms in less time, but they are also travelling at a greater pace. It is this fact which enables the electrons to produce the various wave-lengths which stimulate the different colour sensations in the brain of man.

I think you will have no difficulty in seeing how it is that we come to produce such a variety of wave-lengths – in other words, how we are able to make the waves follow each other more or less rapidly. You will understand that we do not produce colours; we merely make various waves in the æther, and these waves excite the colour sensations in man. I mention this simple fact, because I hear many people speaking of our æther waves as "coloured rays," which, of course, is quite a ridiculous description.

Suppose some of those waves which give rise to the red sensation happen to fall upon a lump of matter which contains only electrons capable of producing waves that affect the green sensation. What will happen? There will be no response, and the object, although viewed by "red light," will appear black.

If an object, such as the white paper upon which my scribe is recording my story, contains a variety of atoms with electrons capable of revolving at all the different rates which produce colour sensations, then when "white light" falls upon the object it appears white (all the colour sensations combined). If, on the other hand, a "red light" only falls upon it, then only the electrons capable of responding to that rate of wave will be set in motion, and the object will appear red, and so on with the other rates of æther waves.

So far I have been telling you what happens when different waves of light fall upon us. Now I shall endeavour to explain how man has caused us to produce artificial light. At present all man's methods in this direction are dependent upon making some substance so hot that it becomes incandescent. Even his most modern methods seem to us to be ridiculously wasteful and most roundabout. I shall speak only of the electric glow lamp, as I have had some experience in connection with this.

On one occasion I had been taking part in a regular forward march from copper atom to copper atom in a conducting wire. I had no idea of the purpose of our march till I suddenly found myself handed over to some carbon atoms, who were in a very lively state of vibration. We had much more difficulty in making our way through this substance, and it was the passive resistance offered to the advance of the electrons who had preceded me that had driven the carbon atoms into this state of great excitement. In our march through the copper conductor we had been offered very little resistance, so that we had left the copper atoms in peace – at least man could not detect easily any excitement (heat). But so long as our forced march was maintained among the carbon atoms, so long did the high temperature exist.

You will understand I and the other marching electrons did not produce the waves of light sent out by the glow lamp. What we did was to set the atoms of carbon into a rapid vibratory state, and they in turn caused their satellite electrons to hasten their pace. Some electrons produced one rate of waves, and some another rate, but by the time the carbon was incandescent there were electrons sending out all the variety of wave-lengths, the combination of which produces the sensation of white.

I have accused man of adopting very wasteful processes, so I had better explain the matter. In the preceding description of what is occurring in an electric glow lamp, I have spoken only of those æther waves which constitute light. But there are myriads of electrons in the carbon of the glow lamp that never attain the requisite speed to produce those waves; they revolve around their atoms at too slow a rate. They certainly disturb the æther, but the crests of the waves are so far apart that they do not affect the eyes of man. The business of these waves is to set up heat in the bodies upon which they fall. You may be surprised to know that in this contrivance of man, called an electric glow lamp, and, indeed, in all his other artificial light-producers, he causes far more electrons to produce radiant heat than the desired light waves. A most wasteful process!

Man has a long way to travel yet before he succeeds in producing artificial light by a reasonable process. Indeed I doubt if any of you can realise, as we do, how exceedingly stupid the existing methods are. Think for a moment of the glow-worm, in which we electrons produce light without setting up any wasteful heat waves. There is a strong contrast between this peaceful plan and that of the excited carbon atoms. When will man succeed in discovering this secret of ours?

CHAPTER XV
WE SEND MESSAGES FROM THE STARS

THE SCRIBE'S NOTE ON CHAPTER FIFTEEN

It is remarkable that man has been able to discover what the distant stars are made of.

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.

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.

The electron explains the whole subject from its own point of view.

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.

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 name light. 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.

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.

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?

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 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?

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 across the heavens. But I must tell you how we electrons succeed in bending these rays of light.

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 reflection of light.

The spectroscope is seen in the extreme left of No. 1 photograph. The instrument is explained at page 207.

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.

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 absorbed by the substance upon which it fell. In both cases the only electrons which take part in these actions are those electrons who can move in sympathy with the incoming waves.

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 transparent; 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.

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 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.

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.

You will understand, however, that we form bright lines in different parts of the 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.

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 glass prism, mounted in a telescope arrangement which he calls a spectroscope. 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.

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 makes no difference to the reading of our messages.

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.