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7: Magnetism

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« on: April 10, 2024, 08:12:21 am »

Chapter Seven: Magnetism
What Magnetism is like, and its analogies with Life.

Active forces are conserved in the world. It has been objected that two soft or inelastic bodies, when they collide, lose part of their force [energy]. I answer that this is not so . . . the loss ensues only in appearance. The forces are not destroyed, but dissipated amongst the minute parts. That is not as if they were lost, it is like the changing of large coins into small ones.---LEIBNITZ.

ONE of the most important things that we know about electrons and protons is that they can never be either brought into existence or put out of existence: they can only be moved about from place to place,---they are in that respect like any other form of matter. Parenthetically, we find ourselves rather singularly in accordance with the electrical views of Benjamin Franklin long ago:---the electron is all electricity, the proton feels more material. He admitted only one kind of electricity: his other kind was "matter." Charge is transfer of one kind. Electrons are easily transferred from one body to another; they can be accumulated so that one body has an excess, but some other body must have an equal defect. An extra number of electrons gives a negative charge to a body: anything with an excess of unbalanced protons is positively charged.

But it may be said, surely when a thing is discharged (that is, when one body sparks into another, as when you connect the two coats of a Leyden jar), surely the two charges disappear! Yes, they "disappear": that is the right word; they are no longer apparent; but they have not gone out of existence. They have re-grouped themselves; the two opposite charges have got close together, they have as it were re-united, they are mutually satisfied, they make no more disturbance or strain, their lines of force have as it were shut up or become exceedingly short, they have neutralised each other so far as outside effects are concerned; but they have not obliterated each other, their existence is not terminated: they are there ready to be separated again, though the oppositely charged bodies have become neutral.

We never really generate or destroy electricity: what one body has gained, another has lost, and when the balance is restored there is equilibrium. We produce or display electric charge simply by transfer, simply by making manifest what was previously existent. We pull out infinitesimal lines of force and make them extend across perceptible space: we thus in a way generate an electric field; but the field was preexistent, though infinitesimal and nonapparent before we displayed it. If we liken the lines of force to elastic threads, they are elastic threads of infinitesimal length, capable of being stretched ad libitum, without limit; the lines never snap, nor do they ever shrink up into absolute nothingness. To make this statement quite safe, we ought to say that they are not "known" to do such a thing in any of our experiments, however violently we treat them. Whether they ever shrink to nothingness of their own accord, remains to be seen: such a discovery has not yet been made.

What we have now to learn is that something of the same sort is true of magnetism: we never really generate magnetism any more than we generate electricity. We can make a magnet, just as we can charge a body; but the magnetism was there beforehand, just as the electricity was: we have only made manifest what was pre-existent.

So far there is similarity: but now there are differences. We cannot charge a body with one sign of magnetism, say the north-seeking kind, leaving another body charged with the south-seeking kind: every magnet has an equal quantity of both kinds, though instead of being close together they can be separated by the whole length of a piece of steel.

That is an old-fashioned method of regarding magnetization, and has been known for centuries, but the inner meaning of it has not been so thoroughly known. There is a fundamental difference between electric and magnetic lines of force, a difference quite definite, though perhaps not easy to specify completely. The main difference is this: an electric line of force has two ends, a positive end on a proton, a negative end on an electron. A magnetic line of force has no ends, it is always a closed loop: we may not think of a magnetic line of force as analogous to an elastic thread reaching from one particle to another and pulling them together; it is more like an indiarubber ring, it is looped or closed on itself, it has no ends. But the loop is one that can be stretched, it can be expanded so as to enclose a big area, or it can shrink up until it is too small to be appreciable. It never shuts up to nothing; it never goes out of existence. If you call these loops magnetism, we never generate magnetism; we open it out. The act of magnetization opens a loop out, and, being elastic, it is always trying to close up. When a loop encloses two bodies, and then shrinks, it pulls them together as if they attracted each other. That is magnetic attraction. Rather like an indiarubber ring holding things together.

An inert piece of iron is full of such infinitesimal loops: the act of magnetization opens them out and makes them perceptible. Part of their course then lies in the air: but the air has nothing to do with them, they do not really exist in the air: they exist solely in the Ether. And the iron is not necessary either: it may have an extra number of the loops, and without iron or some similar substance we might possibly not have discovered the magnetic loops, or not discovered them so soon; but they are there all the time, everywhere.

The Ether is full of them: and it so happens that in or near some large bodies, like the earth, some cause has already opened out a few of those loops; so that the earth behaves like a permanent magnet. What has magnetized the earth we do not completely know; but it was owing to that fact that the Ancients were enabled to discover magnetism. And some substances, even when dug out of the earth, have the power of retaining these loops in an opened-out condition: in other words, some ores of iron are natural magnets. They are not very strong,---artificial magnets can be made much stronger,---and, as the cause of natural magnetism is not known, it is not the most instructive kind for serious contemplation.

It was long ago known however that the power of retaining the loops in an opened-out condition was possessed by steel, and many other substances in a greater or less degree; and there were rather blindfold methods also known by which one magnet could excite another. The natural idea would be that the magnetism of one was transferred to the other, and that what one body gained, the other lost. That is not so. It is so in electric charge; it is not so in magnetism. The magnetic influence, or so-called “induction,” is exercised without loss: one magnet can magnetize any number of others without itself being any the poorer; there is no limit to the amount of magnetization that can be produced, once it is started.

Analogy with Life
In this respect it is rather like Life. An oak can produce a large number of acorns, and each acorn has the potentiality of producing an oak; and so on without limit. Wherever life exists, it can increase prodigiously; not at the expense of the original source, but as if there were an infinite reservoir from which it could be drawn. The analogy is striking, even if not helpful; for though we know only a little about magnetism, we know much less about life. We do not explain the unknown by the still more unknown, but we can draw attention to analogies and similarities, in spite of immense and important differences.

There is this further similarity, however, that production of more magnetism, or more accurately the display of pre-existent magnetism, is not accomplished without expenditure of something. It is not magnetism which is expended, but energy: energy must be expended, that is, work must be done, in order to produce more magnets; and if energy is not expended, nothing happens. So it is with life. A plant can produce innumerable seeds, and thus give rise to innumerable plants, but not in the absence of energy, not without the rays of the sun: there must be available energy, and that is consumed in the process. We live in such a stream of energy, coming from the sun, that we almost forget it: yet it is essential to every movement, it is essential to the display of every form of life. Life may exist in some imperceptible form unknown to us, but without radiant or etheric energy, it could not enter into relation with matter, it could not grow and develop and become conspicuous. Energy may not be necessary to abstract Life, but it is essential to the display or manifestation of life in matter.

What Life is we do not know: what magnetism is we are only beginning to learn. But the two have this in common: they may be dormant, imperceptible, inactive; by means of energy they can be displayed, and displayed in unlimited amount. There is, as it were, an infinite amount available; or if not infinite---that is without limit---the limits are beyond anything that we have detected or imagined. We cannot say much about Life (at least I cannot), but I can say something more about magnetism, which is clearly a much simpler thing, and I will proceed to make some assertions about it.

We not only have the power of passing it on, by help of a piece of magnetized iron ore which we pick up; we have the power of magnetizing a body de novo. We cannot generate the loops, it is true, but we can open them out, even if none already opened out were given us. We do not require a permanent magnet in order to magnetize bodies. What do we require? We require a moving electric charge; that is we require to get an electron and a proton separated from each other, and rush one of them along. We generate magnetism by means of electricity: the two are remarkably inter-related: they are by no means the same thing. Electricity can generate magnetism, with the aid of energy expended: this was discovered by Arago early in the Nineteenth century: and a few decades later Faraday made the tremendous discovery that magnetism could generate electricity,---also by the expenditure of energy. And now every dynamo is doing it.

But these terms are not quite accurate. When I say that electricity can generate magnetism, I am speaking popularly. More accurately, an electric current can open out pre-existent magnetic loops and thus generate a perceptible magnetic field. And when I say that magnetism can generate electricity, I ought to say that a magnet enables energy to generate an electric current, that is to set electrons in motion. Motion, mechanical motion, is the link between the two things, electricity and magnetism: and it is by aid of mechanical motion (which is not an etheric process, pure and simple, but a material one) that electricity and magnetism in combination are able to interact with matter; and it is thus that they have come within our ken. We realise electrical and magnetic phenomena by the motions which they are able to produce; we have sense organs for the purpose. Our physiological organism (in some mysterious way, to which we have grown so accustomed that we fail to realise the mystery) enables us to perceive mechanical motion. We can see pieces of matter moving. When we see the gold-leaves of an electroscope diverge, we know that they are electrically charged: when we see a galvanometer deflect, we know that there is an electric current in its neighbourhood: when we see two pieces of iron or steel jump together we know that they are magnetized.

We have a further most extraordinary sense. When we look at the flame of a fire or the filament of a lamp, or at the moon or a star or a landscape or indeed any visible object, we know---at least some of us have learnt to know---that there is an electromagnetic disturbance in the Ether, travelling at a known pace, reaching our eye, and in some curious way stimulating the optic nerve. The sensations we experience directly: the meaning of those sensations, the causes which have excited them, the processes to which they are really due, are matters for inference, that is for scientific discovery. The senses give us the result, they do not tell us about the mechanism: it has been no easy matter to discover the mechanism, and there is much still to be discovered about it: our explanations are bound to be dependent on the present state of scientific knowledge; we may be sure that posterity will know much more. Meanwhile we can try to learn what is already known: and in so far as our knowledge is inaccurate as well as incomplete, we must be always ready to correct it. We are certain that our knowledge will have to be enlarged: our hope is that it is accurate as far as it goes. But even of that we must not be too certain; and in so far as some of the problems are difficult, we must be prepared for differences of opinion among skilled and expert investigators.

Discussion and friendly controversy are useful in Science. What is not useful is the kind of political controversy and international greed which distract attention from the beneficent processes of nature which humanity can hope to understand and utilise. Persons so afflicted are sometimes seized with madness and seek to apply the knowledge already acquired to the arts of mutual destruction. If the different sections of humanity could only settle down to peaceful co-operation, ascertaining and interchanging knowledge freely, without wasting energy in barbarous conflict, there is no end to the possibilities in front of us. We have learnt so much, we are always learning more; and the utilisation of the energies of the Universe is one of the functions of civilised man. We live among difficulties, our life is bounded by a struggle; but it may be a co-operative and not a competitive struggle.

Knowledge in this respect is like life and magnetism: there is an unlimited reservoir from which to draw, and the imparting of knowledge does not lessen the amount possessed by the imparter, it is transferred without loss, though doubtless with the expenditure of some energy. Knowledge grows from more to more. By diffusion it is increased: what one gains another does not lose. Some energy and skill are needed for broadcasting; but it is an operation that can be conducted without loss . If the transmitter suffers at all, it is only his bodily energy which is consumed. A magnet which has excited other magnets may be even stronger than before: life which has excited other life may still be vigorous. There may be temporary fatigue: a shrub may be temporarily exhausted by producing seeds, but it soon recovers: fatigue is natural to material organisms and to any expenditure of energy; but recuperation follows, and next year it is ready for a fresh crop.

Certainly in the case of a physiological organism, fatigue may be pressed to excess: exhaustion, old age, and death lie in wait for bodily organisms: it is not they which are permanent. A magnet may be knocked into inefficiency by hammering; its loops shrink up into apparent nothingness, but they have not gone out of existence. A loose tile from a house-top may destroy the mechanism of thought, and damage irretrievably the working of an organism: thereby life and mind will disappear from our ken. But if the analogy holds, they have not gone out of existence. So far as we learn from Science, nothing goes out of existence; it only changes its form, it may become inappreciable to our senses, it may to all appearance cease to be. That is the Appearance. What is the Reality? That question must be answered by Science. In the case of magnetism and electricity it has been answered; in the case of life and mind it is in process of being answered,---but of course not without controversy. Friendly discussion and controversy is to be welcomed. In this, as in all other matters, we must learn from the facts.

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