|
880dc34
|
Most creative scientists, even the most prolific and versatile, produce one theory per subject. When that theory has run its course they move on to another topic, or stop inventing. Maxwell was unique in the way he could return to a topic and imbue it with new life by taking an entirely fresh approach.
|
|
|
Basil Mahon |
|
2e3ef01
|
One of the things Maxwell learned from his reading was the fallibility of men's efforts to understand the world. All of the great scientists had made mistakes. He was acutely aware of his own tendency to make errors in calculation.
|
|
|
Basil Mahon |
|
53e9bb6
|
Maxwell's greatest work shows two unique characteristics which stem from his philosophical insight. The first is the way he could return to a subject, often after a gap of several years and take it to new heights using an entirely fresh approach. He did this twice with electromagnetism. The second is even more remarkable. His electromagnetic theory embodied the notion that things we can measure directly, like mechanical force, are mery the ..
|
|
|
Basil Mahon |
|
d66e5e7
|
He wrote up the mathematics and everything fitted together. James had shown how the electrical and magnetic forces which we experience could have their seat not in physical objects like magnets and wires but in energy stored in the space between and around the bodies. Electrostatic energy was potential energy, like that of a spring; magnetic energy was rotational, like that in a flywheel, and both could exist in empty space. And these two f..
|
|
|
Basil Mahon |
|
cb98639
|
David Hume, the great eighteenth century Scottish philosopher, had put the cat among the pigeons with his notion of scepticism: that nothing can be proved, except in mathematics, and that much of what we take to be fact is merely conjecture.
|
|
|
Basil Mahon |
|
2472b69
|
The E and H waves always travel together: neither can exist alone. They vibrate at right angles to each other and are always in phase.
|
|
|
Basil Mahon |
|
617b471
|
His system of equations worked with jewelled precision. Its construction had been an immense feat of sustained creative effort in three stages spread over 9 years. The whole route was paved with inspired innovations but from a historical perspective one crucial step stands out-the idea that electric currents exist in empty space. It is these displacement currents that give the equations their symmetry and make the waves possible. Without th..
|
|
|
Basil Mahon |
|
e8a0b42
|
He had made a discovery of the first magnitude. It opened up an entirely new approach to physics, which led to statistical mechanics, to a proper understanding of thermodynamics and to the use of probability distributions in quantum mechanics. If he had done nothing else, this breakthrough would have been enough to put him among the world's great scientists.
|
|
|
Basil Mahon |
|
d9cfe85
|
In fact, confusion over units was not confined to electricity and magnetism. When two people spoke of a quantity like 'force' or 'power' you could not be sure that they meant the same thing. James saw a prime opportunity to straighten out the muddle. He went beyond his brief for the paper and proposed a systematic way of defining all physical quantities in terms of mass, length and time, symbolised by the letters M, L and T. For example, ve..
|
|
|
Basil Mahon |
|
b06d3f9
|
It sometimes happens that mathematical methods conceived in the abstract turn out later to be so well suited to a particular application that they might have been written especially for it. When he was wrestling with the problems of general relativity, Albert Einstein came across the tensor calculus, invented 50 years earlier by Curbastro Gregorio Ricci and Tullio Levi-Civita, and saw that it was exactly what he needed. James enlisted a met..
|
|
|
Basil Mahon |
|
ddeaa61
|
The new law that he predicted seemed to defy common sense. It was that the viscosity of a gas-the internal frictional that causes drag on a body moved through it-is independent of its pressure. One might expect a more compressed gas to exert a greater drag; even James was surprised at first that the theory said otherwise. But further thought showed that, at higher pressure, the effect on a moving body of being surrounded by more molecules i..
|
|
|
Basil Mahon |
|
f2e2a4e
|
Happy is the man who can recognise in the work of Today a connected portion of the work of life, and an embodiment of the work of Eternity ...
|
|
|
Basil Mahon |
|
8559689
|
Maxwell was not only one of the most brilliant and influential scientists who ever lived but an altogether fine and engaging man. And
|
|
|
Basil Mahon |
|
5dc5fa8
|
Most creative scientists, even the most prolific and versatile, produce one theory per subject. When that theory has run its course they move on to another topic, or stop inventing. Maxwell was unique in the way he could could return to a topic and imbue it with new life by taking an entirely fresh approach. To the end of his life there was not one subject in which his well of inventiveness showed signs of exhaustion. With each new insight ..
|
|
|
Basil Mahon |
|
d93513d
|
His electromagnetic theory embodied the notion that things we can measure directly, like mechanical force, are merely the outward manifestations of deeper processes, involving entities like electric field strength, which are beyond our powers of visualisation. This
|
|
|
Basil Mahon |
|
b052d67
|
I think that the results which each man arrives at in his attempts to harmonise his science with his Christianity ought not to be regarded as having any significance except to the man himself, and to him only for a time, and should not receive the stamp of a society. For it is in the nature of science, especially those branches of science which are spreading into unknown regions, to be continually changing e.
|
|
|
Basil Mahon |
|
7dcbf02
|
In the Treatise James made an important new prediction from his electromagnetic theory-that electromagnetic waves exert a radiation pressure. Bright sunlight, he calculated, presses on the earth's surface with a force of around 4 pounds per square mile, equivalen to 7 grams per hectare. This was too tiny a value to be observable in everyday life and its detection posed a challenge to experimenters. Eventually, in 1900, the Russian physicist..
|
|
|
Basil Mahon |
|
8dc0783
|
Leo Szilard, in 1929, showed that the very act of acquiring information about a system increases its entropy in proportion to the amount of information gathered. As the entropy increases, less of the system's total heat energy is available for doing work. To gather enough information to work the shutter effectively we would have to use up, or render inaccessible, an amount of energy at least equal to the work output of any machine that we c..
|
|
|
Basil Mahon |
|
ccfe491
|
His faith was the guiding principle of his life but it was an intensely reflective personal faith which could not be contained within the rules of a sect. Institutional politics, whether of the church, the state or the university, was a topic that never engaged his interest.
|
|
|
Basil Mahon |
|
4916005
|
First, electric charges attract or repel one another with a force inversely proportional to the square of the distance between them: unlike charges attract, like ones repel. Second, magnetic poles attract or repel one another in a similar way but always come in pairs: every north pole is yoked to a south pole7. Third,
|
|
|
Basil Mahon |
|
354a4a3
|
little of the work of Faraday and others on electricity and magnetism had yet fed through to practical application. In short, science was a splendid hobby for a gentleman but a poor profession.
|
|
|
Basil Mahon |
|
52a2904
|
Goodness knows what Maxwell would make of our current relish for watching people indulging in histrionic self-exposure on television. He would certainly have a wry smile at the irony of the fact that his own electromagnetic theory provides the means of bringing such unwholesome displays into our homes.
|
|
|
Basil Mahon |
|
3c78aa9
|
I know the tendency of the human mind is to do anything rather than think. But mental labour is not thought, and those who have with labour acquired the habit of application, often find it much easier to get up a formula than to master a principle.
|
|
|
Basil Mahon |
|
81c7ba3
|
James was generous with his time to any friend who needed it--as well as to some, like Lawson, who did not! When one friend had eye trouble and could not read, James spent an hour each evening reading out his bookwork for the next day. He bucked up fellow students when they were depressed and on several occasions nursed others who were sick. He helped freshmen who were having trouble with their studies. He also found time to keep up a livel..
|
|
|
Basil Mahon |