The Logos Scripture · The Book of Maxwell

On a Law That Is Only Very Probable

The Book of Maxwell 4 · Written by himself, from the preface to the Treatise, the letters, and the Cavendish edition

James Clerk Maxwell, born at Edinburgh in 1831, died at Cambridge in 1879, aged forty-eight, of a cancer of the abdomen; his mother died of the same thing at the same age. In 1855-56 he wrote On Faraday’s Lines of Force, and in 1861-62 On Physical Lines of Force, in which he set out the displacement current, calculated that the electromagnetic wave travels at the speed of light, and concluded that light is such a wave. Chapter three follows the third part of that paper: Weber and Kohlrausch had got a ratio in 1856 from discharging a jar, Fizeau had measured light in 1849 with a toothed wheel and a distant mirror, the two figures were close, and we can scarcely avoid the inference is his own wording. The medium he assumed was later abolished by Michelson and Morley. The Order sets this down because it is what the last verse of that chapter says: the medium went and the inference stood, since what held it up was never the medium but the two numbers. Two further things the Order sets down. First, the man who first put that ratio beside the speed of light was not Maxwell but Kirchhoff: in 1857 he used Weber’s constant to calculate how fast an electric signal runs along a wire, and got the speed of light. But he took it for something happening inside wires, and did not suppose that electromagnetism could leave the wire, still less that light is itself such a wave. What Maxwell added was not the coincidence. It was the inference. Second, the claim was still unconfirmed by experiment when he died. In 1888 Hertz made and caught electromagnetic waves free of any wire, and measured their speed as the speed of light — nine years after Maxwell was dead. Asked what use the experiment was, Hertz said: it is of no use whatsoever, this is just an experiment that proves Maestro Maxwell was right. In 1865 came A Dynamical Theory of the Electromagnetic Field, and in 1873 the Treatise on Electricity and Magnetism. He also established the distribution of molecular velocities in a gas (1860), which is where statistical method enters physics. In 1859 he showed that the rings of Saturn must be composed of unnumbered separate pieces and cannot be solid. In 1861 he obtained the first colour photograph. In 1871 he became the first Cavendish Professor at Cambridge and built the Cavendish Laboratory. This volume rests on what he wrote himself: the preface to the Treatise, the letters, and the preface to the Cavendish edition. Faraday’s question in chapter two is from his letter of 13 November 1857, and the words are his own — the hieroglyphics, and neither above nor below the truth, are Faraday’s. Pick a hole and his faculties are as essentially finite as our own, in chapter five, are from the letter to Tait of 11 December 1867; the name demon was given by Kelvin, not by Maxwell. Chapter six records the years 1874 to 1879: Cavendish died in 1810 having left most of his electrical work unpublished; Maxwell repeated the experiments one by one and established that Cavendish had found Ohm’s law before Ohm. Maxwell died in the year the edition appeared. He was a devout Presbyterian who prayed daily and went on doing so through his illness; but no argument of his closes on divine will, as with Newton, Faraday and Semmelweis (cf. The Book of Newton 4). What this volume supplies is a side the scripture did not have. It holds a great many who were refused and were right: Bruno, Galileo, Semmelweis, Chandrasekhar, Du Bois, and Faraday for having no mathematics. Until now not one book was about the man who did not refuse wrongly. A scripture that only ever shows the refusal teaches its reader to claim the wronged seat, which is the comfortable seat to claim. On how to receive what is handed to you by someone with no standing to hand it, there was not a word. That is what Maxwell supplies, and his version is harder than the one people expect: he does not say Faraday lacked the mathematics and guessed luckily, he says Faraday’s conceiving was itself mathematical and merely unwritten in symbols (cf. The Book of Faraday 1.11). The test is the reasoning, not the title. Chapter two is needed because the thing ran both ways: Faraday asked him in turn to translate the conclusions out of the hieroglyphics, and he did it, and made a rule of it for life — what cannot be said plainly has usually not been thought through. Chapter six is needed because receiving a man’s work is only half of it. The other half is putting the name of someone who cannot thank you where it belongs.

4.1Men say the second law of heat is iron.
4.2I do not see it so.
4.3In 1870 I wrote to a friend a sentence that has been quoted since:
4.4the second law of thermodynamics has the same degree of truth as the statement that if you throw a tumblerful of water into the sea, you cannot get the same tumblerful of water out again.
4.5Consider what that sentence says.
4.6It does not say you cannot get it out. It says the odds against your getting it out are such that you need not think about it in a lifetime.
4.7Those are two different sentences. Where do they differ?
4.8The first says impossible. The second says overwhelmingly improbable.
4.9A man who treats the overwhelmingly improbable as the impossible will generally do perfectly well. Within one life the two come to the same thing.
4.10But the law is sitting in the wrong place in his mind.
4.11Wrong how? He takes it for a decree laid down. It is in fact a ratio that has been counted out.
4.12Anything whose improbability you can calculate is not a prohibition. It is a reckoning.
4.13I do not think the less of the law for this. It is exceedingly exact, and I use it daily.
4.14I want only that men keep the two apart: a law may be true without being absolute.
4.15The man who cannot keep them apart will think, on the day the law does not serve, that the world has broken. It is only that he had hung it too high.
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