Measured Tones: Physics and Music by Ian Johnston

Author:Ian Johnston [Johnston, Ian]
Language: eng
Format: epub
Tags: Music
Publisher: Taylor & Francis
Published: 2002-03-15T04:00:00+00:00

The legacy of electromagnetism

It is interesting that acoustics wasn’t the only part of physics that was changed fundamentally by electromagnetism. It all started with experiments which newly measured the speed of light at the end of the 19th century. At the same time that Wallace Sabine was doing his work on architectural acoustics in Boston, another American, Albert Michelson from Chicago University, was carrying out a series of experiments to measure accurately how fast light travels. The story of how it became for him a lifelong obsession is a fascinating tale in itself, but not what I want to talk about now. Ever since Maxwell had shown that light was an electromagnetic wave, the big question was: what was the medium that was ‘waving’? And the evidence that came from Michelson’s experiments was soon irrefutable: there was no medium at all! But, as we saw earlier in the case of sound, the properties of the medium are what determine the speed of the wave. So if light needs no medium, what determines its speed? Why should there be a special speed at which nothing moves through nothing?

The answer, when it came, involved a complete rethinking of what we mean when we measure speed, distance and even time itself. These quantities are not absolute, they must always be thought of in relation to other quantities. Hence the name given to this new theory was Relativity. Many workers were converging on these new ideas; but the man we usually associate with it, from the time he gave the world its first clear exposition in 1905, was Albert Einstein.

He was born and educated in Germany, but did much of his early work in Switzerland and spent his last thirty years in America. He developed early a deep love of the violin, which he played all his life—passably well, I believe. He even got to play (as one of the perks of being a world-famous scientist) with top rank professionals like Isaac Stern. And it is an often-repeated story that, during one such session, Stern remarked in exasperation: “The trouble with you, Albert, is that you can’t count!”.

I often think it’s ironical that Einstein, who made such a mark on the public consciousness because of the wisdom and gentleness he displayed in later life, should have been the one to turn physics upside down, and whose work would eventually lead to that ultimate horror—the atom bomb. For physics was changed beyond recognition by his paper on relativity. Above all, it was the old complacency that was lost, the belief that we knew it all; and this was probably a good thing. The new mood that took its place was beautifully summed up by the English humourist, J.C. Squire, who transformed that couplet of Pope’s that I quoted in Chapter 4, into a quatrain:

Nature and Nature’s laws lay hid in night,

God said “Let Newton be!” and all was light.

It did not last. The devil, crying “Ho!

Let Einstein be!”, restored the status quo.

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