Too Short for a Blog Post, Too Long for a Tweet 193

Here are a few excerpts from a book I recently read, "The Perfectionists: How Precision Engineers Created the Modern World," by Simon Winchester.

Precision, in other words, is an absolute essential for keeping the unforgiving tyranny of a production line going. As far as a handmade car is concerned, though, upfront precision is quite optional. It is a need that could be attended to during the hand-making process, as the process itself never depends (at least, not in the Silver Ghost days) upon every component’s being precise from the commencement of manufacturing. The irony remains: a Rolls-Royce is so costly and exclusive and has enjoyed for so long a reputation of peerless creation and impeccable performance, but it does not require absolute precision at all stages of its making. A Model T Ford, however (or, indeed, any modern car, now made by robots rather than human beings, by Chaplinesque figures staring glassy-eyed at the endlessly flowing river of parts), requires precision as an absolute essential. Without it, the car doesn’t get made.

There are scores of blades of various sizes in a modern jet engine, whirling this way and that and performing various tasks that help push the hundreds of tons of airplane up and through the sky. But the blades of the high-pressure turbines represent the singularly truest marvel of engineering achievement—and this is primarily because the blades themselves, rotating at incredible speeds and each one of them generating during its maximum operation as much power as a Formula One racing car, operate in a stream of gases that are far hotter than the melting point of the metal from which the blades were made. What stopped these blades from melting? What kept them from disintegrating, from destroying the engine and all who were kept aloft by its power? It seems at first blush so ludicrously counterintuitive: that a piece of normally hard metal can continue to work at a temperature in which the basic laws of physics demand that it become soft, melt, and turn to liquid. How to avoid such a thing is central to the successful operation of a modern jet engine. 

For, very basically, it turns out to be possible to cool the blades by performing on them mechanical work of a quite astonishing degree of precision, work which allows them to survive their torture for as many hours as the plane is in the air and the engine is operating at full throttle. The mechanical work involves, on one level, the drilling of hundreds of tiny holes in each blade, and of making inside each blade a network of tiny cooling tunnels, all of them manufactured at a size and to such minuscule tolerances as were quite unthinkable only a few years ago.

John Wilkinson’s cylinder fit inside James Watt’s steam engine with a degree of precision amounting to the thickness of an English shilling, about one-tenth of an imperial inch. Such precision had never been achieved before, but after that, the world never once looked back. 

Two and a half centuries on, and the engineers at LIGO have also made their test mass as a cylinder. This one was constructed out of fused silica—a pure form, effectively, of sand, of as elemental a substance, literally and metaphorically, as the iron that was used by John Wilkinson. 

The test masses on the LIGO devices in Washington State and Louisiana are so exact in their making that the light reflected by them can be measured to one ten-thousandth of the diameter of a proton. They can also compute with great precision the distance between this planet and our neighbor star Alpha Centauri A, which lies 4.3 light-years away. 

The distance in miles of 4.3 light-years is 26 trillion miles, or, in full, 26,000,000,000,000 miles. It is now known with absolute certainty that the cylindrical masses on LIGO can help to measure that vast distance to within the width of a single human hair. 

And that’s precision.