Stephen R. Wilk: How The Ray Gun Got Its Zap

Cover of "How The Ray Gun Got Its Zap", by Stephen R. WilkI sometimes think that we should spend at least a little time explaining everyday manifestations of physics to undergraduates, so that they can talk about phenomena that appear in everyday lives.

How The Ray Gun Got Its Zap (2013), is subtitled Odd Excursions Into Optics, which (combined with the manifesto above) pretty much covers what it’s about.

Stephen R. Wilk is a Contributing Editor for the Optical Society of America (OSA), with a CV that includes time spent working with lasers in both academic and commercial laboratories. The book is made up of a series of short articles, which are revised and expanded versions of pieces originally published by OSA’s Optics and Photonics News, as well as The Spectrograph, the newsletter of the George R. Harrison Spectroscopy Laboratory at MIT.

The object of the exercise, Wilk says, was “Education by Stealth”—packaging some useful nugget of science into an article that strayed entertainingly into little-visited byways.

For the book, he has sorted his articles into three sections—History, Weird Science and Pop Culture.

“History” covers a lot of ground, including: how the ancients might have been able to do close miniature work using a pinhole, before magnifying lenses were invented; a mysterious optical phenomenon sighted by Antonio de Ulloa in 1735; the real reason Newton insisted on having seven colours of the rainbow; and the history of the camera lucida, an open-air version of the more familiar camera obscura projection system.

Camera Obscura
A camera obscura being used to project an image into a darkened room for copying

Some of the “Weird Science” isn’t particularly weird—there’s a very satisfying and comprehensive article on retroflectors, for instance. I also enjoyed the discussion of the derivation of the expression “once in a blue moon”, but the description of how Mie scattering can conspires to make the full moon actually appear blue was utterly impenetrable—Wilk describes the shape of a graph to us, instead of plotting one and marking it up appropriately. And that’s a serious shortcoming of this book, I have to say—Oxford University Press seem to have been happy to spring for a few uninformative copies of historical illustrations, but the book doesn’t contain a single original diagram. It’s a book on optics, with no diagrams!

Here’s Wilk, forced to verbally handwave a Penta Prism reflector, without recourse to illustrations:

This is a block of glass with two faces set at an angle of 45º to each other. Next to each of these are two faces, usually square, that meet at a right angle to each other and each of them makes a [sic] angle of 112.5º with the other two faces. The prism can work as it is, with only four faces, but the 45º angle is far from the rest of the prism and gives it an unwieldy long “tail” […] so it’s usually cut off, adding a fifth face, hence “penta” prism.

Got that? I thought not. Here’s a diagram:

Pentaprism
Image by DrBob, used under Creative Commons Attribution-Share Alike 3.0 Unported licence

Would it have killed Oxford University Press to do that?

A fair proportion of “Weird Science” is laser-heavy: edible lasers, pyrotechnic-pumped lasers, laser systems that have never been used, the author’s own problems with lasers … It’s Wilk’s special interest, but this was the least interesting section for me, in the main because, in his enthusiasm, Wilk occasionally forgets to translate for his lay audience:

You can perform this trick with perfectly reflecting metal microspheres, too, but you have to suspend them in a beam having a TEM01 “donut” mode, for obvious reasons.

Well, yeah. Obviously.

Finally, “Pop Culture”. Here, Wilk riffs on anything vaguely optical that takes his fancy: the infamous patent on the idea of using a laser pointer to play with your cat; the development of the ideas of “ray guns” and “tractor beams” in science fiction; whether it might be possible to create jewels that glow in the dark, like in the movies; and how lasers have been portrayed by film-makers over the years.

It’s all great fun, I suspect there’s something here for everyone with any interest in optics, and I am positively in awe of Wilk’s ability to ferret out obscure references and the earliest historical glimmerings of scientific ideas.

But it could have been so much better with diagrams, graphs, and some better proof-reading—shame on the Oxford University Press.

3 thoughts on “Stephen R. Wilk: How The Ray Gun Got Its Zap”

  1. Testing – as you can see you really wouldn’t have missed much.

    (I wrote a fascinatingly interesting and considered response to this piece only for it to be rejected as spam. I have tried again but I am sure that it will not match the brilliance of my first effort.) 🙂

    I am amazed that you didn’t instantly grasp why “having a TEM01 “donut” mode,” was an obvious necessity. We often spoke of nothing else in my office – yeah. I have googled the term and am really not much the wiser.

    The edible laser however was a pleasant surprise and something that I have never heard of before.

    The lack of illustrations, graphs etc seems a surprising omission. When I read the paragraph you quoted my eyes instantly glazed over. Normally I would expect a book like this – which is of a type I usually enjoy reading – to have copious illustrations.

    Thanks for doing a post on this book.

  2. Sorry about the spam thing. I think it might be related to JavaScript, but I’m not sure. I’ll fiddle with various settings and do some tests, so there’s the potential for a temporary problem re-appearing while I’m doing that over the next few days.

    There seems to be a whole list of edible dyes that can be persuaded to “lase” under the right circumstance, though it appears no-one has ever actually made the fabled jello laser or laser cocktail.

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