Bench Degree·PLASMAchapter

On the Cover

How the cover of every Bench Degree volume is chosen. One question, and it is not who got there first or who is famous. If we could bring anyone back to teach you this subject, who would you actually want at the bench? That is the whole test. It picks people who did the work with their hands, who checked things themselves, and who would be worth standing next to. Every one of them actually lived, which is why a cover portrait in this series is either a real document or openly a drawing, and never a photograph of something that did not happen.

Irving Langmuir, engraved from a public-domain portrait.

He has the strongest claim of anyone in this series to the volume he is on. He named the subject. The word plasma, in the sense used on every page of this book, is his, from 1928. The instrument in Chapter 15 is called a Langmuir probe because he worked out how to read a bare wire pushed into a glowing gas. The screening length of Chapter 2 becomes the sheath of Chapter 10, which is the thing that does the cutting in every semiconductor plant on earth. He took the Nobel Prize in Chemistry in 1932, and he did all of it in a company laboratory rather than a university, on problems that arrived as complaints. He came to this subject because light bulbs were going black.

None of that is why he is on the cover.

In December 1953 he gave a colloquium at his own laboratory titled Pathological Science, on how careful, honest, competent people come to believe in results that are not there. He worked through cases: N-rays, the Davis and Barnes effect, the Allison effect, extrasensory perception. Not one was a fraud. Every one was produced by a real scientist doing real work who had stopped being able to tell his signal from his hope. Langmuir listed the symptoms, and the list is short enough to memorise: an effect at the limit of detection, an effect that does not grow when you increase the cause, claims of fantastic accuracy, and excuses that arrive exactly as fast as the objections do.

For a book about glowing gas, that lecture is almost too apt. A discharge is beautiful, it is easy to photograph, and it will show you whatever you brought with you. Chapter 12 is about a technology that has been thirty years away for seventy years, and Chapter 15 hands you a probe whose curve can be read, with a little wishful arithmetic, to give the electron temperature you were hoping for. The man who wrote down how that happens is the right man to have watching from the front of the book.

About the portrait, and it is an engraving. The source is a photographic portrait of Langmuir in the public domain, and it is small, far too small to print at the size it appears on the cover. That is why the plate is a line engraving. A program lays down the lines and sets each one’s thickness from the local tone of the photograph, which is arithmetic on a real document. No generative model touched it, nothing was upscaled or sharpened into existence, and no part of his face has been altered.

There was an easy route here: ask an image model for a photograph of a chemist in a 1930s laboratory and put his name under it. That is a picture of a man who never stood there, and on a book about scientific self-deception it would be a joke at the reader’s expense.

The rule for this series is that a cover portrait is a document or it is openly a drawing, and it is never a photograph of something that did not happen.

The full account of how this book was made, including which parts were written with the help of a language model, is on the copyright page and on the back cover, itemised using the five credits published at bookcredits.org.

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