Archive for the ‘Science’ Category

Jerry Nelson

July 16, 2017

Last week I had the sad pleasure of participating in Nelsonfest, a symposium celebrating the many achievements of Jerry Nelson in observational astronomy, especially the Ten-Meter Telescopes at the Keck Observatory, to which I made a small contribution (well, actually two).

It was a pleasure because it was gratifying to meet many people for whom, as for me, working with Jerry was a stimulating, edifying and enjoyable experience. It was sad because Jerry had died about a month earlier, and so what had been meant as a series of technical presentations became mingled with reminiscences.

Jerry was one of those fortunate few who conceived a radical idea and then were able to carry it to full fruition, overcoming intellectual opposition, financial uncertainty and technical challenges. He did so by convincing people with the sheer force of his ideas. There was no ego at play.

Unlike many famous technological innovators who advance their plans by force of personality, depending on their subordinates for most of the details but taking credit for their work (the likes of Gustave Eiffel, David Sarnoff or Steve Jobs), the ideas for the Ten-Meter Telescope were Jerry’s, but he was, if anything, overly generous in giving credit to his collaborators, starting with the key notion of the segmented mirror produced by means of stressed-mirror polishing, for which I derived the formal theory. (It may not be generally known that the Eiffel Tower was not designed by Eiffel but by two engineers and an architect working for his company, whose patent rights he bought out.)

Jerry was sui generis, and his like may not be found again, especially in this age of pygmies masquerading as tech giants.



Science fiction

January 9, 2017

Being a scientist, I have long been bothered by the use of “science fiction” to denote, in literature and film, improbable fantasies with no connection to science. If detective fiction (I dislike the term “mystery”) is about detective work, spy fiction is about espionage, historical fiction is about historical characters, why shouldn’t science fiction be about science — scientists and their work?

I have just finished reading a novel that’s a perfect example of what I mean, Ann Patchett’s State of Wonder (about which I posted a bit of ling-crit the other day). Most of the principal characters are scientists, and their work — in this case pharmacology and ethnobotany — is at the heart of the action. It’s fiction, of course — the drug that serves as the story’s MacGuffin is fictitious, as is the tribe in whose habitat it’s found — but it’s all plausible, with a fair amount of biomedical detail. While Ann Patchett did not study biology at university (as did, say, Diana Gabaldon and Barbara Kingsolver), she is married to a physician, a fact that I’m sure helped with the details.

If I come across another example of science fiction as I have redefined it here, I’ll write about it.

What X-ists do

October 17, 2014

I spent most of my adult life as a professor of engineering science; I still have the title, with “emeritus” thrown in. My work involved primarily teaching, doing research in, and writing papers and books about the mechanics of solid bodies. Now most people know that mechanics is a branch of physics, usually the first subject matter that is taught in physics classes. But the kind of mechanics that I worked in — classical or Newtonian mechanics — stopped being of interest to physicists early in the 20th century, when relativity theory and quantum mechanics came into play. And so, in accord with the maxim “physics is what physicists do” (of unknown origin, though often attributed to various famous physicists), the work that I did was not physics. Applied physics, perhaps, but not just-plain physics.

Now, of course, most physicists do a great many things in their lives that non-physicists do as well. “What physicists do” has to be construed as “what physicists do when they are doing physics,” which is almost circular, or “what physicists do as physicists”: teach physics classes, perform experiments in physical laboratories,  publish papers in physics journals or present them at physics conferences.

I have often though of “X is what X-ists (or X-ians) do” (with the qualification I just discussed) as a kind of meme that can be applied not only to other sciences but to other fields of activity. For example, religion: one could say “Judaism is what Judaists do,” except that that the saying would have to apply to each of the several Judaisms ( in North America, for example, Orthodox, Conservative and Reform), and one would have to emphasis Judaists and not Jews (who may or may not be Judaists).

Similarly — and this is my main point — one could say that “Islam is what Islamists do.” I used to say “Islam is what Muslims do,” but there are many people who think of themselves as Muslims by cultural heritage but do not practice the tenets of Islam, and so the distinction between Muslims and Islamists becomes useful. But what practitioners of Islam as such do can be used to define Islam; not what a supposedly objective reading of the Qur’an or the Hadith might say, but what those who teach and preach Islam claim it says. And so, whatever political correctness might dictate, I am afraid that female genital mutilation, the execution of Christians on charges of blasphemy, and the various practices of Islamic State are Islam. The fact that IS’s propaganda readily finds recruits wherever there are Muslim communities is only one indication of many.

I have been meaning to write on this topic for a long time. What has spurred me this time is the currently ongoing debate on Islamophobia and “Islamorealism,” which seems to have split the left in the United States into acrimoniously opposing sides. I don’t think of myself as  -phobic in any way: I have no irrational fears that I know of. I do think of myself as a realist: I like to see things as they are. That puts me on the side of “Islamorealism,” I suppose, except that I have no sympathy with Pamela Geller and her ilk, who are the spearheads of the fear-mongering movement brandishing this banner. And, if Islamorealism is what Islamorealists do, then I am not an Islamorealist.

Pullum rides again

January 26, 2014

Geoffrey K. Pullum is an eminent Scottish-English-American linguist. He taught at UC Santa Cruz for many years, and is now Professor of General Linguistics and Head of Linguistics and English Language at the University of Edinburgh. He is a coauthor (with Rodney Huddleston) of the controversial (and very expensive) Cambridge Grammar of the English Language (CGEL), described in Wikipedia as “a book that presents a comprehensive descriptive grammar of English,” and a contributor to Language Log, an online forum of linguists who, scientists that they are, can be generally classified as descriptivists. That is, they seek to describe language as it is actually used and not prescribe how it should be used. One of the categories of posts on Language Log is in fact called “prescriptivist poppycock,” and Geoff Pullum’s posts are frequently filed under it. He can get on his high horse and be quite vituperative when writing about Strunk and White’s The Elements of Style (which he has called “that vile little book”) or George Orwell’s  essay Politics and the English Language, and nothing angers him more than these authors’ advice to “avoid the passive.”

Well, maybe something does anger him more: it’s when writers (especially journalists), possibly brought up on this advice without fully understanding it, apply the word passive — calling it passive construction, passive voice, or even passive tense(!)to discourse in which the verbs are not actually in what grammatically is known as the passive voice. In a post published two days ago, he cited one journalist’s reference to a passage in another journalist’s article as “a lovely passive construction” and then proceeded to analyze the passage in question, finding that of the 23 verbs contained in it not one was passive. He has written an essay titled Fear and loathing of the English Passive in which the matter is discussed (see, I fear not the passive!) at length.

But to all appearances Geoff Pullum, who seems to have a very good sense of humor, doesn’t see the irony in a descriptivist like him railing against language change. The fact is that, at least in journalistic language, passive seems to have morphed from its grammatical meaning to something vaguely associated with a relatively impersonal form of discourse, modeled perhaps on the Nixonian “mistakes were made” (which actually is in the passive). It so happens that English has no regular form of impersonal construction: it has neither the impersonal pronoun like on in French or man in German, nor does it have the subjectless reflexive like Spanish, Italian or Slavic, so that the English equivalent of on parle français, man spricht deutsch, se habla español, говорится по-русски and the like is English [is] spoken. And so it seems that a generalization of passive to mean ‘impersonal’ is natural language evolution, somewhat like the way gridlock (originally the kind of traffic blockage that happens in a street grid when stopped vehicles obstruct intersections) has come to mean any kind of traffic jam, as when, in connection with the Fort Lee lane-closure scandal, we have heard about “gridlock on the bridge.”

But I have not heard any complaints from traffic engineers about media misuse of the term gridlock.  Nor do I hear kvetching form mathematicians, astronomers, physicists or seismologists when people use least common denominator, light-year, quantum leap or epicenter with meanings quite remote from their technical ones. Perhaps this is because specialists in technical or scientific disciplines are aware that common language is in a different realm from technical language. Mathematicians, for example, have borrowed words like field, group or ring and given them technical meanings, and to mechanicians (like me) the words forcepower, strength and energy (which are virtually synonymous in ordinary language) have precise and distinct meanings.

It seems to be different with linguists, perhaps because they deal with language per se. They seem to forget that the word linguist itself originally meant ‘someone who knows several languages’ (thus in Shakespeare and still in popular use as well as in official use in the armed forces) and resent its being applied to anyone but them. Linguistics has also given grammar a meaning far more restrictive (though they don’t always agree on what that meaning is) than what it originally meant: the study of a formal literary language, typically for the benefit of learners of said language who don’t speak it (because it’s either a dead language or a foreign one). And traditionally books on grammar, even those of living languages (beginning with Nebrija‘s grammar of Spanish), have dealt with such things as orthography and punctuation; it’s not a coincidence that the word is related to the Greek word for writing. But when people refer to spelling or punctuation mistakes as grammatical ones, linguists like Geoff Pullum get peeved.

Geoff Pullum, alone among the Language Log contributors, does not allow comments to his posts. He often displays an I’m-right-and-everyone-else-is-wrong attitude, as in his recent defense of CGEL’s  categorization of because as preposition (everyone else considers it a conjunction). And so I expect him to go on railing about misuse of passive or grammatical and other sins against linguistics. I don’t mind: he writes entertainingly, and he can own up to mistakes (as he did today). Go get ’em, Geoff!


January 4, 2008

A month ago I wrote a post about the BMI, in which I pointed out that an index that was developed — on a sound scientific basis — to help with the design of chairs has been (mis)applied as a measure of obesity.

A few days ago I read, in Language Log, a post by the linguist Sarah (Sally) Thomason titled “Why I Don’t Love the International Phonetic Alphabet,” in which she complains about the IPA’s inadequacies as a medium of field transcription. Two of her main peeves are (1) the IPA’s lack of simple symbols for affricates, requiring the use of digraphs and (2) the IPA’s use of [a] for the fully open front vowel, rather than the open central vowel that is represented by the letter a in an overwhelming majority of the languages that use the Latin alphabet.

As I wrote Sally Thomason in an e-mail message, the IPA was not originally designed for phonetic field transcription, but to help French people to learn foreign languages. (The International Phonetic Association grew out of L’Association Phonétique des Professeurs de Langues Vivantes.) And the French, perhaps more than most other people learning foreign languages, don’t try to master their phonetics, but only to approximate them with French sounds (hence the famous “French accent”).

Now French has no affricates (old French had them, hence the affricates in such English words of French origin as judge or chart). When it borrows foreign words that have them, they are pronounced distinctly as a stop followed by a fricative; one need only listen to a French person saying such words as jazz, pizza, tsar orTchad. It’s natural that this practice would be extended to words in an actual foreign language. There is always some chance of being misunderstood (think catch it vs. cat shit), but it’s slight, and the professeurs de langues vivantes may well have thought that time needed to teach their pupils to pronounce affricates would be better spent teaching grammar and vocabulary.

Similarly, French has no truly central fully open vowel, only a (slightly) front one as in patte and a (slightly) back one as in pâte. As a rule it’s the former that’s preferred in loanwords (as in the four examples above), sο it’s natural that the simpler symbol [a] would denote this sound, and a different one, [ɑ], would be used for the other.

So the IPA is, in a way, like the BMI: a didactic device that was invented in the 19th century for one purpose and that has since been semi-scientifically diverted to a quite different use. In both cases the inadequacies have been masked by fixes, modifications and qualifications, but not eliminated in a way that a complete redesign would do.

Are we 2-D? BMI!

December 2, 2007

Once again, a rash of media articles about obesity in the United States has broken out. And once again, the obesity statistics are defined in terms of BMI. Here is an example, from

To determine which cities were the most obese, we looked at 2006 data on body mass index, or BMI, collected by the Centers for Disease Control’s Behavioral Risk Factor Surveillance System, which conducts phone interviews with residents of metropolitan areas about health issues, including obesity, diabetes and exercise.

In this case, participants report their height and weight, which survey analysts use to calculate a BMI. Those with a BMI between 18.5 and 24.9 are considered at a healthy weight, those with a BMI between 25 and 29.9 are considered overweight, and those with a BMI of 30 or higher are considered obese. About 32% of the nation is obese, according to the Centers for Disease Control; Memphis ranked above the national average at 34%

Never mind that the city that ranked third in obesity, Nashville, turned up among the 25 “fittest” (as opposed to “fattest”) in a different survey, this one by Men’s Fitness (and, as far as I can tell, not based on BMI). I am not interested in the results, only in the use of BMI. And, what’s more, after entering “obesity BMI” in a Yahoo news search, not one of the first ten articles that I clicked on included an actual definition of BMI.

The BMI, or body-mass index, is defined very simply as a person’s weight (in kilograms) divided by height (in meters) squared. Thus, since I weigh 66 kg (145 lb.) and stand 1.71 m (about 5 ft 7½ in), my BMI is 66÷1.71² ≈ 22.5.

Now anyone with any familiarity with physical science will recognize a quantity defined as force (such as weight) divided by length squared (or area) as representing pressure or stress. For example, for people of different sizes but with similar body proportions, the area of any portion of their body surface – for example, the portion that is in contact with a chair on which they may be sitting – will be proportional to the square of the height. If the chair bears a person’s full weight, then the average pressure on the chair’s seat, equal to the weight divided by the contact area, will be proportional to that person’s BMI.

It is precisely for this purpose – the design of office chairs – that the quantity now known as BMI was invented by the nineteenth-century Belgian mathematician Adolphe Quetelet.

But human bodies are three-dimensional, not two-dimensional. For people of different stature but similar geometric proportions, the body volume is proportional to the cube, not the square, of the height. And if the proportions of the various constituents of body mass (bone, muscle, fat etc.) are similar, then the weight is proportional to the volume, and consequently to the cube of the height. Consequently, what people who are geometrically and physiologically similar have in common is the weight divided by the height cubed, not squared.

What this means is that people with the same build will have a higher BMI if they are taller and a lower BMI if they are shorter. It has already been noted that very tall people who are quite fit — for example, professional basketball players — have BMI values that would rank them as overweight. Thus, an NBA guard who is two meters (about 6 ft 7 in) tall and who has the same build as I do would weigh 66×(2.0÷1.71)3 ≈ 106 kg (232 lbs) and his BMI would be 26.4, in the “overweight” range.

It has also been remarked that in populations that, on the average, are significantly shorter than European (or European-descended) ones, a lower overweight threshold is necessary. For Southeast Asians, for example, it’s 23 (as in this document from Singapore). Were the body types the same, this would be consistent with average height being about 8% less. In fact, the average adult height in China, for example, is 6–7% less than the average of white Americans. But the body types are in fact different (for example, the waist-hip ratio of Chinese men is 0.87 while that of white Americans is 0.98, as given here).

I have no doubt that if an index were defined on the basis of weight divided by height cubed, the discrepancies would become negligible.