Number of the Month

July 2013

All quiet on the third front

 As we enter yet another silly season Geoffrey Lean is quick off the mark, trying to stir some life into the current thin ragout of vacuous scares. There are signs of desperation in his attempt to resuscitate the one he was promoting a couple of years ago in April 2011. The new headline Why is killer diesel still poisoning our air? is a bit rich, even for our Geoff. There is no scientific evidence to support such hyperbole, only bog-standard epidemiology. Back then we described his first sortie as the opening of the third front in the war against carbon in its role of proxy for energy, manufacturing and transport, the mainstays of a modern state. What is not superficially evident in these individual forays is the length of the period of gestation that led to them.

Our number of the month for March 2011 was 15, referring back to a quarter of a century ago, when the particle battles were just gleam in the eyes of the watermelon bureaucrats who had seized control of research funding At that time I withdrew from a multidisciplinary bid for a tranche of the generous funding offered for “research” into atmospheric particles, on the grounds that the officials were simply “out to get” particulates. They were clearly not interested in genuine research, but just wanted to purchase pre-determined results. We had not yet in those innocent days identified the phenomenon of watermelons as such, but the combination of savage funding cuts with the imposition of bureaucratic control had induced a feeling of desperation in British science.

In fact, I was well qualified to contribute to the monitoring of sub-microscopic particles, as I had done the same thing before in liquids many years earlier, using then uniquely advanced techniques of digital electronics and computation that had been originally developed for military purposes. As it happens, we found those particles innocent of all charges (in more ways than one). It is one of the little ironies of a life in science that a new theory can be cooked up in, say, three weeks, but it takes three years of gruelling experimental work to knock it down. This, however is, or was, the very essence of science. In those days some of the theorists probably felt secure that their conjectures could not be practically tested, but there were also some experimentalists with an obstinate streak. Back in the scientific era we had to provide evidence of correlation of particles with physical phenomena; now they just assume it on the vaguest of reasoning.  Furthermore, thousands of “experts” are now all waiting for the next point on a noisy waveform and making contrary deductions from it. The past is a foreign country: they do things differently there. Should any reader be curious about that work, I append the relevant announcement in Nature (1976) as a PDF file; as always hastening to add that in those days it was a respectable scientific journal. Indeed, it was a particular honour to have your results published there.

By the way, whatever happened to diesel particulate filters and catalytic converters?

As for the ludicrous repetition of the claim of 29,000 deaths a year, we make our usual reply – Name one!



Of weeds and archers

Last month there appeared a headline that was widely repeated. It was so banal and irrelevant that it caused but a momentary irritation, unworthy of comment.  In the case of your bending author, however, it morphed into a repeated refrain, like those scraps of music known as ear-worms, that needed exorcism. The headline was Plants do maths. It is symptomatic of a new trend among some contemporary scientists, who seem unable to distinguish between the real world and their own models of it. Of course, it was among the global warming scaremongers that such folly reached a destructively costly peak. Other zealots, such as the relatively new salt fanatics, choose to ignore the existence of efficient control mechanisms (homeostasis) that blights their cause. If the interpretation behind this particular headline were true, then virtually every organ in the human body does mathematics. The largest human organ, the skin, takes part in a remarkably precise mechanism for controlling temperature (and, as it happens, salt) which is only thought about when disrupted by disease or deficiency, sometimes leading to death. In the case of salt, the deficiency (hyponatraemia) can kill (real people with real names and post-mortems, not the imaginary products of fantasy epidemiology).

Most control systems (particularly biological ones) do not do division. They tend to work on the difference between the real physical variable and a target value. They apply negative feedback, with damping to obviate oscillatory responses. The mathematical model for this is generally a second order differential equation (not necessarily linear). The equation is not the system. It is an imperfect model of it, but a considerable aid to understanding or design.

Without knowing all the details of the plant starch case, one may surmise that all that is required is for usage to made proportional to the concentration, which, by simple mathematical model, defines an exponential decline that never reaches zero. You do not need to measure time to set a time constant. The initial conditions set the trajectory. An electrical analogue is a capacitance charging through a resistance, which becomes linear if the resistance is replaced by a constant-current generator. It should not be beyond the wit of man to create an analogue system, without division, that behaves in the manner of thale cress with starch. The observations pose a number of questions, such as – what is the survival advantage of running down the fuel tank to zero every day?

The champion archer hones his skill by many hours of practice; the archer fish does it by many millennia of evolution. Neither benefits from doing long division. The human scrotum does not say to itself “let x be the unknown” when the weather turns warm. What we have here is a very interesting piece of research trivialised by headline hooks and glossy presentation.

Number of the month – 2

This is the distance in metres at which the archer fish  can bring down its insect prey, without “doing mathematics”.


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