May 21, 2011
Of mice and graduate students
Reading Amy Stewart’s Wicked Bugs and was greatly taken with this tale of the deadly Asian giant hornet:
After the larvae have finished their meal [of dead insects], the adults tap on their heads, which prompts the larvae to offer up a “kiss” consisting of a few drops of clear liquid. The adults drink this liquid, using it as a source of fuel. The Japanese scientists harvested the clear liquid, one drop at a time, from larvae they found in over eighty hornets’ nests. In the laboratory they demonstrated that both mice and graduate students showed reduced fatigue and an increased ability to turn fat into energy after drinking the juice.
Stewart does not specify whether they tested it on the mice or graduate students first.
Say what you like about category theory not having any practical applications, at least my supervisor never made me drink hornet barf.
December 22, 2010
Why basic numeracy is important
A quite extraordinary transcript of a billing dispute:
[Caller]: Okay, I think I have to do this again. Do you recognize that there's a difference between one dollar and one cent?
[Caller]: Do you recognize there's a difference between half a dollar and half a cent?
[Caller]: Then, do you therefore recognize there's a difference between .002 dollars and .002 cents?
[Agent]: I mean there's... there's no .002 dollars.
Via. If a dispute over $71 versus 71c seems beneath your notice, scroll up to the top of the thread where the business and economics editor of a major US magazine gets equally defensive about a similar error, except on the order of trillions of dollars.
Then again, given that the said economics editor is apparently paid $200000 per year despite a history of such errors, maybe the title should be “Why basic numeracy is not important.”
November 28, 2010
Big news from a small place
If this is right, then it is simply huge.
Of course, that is a very big if. Then again, if there is one hypothesis in cosmology that has been proved beyond doubt, it is Haldane’s: that “the Universe is not only queerer than we suppose, but queerer than we can suppose.”
October 16, 2010
This fragment will be put on its own line for no obvious reason
Martin Robbins administers a kicking to popular science reporting. Also has a picture of a triceratops in space.
July 19, 2010
Pass the crop circle palmistride, please
July 05, 2010
This has the feel of being one of those rare iconic images.
February 04, 2010
Breaking the silence
I find this simply amazing: “With one [vegetative state] patient – a Belgian man injured in a traffic accident seven years ago – they asked a series of questions. He was able to communicate ‘yes’ and ‘no’ using just his thoughts. The team told him to use ‘motor’ imagery like a tennis match to indicate ‘yes’ and ‘spatial’ imagery like thinking about roaming the streets for a ‘no’.”
April 02, 2009
Mathematics and programming
Jeff Atwood disputes the theory that competent programmers should be mathematically inclined. His conclusion may or may not be correct – I don’t have any evidence one way or the other. His reasoning, however, is wrong.
Jeff observes that “the vast bulk of code that I've seen consists mostly of the ‘balancing your checkbook’ sort of math, nothing remotely like what you'd find in the average college calculus textbook, even,” and gives the example i = j++ / (x + v) -- “not,” he rightly observes, “exactly the stuff mathletes are made of.”
Right, and nothing to do with being mathematically inclined either. Jeff seems to be one of those people who believes that what mathematicians do is sit around doing ever harder calculations. The sort of people who can only imagine Andrew Wiles proved Fermat’s Last Theorem by a fiendishly complicated process of long division.
In reality, the bulk of mathematical effort goes not into performing calculations, but into hypothesising and proving general truths. Let’s take a quick run down of the kind of skills mathematicians really use in doing this:
- Identifying useful abstractions – separating out the salient points of a problem.
- Formulating a path from A to B – building a high-level plan of attack for a problem or proof.
- Turning that plan of attack into a series of precise and rigorous steps, expressed using an abstract and formal notation.
- Bundling up appropriate partial results into handy lemmas – another example of identifying useful abstractions.
- Thinking about special cases that might invalidate the assumptions of the proof or require special handling.
The core skills of mathematics sound awfully like the core skills of programming. It is only “very hard … to draw a direct line from ‘good at math’ to ‘good at programming’” if you confuse mathematics with “mathletics.”
July 11, 2008
MONIAC: adventures in analogue computing
Thanks to the wily Kirk Jackson and the, er, New Zealand Association of Economists, I had the pleasure this afternoon of seeing an unusual piece of computing history in action. MONIAC, the Monetary National Income Analogue Computer, also known as the Phillips Machine, was an analogue computer invented by Bill Phillips (he of curve fame) to model and simulate the relationships between various economic factors. Nothing unusual about that, except that it was invented in the 1940s... and instead of processing 0s and 1s, it processed water. The Reserve Bank of New Zealand has one of the few Phillips Machines still around and in working order, and as part of a lunchtime session for the NZAE conference they had cranked it up and were demonstrating it.
The machine works by circulating water around a network of tanks, taps, pumps and pipes. Values are represented by the levels of water in various tanks, parameters by opening and closing taps or moving valves up and down, and the key readouts of income and interest rates are recorded by pens moving against graph paper. Water, of course, represents money, though demonstrator Geoff Bertram was careful to refer to it at all times as "the circulating medium." I have to be a bit vague about what sort of things the various tanks and taps and throttles represented: explanations of the various bits in terms of private sector liquidity requirements and endogenous money supply undoubtedly made sense to the mainly economist audience but I'm afraid I struggled. Still, I gathered it was a pretty accurate simulation of the economic theories of the 1940s and 1950s; according to the demonstrator it effectively shut down a major debate of the time by convincing both sides that their arguments were actually compatible.
Of course, not being programmable, MONIAC can't be updated to reflect new factors and new economic conditions (such as globalisation). The demonstrator did, however, relate how one lecturer used to set up two MONIACs, one representing the US economy and one representing the UK, hook up the relevant bits of piping between the two machines, and challenge two sets of students to do the best for "their" economy, so within the constraints of the model there was a certain amount of flexibility.
On the other hand, MONIAC's analogue approach still rivals the digital approach in some ways. "It's solving nine simultaneous differential equations," noted the demonstrator. Given the sophistication of modern numerical techniques, and the effort that has undoubtedly been poured into economic simulation and prediction, it's no surprise that the Phillips Machine has been superseded, but I suspect that ultimately the digital equivalents are just badly simulating water flow, only more flexibly and a lot faster. One member of the audience, noting that the Phillips Machines had been used largely for educational purposes, asked Dr Bertram how he would present the same ideas now. "I'd draw a hydraulic diagram," he replied.
This being a computer demo, of course, things did not go quite to plan; but this being an analogue computer demo, they went not to plan not through the usual syntax errors and unhandled exceptions, but instead because the bit of plastic representing the level of imports had fallen off and had to be stuck back on with blu-tack, and the export doohickey had become stuck against its housing. Kernel fans will also be pleased to know that the Phillips Machine's ultimate failure mode is also described as "dumping," except in this case you end up with wet shoes and a massive carpet cleaning bill instead of just a nice convenient file. "Now it sits in this bath here, and we've fitted a drain through to the outside," noted Dr Bertram ruefully.
(Incidentally, Bill Phillips was a New Zealander: connoisseurs of Kiwiana will therefore note that the use of blu-tack to hold the level of imports steady counts as Kiwi ingenuity, while the failure mode of spewing the "circulating medium," i.e. the national economy, all over the floor represents classic Kiwi ingenuity, or possibly Rogernomics.)
This highlights another interesting feature of the analogue approach: its unpredictability. When the demonstrator was showing us "fiscal shocks" and "monetary shocks," he commented on how long the simulated economy took to react to stimuli such as suddenly injecting government investment or restricting lending. "Sometimes they take 30 seconds, sometimes they take five minutes," depending on the mood of the machine. Given the unpredictability of real economies, this in some ways seems like an attraction of the analogue approach. The downside? "Sometimes you'll be standing there talking about how things eventually come back to equilibrium, and everything's crashing and burning behind you." At least when my demos tank they don't take national economies with them.
Due to short notice, I don't have any pictures, but Wikipedia does (as does NZIER at the link above), and if you're in Australia or the UK, I gather there are also kinda-maybe-working machines at Melbourne University and at the Science Museum. There is also apparently one lost in Guatemalan jungle, so any budding Indiana Joneses of computing, now's your chance.
June 28, 2008
Another sf prediction lets us down
BBC News: "Martian soil appears to contain sufficient nutrients to support life - or, at least, asparagus."
In all the mass of science fiction dealing with the terraforming and colonisation of Mars, I don't think anyone has ever depicted a market garden economy based on asparagus. Reality-shaping drugs? Sure. Angels? Absolutely. Elvis? Everywhere. Paul McAuley even placed a side bet on yaks. But nobody ever anticipated this, did they?