Imaginary Potential

I went to the weekly computing seminar yesterday, because it was on a statistical data mining tool that is being simultaneously used by physics experiments and marketing firms. The speaker is a physics professor, used to work for the PLUTO Collaboration, DELPHI, and now is variously associated with CDF and CMS. The company, Phi-T, is now totally private, and employs a couple dozen ex-physicists, or physicists, depending on how much of a purist you are. The software is proprietary and closed source, and the speaker was severely vague about what specific tools were actually used, but there is an interface in C++/ROOT/C#/Lisp already made, so its (supposedly) trivial to use, with a discounted academic licence.

So what is it? Basically, you have a vector of measureables, like detector channels, and some target, like say Resonance mass. Or Age, profession, #kids, and your target is “How much will this person cost us in Health Care in the next n years.” You then train the thing on your historic or simulated data, and it generates Bayesian posteriori distributions for new data. This is pretty common in neural computing literature, but this thing seems actually practical.

The only really fascinating thing is the generality of the thing, which was (supposedly) applied with minimal expert consultation on problems like car insurance premiums, to B_s mixing at CDF. Here’s a list of referred journal articles with their stamp. So whats inside? A neural network you say? No! The guy said in most applications they skip the neural net entirely and just use “Other” statistical methods. It’s clear that he was using some kind of input decorrelation like principle component analysis, but he wouldn’t say what specifically. He used a bunch of phrases that were cryptic to me like “zero layer network” to mean something other than a perceptron (I asked), and “zero iteration training” of a network. Maybe these things mean something to yall statters, but nothing to me. Anyways, the output of whatever was a discretized probability histogram that got splined together.

I’m unconvinced that the “default settings” he mentioned could schedule re-stocks for the largest book distributor in Germany AND find the X(3872) resonance, but what do I know? He also said that the companies own stock were controlled by this thing, but that selling it for this purpose is somehow illegal. Anyone know what he was talking about? Here’s a paper on it, by the speaker.

In the end, the talk was a sales-pitch/head-hunt, but if anyone out there needs to solve a highly nonlinear problem and has a cushy grant, go nuts.

If, today, you feel as if you should be doing work, but don’t really want to do any, may I suggest a video of a Sidney Coleman Lecture: Quantum Mechanics in Your Face? You’ll learn and be entertained.

The lecture is fantastic and consists of the late, great Coleman discussing a version of Bell’s theorem (which is much easier to understand than the standard treatment), and then going on to discuss the “mysterious” “collapse of the wavefunction”. It’s great stuff. All that’s required for enjoyment is a basic undergrad QM course…

Before a seminar last week, I was discussing a colleague’s masters thesis, and she told me something I’m fairly jealous of:  She gets to invent her own physics words.  You see, this colleague comes from Ukraine, and her University has recently changed its thesis requirements from Russian to Ukrainian.  The two languages are closely related, but have significant differences in alphabet, vocabulary and grammar.  Ukrainian has been the official language of the Ukraine since 1991, but it was suppressed to varying degrees during the Soviet Era, and the CIA Factbook lists currently at 67% of the population claim it as their native language.  Since it has only recently been officially used at the university level, there are many technological words which are currently loaned from Russian or English.  This isn’t really unique to her situation, as that anyone who studies physics in any language has solved a problem by an ansatz, and heard of bremsstrahlung*.  What is unique is that there is pressure to develop Ukrainian, and therefore pressure to remove these loan words.  She was vague about how many loan words would be officially tolerated, but indicated that some technical vocabulary could be naturally adapted, but some would need to be basically invented from scratch to make them genuinely Ukrainian.  That’s got to be 50% fun, and 50% intractable.

*Bremsstrahlung is in firefox’s En. spell checker.  Thats awesome.  Ansatz isn’t, but ersatz is?

I had a Eureka moment this week. Fortunately I was not sitting in a bath at the time and so I did not have to decide whether to suppress the urge (apparently written into the laws of physics for moments like this) to run around the streets naked, shouting happily about my discovery. Thinking about it though, if I’m ever going to try that, it should be while I live in southern California near the beach. In my neighbourhood, such behaviour would probably just count as part of the social background noise rather than anything significant.

The Eureka itself was to do with how bubbles behave acoustically when fragmenting in turbulence (for example underneath a breaking wave). It turns out that some bubbles are disguising themselves acoustically as other bubbles (because the dominant resonance is not at their natural frequency). This explains a gap in the data which was previously unexplained, and I am very happy because my model matches the data pretty well. Or, it matches it pretty well up to now. There are still lots of things to be tested, but the fact that it explains this major feature is very encouraging. So I worked all this out, plotted most of the relevant stuff and hopefully this is sufficient for the time being to exorcise the bubbles-on-the-brain demons. Just before I worked out what was going on, piles of ideas were sitting untidily round in my head, overflowing into corners that they really didn’t belong in (for example, the ones associated with eating yogurt and inventing cocktails). They jostled each other and squeaked and squawked and squeezed and generally wouldn’t leave me alone. So now they’ve been put in order and I can get on with some other things. Good ideas. Sit. Stay…

I was reading a book called “The Revenge of Anguished English”, and although the content doesn’t live up to the promise suggested by the title, there was a nice physics typo mentioned near the end: “He got his degree in unclear physics”. The question is whether that tiny letter substitution makes that much difference to most people who might be reading a newspaper biography of someone. Are nuclear and unclear synonyms to everyone who doesn’t have a physics degree? I would guess that for all practical purposes they could often be interchanged. I don’t want to be snobbish about it - I’m sure that I wouldn’t blink at an article about”More sculpture” when it was meant to be about “Moore sculpture”. Perhaps nuclear physicists should be upfront about it and just go with it. An “unclear power station” sounds quite aesthetically pleasing, as if it faded into the background on sunny days. And at least G.W. Bush could talk about such an entity without inducing a snigger from every science graduate (and indeed every literate person) in the English-speaking world.