Category: Science

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Not the Sydney Project: Questacon

This year is my sonÂ’s last year before he begins full time schooling in 2015. Welcome to our year of child-focussed activities in SydneyÂ… only without the Sydney bit this once.

We rudely interrupt the Sydney Project to bring you a Canberra attraction: Questacon. In short, Questacon works nicely for V in a way that the Powerhouse did not, probably because it’s pretty shameless about catering entirely to children, complete with buttons, lights and hard hats.

We were there on a very busy day: the Saturday of the Easter weekend, the middle weekend of NSW school holidays. It was merely obnoxiously busy; I guess being used to Sydney crowds was helpful. That said, we did get there at 9:15, just after it opened. And as it was, the admission tickets to Mini-Q, the under 6 area, which is in limited numbers sessions on busy days, were only available from 11:30 onwards. I think they’d completely gone by about 10:30 in the morning. Go early, go often.

We’ve been once before, about a year ago, and Questacon was a hit to the point where for some time afterwards he asked to “see the science again!”. It took him longer to warm up to it this time. Much like last time, he shot through Measure Island without engaging. It took him a while to settle into Wonderworks, eventually getting interested in the Energy Machine and Frozen Shadow. Much to my disappointment, he’s never given a toss for my precious Harmonograph. (Much of Wonderworks has been there since I was a kid. Questacon’s exhibits are surprisingly timeless in their appeal.)

Best exhibit

Andrew and I and his father were very taken with the Cloud Chamber, which is in its own little-visited room from the steps between Wonderworks and Awesome Earth (closed for renovations), in which subatomic particles leave continuous trails through a cloud of vaporised alcohol. Andrew is keen to bring a banana next time. V was not willing to stand still for a story about how all the time, everything is being hit with tiny tiny particles moving at high speeds. Perhaps not one for the littlies.

V’s favourite exhibit is pretty unique to him. He can roll ping pong balls down a ball rollercoaster for about an hour at a time. Other children come, roll five or ten balls and go. He stays. We only extracted him with a promise to return after.

Blue tunnel

Next up was one for the watching adults, Excite@Q. V was most naturally drawn to the blue tunnel, and he was one of several smaller children jostling under Whoosh to grab a scarf and stuff it back in the wind tunnels. But we were there for one thing: to see our four year old agree to do Free Fall. I wrote about this elsewhere:

It’s a horizontal bar suspended over a very steep slide. You hold the bar. You let go. You drop freely for three metres or so before hitting the slide and sliding to the floor of the room.

The ride is, as you’d hope, very into consent. You go to the top. You get a briefing about how it works. You are told, repeatedly, that it’s OK to say no. And the day we were there, about three quarters of children did say no. (It’s a bit of a study in gender performance actually. Adult men by and large grab the bar, drop themselves down to dangle, let go and are done. Everyone else takes far far longer.)

V loves slides and heights, and so we asked him if he wanted a go. He said yes. He was dressed in the safe suit for it (I guess no risk of catches or tears), he waited in the queue and watched child after child look at the drop and shake their head and walk back down the stairs with an adult for a hug. Andrew took him to the top. He got the chat about whether he wanted to say no. He gave them a puzzled look. He got his instructions. He took them very seriously.

He held the bar:

Preparing for free fall

He dropped his weight from it:

Dangling

He looked down:

Looking down

And he let go:

Fall

He seemed to have fun, if a mystified about why this was such a very big deal.

Vincent the builder

After Free Fall, his ticketed time for Mini-Q came up. I didn’t go in, but apparently it was all construction all the time in there.

Finally, for bonus points, I put my camera down somewhere in Wonderworks, and someone found it and handed it into staff. “People who come to Questacon are generally very honest,” the information desk staffer told me, although somewhat spoiling the effect by saying she’d been tempted to keep the camera herself.

Cost: $23 adults, $17.50 children 4 and over, younger children free.

Recommended: yes, has something for the jaded adult radioactivity fans and the child who wants to drop from extraordinary heights, wear a hard hat in a playground, and roll ping pong balls down a slide for an hour alike. Try not to go on holiday weekends, and try not to leave your camera lying around.

More information: Questacon website.

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Sunday spam: muesli bars and gummy snakes

Muesli bars and gummy snakes are what I ate at about 7am before my recent 9am childbirth… thus thematically appropriate for this small collection of links, some of which I’ve had sitting around for a while.

Using WOC in the Natural Childbirth Debate: A How-To Guide.

If you are a progressive in the Natural Childbirth Movement (or any other, for that matter), use Africa City women to promote the idea that “natural is better.” Talk about women who toil in the fields, squat down to give birth and return to picking rice. Or peanuts. Or anything else that can be picked. After all, the women of Africa City are resilient! Strong. So strong that they do not even require support from the other women of Africa City. Or medication. Or comfort. This example–of giving birth in the field–illustrates how over-reliant “we” have become on useless technology. Of course, you don’t expect “us” to be quite that strong. We are not beasts of burden, after all…

If you oppose the Natural Childbirth Movement (or any other, for that matter), use Africa City women to remind “us” of how bad “we” used to have it, before all of our live-saving medical advances. If women die in childbirth in Africa City, it is only because they lack the Modern Technology we should be grateful that every last one of “us” has unfettered access to. Use infant mortality statistics from the most war-torn countries to argue why a healthy woman from Portland shouldn’t give birth in her bathtub with a midwife who carries oxygen and a cell phone. Redact all mentions of Africa City women who are not hopelessly impoverished. Ignore those who are systematically abused with Modern Technology, sacrificed as Guinea pigs on its altar. All bad outcomes in Africa City are due to the lack of Medical Technology, never unrelated to it, and certainly never caused by it.

Early Labour and Mixed Messages

The emphasis on hospital as a place of safety whilst also encouraging women to stay away results in some very contradictory messages and ideas (please note these statements do not represent my own views)[…] We are the experts in your labour progress, our clinical assessments can predict your future labour progress… we will send you home if you are found to be in early labour… if you then birth your baby in the car park it is not our fault as birth is unpredictable[…] This is a safe place to labour…. but you can only access this safety when you reach a particular point in your labour… preferably close to the end of your labour i.e. you should do most of it on your own away from safety.

Warning for discussion of pregnancy loss. The Peculiar Case of Miscarriage in Pop Culture

Miscarriage is a tricky cultural thing, pop culture or not. It’s a deeply forbidden subject, much like many other things deemed ‘mysteries of womanhood,’ like menstruation, like pregnancy itself. People don’t talk about miscarriages and that discouragement means that many people aren’t aware of how common they are, let alone how devastating they can be. When people lose a child, they can reach out to their community for help and they are given space and time for healing. When they lose a fetus, they’re expected to keep it to themselves.

Sadly, sometimes pro-choice people can be the most vehement about this, concerned about blurring the lines between fetus and child, and saying that claiming a fetus is morally or ethically equivalent to a fully-developed, extrauterine human being could be dangerous. This makes the mistake of applying broad strokes to the issue, though. Legally, of course, a fetus should not be equivalent to a child. Personally, however, losing a wanted pregnancy is an intensely emotional experience and it can feel on some level to the parents like losing a child, with the added burden of not being allowed to acknowledge it, talk about it, or ask for help.

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A year with orthokeratology

A year ago, I did something that’s very rare for me, I made an expensive impulse purchase. Specifically, I was fitted for orthokeratology lenses. These are a vision correction technique: hard contact lens you wear while you sleep, that mold your cornea into a corrected shape so that you don’t need to use vision correction while you’re awake.

I have mild myopia (-1.75 left and -0.75 right, I think) and very mild right-eye astigmatism and I’ve had vision correction since I was about ten (initially only for my left eye, my right eye only became measurably myopic about 5 years after that). I’ve worn glasses and contact lens each about half the time. I like contacts better than glasses but still find them annoying when they are dry or one gets stuck to the wrong part of my eye. I have enough medical and surgical anxiety that I’m not going to be interested in surgical correction any time soon. So that was the appeal of orthokeratology.

To cut to the chase, while I’ll keep wearing them now I have a good fit, my recommendation is mixed at best.

The first few days and weeks were not promising. The problem with anything that’s supposed to be “uncomfortable” or “take some getting used to” is determining when something is actually wrong. So when I first put my lenses in in the optometrist’s office and my eyelids slammed shut in agony over the top, I figured it was par for the adjustment course. In addition, it took a while to achieve good correction, I think a week or more to be reasonable and another week or two until I tested as having an acceptably negligible prescription. During this time, in transition, I couldn’t use my glasses either. So in the evening, it was a question of putting them in and then immediately staggering upstairs feeling my way to bed while my husband probably cooed lovingly at his loyal un-painful glasses. It’s also, as you would think, not especially easy to get to sleep when your eyes are trying to alert you to their imminent death, although once I was asleep I tended to sleep well and wake up with them adhered to my eyeballs (once they seal on, it hurts less). The crisis in the mornings seemed to be more that they adhered too well, and the force required to get them off tended to flick them around the bathroom at random and I’d get stressed and need to get Andrew downstairs to help me find the lenses (replacement cost is multiple hundreds of dollars).

Which reminds me, these require touching your eyes a lot more than soft contact lenses do. Getting them on involves applying them straight to your pupil, and getting them off is done (most easily) with a little suction device, again, more or less applied to the lens over the pupil. Getting them off sounds like it should hurt, but it doesn’t, it’s just a slight pulling sensation. But a large number of people cannot bear to touch their eyes, or at least not very much. That is, at least, a caution to many people. This wasn’t something I was asked about or warned about at all; luckily I am very able to touch my eyes, but it seems like I should have been asked.

Once the teething pains, as it were, were over, I had a nice few weeks of naked daytime eyes. Even Andrew briefly expressed envy, swimming at Waikiki, that I could see everything and also not have to worry about losing a lens in the water. It wasn’t to last long, as on that same trip, one morning I woke up with my eyes in agony. The only relief I could get, even slight, was to keep them open behind very dark glasses for most of the morning. I put it down to bad cleaning and made a note to be extra careful.

But it kept happening, with increasing frequency. On the fourth or fifth time, back in Australia, I ended up at the optometrist. He couldn’t find anything wrong other than dryness… and that my vision correction was weakening badly to boot, so I wasn’t even getting much for the pain. He wanted me to stop wearing them. He doesn’t seem to be a terribly good communicator; all I could get out of him was a vague promise that I wouldn’t be out of pocket. I got a call a few weeks later to come and pick up new lenses. He wasn’t even around so I didn’t really know what the deal was until my next check up: it emerged he’d actually done a fair bit of work phoning different suppliers trying to find lenses big enough to cover my (of course) enormous corneas, thinking that probably the fit was actually the issue.

Sure enough, the bigger set of lenses have solved the problem of the mornings of extreme pain and dryness. They were also never as painful as the first set, despite several weeks break before starting to use them, which makes me wonder if the level of pain inserting the first set was always a bad sign. (But then, “may take some adjusting” and “may be uncomfortable” means “don’t complain for a while”, so they’ll never know.) I also don’t end up having to scan the bathroom inch by inch for them every morning. The correction is pretty good; I actually have to be careful with the right eye not to wear a lens every night because it’s easy to overcorrect. I wear the left one about three nights in four and the right one one or two nights in four. It’s more of an artform than I’d like, to be honest.

Given the initial pain and the lengthy adjustment period, I think with hindsight that I wouldn’t choose to start the process, which is why I am hesitant to recommend it to others. Most reviews I’ve read have had better experiences, although the only other person I know who tried it had to give it up entirely because it caused such bad night blindness it wasn’t safe for her to drive (not a problem I’ve had). Proceed with care.

Update January 2021: this remains one of my most popular blog posts, so here’s an update. I stopped using orthokeratology around 2016, returning to a mix of glasses (most days) and single-use contact lenses (for sports or nights out). I don’t miss the mild nightly discomfort and the care routine for the lenses.

I’ve idly considered laser correction, but I’m coming up on the age where I will get longsighted and I’m not sure that a mere couple of years break from glasses is worth it.

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Acceleration, or my general relativity binge

Week 3 of the Alphabet Sufficiency: A. I’m just late this week. I’ll probably have some commentary on that at some point.

I saw the solar eclipse in November, or at least the right half of it, and thus began a six month dabbling in general relativity. It all started innocently enough, looking at astronomy websites to learn about, eg, why there isn’t a solar eclipse every month, which isn’t a relativity question at all..

Since New Moon occurs every 29 1/2 days, you might think that we should have a solar eclipse about once a month. Unfortunately, this doesn’t happen because the Moon’s orbit around Earth is tilted 5 degrees to Earth’s orbit around the Sun. As a result, the Moon’s shadow usually misses Earth as it passes above or below our planet at New Moon. At least twice a year, the geometry lines up just right so that some part of the Moon’s shadow falls on Earth’s surface and an eclipse of the Sun is seen from that region.

Solar Eclipses for Beginners

Well that’s that answered, but I’d made the mistake of visiting Wikipedia, and we all know how Wikipedia works:


xkcd: The Problem With Wikipedia

Or actually, we don’t quite, because Randall Munroe apparently uses Wikipedia differently from me. If I end up on Wikipedia, I won’t be spread out among William Howard Taft and wet t-shirt contests, I will be in one of two places: poisons, or black holes. I can’t explain the poisons thing either, but black holes are pretty self-explanatory: relativity! spacetime! breaks down! infinite density! spagettification! gamma ray jets!

Or you can get your poisons and your black holes in the one place:

A supernova or hypernova produced by Eta Carinae would probably eject a gamma ray burst (GRB) out from both polar areas of its rotational axis. Calculations show that the deposited energy of such a GRB striking the Earth’s atmosphere would be equivalent to one kiloton of TNT per square kilometer over the entire hemisphere facing the star, with ionizing radiation depositing ten times the lethal whole body dose to the surface.

Wikipedia: Eta Carinae

Eta Carinae, one of the most massive star systems in the Milky Way, is 7500 light years away. So, imagine that: a radiation jet so powerful that it would deliver lethal radiation doses to us across thousands of light years, if we happened to lie in the path of the axis of rotation at the time of a supernova. Which, luckily, we probably don’t.

I thought, in high school, that I’d be a physicist one day. I read the popular works of Stephen Hawking and Richard Feynman and Paul Davies. In Year 11 and 12, when NSW high school students only take English as a compulsory subject and all else is elective, I loaded up with maths, physics and chemistry. When I went to National Youth Science Forum, I asked to be placed in one of the groups for students most interested in physics. I went to the International Science School for high school students (not especially international, I might add) and poured over the pictures of physics PhDs and postdocs imagining myself among them.

And then various things happened and I’m not a physicist. I didn’t even take university physics in my first year. One of those things was a poor assignment of teacher in Year 11 physics: it was hard to dent my academic performance in high school but possible to dent my academic enthusiasms. Another of those things were that I had a lot of trouble with the intuitions of classical mechanics, especially of tension, and found myself regurgitating definitions by rote to get the right answer, and I had a lot of choices of subjects where I didn’t have to do that. (I hit similar walls with chemistry in first year university and mathematics in second and third year. Probably, like with physics, a break of a decade or two would have helped a lot: I revisited classical mechanics over a few hours with Andrew’s help about four years ago and now I know that in the idealised situations we were dealing with, the ropes and strings are rigid. Such simple things. I might be a scientist now if I’d had more age-peers.)

I don’t even especially regret this, I think my passion for physics was more a passion for strange phenomena than a passion for making novel discoveries of strange phenomena. I’m still not especially good at telling the difference between things I want to research and things I want to read about.

I imagine this isn’t an uncommon way to view one’s personal history, but I feel like I straddled two major technological transitions just as I reached adulthood. The first is the ubiquity of mobile phones: when I started university in 1999, rich kids had them. When I returned for my second year, everyone had them. The second is the Web. I remember writing reports in primary school—if allowed to choose my topic, they’d either be on astronomy or on the human brain—relying on the local library. Which to be fair, was information dense enough for me at the time.

But that’s not how I answer my questions now. Seeing the solar eclipse, meant lots of wiki walks and Google queries that ended in black holes, or at least quite near them. And frankly, for the first time ever, I started to feel like the Internet might be too close to being my mind, externalised, only with more answers. I don’t need to exert effort, I can just mainline facts. I am generally suspicious of “information diet” kind of sentiments: I usually analyse them as in part an aesthetic or moral preference for having to do labour, which I don’t think is justifiable in and of itself. Neither simplicity nor labour are in my opinion a good thing, they’re just means to ends. But… obviously I partake of the culture that creates these ideas and frankly, it’s a little spooky that there’s entire sections of the Internet set up to teach people who are apparently just like me in terms of background knowledge (some) and willingness to do work (little) about black holes and general relativity.

I had better justify the use of the ‘acceleration’ topic first:

In the physics of general relativity, the equivalence principle is any of several related concepts dealing with the equivalence of gravitational and inertial mass, and to Albert Einstein’s observation that the gravitational “force” as experienced locally while standing on a massive body (such as the Earth) is actually the same as the pseudo-force experienced by an observer in a non-inertial (accelerated) frame of reference.

Wikipedia: Equivalence principle

And so I will spend my acceleration efforts on general relativity and gravity. You see why you need to be comfortable in your own intellectual laziness on the Internet these days, don’t you?

It’s probably fairly obvious how one gets from solar eclipses to black holes, but for the record, I believe it was via a bunch of reading about solar astronomy, with a detour through Wikipedia: Health threat from cosmic rays. You don’t spend long on cosmic rays before you end up considering this baby:

The Oh-My-God particle was an ultra-high-energy cosmic ray (most likely a proton) detected on the evening of 15 October 1991… Its observation was a shock to astrophysicists, who estimated its energy to be approximately 300 exa-electron volts (3×1020 eV or 50 J)[1]—in other words, a subatomic particle with kinetic energy equal to that of a 5-ounce (142 g) baseball traveling at about 100 kilometers per hour (60 mph).

Wikipedia: Oh-My-God particle (see also xkcd what-if?)

And from there, you’re pretty much considering what happens if Eta Carinae goes supernova. And secretly worrying that whatever the quantum gravity prediction is is less cool than general relativity. Which it probably will be. I own my aesthetic preferences, and they are on Einstein’s side.

After that the true recognition that there are thousands and thousands of people on the Internet really established itself. Every time I thought of a question about black holes, there was some ancient FAQ (1995? dawww) that answered them.

First, ones that had puzzled me for a while. There’s extreme time dilation around black holes from the point of view of a sufficiently distant observer: do they therefore see me hovering around the black hole forever? Do I see the entire universe flash before my eyes before my time is up?

I had assumed the answers were yes and yes, but they’re actually no and no, at least if you stick to Schwarzschild black holes as more ore less everyone does. Matt McIrvin sorts this out pretty much back-to-back in his FAQ:

Won’t it take forever for you to fall in? Won’t it take forever for the black hole to even form?

Not in any useful sense. The time I experience before I hit the event horizon, and even until I hit the singularity—the “proper time” calculated by using Schwarzschild’s metric on my worldline—is finite. The same goes for the collapsing star; if I somehow stood on the surface of the star as it became a black hole, I would experience the star’s demise in a finite time…

Now, this led early on to an image of a black hole as a strange sort of suspended-animation object, a “frozen star” with immobilized falling debris and gedankenexperiment astronauts hanging above it in eternally slowing precipitation. This is, however, not what you’d see. The reason is that as things get closer to the event horizon, they also get dimmer. Light from them is redshifted and dimmed, and if one considers that light is actually made up of discrete photons, the time of escape of the last photon is actually finite, and not very large. So things would wink out as they got close, including the dying star, and the name “black hole” is justified.

As an example, take [an] eight-solar-mass black hole… If you start timing from the moment the you see the object half a Schwarzschild radius away from the event horizon, the light will dim exponentially from that point on with a characteristic time of about 0.2 milliseconds, and the time of the last photon is about a hundredth of a second later. The times scale proportionally to the mass of the black hole. If I jump into a black hole, I don’t remain visible for long…

Will you see the universe end?

If an external observer sees me slow down asymptotically as I fall, it might seem reasonable that I’d see the universe speed up asymptotically—that I’d see the universe end in a spectacular flash as I went through the horizon. This isn’t the case, though. What an external observer sees depends on what light does after I emit it. What I see, however, depends on what light does before it gets to me. And there’s no way that light from future events far away can get to me. Faraway events in the arbitrarily distant future never end up on my “past light-cone,” the surface made of light rays that get to me at a given time.

Physics FAQ

Fine then, answer all my questions. After reading that I huffed over to Google and typed in “does gravity move at the speed of light?” just to see whether the Internet is all it is cracked up to be. And a different section of the same damned FAQ actually answers this more or less in that form. Actually the answer is kind of cool: general relativity predicts that the distortions that gravity creates in spacetime propagate at the speed of light, yes, but in such a way that in most cases the source appears to be the instantaneous location of the massive object. Which is in turn super-lucky because otherwise you don’t get remotely stable orbits. Which as I recall resulted in a breather at Wikipedia: Anthropic principle but I was willing to fight on for a bit.

I wasn’t done, because I had encountered brief mentions of an interesting property of black hole event horizons, which is that inside the event horizon, one dimension of space becomes timelike, which can be informally considered as “the singularity is in your future”. I kept talking excitedly to Andrew about this late at night, I think when I was supposed to be working on something else (often cooking dinner) and the more I talked, the more I realised that I had absolutely no idea what this really meant. This required actual work on my part in terms of poking at Google queries, but luckily for this project, not very much, and it wasn’t long before I ended up at Jim Haldenwang’s Spacetime Geometry Inside a Black Hole which breaks out mathematics, and is worth a read in full. In addition to some of the mathematics, including that property of event horizons, it talks a bit about the historical development of the understanding of black holes, including the fact that the event horizon was also a singularity in the original coordinate system and it took more than thirty years to show that in some coordinate systems, it isn’t.

Frankly, I remain a little horrified at how little work I had to do to find any of this out. No overdue library books? No interacting with knowledgeable humans in real time? Some time in my 20s the future appears to have arrived with a vengeance, as it so often does. Outside of black holes, anyway.

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Citation delusions: "The most influential paper Gerard Salton never wrote"

In trying to finalise my PhD revisions, I am giving some background on text categorisation.

Extremely briefly, the problem of text categorisation is this: you have a document and some (usually pre-defined, unless you’re clustering) categories. For example, the categories might be news and editorial. Or academic article, newspaper article and blog entry. The choice of categories is application dependent.

Then you have a document you wish to assign to a category. Is it news, or editorial? The typical way of doing this is to assemble a set of training examples: pre-assigned news and editorial pieces. Then you measure the similarity of your new document to the pre-assigned collections, and whichever category it is most like is your document’s category. You might notice that I have not here defined “measure the similarity” and “most like”: that’s often the research question. How can you represent the collections efficiently so that they can be compared against new documents? What are good measures of similarity?

A fairly common way to picture this is (for historical reasons, as we’ll see), a vector. For each word in the vocabulary (the vocabulary being the set of terms used in every document in the training examples, typically, sometimes you might try and smooth the morphology out or similar), you construct a numerical representation. Say the vocabulary is no-good, bad, rotten, and a document reads “no-good no-good bad”, you might describe it as a vector , showing two uses of the first vocabulary item, 1 of the second and none of the third. (Again, whether you count vocabulary items, or weight them in various ways, is a research question. You may also notice that this counting-of-occurences model is a “bag of words” approach, that is, it does not distinguish between “bad rotten” and “rotten bad” even though in language word order and syntactic structure is meaningful. It’s possible to transform the vectors so that this orthogonality of individual words does not hold.)

For reasons that I won’t go into here, I am trying to discuss this model briefly in my PhD thesis — actually, more briefly than I did above — and therefore looking to cite the originator of the idea. I started coming across citations in other papers that looked something like: “Gerard Salton [and others] (1975). A vector space model for information retrieval.” Sounds good. It’s got the key words in it, and quite a few citations!

I like to sight before citing though, which means I found this interesting paper:

David Dubin (2004). The Most Influential Paper Gerard Salton Never Wrote, Library Trends 52(4):748–764.

Gerard Salton is often credited with developing the vector space model (VSM) for information retrieval (IR). Citations to Salton give the impression that the VSM must have been articulated as an IR model sometime between 1970 and 1975. However, the VSM as it is understood today evolved over a longer time period than is usually acknowledged, and an articulation of the model and its assumptions did not appear in print until several years after those assumptions had been criticized and alternative models proposed. An often cited overview paper titled “A Vector Space Model for Information Retrieval” (alleged to have been published in 1975) does not exist, and citations to it represent a confusion of two 1975 articles, neither of which were overviews of the VSM as a model of information retrieval. Until the late 1970s, Salton did not present vector spaces as models of IR generally but rather as models of specific computations. Citations to the phantom paper reflect an apparently widely held misconception that the operational features and explanatory devices now associated with the VSM must have been introduced at the same time it was first proposed as an IR model.

Naturally such a subtle treatment of the history of the model is not great for my immediate purposes: I need That One Citation! (As best I can tell from Dubin, if I have to pick one it should be G. Salton, (1979). Mathematics and information retrieval. Journal of Documentation, 35(1), 1–29.) but it’s fun to come across the analysis of an idea in this form.

Update: if you want a reasonable overview of text classification/topic classification/topic assignment, the survey of choice seems to be Fabrizio Sebastiani (2002). Machine learning in automated text categorization, ACM Computing Surveys, 34(1):1–47. You know, modulo 11 years now.

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2012: resume fodder

Because I had quite a difficult year in several respects, especially health-wise, some short notes on my 2012 accomplishments.

Total eclipse, partially obscured by cloud
by Flickr user 130GT

Ran AdaCamp. AdaCamp is really originally my baby and AdaCamp Melbourne was significantly my work (with Val, and Skud as local organiser). AdaCamp DC was significantly less so (because I was on study leave between March and May), but still, even on the day they’re a lot of work.

Delivered three talks at linux.conf.au. We gave an Ada Initiative update and an allies workshop at the Haecksen miniconf and our Women in open technology and culture worldwide talk at the conference proper.

Submitted PhD thesis. This was, of course, the end of a huge project. I enrolled in March 2006 and was full-time until December 2009. I was then enrolled part-time from July 2010 (after maternity leave) until May 2012 when I submitted the thesis. The submitted version is 201 pages long, word count is difficult with LaTeX.

Delivered the keynote address at Wikimania. This is to date my largest ever audience, I think.

Saw a total solar eclipse. Less of the work, just as much reward. The photograph of the eclipse shown here isn’t mine, and isn’t exactly like our view (we saw the top rather than the bottom through our bank of cloud) but it’s also from Port Douglas, and is very similar.

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Sunday spam: porridge and honey

What is cultural appropriation?

The problem isn’t that cultures intermingle, it’s the terms on which they do so and the part that plays in the power relations between cultures. The problem isn’t “taking” or “borrowing”, the problem is racism, imperialism, white supremacy, and colonialism. The problem is how elements of culture get taken up in disempowering, unequal ways that deny oppressed people autonomy and dignity. Cultural appropriation only occurs in the context of the domination of one society over another, otherwise known as imperialism. Cultural appropriation is an act of domination, which is distinct from ‘borrowing’, syncretism, hybrid cultures, the cultures of assimilated/integrated populations, and the reappropriation of dominant cultures by oppressed peoples.

Aircraft Carriers in Space

An article about naval metaphors in fictional space warfare. Sometimes I suspect that I like science fiction meta way more than I like science fiction.

“I’m not like the other girls.”

A quote I saw making the Tumblr rounds, which said, “I’m not like other girls!” It went on to avow wearing Converse instead of heels, preferring computer games to shopping, so on and so forth. When I saw it, about 41,000 girls had said they weren’t like “the others.”

Is Australia in Danger of Becoming Greece? Austerity and Blackmail Down Under

It is not enough to respond to this ongoing rhetoric about Australia’s supposed calamitous future by pointing out, as Ms Gillard correctly did, that these comparisons are ridiculous given the state of European periphery countries. Yet the ideological blackmail is strangely telling, precisely because the financial sector in the form of the troika (the International Monetary Fund, the European Commission and the European Central Bank) has held Greece’s politicians hostage, forcing a slashing of the government in exchange for “bail-out” loans.

The Start-to-Hate Review System

The concept is simple: Rate media based on how long it takes to encounter something bigoted. The longer it takes, the better the media.

An Investigation Into Xinjiang’s Growing Swarm of Great Gerbils

I am subscribed to two “long form” websites: the picks of Long Reads, which focuses on newer pieces, and the editor’s picks of Longform, which tend to skew a little older. Hence, this, from McSweeny’s in January 2005. I always like a piece that clearly ended up not being about what the original pitch was about. In this case, the writer wanted (or supposedly wanted, I guess) to investigate a gerbil plague, and ended up writing an article about gerbil social structures, text messaging on Chinese phone networks, and, several times, the Black Death. Which is how I ended up reading Wikipedia articles about pandemics the same night I was getting sick with the first illness I’ve had since I got out of hospital.

Mariana Trench Explosion

I think of Randall Munroe as a science writer who happens to be funded by merchandise sales from a comic. I don’t regularly look at the comic any more but I follow his blag and his What If? Answering your hypothetical questions with physics, every Tuesday writing more closely. This What If? is one of my favourites to date, although it’s hard to beat the first one. However, this one features an excursion into unpublished work by Freeman Dyson. SO HARD TO CHOOSE.

Do bicycle helmets reduce head injuries?

It’s impossible to follow Liam Hogan on Twitter without becoming interested in urban transport issues. At the moment the big conversation is helmet laws in Australia, which are arguably interfering with take-up of bike share schemes (if you’re going to have to get hold of a helmet, you don’t just jump on the bike, hence, scheme falls apart), although see Why is Brisbane CityCycle an unmitigated flop? for several other reasons that scheme may be failing.

Anyway, this one: A new study reports the rate of hospitalisations for cycling-related head injuries in NSW has fallen markedly and consistently since 1990. The authors say it’s due to helmets and infrastructure.
The drugs don’t work: a modern medical scandal and Ben Goldacre: ‘It’s appalling … like phone hacking or MPs’ expenses’

Reboxetine is a drug I have prescribed. Other drugs had done nothing for my patient, so we wanted to try something new. I’d read the trial data before I wrote the prescription, and found only well-designed, fair tests, with overwhelmingly positive results. Reboxetine was better than a placebo, and as good as any other antidepressant in head-to-head comparisons… In October 2010, a group of researchers was finally able to bring together all the data that had ever been collected on reboxetine, both from trials that were published and from those that had never appeared in academic papers. When all this trial data was put together, it produced a shocking picture. Seven trials had been conducted comparing reboxetine against a placebo. Only one, conducted in 254 patients, had a neat, positive result, and that one was published in an academic journal, for doctors and researchers to read. But six more trials were conducted, in almost 10 times as many patients. All of them showed that reboxetine was no better than a dummy sugar pill. None of these trials was published. I had no idea they existed.

Given that I favourited two separate articles about this, I’m going to buy the book. Now you know.

Going blind? DRM will dim your world

[I]t turned out I needed Adobe Digital Editions to ‘manage my content’… It tried, of course, to force me to give Adobe my email and other details for the ‘Adobe ID’ that it assured me I needed to get full functionality. I demurred… and was confronted by a user interface that was tiny white text on a black background. Unreadable. Options to change this? If they exist, I couldn’t find them.

Getting this far had taken me half an hour fighting my way through a nest of misery and frustration with broken eyes and a sinking heart. Along the way, I’d been bombarded by marketing messages telling me to “enjoy the experience” and “enjoy your book”.

Reader, I wept. Marketing departments, here’s a top tip: if your customer is reduced to actual, hot, stinging tears, you may wish to fine-tune your messaging.

5 Plans to Head Off the Apophis Killer Asteroid

Friday the 13th of April 2029 could be a very unlucky day for planet Earth. At 4:36 am Greenwich Mean Time, a 25-million-ton, 820-ft.-wide asteroid called 99942 Apophis will slice across the orbit of the moon and barrel toward Earth at more than 28,000 mph. The huge pockmarked rock, two-thirds the size of Devils Tower in Wyoming, will pack the energy of 65,000 Hiroshima bombs–enough to wipe out a small country or kick up an 800-ft. tsunami.

On this day, however, Apophis is not expected to live up to its namesake, the ancient Egyptian god of darkness and destruction. Scientists are 99.7 percent certain it will pass at a distance of 18,800 to 20,800 miles… Scientists calculate that if Apophis passes at a distance of exactly 18,893 miles, it will go through a “gravitational keyhole.” This small region in space–only about a half mile wide, or twice the diameter of the asteroid itself–is where Earth’s gravity would perturb Apophis in just the wrong way, causing it to enter an orbit seven-sixths as long as Earth’s. In other words, the planet will be squarely in the crosshairs for a potentially catastrophic asteroid impact precisely seven years later, on April 13, 2036.

It turns out that with current technology we might be able to move the asteroid prior to the (potential) 2029 entry into the gravitational keyhole, but if it did so we would be unlikely to perturb the orbit sufficiently after that point to avoid a civilisation-ended impact. So it’s the question of how many resources to spend on a low-probability but enormously catastrophic event.

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Sunday spam: French toast with bacon

The Myth of Looming Female Dominance

[One] should always be wary of raw numbers in the news. In fact, when you look at the trend as published by the Census Bureau, you see that the proportion of married couple families in which the father meets the stay-at-home criteria has doubled: from 0.4% in 2000 to 0.8% today. The larger estimate which includes fathers working part-time comes out to 2.8% of married couple families with children under 15. The father who used the phrase “the new normal” in [the NYT story] was presumably not speaking statistically.

Miley Cyrus haircut shocker: Short hair isn’t a cry for help

So just to remind you: A young woman changing her look in a way that doesn’t scream, “Please, world, love me because I am a Victoria’s Secret model,” right now, in the year of our Lord 2012, freaks people out. It actually makes them wonder if she’s lost her mind.

Scientists Claim To ‘Block’ Heroin, Morphine Addiction: One Skeptic’s Reaction

THe “one skeptic’s reaction” is actually along the lines of “this is very interesting research, that appears to have not much application to blocking existing addiction, but might to making opiates more effective for pain while being less addictive.”

Tribalism and locavorism

Why does the idea of “food miles” bug (some) freemarketeers while (some) environmentalists resist evidence that it’s not environmental friendly? This appears to be against both their stated ideological positions.

Why Aren’t Female Ski Jumpers Allowed in the Olympics?

Dating to the 2010 Winter Olympics.

The International Olympic Committee (IOC) says the women’s exclusion isn’t discrimination. President Jacques Rogge has insisted that the decision “was made strictly on a technical basis, and absolutely not on gender grounds.” But female would-be Olympic competitors say they don’t understand what that “technical basis” is. Their abilities? They point to American Lindsey Van, who holds the world record for the single longest jump by anyone, male or female.

The foibles of flexibility

Since the average age of those studying for a PhD is 37 most of you will have some kind of family commitment, and yes – pets count. I find it mystifying that so many of the ‘how to get a PhD’ books offer precious little advice on how to cope.

Am I Black Enough For You?

I watched this case unfold with particular interest. Why? Because I am married to an Aboriginal man and I have an Aboriginal daughter (they are of the Ngarigo people and the Gunditjmara people). And my daughter has fair skin, dark blond/light brown hair and very blue eyes. She is one of these “white Aboriginals” that Andrew Bolt decries.

We’re not here for your inspiration

And there’s another one of a little boy running on those same model legs with the caption, “Your excuse is invalid”. Yes, you can take a moment here to ponder the use of the word “invalid” in a disability context. Ahem.

Then there’s the one with the little girl with no hands drawing a picture holding the pencil in her mouth with the caption, “Before you quit. Try.”

I’d go on, but I might expunge the contents of my stomach.

Let me be clear about the intent of this inspiration porn; it’s there so that non-disabled people can put their worries into perspective. So they can go, “Oh well if that kid who doesn’t have any legs can smile while he’s having an awesome time, I should never, EVER feel bad about my life”. It’s there so that non-disabled people can look at us and think “well, it could be worse… I could be that person”.

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Sunday Spam: bagels, lox and smoked salmon

In belated honour of my breakfast in New York, Sunday July 8.

Baby Loss and the Pain Olympics
Warning for baby loss discussion.

I really have to question why seeing someone else processing their emotions is her pet peeve.

Do I believe a miscarriage and neonatal death is the same thing — of course not. If they were the same thing, they would share the same term. But just because I see them as apples and oranges doesn’t mean that I don’t also see them as fruit. They are both loss.

The deadly scandal in the building trade

Readers would not guess from the “national conversation” that the construction industry is sitting on a story as grave in its implications as the phone-hacking affair – graver I will argue. You are unlikely to have heard mention of it for a simple and disreputable reason: the victims are working-class men rather than celebrities… The construction companies could not be clearer that men who try to enforce minimum safety standards are their enemies. The files included formal letters notifying a company that a worker was the official safety rep on a site as evidence against him.

On Technical Entitlement

By most measures, I should have technical entitlement in spades… [and yet] I am very intimidated by the technically entitled.

You know the type. The one who was soldering when she was 6. The one who raises his hand to answer every question–and occasionally try to correct the professor. The one who scoffs at anyone who had a score below the median on that data structures exam (“idiots!”). The one who introduces himself by sharing his StackOverflow score.

Puzzling outcomes in A/B testing

A fun upcoming KDD 2012 paper out of Microsoft, “Trustworthy Online Controlled Experiments: Five Puzzling Outcomes Explained” (PDF), has a lot of great insights into A/B testing and real issues you hit with A/B testing. It’s a light and easy read, definitely worthwhile.

Selected excerpts:

We present … puzzling outcomes of controlled experiments that we analyzed deeply to understand and explain … [requiring] months to properly analyze and get to the often surprising root cause … It [was] not uncommon to see experiments that impact annual revenue by millions of dollars … Reversing a single incorrect decision based on the results of an experiment can fund a whole team of analysts.

When Bing had a bug in an experiment, which resulted in very poor results being shown to users, two key organizational metrics improved significantly: distinct queries per user went up over 10%, and revenue per user went up over 30%! …. Degrading algorithmic results shown on a search engine result page gives users an obviously worse search experience but causes users to click more on ads, whose relative relevance increases, which increases short-term revenue … [This shows] it’s critical to understand that long-term goals do not always align with short-term metrics.

Angels & Demons

One of the various Longform collections, and like many of them, a crime piece:

On June 4, 1989, the bodies of Jo, Michelle and Christe were found floating in Tampa Bay. This is the story of the murders, their aftermath, and the handful of people who kept faith amid the unthinkable.

On Leaving Academia

As almost everybody knows at this point, I have resigned my position at the University of New Mexico. Effective this July, I am working for Google, in their Cambridge (MA) offices.

Countless people, from my friends to my (former) dean have asked “Why? Why give up an excellent [some say ‘cushy’] tenured faculty position for the grind of corporate life?”

Honestly, the reasons are myriad and complex, and some of them are purely personal. But I wanted to lay out some of them that speak to larger trends at UNM, in New Mexico, in academia, and in the US in general. I haven’t made this move lightly, and I think it’s an important cautionary note to make: the factors that have made academia less appealing to me recently will also impact other professors.

Ethics, Culture, & Policy: Commercial surrogacy in India: A $2 billion industry

Since its legalization in 2002, commercial surrogacy in India has grown into a multimillion-dollar industry, drawing couples from around the world. IVF procedures in the unregulated Indian clinics generally cost a fraction of what they would in Europe or the U.S., with surrogacy as little as one-tenth the price. Mainstream press reports in English-language publications occasionally devote a line or two to the ethical implications of using poor women as surrogates, but with few exceptions, these women’s voices have not been heard.

Sociologist Amrita Pande of the University of Cape Town set out to speak directly with the “workers” to see how they are affected by such “work.”

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Paul Offit's Vaccines course

People in my research group have been understandably excited about, eg, Andrew Ng’s online machine learning course (you can also do Natural Language Processing with Dan Jurafsky and Chris Manning, respectively co-authors of Speech and Language Processing and Foundations of Statistical Natural Language Processing, so you need never choose between NLP textbook authors again).

Since submitting my PhD — I never mentioned that here, sorry, but if you follow me anywhere else you’ve probably heard! It’s under examination presently — I’ve zoned out some and eventually decided to head on over to Coursera and see what was on offer, in case I went two weeks without computer science and had withdrawal I guess. There’s nothing that exactly lines up with my desired enrollment dates right now, so instead, I’m in Paul Offit’s Vaccines course, starting June 25. Looking forward to it! Apparently there will be “challenging” assessment quizzes: I’m hoping to write up anything particularly interesting that comes up in the course, although I suspect that for people familiar with Offit’s various books and lectures (I’m not) it may be something of a repeat.

Note: never say never I guess, but anti-vax comments are unlikely to be published.