QFT is (not) hard

Yesterday was our faculty's postgrad symposium, where science students of all descriptions attempted (usually with some measure of success) to explain to science students of all other descriptions what their research is all about. This necessitates some creativity and has left me thinking (not for the first time) about whether or not QFT is indeed inexplicable. It seems worth writing up a few thoughts here.

QFT is hard.

There's a reason that nobody less than four years out of high school gets QFT (for an approximate value of nobody and allowing 'gets' to be ill-defined) and nobody with less than six years of tertiary education has actually used it in any practical way. (Again, generalisation, but I don't think it's far off the mark.) QFT is a very abstract, mathematical theory and divorcing it from the mathematics is like trying to explain swimming without water. If you want to understand QFT, come back when you have a degree's worth of mathematics. This is perhaps a little too depressing, so let's try another tack. 

QFT is not hard

Sure, the scientists who do QFT research need lots of training and deal with scary equations all day, every day, but that's not the heart of what they're doing. They're actually doing calculations on "god particles" and quarks, which are basically very small marbles glued to elastic bands which are other particles called gluons and the gluon is massless which means it's like a fish that can swim through the god particle molasses slickly, unlike the other particles, which are like whales because they have masses.

Now, I will admit that our building houses not just the physics department, but also the oceanography department and the Marine Research Institute, but we are separate departments. A quark or a Z boson is nothing at all like a whale. In fact, the work I do on a day-to-day basis involves talking about mathematical abstractions that can be experimentally tested using the ideas of such particles, but doesn't really talk about particles at all. So while I do think that non-specialists should be able to get an idea of what's going on in QFT, I'm not convinced that these analogies do much more than make people think they know what's going on. Which is perhaps worth something, but seems suboptimal.

QFT is (not) hard

QFT is an abstract theory based on abstract mathematics. If you want a genuine feeling for how it behaves, you need a genuine feeling for how maths behaves. To reuse an analogy (since I've decided they're not all bad), you can't understand swimming if you don't know what water is. QFT is related to abstract maths just as intimately and shying away from it doesn't help. But what I think we miss is that all you need is a "genuine feeling for how maths behaves". I say 'all', but of course such a feeling can be hard to come by. However, it's an awful lot easier to come by than a degree in mathematics. It almost has to be.

I don't think you need to be able to calculate a commutator to get a feel for what's going on in QFT. I do think you need to know that sometimes in maths, as in life, order matters. 2 + 3 = 3 + 2. I don't care whether you put on your hat and then scarf or you scarf and then hat. But pq is not the same as qp and you should put on your socks before you put on your shoes, unless perhaps you're going to a fancy dress party.*

For some reason we don't seem to want to explain QFT this way. Perhaps it's because we've all learned in school that maths is terrifying. Perhaps it feels like it takes us too far off topic. (I feel this every time I try to give a talk about QFT, but I find there's nothing to say if I take out the maths.) Perhaps we just haven't thought about it enough. (We almost certainly don't think about science communication enough.) Perhaps it is happening, but I'm not aware of it (and neither are my scientist friends, which would mean it needs way more publicity).

I'm still working out where  this leaves me. It means that when I talk about QFT for a general audience, I don't shy away from the maths. Maybe it means I need to write and/or talk about these ideas more often (she said, guiltily writing her first blog post in months). Maybe it's enough to be aware of it and to talk about. Maybe I need to pick fights about it. Maybe (definitely) it's not all a problem for me to solve, all on my own, today. But it's a topic that deserves some thought, in the midst of marking and debugging and trying to put in those six years you need to learn to use QFT. We'll see.

____
* I feel like a cheat putting in mathematics without explaining the physical significance. The p and q here are representing the tools we use to measure the position and momentum (which gives us the speed) of a particle respectively. The maths tells us that the order in which me measure them matters, because pq ≠ qp. This means that making one measurement must somehow corrupt the other (it doesn't tell us how that happens, sadly). This in turn means that if we measure the position correctly, we can't measure the momentum and vice versa. This is Heisenberg's Uncertainty Principle (which is one of the most obvious and well known consequences of order mattering, although not the only one). You can talk about thought experiments, like the Heisenberg microscope, to make it seem more intuitive, but it comes from the fact that if we choose maths that gives us the right answers, order matters when you write down p and q.

Definitions and Discoveries

At first glance it seems that it would be rather silly to mix up the ideas of a definition and a discovery, but at least in maths (and perhaps especially theoretical physics) it's surprisingly easy to do. Both processes produce rules that allow us to go on and derive new rules and descriptions -- the big difference is where they come from.

Might require a change of maths.

Suppose, for instance, that I want to construct a rule using the word "good". Then I would work out what the word "good" means for the rule by seeing how it works in the world -- I would discover it, rather than defining it. (There might be situations where you would choose to define it differently from how it works in the rest of the world, but you would have to be clear that you were doing something funny then.) This is rather like how we decide to write the description of gravity as pulling things together. Mathematically you could write about it as a force that pushes things apart, but that wouldn't describe the gravity we experience. Likewise, if you want to describe arithmetic as we know it, you can't decide whether 2+3 and 3+2 are the same thing. You discover that you don't get the expected results unless they are. (One might decide to define it differently anyway, but then one would no longer be talking about ordinary arithmetic.)

Things get more complicated if I have a procedure that involves putting "un" at the beginning of words. I can't go out and discover the meaning of "ungood", because it's not a word you can find in the world. Nothing about the way people talk changes if I interpret "ungood" as meaning "butterfly" or "convenient" or "pirouetting", because people don't say "ungood" in the first place. Situations like this tend to crop up in the intermediate mathematical steps of a physics problem. I've translated the situation into equations and now I want to solve them. Solving equations doesn't mean anything physically, although the solutions should be something we can translate back. That means there aren't clear physical requirements on what is or isn't allowed in trying to solve the equation. 

If I want to be able to use the "un" procedure, I have to come up with a meaning for "ungood". There's nothing stopping me from picking any definition I like -- but some will be more useful than others. I'd like to pick a definition that means the "un" procedure does the same thing it does to other rules. "Decided" becomes "undecided", "expected" becomes "unexpected" and "forgettable" becomes "unforgettable", all of which do mean things already. It makes sense that when "good" becomes "ungood", it means the opposite of "good". We might define "ungood" to mean "bad".

We don't have to define it that way, though. We could go by similar phonetics instead and define "ungood" to mean "unguent". The "un" rule wouldn't work as expected any more, of course. But if I were writing a speech-to-text program, say, that might be less important than the phonetics. Besides, it's not like the "un" rule is infallible anyway -- look at how "til" becomes "until". It's only if I want the definition to work in a system where the "un" rule always produces opposites that defining "ungood" to mean "unguent" would be inconsistent.

The same thing happens mathematically. If something doesn't exactly match up to some physical observable, we need to define what it means. Some definitions make more sense than others when it comes to translating back and those are the ones we choose. But unlike making a discovery, it is a choice. We decide that we want certain rules and procedures to do what they do elsewhere and choose to define things accordingly. The definition isn't forced upon us by the way the world works. 

Why do I care about such a subtle difference? If you just want to apply the rules, it doesn't really matter. But if you want to understand where they come from and what makes physics tick, you need to know what's required to describe the world and what's just a helpful way of thinking about intermediate maths. And that's why I'm quite sure I'm neither the first nor the last physics student to say "Oh is that just a definition? It all makes sense now..."

Savo 'lass a lalaith.

What exactly counts as open?

I'm currently writing a paper for a journal that accepts submissions only in .doc format. That doesn't sound like a problem – everyone uses Microsoft office anyway, right? Well, no, I don't. Because MS Office doesn't run under Linux, which I'm using. And even if it did, there are places I'd prefer to throw my resources, given a choice. But aren't there open source alternatives that can produce those files? Well – kind of. LibreOffice will produce a .doc file alright. And if it contains straightforwardly formatted text with the occasional picture, MS Word would handle that file fine. However. I need equations. And while both LibreOffice and MS Word have equation editor functions, they're not entirely compatible. Nor are they particularly fun to use. Why can't I just use LaTeX?

Well, okay, I know why I can't. It's a general science journal, and unless you're doing fairly mathematical science, the LaTeX learning curve may not seem or be worth the (relative) ease of use. (And, I suppose, not allowing LaTeX forces me to consider if I really need to include that obscure equation in the paper.) LaTeX documents are not, for most people, as easy to read and edit as is a .doc file. It is free, though. Which MS Word is not.

It raises an interesting question about which method is really more "open". Requiring Microsoft formats means I need to buy – or, more realistically, borrow – an expensive piece of software to contribute to the journal. Requiring LaTeX formats forces contributors to pick up a non-trivial skill set before submitting. Neither of these is really entirely open. Perhaps simply offering a choice of format would be a reasonable workaround, although it does still feel like a workaround. Improving the compatibility of LibreOffice (or other open source office suites) with MS Office, while far beyond the reach of the journal, might be a slightly better fix. I think that will happen, but not until long after I've written this paper!

In the meantime, I'll be sulking in the corner because a side effect of using an office suite format is that I can't work in vi.

Book Log: Goodnight Mister Tom by Michelle Magorian

("Good night" seems like two words to me, but it's one on the cover. Oh well.)

One of my criticisms against 'Skull in Shadows Lane' was that it read like a children's book (which it was, so it's not a terrible thing). Goodnight Mister Tom, which is also about children in wartime England, did not read like a children's book. I think this is a good thing (certainly, I enjoyed it), although part of me wonders if it really is a children's book.

William is evacuated from his meagre home in London to a surprisingly pleasant place in the country, where he stays with a crusty, but kind childless old widower: Mister Tom. Will blossoms in the wholesome new environment and it's a delight to watch his character unfold. Part of the delight, certainly, is being able to see things coming when he can't. I'm not sure how much that would change between an adult and a child's perspective.

It's a little odd to realise that I just don't know. As I write now, looking for an example that's more adult-oriented than kid-oriented, I can't think of a specific example. It's rich - I found some of the Heidi parallels rather fun, especially when somebody mentions the novel in a different context, but I don't imagine every reader would notice/appreciate that. The division probably doesn't have much to do with age, though. Some of the topics it deals with are horrible, but it does handle them well. I guess I wouldn't read it to small children, but that doesn't mean it's not a children's book at all.

I think I'll take it as this novel correcting the fault I found with 'Skull in Shadows Lane'. It has as much depth and colour as I could ask for, without particularly moving out of the realm of children. There's lots going on, but it's understandable. And if it takes more than one read to get all the goodness out of it - well, that's a sign of a good book, isn't it?

'Goodnight Mister Tom' is a coming-of-age novel that looks at some relevant topics of varying difficulty (abuse; discrimination; "gifted" education; interactions of family and state) rather well. The author loses herself very well, so that I'm not thinking about gender equality in education, but only wondering whether or not Connie will be able to go to high school. Which may lead me to the same topic, but lets me think about it in my own way. And I think these topics deserve some thought.

I enjoyed this. I'd like to read it again at some point.

FameLab

I missed my Wordless Wednesday post this week and then I missed my Friday Five too. And I've started reading The Return of the King without blogging about The Two Towers. I could probably blame my honours quantum mechanics course or my insistence on making the wraps we had for dinner from scratch, but I'm going to pin it on FameLab instead.

FameLab is an international event/competition that promotes young scientists "Talking Science" with the general public. Conversely, it promotes people hearing - and hopefully learning - about science, which is a Good Thing in my book. It's all done through the form of three minute presentations where PowerPoint slides and more props than you can carry are banned. This works really, really well, despite its simplicity.

For one thing, "Death by PowerPoint" and related maladies were almost entirely banished. For another, three minutes is barely long enough to get bored. The time limit was strictly enforced by vuvuzela (I assume other countries have equivalents) - although just the threat seemed enough for the people I watched. Regional heats were open to any (practising or studying) scientist in the 21-35 age range, which seems to have ensured that everyone had something worth saying - and not enough time to make it boring.

There was feedback from the judges after each presentation - I was impressed at how much this stayed positive, helpful and interesting to the audience. Presenting and being scrutinised was a little scary - the cameramen and microphones and masking tape squares on the floor didn't help - but an awesome experience.

A handful of us were invited back to regional finals - another three minute presentation a couple of hours later, taking into account the judges' feedback. The fact that it had to be a different presentation seems like a rather effective test of breadth. It felt like a test of improv skills too when we were suddenly called for on-camera interviews! It's surprisingly tricky to do that sit-sideways-and-smile-at-the-camera drill, never mind actually answering questions! Not that I'm complaining: it was all part of the excitement.

The regional finals were awesome. While some of the first round presentation were a bit rough, these were all fascinating. The kind of thing that would make for a great school field trip or the like, I thought. The scientific basis for the zombie apocalypse; a eulogy for coal; forensics and DNA testing. (You can see something of the impressive breadth the presentations covered there too.)

My nails probably owe their continued existence to all the interesting people I had to talk to while the judges deliberated, between the scientists and the competition staff. The compere seemed less friendly when she started stalling the results, though . . .

Three of us went through to the national finals. One of them was me! Um, what? I entered this thing just for kicks - the first round really is an experience in itself (next year I'll be telling everyone else to do it too). I'm just this girl who likes showing people how things work, not some kind of professional anything.

But apparently I'm going SciFest Africa in Grahamstown. I think. If I were dreaming I would've woken up by now, right? And it wouldn't have left me so ridiculously tired.

Learning/Understanding

(Two sides of the same coin)

Abstract

Mathematics, like poetry,
half-conceals truths
so abstract that,
were they made explicit,
the very substance of the universe
would burn.

You must learn what they
can express
to understand
what they can't.

 Lauren (aka SilverInkblot) of Autumn Brontide has been writing poetry in a series she calls "A Poetic Education". (The poemish thing above is part of my attempt at a response.)  My favourite so far is Half. The series is, I think, an interesting exploration of learning and schooling and education and how the three get tangled up together or end up (very sadly) excluding each other. I muddled around what she'd written a little, and she responded and expanded on her thoughts here. In consequence, I am thinking about education.

I read a few blogs about homeschooling, higher education and occasionally both. They're interesting, but I don't often do anything about them. I'm not a homeschooler. I'm not  a university professor. I guess I do a little bit of TA-ish work, but I've yet to discover a blog about those sorts of things! Despite that, I think it's worth reading those blogs.

Partly, they're just interesting. If something's interesting, I like to learn more about it. (Perhaps this is because I'm lucky in having received an education that by and large nurtured my love of learning, rather than crushing it.) Partly, I think they're useful even when I don't immediately act on them. Becoming aware of how education and learning work means that if I do end up making a decision about them, I have data to work with. And I'm sure I make minute day-to-day choices slightly differently when I make them against a broader background.

That is, I think awareness makes a difference and I think that an education -- even an education on education -- has to be built up over time. Which is why I think that saying something about it will almost always be better than saying nothing, even if the something has to be accompanied by and admission that it's a long way from being everything. I don't think the difficulties education has to overcome can go away overnight. But by engaging with them and thinking about them, we make change possible.

Feminine(?) Role Models

Preface: Apparently the people at The Aperiodical are not as great as I think they are. You should make your own judgement, though. (In my undenied naivete, I think it's cool that somebody mentioned me on a podcast. Two, actually.)

 So recently some people at Michigan university did some research finding that feminine maths and science role models are not inspiring. I've been wondering for a little while why the article bothers me. Perhaps it's because I exhibit most of the characteristics that they say put girls off studying STEM (science, technology, engineering, mathematics, if I recall correctly) subjects. Which is, you know, kind of sad. I would not like to think that by wearing pretty skirts and getting good marks I send out a message that other people can't . . . can't what? Do mathematics? Understand physics? That sounds plain ridiculous.


Part of it is that the study was actually fairly limited -- it only looked a middle school girls. More significantly, from what I understand, 'feminine' here means something more like 'glamourous' than, say, 'womanly'. (The introduction to the paper proper refers to "pink-laptop-toting ‘‘Computer Engineer Barbie,’’" for instance.) That's not my immediate interpretation of feminine, but perhaps it's other people's. (If you're reading this, I'd love to know what you think.) I can believe that most girls don't think they have the potential to be the real-life version of Computer Engineer Barbie. I for one don't even want to. Does that make me unfeminine?

I like pretty dresses and I have a formidable collection of hair ribbons, but I can't be bothered to go through a fifteen minute make-up routine every morning. I own pretty high heeled sandals, but I don't wear them often. For one thing they're impractical for running up to the Physics department on the second (I think that's third in the USA, where people count funny) floor of Science block. For another, I'd feel overdressed when I arrived amidst the rest of the jeans-and-sneaker-clad students. If that's unfeminine, then I guess all those conclusions about STEM-successful women being unfeminine are probably true. Only I'd be inclined to think that most women are rather unfeminine then. (In fact this is semi-almost-implied in both the press release above and the paper proper.) Motherhood certainly doesn't sound feminine by this metric, which strikes me as rather odd.

If feminine means putting a fair amount of time and effort into satisfying certain perceptions of beauty, then being feminine means having less time to be good at anything else. It also means that anyone with a different idea of what beauty is will rather dislike being labelled as feminine. It wouldn't surprise me that many women who are successful in any number of other fields qualify as 'unfeminine'. On the other hand if being feminine is simply being typically female, I don't think it's nearly as likely to scare girls away from maths and science. (Of course STEM-successful women may still be perceived as unfeminine, which is not cool, but not something I really want to get into here.)

I do think the study is interesting and even useful, but I don't like the lack of definition of 'feminine'. It seems to mean something different every time I see it, until I find myself wondering how I've ended up in a world where it's referred to as counter-stereotypical for a woman to be feminine.

Perhaps I'm overthinking things, but that does strike me as a little odd.

In which a year does not fit into a blog post at all well

(And I ignore the concept of 'title case' in writing my title.)

Tomorrow will be a brand new year! Imagine that. It will be the twenty second year I've been alive in and all sorts of interesting things will happen in it. If I don't write about them here, I might remember to write about some of them tomorrow or, you know, in the course of their actually happening. In the mean time, I will have a bash at writing about some of the interesting things that happened this year.

I changed my degree. Actually, most of the decision making related to this happened way back in 2010, but the living it out was part of 2011. It's been tough at times, but I'm not the least bit sorry I did it; and really, for all I think it's been tough, it couldn't have been very much easier than it was. The paperwork was awful, but is finished forever, now. I've missed my engineering friends and classmates, but I've made new friends too. I haven't missed the engineering mindset: it's an incredibly useful (and I think to many people natural) way of looking at things, but I didn't find it nearly as fun as the 'pure' science perspective. I certainly haven't missed the move to a bigger, less personal campus. I love class sizes of fifteen and twenty and the very real interaction that just about has to happen in classes that small. I've felt the thrill of being the 'senior' science student first-year-me thought I never could: silly things, really, but happy things. I can walk past hordes of first years into the labs without waiting for demonstrators or technicians. I know the code for the lock on computational physics department door. (I also know that there are just two rooms behind that door: the dedicated postgrad and undergrad physics LANs.) I've begun to understand the complicated geography of the Maths/Stats/Comp. Sci. floor of science block and I've spent entire days without leaving that building until I go home. Somehow it might be most significant that I've learned that there will always be proofs and theorems omitted -- but sometimes you know you'll come back to them later.

I've discovered an academic-ish subculture. I read maths webcomics. I know that if I take my homework to the Physics LAN, there's a good chance I'll end up talking instead of getting work done. Also, that that's okay. I've found authors like Richard Feynman and Tom Korner who make maths and physics as beautiful as I think it should be (and sometimes leave me feeling rather stupid). I can get distracted trying to derive a formula for the volume of a right rectangular pyramid (it's rather pretty) or realise in the middle of reading a novel that I suddenly understand Gauss' law of electrostatics (I don't know why I still get mixed up about it). I've found out that I'm not the only person in the world who does things like that.

I've made a fuss about things that matter. I'm not very good at 'being an activist'. I don't have lots of (or any) posters, bumper stickers, hyperlinks or explanatory texts about the things I care about. But that doesn't have to mean I don't care. I've run events that were in danger of neglect and made a little me-sized difference. I've fought fights that jolly well ought to be fought, even when people have forgotten to care that things are being done wrong. I've ignored things too, wisely and unwisely, but I've learned that I know how to kick up a fuss. I joined the church youth leadership team. I decided that things should happen in Sunday School and did [some of] them. I [sometimes] stuck up my hand and said 'Shouldn't there be an extra term in that equation?' instead of just making an adjustment to my notes. I found out where the uni timetabling offices are, looked up the contact email and spent [a little] less time moaning about maths/physics clashes. Even small things have to count for something.

2011 has been a spectacular year. I can't believe that it's already finishing or that I walked into my first Physics II lecture less than twelve months ago. There have been ups and downs, but looking back, Romans 8:28 seems awfully applicable. And we know that in all things God works for the good of those who love him[.]