Week 3: Avalanches, Rockslides, and Sandpiles, Oh My!

Hello everyone!
If you've been following me up to this point, you're probably starting to wonder what the details of my project are.  I realized this week that while I've been busy talking about the gloriously cool things I've been finding, I have yet to mention what I'm doing on a day-to-day-basis.
So let's do that!

So far, my project has two parts; for the first part, I am working with Dr. Roy Frieden (at the U of A), who has done econophysics research in the past.  He has been directing me to the materials I should read next, in addition to helping explain some of the gnarly statistics.
Dr. Frieden's research (econophysics-related and otherwise) deals primarily in the field of Fisher information, which I feel like I know quite a lot about by this point and plan on sharing with you all in the very near future.

For the second part of the project, I am working with Dr. Srin Manne (also at the U of A).  Dr. Manne is helping me to design an experiment about avalanche dynamics, because as it turns out, the inner workings of avalanches somewhat resemble the inner workings of economic collapses.

I should point out that I'm not referring to snow-based avalanches here, which seem to be the first thing to leap to everyone's mind.  As cool (and terrifying) as those are, they are rather tough for a high school student to model quickly and cheaply.

(While I'm all for Grant's suggestion that I just build a mountain of Eegee's for observation, there's still the melting problem to consider.  And then we'd have a waste of perfectly good Eegee's on our hands, and that's not even justifiable in the name of scientific progress.)

Way to go, Grant.  Now I really want some.

So the avalanches I will be working with are rock-based, rather than snow-based.  This distinction doesn't matter too much, because rock-based avalanches (sometimes called rockslides) actually behave really similarly to snow-based models as long as they "flow" fast enough.
(Avalanches are part of a field called granular physics, which is distinctive because materials following granular behavior behave differently from other "standard" forms of matter, e.g. solid, liquid, and gas.  For example, a rockslide can behave as a liquid entity even though its individual components are solid.)

There are lots of ways to model rocks falling down a hill, it turns out.  One paper I came across actually used  fragmented blocks of coal.  The most famous (and best-explored) model, though, is the sandpile model, which is (surprise, surprise) basically a pile of sand.

Sandpiles (and, by extension, avalanches) are systems that obey self-organized criticality (SOC).  That's a fancy way of saying that the system is attracted to a certain critical point.  For example, if building a sandpile from scratch (as in the above picture), it would collapse in on itself at some critical angle, and stop growing taller.
Classic (non-SOC) examples of "critical points" are defined by an exact parameter.  For example, a phase transition, like liquid turning to gas, occurs at some exact temperature.  However, in SOC systems, the parameters are not exact-- we have no way of knowing which grain of sand will be the one to tip the pile over; it's different for every trial.

In the same way, when dealing with forecasting economic predictions, we might not know exactly which news, action, or other variable will tip the market downwards.  However, we can (hopefully) have some idea of when such a downward spiral might occur, by looking at the patterns.  (Consider the 2008 housing bubble; it followed a familiar and predictable economic pattern.  If we were to somehow repeat the situation, we would still expect some form of market collapse, but it could be from an entirely different variable.)

Obviously, I still have a lot of work to do, as right now I'm working on actually designing the experiment.  I have some ideas; for example, while considerable work has been done with the standard sandpile, which consists of point particles (the grains of sand), Dr. Manne and I are both curious what happens if we were to make a "sandpile" of string particles instead-- e.g. many beaded chains.
Not to worry, though, as soon as I get past the developmental phase and actually start gathering supplies and building the models, I'll be sure to keep you all updated.  Including real live pictures!

Hope you're all having a good week.  Feel free to comment below if you have anything to say!