Blag Break

Lots of #!$#% to get done. Will be away from the Blogohedron for a while. (That includes snarkfests in other people’s comment threads.) Will hopefully come back with upgraded software, a satisfactory comment system and all that, in the not-too-distant future.

Meanwhile, why not help science bloggers build something a little more lasting than usual, and support The Open Laboratory?

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Or watch Ed Witten on TV?

Pressures to Explain

Evelyn the Skepchick, whom I met a few times before she left the Boston crowd for the Woods Hole Oceanographic Institution, recently wrote about what it’s like to be a geologist in interesting times:

I am a hard rock geologist and a geochemist. As a geologist, I know about compasses, maps, GPS units, minerals, and hammers. As a geochemist, I know about acids, being paranoid about contamination, mass spectrometers, the periodic table, and the table of the nuclides. I know very little about ocean water and oil, and I know even less about deep-sea drilling rigs. Yet, over the past 101 days since the Deepwater Horizon Oil Spill began, I have been asked numerous times about the oil spill and its implications. As soon as people know I work at WHOI, they presume I am an expert about everything related to the oil spill.

I suppose that I should count myself lucky. Most of the people who know that I was trained in science also know that I studied theoretical physics, so I have nothing to say about anything important, ever, including the major disasters of our day.

I have sometimes been asked questions like, “So, what do you think of that surfer dude’s Theory of Everything?” This is where oceanographic eschatologists have a bit of an advantage: their subject is (all too) tangible. The difficulties with their work, or at least some of them, admit comparably easy explanations, such as, It’s hard to tell how much oil got spilled, because the gunk that spewed out is a mix of different stuff, and a lot of it is still beneath the surface. By comparison, when something hits the news which sounds like I would know about it, the issues have been . . . what’s the word? . . . esoteric. (Not to belittle the complexities of anybody else’s scientific field — the issue here is what questions get asked from outside, not what an individual scientist does on any working day.) By the time a story gets from the arXiv, through the physics blogs and into a newspaper, the juice can be sucked right out of it. When there’s nothing left but vague analogies for metaphors for speculations, when the residuals are more metaphysical than physical, what’s there to talk about?

Sometimes, I’ve tried to play Asimov: “Well, the mathematical structure the guy tried to use to fit all the different subatomic particles into a pattern didn’t have enough room to hold them all. And, when you try and squeeze the pattern to make them fit, it gets even worse: your mathematics says that new kinds of particles must show up, which don’t exist in the real world.” I always have a little paranoia about doing this, since invariably, the physics making the headlines hails from a subfield which I’ve never specialized in. So, while I might know more about it than the vast majority of the human population does, and I might be moderately well-equipped to learn more should the need arise, I can smack awfully hard into my limitations.

I’ve also tried to go for general background principles. “Most new ideas on the frontier turn out to be wrong. That’s only natural. If science were easy, we’d be done by now.” Or, getting into a bit more depth, I’ve tried to explain what physicists mean by symmetry, or by some other concept lurking behind the controversy du jour, on the logic that understanding a “basic concept” — that which one must know in order to know lots of other things — is a more lasting and valuable achievement than being able to repeat a soundbyte which will date itself in six months’ time.

Curses Curses Squared, Google Books Edition

And speaking of things which we couldn’t even have complained about a few short years ago, you know what bugs me? Reading through a chapter of something interesting — say, David Berenstein‘s “Large-N field theories and geometry” — and having pages missing from the middle, at the whim of Google Books. It’s like a game to test one’s knowledge: if page 260 ends with the Polyakov action in the conformal gauge, and page 263 has what looks to be a Virasoro constraint in light-cone coordinates, what could have gone between? Of course, this doesn’t work so well if the missing page has something new you’d like to learn . . . .

The New Now

The best thing about the edgy, hit new procedural Sledgehammer and Whore is how very now it is. Nothing in the pilot episode would have been possible five years ago. If their analogues had been included, the story would have played like some urban fantasy set in a tangent reality, in which popular culture is offset, skewed. I mean, describing somebody’s shoes in terms of the colours of a “soccer” team? Or, it would have played like science fiction, with technology which is not just unusual, like a James Bond gadget, but as ubiquitous in the fictional world as it is unknown in ours. It is one thing to portray NORAD using computers with strange powers, but it is another to have everyone on the Network.

I can’t say I think much of the music, tho’. At least they didn’t try to “enhance” the security camera footage during the montage.

(Via Jennifer Ouellette and Sean M. Carroll.)

Python Exercise: The Logistic Map

Nostalgi-O-Vision, activate!

A month or so after I was born, my parents bought an Atari 400 game console. It plugged into the television set, and it had a keyboard with no moving keys, intended to be child- and spill-proof. Thanks to the box of cartridges we had beside it, Asteroids and Centipede were burnt into my brain at a fundamental level. The hours I lost blowing up all my own bases in Star Raiders — for which accomplishment the game awarded you the new rank of “garbage scow captain” — I hesitate to reckon. We also had a Basic XL cartridge and an SIO cassette deck, so you could punch in a few TV screens’ worth of code to make, say, the light-cycle game from TRON, and then save your work to an audio cassette tape.

From my vantage point in the twenty-first century, it seems so strange: you could push in a cartridge, close the little door, turn on your TV set and be able to program.

Continue reading Python Exercise: The Logistic Map

How Not to be a Network-Theory n00b

Copied from my old ScienceBlogs site to test out the mathcache JavaScript tool.

Ah, complex networks: manufacturing centre for the textbook cardboard of tomorrow!

When you work in the corner of science where I do, you hear a lot of “sales talk” — claims that, thanks to the innovative research of so-and-so, the paradigms are shifting under the feet of the orthodox. It’s sort of a genre convention. To stay sane, it helps to have an antidote at hand (“The paradigm works fast, Dr. Jones!”).

For example, everybody loves “scale-free networks”: collections of nodes and links in which the probability that a node has $k$ connections falls off as a power-law function of $k$. In the jargon, the “degree” of a node is the number of links it has, so a “scale-free” network has a power-law degree distribution.
Continue reading How Not to be a Network-Theory n00b

Textbook Cardboard and Physicist’s History

By the way, what I have just outlined is what I call a “physicist’s history of physics,” which is never correct. What I am telling you is a sort of conventionalized myth-story that the physicists tell to their students, and those students tell to their students, and is not necessarily related to the actual historical development, which I do not really know!

Richard Feynman

Back when Brian Switek was a college student, he took on the unenviable task of pointing out when his professors were indulging in “scientist’s history of science”: attributing discoveries to the wrong person, oversimplifying the development of an idea, retelling anecdotes which are more amusing than true, and generally chewing on the textbook cardboard. The typical response? “That’s interesting, but I’m still right.”

Now, he’s a palaeontology person, and I’m a physics boffin, so you’d think I could get away with pretending that we don’t have that problem in this Department, but I started this note by quoting Feynman’s QED: The Strange Theory of Light and Matter (1986), so that’s not really a pretence worth keeping up. When it comes to formal education, I only have systematic experience with one field; oh, I took classes in pure mathematics and neuroscience and environmental politics and literature and film studies, but I won’t presume to speak in depth about how those subjects are taught.

So, with all those caveats stated, I can at least sketch what I suspect to be a contributing factor (which other sciences might encounter to a lesser extent or in a different way).

Suppose I want to teach a classful of college sophomores the fundamentals of quantum mechanics. There’s a standard “physicist’s history” which goes along with this, which touches on a familiar litany of famous names: Max Planck, Albert Einstein, Niels Bohr, Louis de Broglie, Werner Heisenberg, Ernst Schrödinger. We like to go back to the early days and follow the development forward, because the science was simpler when it got started, right?

The problem is that all of these men were highly trained, professional physicists who were thoroughly conversant with the knowledge of their time — well, naturally! But this means that any one of them knew more classical physics than a modern college sophomore. They would have known Hamiltonian and Lagrangian mechanics, for example, in addition to techniques of statistical physics (calculating entropy and such). Unless you know what they knew, you can’t really follow their thought processes, and we don’t teach big chunks of what they knew until after we’ve tried to teach what they figured out! For example, if you don’t know thermodynamics and statistical mechanics pretty well, you won’t be able to follow why Max Planck proposed the blackbody radiation law he did, which was a key step in the development of quantum theory.

Consequently, any “historical” treatment at the introductory level will probably end up “conventionalized.” One has to step extremely carefully! Strip the history down to the point that students just starting to learn the science can follow it, and you might not be portraying the way the people actually did their work. That’s not so bad, as far as learning the facts and formulæ is concerned, but you open yourself up to all sorts of troubles when you get to talking about the process of science. Are we doing physics differently than folks did N or 2N years ago? If we are, or if we aren’t, is that a problem? Well, we sure aren’t doing it like they did in chapter 1 of this textbook here. . . .

All the Physics Stories We’ll Ever Need

“ZOMG! The Higgs field is actually an entropic force due to holographic degrees of freedom whose gauge group is embedded in a noncompact real form of E8! (No, we don’t know what that means, either, but we found two scientists with three amusing hobbies among them to pretend to explain it to you, and we’ll preface their interviews with a video clip or written blurb crafted by a high-school intern who will never take a math class again after getting that C in trigonometry! And after reading our story or seeing our clip, you too will know everything you need in order to complain about string theorists getting taxpayer money!) But we’ll never know if it’s true, because if we do an experiment to find out, hydrinos will travel back in time and cause seagulls to drop baguettes into our apparatus!

“On his Huffington Post blog, Deepak Chopra explained how this research proves the quantum nature of bodacious sitar riffs.

“Now this.”

Currently (Re)reading

I noticed this one when it first hit the arXivotubes a while back; now that it’s been officially published, it caught my eye again.

G. Rozhnova and A. Nunes, “Population dynamics on random networks: simulations and analytical models” Eur. Phys. J. B 74, 2 (2010): 235–42. arXiv:0907.0335.

Abstract: We study the phase diagram of the standard pair approximation equations for two different models in population dynamics, the susceptible-infective-recovered-susceptible model of infection spread and a predator-prey interaction model, on a network of homogeneous degree [tex]k[/tex]. These models have similar phase diagrams and represent two classes of systems for which noisy oscillations, still largely unexplained, are observed in nature. We show that for a certain range of the parameter [tex]k[/tex] both models exhibit an oscillatory phase in a region of parameter space that corresponds to weak driving. This oscillatory phase, however, disappears when [tex]k[/tex] is large. For [tex]k=3, 4[/tex], we compare the phase diagram of the standard pair approximation equations of both models with the results of simulations on regular random graphs of the same degree. We show that for parameter values in the oscillatory phase, and even for large system sizes, the simulations either die out or exhibit damped oscillations, depending on the initial conditions. We discuss this failure of the standard pair approximation model to capture even the qualitative behavior of the simulations on large regular random graphs and the relevance of the oscillatory phase in the pair approximation diagrams to explain the cycling behavior found in real populations.