Thursday, May 29, 2008
http://arxiv.org/abs/0805.4182, "A model of a 2d non-Fermi liquid with SO(5) symmetry, AF order, and a d-wave SC gap," Eliot Kapit and A. LeClair
http://arxiv.org/abs/0805.2951, "A unique non-Landau/Fermi liquid in 2d for high Tc superconductivity," Eliot Kapit and A. LeClair
http://arxiv.org/abs/0805.4200, "On the New Model of Non-Fermi Liquid for High Temperature Superconductivity," Henry Tye
High-temperature superconductors are a class of materials (doped cuprate compounds) that are superconductors -- i.e. transmit currents without resistance -- at much higher temperatures than conventional superconductors (mostly metals). Why they do this -- or, indeed, why they become superconductors at all -- has been one of the big open questions in theoretical condensed matter physics for 20 years.
I don't yet know what the response to these papers will be; however, if their analysis is correct, they appear to constitute an explanation of high-temperature superconductivity. I wonder about the opacity of the titles. Andre LeClair is a mathematical physicist at Cornell; I met him briefly when I visited Cornell as a prospective grad student, and he strongly discouraged me from working with him on the grounds that most of his recent research projects hadn't worked out.
Tuesday, May 20, 2008
1. Obama vote vs. black population. States with very few, and very many, black people go for Obama; states with black populations in the 8-15% range go for Clinton. This is a combination of two monotonic curves -- the white vote for Obama varies inversely with black population, whereas the black vote goes en bloc to Obama. This is generally attributed to the notion of "racial threat" -- i.e. "the more black people you see the less likely you are to vote for one."
2. Obama vote vs. Republican population in heavily white areas. Counties with very few, or very many, Democrats are relatively strong for Obama; "swing" counties for Clinton. Heavily Dem counties favor Obama largely because they tend to be urban, young, and relatively heavy-minority. The other end of the parabola is slightly more puzzling, but very persistent. Jay Cost shows that this effect held even in Central Pennsylvania, where everything else was going against Obama. (He lost several counties by 20% that he was supposed to lose by 30-35%.) So, Cost now suggests, Obama did better in Indiana than Ohio -- which has similar demographics -- because it's so Republican. He explains this by saying that culturally conservative Dems prefer Hillary, but in heavily Republican areas the cultural conservatives tend to be Republican.
I think these are both causation-correlation fallacies to some extent, though it's hard to control for all the variables. Some observations:
A. Hillary's strength among whites in southern states is at least partly an artefact of her overwhelming strength in Appalachia, which is almost entirely white and would fall on the "Obama" part of parabola 1 (see: WV, KY). Carving off the Appalachian parts of VA and NC increases Obama's percentage of the white vote in those states. Besides, the most heterogeneous counties are all cities, and Obama seems to do OK with the urban white vote (though cities are wealthy and that helps him).
B. The other geographical feature of note is that Obama dominates the entire upper midwest and northwest. These states are all very white, and a lot of them are heavily Republican. Is Obama benefiting from the exodus of racists etc. to the Republican party? And how about Wisconsin and Iowa, which are not particularly rich and not particularly Republican? Is the determining factor something else that's correlated with geography? Why is there less "racial threat" in these states than in WV? The notion that there's something geographical about this, btw, has some support from Cost's data. He notes somewhere that NW Ohio and Indiana were a lot less pro-Hillary than SE Ohio despite similar demographics. (It's also more Republican, which fits his pattern.) Indiana was apparently even less pro-Hillary than NW Ohio. Is this just because it's further west?
C. Five-thirty-eight says the time series data shows that some aspects of the race have changed since January, e.g. it used to be that the liberals went for Hillary and the moderates for Obama; recently it's been the other way round. You could put this down to Rev. Wright etc. If this were substantially true it would invalidate parabola 1. I think the time-series is just an artefact of the order in which different states voted, i.e. Obama would've drawn the "liberals" in PA and the "moderates" in Iowa and NH no matter what. He's still polling well ahead of Hillary in Iowa, which has a lot of "moderates." On the other hand, states outside of Appalachia are probably more susceptible to "momentum"; only diehard Hillary fans would even bother to go vote for her at this point.
I feel like there probably ought to be something to both the arguments I've been quibbling with. However, they're really not that solid, and there do seem to be people out there who should have the time to clean them up and test them.
Update. Exit data from Oregon backs me up on point C. Obama won the weekly churchgoers, just as he had in Iowa and NH.
And so now in defeat, the President was in the unfamiliar position of straining for comity. Unpracticed at humility, Bush’s appeal was not very convincing. “You’re from the West. I’m from the West,” he said to me. “We’re both just two dudes from the West.”
Saturday, May 17, 2008
Thursday, May 15, 2008
In 1989, [Harvard Law Prof Laurence] Tribe took Obama on as a research assistant, putting him to work on a paper entitled, “The Curvature of Constitutional Space: What Lawyers Can Learn from Modern Physics,” which sounds like something Learned Hand wrote from Mars. “To deal with it, one had to get a reasonable command of the general theory of relativity and Heisenbergian physics,” Tribe explained. “So I got to know him in a context that really tested the qualities of his mind. It wasn’t a grinding kind of a job. It required a very wide-ranging intellectual curiosity and imagination.” Heisenbergian physics, the cynic believed, was smart enough. Harvard Law was smart enough.
I read the first few pp. of the article (Harvard Law Review 103(1), 1-39 (1989)) and it's just as bad as you'd think, though this is hardly Obama's fault.
Wednesday, May 14, 2008
Nature has a news item, which someone evidently enjoyed writing, called "A Side-Splitting Tale" about new simulations of why condoms break ("erupt" is the correct technical term), using "adjustable 'thrust-hole' diameter, thrust rate, and lubrication." Read the whole thing. The conclusion is somewhat dispiriting:
“Just about the only thing that humans aren't strong enough to break, that is also thin and flexible enough, is parachute nylon — but that's porous,” comments White.
Tuesday, May 13, 2008
I should stop posting maps.
"Everyone stumbles. I'm not going to hide or run or live in denial, or with regrets," Forgaard told Reuters in an interview. "On the surface it looks like total devastation but it's just the opposite. I'm confident our lives will be much, much richer as a result."
Monday, May 12, 2008
N.B. The latest polls are roughly 60-25% for Hillary. I assume most of the undecideds will vote for her if they vote at all, since Obama isn't campaigning. High turnout implies something like a 75-25 margin for her. Sucks for her that it's probably too late to make a difference.
Sunday, May 11, 2008
Science 16 November 2007:Vol. 318. no. 5853, pp. 1155 - 1158DOI: 10.1126/science.1144259
Social Integration of Robots into Groups of Cockroaches to Control Self-Organized Choices
J. Halloy,1* G. Sempo,1* G. Caprari,3 C. Rivault,2 M. Asadpour,3 F. Tâche,3 I. Saïd,2 V. Durier,2 S. Canonge,1 J. M. Amé,1 C. Detrain,1 N. Correll,4 A. Martinoli,4 F. Mondada,5 R. Siegwart,3 J. L. Deneubourg1
Collective behavior based on self-organization has been shown in group-living animals from insects to vertebrates. These findings have stimulated engineers to investigate approaches for the coordination of autonomous multirobot systems based on self-organization. In this experimental study, we show collective decision-making by mixed groups of cockroaches and socially integrated autonomous robots, leading to shared shelter selection. Individuals, natural or artificial, are perceived as equivalent, and the collective decision emerges from nonlinear feedbacks based on local interactions. Even when in the minority, robots can modulate the collective decision-making process and produce a global pattern not observed in their absence. These results demonstrate the possibility of using intelligent autonomous devices to study and control self-organized behavioral patterns in group-living animals.
But Vendler is an excellent critic and it goes without saying that I'll read her new book when I find it.
From the introduction:
"Using the same method, we also analyzed the generalized performance of a student supervised by a moving teacher that goes around a true teacher."