He of uncertain principles asks Which do you prefer: transverse waves, or longitudinal waves? The fact builder chimes in with a clarification of a common misconception.
Myself, certainly I’m going to go for transverse waves. Not only are all the cool waves transverse (well sort of), electromagnetic waves, gravitational waves, stadium waves, etc, but you can’t surf on a longitudinal wave.
And of course, how cool are gravitational waves? So cool they produce this mesmerizing action on a ring of particles:
Interestingly while light is often used as the quintessential example of transverse waves, (the example being give is usually that of plane waves of light) if you talk about light beams with finite diameter, longitudinal modes appear. (For example, see here) But I don’t fault my physics teachers for not teaching me this: learning physics is really just a series of less lying anyway isn’t it?
Hawking Hospitalized
Story here.
Update: Comfortable at hospital, hope for full recovery.
arXiview: A New iPhone App for the arXiv
Over 9 months ago I decided to apply for teaching tenure track jobs. Then the economy took what can best be described as a massive, ill-aimed, swan dive. Thus creating an incredible amount of stress in my life. So what does a CS/physics research professor do when he’s stress? The answer to that question is available on the iTunes app store today: arXiview. What better way to take out stress and at the same time learn objective C and write an iPhone app that at least one person (yourself) will use?
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Off to the March Meeting I Go
Tonight I hop on a red-eye to Pittsburgh to attend the APS March meeting. 7000 physicists in Pittsburgh, now that’s a scary thought for poor Pittsburgh (punishment for winning the superbowl, I guess.)
A list of highlighted papers includes some fun ones:
11:15AM, Tuesday Session B15: “Walking on water: why your feet get wet” Michael Shelley , Jake Fontana , Peter Palffy-Muhoray
1:15PM, Wednesday Session Q15: “Statistical laws for career longevity” Alexander Petersen , Woo-Sung Jung , Jae-Suk Yang , H. Eugene Stanley
Zotero 1.5 Beta and More
Zotero, a Firefox extension for managing research sources, has announced the release of Zotero 1.5 beta. I’ve heard good things from those who use Zotero. This major update adds some nifty synchronizing and automatic backup. The next step after this for Zotero, I believe, is adding sharing capabilities.
By the way does anyone know what happened to arXiv on you harddrive? It’s not been updated in over a year, which is a shame. Personally I find the arXiv’s lack of publicity accessible methods for obtaining the full text kind of a bummer. There is so much fun you could have given the ability to have the arXiv on your own local system. Sure there are bandwidth issues, but I’ve been hanging around long enough with computer scientists to know that there are serious good solutions to these problems as well.
Perimeter Distinguished Research Chairs
In addition to the distinguished Dr. Hawking, the Perimeter institute lands nine very impressive distinguished research chairs, including some familiar quantum names.
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Dark Side of the…Whah?
Over at the fact builders blog, the fact master discusses The Physics of….Pink Floyd. Being two areas I greatly enjoy, I was reminded by the fact builders picture of the cover of “The Dark Side of the Moon” of a little known piece of Pink Floyd strangeness. Anyone notice something peculiar about the back and cover of DSOTM:
Update: Ian provides a picture of the inside of the DSOTM, where, we find, all hell breaks loose:
More on Fixed Points
In a prior post I asked about the how the structure of fixed points of stochastic maps changes under composition of such maps. Robin provided an interesting comment about the setup, linking this question at least partially with zero error codes:
R has at least one fixed point. If it’s unique, there need be no relationship between fixed points of P and R. (Q can project to a single vector, which becomes the unique fixed point of R.) If R has N > 1 fixed points, then things get more interesting. The fixed points are closed under linear combination, so they’re a subspace (I’m actually assuming N is the dimension of the subspace). An N-dimensional fixed subspace gives an N-symbol noiseless code for N (not necessarily obvious, but see arxiv/0705.4282), and therefore an N-symbol correctable code for P. Q is the recovery map. So, the dimensionality of R‘s fixed-point space (N) is tightly bounded by the size of P‘s largest zero-error code, and the fixed-point set itself has to be a subspace of one of those codes. You can also transpose R and get an identical bound in terms of QT‘s zero-error codes. (Yes, I know QT isn’t necessarily stochastic, but it works anyway). The zero-error codes are independent sets of P‘s adjacency graph, so (a) there can be quite a few of them, and (b) finding the bound on N is isomorphic to Maximum Clique.
Robin scores double bonus old school points for linking to a paper by Shannon. Okay, so given that the general case seems hard (and my question was vague), maybe it’s better to work with a simpler concrete example of what I’m thinking.
Benasque 2009
I’ve never made it to Benasque, and am always profoundly jealous of those who have gone:
Dear Colleague,
We are pleased to inform you that following a very successful editions of Benasque 1998, 2000, 2003, 2005, and 2007, we are organizing another workshop of the similar type in June 2009. This is to invite you to apply using the electronic form that you can find on the website specified below. We encourage you to apply as soon as possible and not later than the end of March 2009. The number of participants at the Benasque Centre at any given time is limited to about 50. We will do our best to accommodate most of the applicants,however, in some cases we may be unable to find suitable time slots for all of them, i.e. we cannot guarantee acceptance.
Budget permitting, we expect to offer a modest allowance to some participants. Preference will be given to those staying for the whole duration of the workshop.
We do hope to see you in Benasque!
Ignacio Cirac and Artur Ekert
_________________________________________________________
BENASQUE 2009
Title: Quantum Information
Venue: Benasque in the Spanish Pyrenees.
Date: The 3 week period 7– 27 June 2009.
Website: http://sophia.ecm.ub.es/2009qi/
Registers at: http://sophia.ecm.ub.es/2009qi/cgi-bin/appl.pl
Perimeter Scholars Institute
The Perimeter Scholars Institute is a Masters level course designed to prepare students for cutting-edge research in theoretical physics. It looks pretty cool with some outstanding lecturers. The application deadline is February 1. All accepted students will be fully supported. Details below the fold.
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