To all physicists....

chiral3 · Post by **chiral3** » Fri Sep 24, 2004 10:14 pm

I was reading Derman's book last night and he discussed his first experience outside of South Africa, which he had at Columbia when we went to grad school. Now myself, like most people here, used Jackson for graduate E&M (maybe Shwinger). His prof made them read Lorentz's pre-Einstein treatise, which was sans invariance, etc. The idea was to have a pedagogy that took the path that history took, the fits and starts, so that an appreciation and special intuition can be fostered. I agree with this technique if you are dealing with smart and motivated kids.

Anyway, it reminded me of this wonderful book that I bought in 1997 called "The Dawning of Gauge Theory" by Lochlainn O'Raifeartaigh. Lochlainn has since passed away, but his research at the end of his life was quite interesting (which I will not get into here but).

Anyway, I have nothing but good thngs to say about this book. Lochlainn has papers which span about 50 years, beginning with Weyl's Gaue transforms in E&M and ending with Utiyama's general approach while at Princeton. He interjects to explain things in retrospect or to clarrify certain points. The sections on "Generalizations to Einstein's Theory", "The Renaissance of Weyl's Idea: EM Gauge Theory", and "The Yang-Mills Theory" are wonderful.

I would highly recommend it to anyone (bloodninja) with a love for this stuff.

bloodninja · Post by **bloodninja** » Fri Sep 24, 2004 10:35 pm

Thanks for the recommendation; if / when I get a chance I'll take a look.

bloodninja · Post by **bloodninja** » Fri Sep 24, 2004 10:39 pm

So, I started writing that thing and I'm wondering where's a good place to put it 'cause it's big and off topic of the main line of the RT watch thread.

How 'bout here?

---------------------------

Just in case people are waiting around: It's going to take me *awhile* to get the whole thing down. I may or may not have it finished tonight or maybe not until tomorrow.

chiral3 · Post by **chiral3** » Fri Sep 24, 2004 10:47 pm

go for it

chiral3 · Post by **chiral3** » Sat Sep 25, 2004 12:34 am

Actually, fuk it. Check this out BN http://arxiv.org/PS_cache/physics/pdf/0209/0209108.pdf It is a short read. It relates fluid mechanics and non-commuting gauge theories. This sheah is interesting as hell, although I think that many have been Alain Connes stuck for about 3 years now.

chiral3 · Post by **chiral3** » Sat Sep 25, 2004 12:36 am

if you got a couple of days and you want to break your shit thinking, try this
http://arxiv.org/PS_cache/hep-ph/pdf/0407/0407101.pdf

bloodninja · Post by **bloodninja** » Sat Sep 25, 2004 12:43 am

Alright, so this ended up being a lot smaller then I orginally planned. But here's the point ('cause going through the nine yards of it ultimately misses my point):

String theory people (from what I've seen) tend to work on a lot of different problems at the same time (whether or not the problems are successful). So, to be a string person means you've got to be flexible ( change directions; keep an eye on a lot of different stuff at the same time cosmology / thermo / quantum / high energy / solid state stuff etc). That flexibility seems like it would be useful to the stat arb game.

String theory roughly has to do with 2d quantum fields (among a lot of other things). Quantum fields contain (in some limit) quantum particles and (in other limits) quantum matrices. So, string theory people tend to get involved with all of these things: quantum strings, particles, and matrices. The mathematical objects of quantum strings, particles, and matrices aren't too far away from some of the *mathematical* objects one encounters in finance and stat arb (things like gaussian measures, random walks in various dimensions, etc). Infact, in some cases the two (quantum particles / strings / matrices versus random walks etc) are completely indistinguishable mathematically. So, in other words, some (not all) of the math stuff string people do goes over completely into the stat arb world which means that string people can bring in some of their intuitions about (at least) some of what's going on.

Finally, the string people I've encountered not only tended to be pretty competitive people (real type A type stuff) that put in serious amounts of work, almost all of them (that i came across) did a lot of computational stuff on a regular basis (which they seemed to take pride in doing). The comp stuff were things like symbolic computations (some of which were *BIG*) to UNIX administration to messing around with their blogs and doing who knows what to them. I didn't meet any string guys doing numerical work (infact I talked to some that needed to do some numerical work and were looking for some general ideas on finite differencing something), but from what i understand there isn't a lot of that kind of thing in stat arb-ish projects.

In terms of what I mean by competitive type A stuff here are some examples:

http://en.wikipedia.org/wiki/Talk:Loop_quantum_gravity

http://motls.blogspot.com/

http://groups-beta.google.com/groups?as_q=Woit&safe=off&as_ugroup=sci.physics.research&lr=&num=100&hl=en

http://www.physicsforums.com/forumdisplay.php?s=2ccbdebe45b095ca212d166b3efbcda7&f=66

etc

Nonius · Post by **Nonius** » Sun Mar 22, 2009 9:12 am

does anyone have a copy of Geroch and Hartle "Computability and Physical Theories"?

jslade · Post by **jslade** » Mon Mar 23, 2009 9:18 pm

pm1.bu.edu/~tt/qcl/pdf/geroch_r198601131c19.pdf

Damn cool paper, Nonius; thanks.

I did a little work trying to relate quantum computability to Gutzwiller's trace formula. Never published, and in the end it was probably just saying the same thing as Marty G. was saying about chaos and quantum mechanics, but I always liked that sort of marriage of information theory with physics.

Carlo Rovelli came damn close to reformulating quantum mechanics as a form of information theory in the mid-90s also. That was a really exciting seminar: I was lucky to be one of the first to hear it.

http://www.citeulike.org/user/jrw/article/612863

There was another mind blowing one I read about thinking about quantum mechanics in terms of public key cryptography... It would take me a while to track that one down.

athletico · Post by **athletico** » Mon Mar 23, 2009 10:54 pm

Re information theory / quantum mechanics connection, I found this book helpful:

Physics from Fisher Information: A Unification

The principle of least action is reinterpreted as a new principle the author calls Extreme Physical Information. Lagrangians are recast as the sum of Fisher information and physical information, and the Klein Gordon eqn is eventually rederived in this set-up.

Also, everyone seems to quote Wheeler's 'It From Bit' paper - I have that around somewhere if it would be helpful (I remember several Wheeler-esque diagrams in the paper).