On Tuesday, July 9, 2002, at 11:08 AM, Bruno Marchal wrote: > > Me too. Now, I feel almost like you about ... knot theory. > And this fit well with your cat-enthusiasm, for knot theory is > a reservoir of beautiful and TOE-relevant categories > (the monoidal one). I've just > ordered Yetter's book: functorial(*) knot theory. It is the number 24 > of Kauffman series on Knots and Everything (sic) at World > Scient. Publ Co. A series which could be a royal series for this > list ... > May I recommand the n° 1, by Louis Kauffman himself: knots and physics? > A must for the (quantum) toes, and (I speculate now) the comp toe too!
I've looked at some of the knot series books, but have put them off for now. A good book to prepare for these books is Colin Adams, "The Knot Book: An Elementary Introduction to the Mathematical Theory of Knots," 1994. Whether knots are the key to physics, I can't say. Certainly there are suggestive notions that particles might be some kind of knots in spacetime (of some dimensionality)...a lot of people have played with knots, loops, kinks, and braids for the past century. One thing that Tegmark got right, I think, is the notion that a lot of branches of mathematics and a lot of mathematical structures probably go into making up the nature of reality. This is at first glance dramatically apposite the ideas of Fredkin, Toffoli, Wheeler1970, and Wolfram on the generation of reality from simple, local rules. Wolfram has made a claim in interviews, and perhaps somewhere in his new book, that he thinks the Universe may be generated by a 6-line Mathematica program! However, while I am deeply skeptical that a 6-line Mathematica program underlies all of reality, enormous complexity, including conceptual complexity, can emerge from very simple rules. A very simple example of this is the game of Go. From extremely simple rules played with two types of stones on a 19 x 19 grid we get "emergent concepts" which exist in a very real sense. For example, a cluster of stones may have "strength" or "influence." Groups of stones develop properties which individual stones don't have. Abstraction hierarchies abound. The Japanese have hundreds of names for these emergent, higher-order structures and concepts. All out of what is essentially a cellular automata. So even if our universe is a program running as a screen saver on some weird alien's PC, all sorts of complexity can emerge. Getting down to earth, most of this complexity is best seen as mathematics, I think. I expect to take a closer look at knots after I get more math under my belt. > ....Now I know the z logics really should have "tensorial semantics", > sort of many related (glued) von neumann type of logics (which are > themselves atlases of boolean logics). > But where (in Zs logic) those damned tensorial categories come from??? > Knots gives hints!!! This would explain the geometrical appearance > of realities. > > Bruno > > (*) For the other: "functorial" really means categorial. Functors are > the morphisms between categories. The first chapter of Yetter's book > is an intro to category theory, the second one, on Knot theory, ... Exciting stuff. --Tim May (.sig for Everything list background) Corralitos, CA. Born in 1951. Retired from Intel in 1986. Current main interest: category and topos theory, math, quantum reality, cosmology. Background: physics, Intel, crypto, Cypherpunks