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So this is sort of a belated response to some comments that were made in here over the last couple weeks and that I've been thinking about since.
In the thread about the Lisi article in the New Yorker, Mtd2 and Kea were asking Garrett about whether he is still using a "superconnection" and how he intends to go from there to actually answering questions about the standard model, and eventually he responded:
There was another statement I unfortunately can't find which I believe Marcus made at about the same time (maybe it was this?, I think it may have been something about the Friedel work concerning feynman diagrams and spinfoams) that made it at least sound like spinnets/spinfoams can be the basis of a quantum theory even separately from the QG case specifically.
These uses of the term "spinfoam" were a little confusing to me. In my previous attempts to understand spinfoams, I had gotten the impression that spinfoams were something that was derived from loop quantum gravity-- something along the lines that when you look at the wilson loop representation of quantum gravity, and then cut down the space of states by identifying those states which are equivalent under diffeomorphism invariance, the structure that remains is described by spin networks; the evolution of these spin networks in "time" produces spinfoams. Right? And although I know spin networks had been around for a long time before this link with LQG was discovered, as far as I knew LQG was the origin of using spinnets/spinfoams as the basis of a quantum theory, my understanding is before that spinnets were only used in speculative models of combinatorial spacetime.
Now though I am seeing some statements which make it sound like there's more to spinnets than this, and I am curious exactly how deep this rabbit hole goes. Can anyone explain:
1. What exactly does garrett mean that his superconnection could be quantized "as a spin network"?
2. Is there some generic sense in which we can say thing things, potentially things other than the spacetime fabric, can be quantized "as" spinfoams? Or is the sense in which Garret speaks above peculiar to connections and/or superconnections?
(I also should probably stop to make sure I understand what a "superconnection" is in the first place. Would I be correct in saying this is just a connection where the lie algebra of the connection happens to be a supergroup? Also is there a difference between "Quillen superconnections" and generic superconnections, or are superconnections just called "Quillen superconnections" because they were first analyzed by Daniel Quillen?)
In the thread about the Lisi article in the New Yorker, Mtd2 and Kea were asking Garrett about whether he is still using a "superconnection" and how he intends to go from there to actually answering questions about the standard model, and eventually he responded:
My guess is that the superconnection will be quantized as a kind of spin foam.
There was another statement I unfortunately can't find which I believe Marcus made at about the same time (maybe it was this?, I think it may have been something about the Friedel work concerning feynman diagrams and spinfoams) that made it at least sound like spinnets/spinfoams can be the basis of a quantum theory even separately from the QG case specifically.
These uses of the term "spinfoam" were a little confusing to me. In my previous attempts to understand spinfoams, I had gotten the impression that spinfoams were something that was derived from loop quantum gravity-- something along the lines that when you look at the wilson loop representation of quantum gravity, and then cut down the space of states by identifying those states which are equivalent under diffeomorphism invariance, the structure that remains is described by spin networks; the evolution of these spin networks in "time" produces spinfoams. Right? And although I know spin networks had been around for a long time before this link with LQG was discovered, as far as I knew LQG was the origin of using spinnets/spinfoams as the basis of a quantum theory, my understanding is before that spinnets were only used in speculative models of combinatorial spacetime.
Now though I am seeing some statements which make it sound like there's more to spinnets than this, and I am curious exactly how deep this rabbit hole goes. Can anyone explain:
1. What exactly does garrett mean that his superconnection could be quantized "as a spin network"?
2. Is there some generic sense in which we can say thing things, potentially things other than the spacetime fabric, can be quantized "as" spinfoams? Or is the sense in which Garret speaks above peculiar to connections and/or superconnections?
(I also should probably stop to make sure I understand what a "superconnection" is in the first place. Would I be correct in saying this is just a connection where the lie algebra of the connection happens to be a supergroup? Also is there a difference between "Quillen superconnections" and generic superconnections, or are superconnections just called "Quillen superconnections" because they were first analyzed by Daniel Quillen?)