So, I have noticed Smolin proposing this "evolving universes" idea in several of his writings. Every time I have noticed Smolin mentioning this, he does not seem terribly enthusiastic about it-- his tone usually seems to be "this is an idea I keep thinking is interesting, and I don't really take it very seriously, but by the way I wish people would mention I had this idea in 1995 when they talk about the history of anthropic/multiverse reasoning" :)
But, what I am trying to figure out is whether this research is really in the same line as his previous "evolving universes" idea? Your OP makes the new paper here sound a lot like the old "evolving universes" stuff, with the difference being that he gives a specific way in which a universe could be "described" and that this would act like DNA. (I assume this to be the state space of the cubic "meta-theory" he proposes.)
However reading the paper, although I don't think I'm qualified to understand all of it, it seems like his paper entirely talks about this cubic matrix model "meta-theory" and doesn't discuss the evolutionary idea at all. May I assume that the reason why you talk about this paper using the evolutionary language in your OP is because there is a connection you see between this "meta-theory" stuff and Smolin's older evolutionary-universe stuff?
Here's what I understand of where Smolin was up until now: Smolin's previous "evolution of the universe" idea involved proposing a theory where universes could spawn other universes, with each spawn creating a universe whose laws and constants were similar to, though somehow slightly different from, the parent universe. Smolin proposed this in part to explain how certain settings of fundamental constants are picked out given a random starting point-- since even if the "universal ancestor" universe had random physical laws, if you consider the totality of the tree of universes it will naturally be dominated by that branch of universes that happens to stumble upon that that general family of laws+constants which maximizes the number of child universes per parent. (For example if the way in which universes spawn other universes is that bubble universes occur within black holes, then we would expect our universe's laws to be somewhere close to a maxima for the probability of creating lots of individual black holes over the universe's lifetime.) This principle would allow one to identify some set of the phase space for possible universes as preferred, while retaining maybe slightly more productivity than one would be given by concepts like the "principle of mediocrity". Does that sound about right?
This new paper however seems to be describing a slightly different type of thing. This is the part of Smolin's new paper which seems to describe the idea most succinctly:
Third, there have been a number of suggestions that physical processes are computations[12].
However, the central result in computer science is the universality of computation, that
all computers are equivalent to a universal computer, a Turing machine. Any computer
can be simulated on any other computer, by writing an appropriate program. Might it be
that there is also a universality class of dynamical theories, any solution of one may be
represented by a solution of another by a precise choice of initial conditions?
...so, since I am a CS person this of
course is the part that sticks out to me :) (And I find this a
very interesting question to ask because I've seen a couple of visible attempts [say, Tegmark] to suggest computational models are sufficient to produce the laws of physics, but very few people doing this in a way that seriously asks the question of
which computational model is most appropriate-- i.e., are vanilla turing machines
enough?)
But, this also seems to be asking a different question from his previous evolutionary-universe ideas. In fact he appears to allude to his evolutionary ideas at the top of page 3 (mentioning a multiverse with "a meta-theory that evolves in time") and then suggest this paper is trying to talk about something different.
In this paper, Smolin appears to be suggesting that is slightly confused to take some theory (say, the laws of our universe) and then ask "what is the meta-theory from which these laws emerged?". His argument instead is that it is reasonable to suggest that
any dynamical theory of a certain expressive power qualifies as such a meta-theory, in the sense that properly formed initial conditions can cause that theory to "truncate" (I'm not entirely sure what this means) to the action of one of the other theories in the class. So for example maybe there is some set of initial conditions for string theory which, if you run string theory, the resulting dynamics are a perfect simulation of Twistor theory, and likewise there is some set of initial conditions for Twistor theory from which emerges the behavior of string theory (I picked these two randomly and I don't know if either would be in Smolin's universality class). Smolin then proposes a specific model, a "cubic matrix" model, to act as the examplar for theories in this universality class-- like a turing machine, in the sense that if you show some theory has initial conditions which produce the behavior of the cubic matrix model you have also shown that your theory can produce the behavior of any other theory in the universality class. Does that sound about accurate?
So if this is Smolin's point, then it seems like when he talks about one theory "evolving" from another within this framework he doesn't mean "evolve" in the Darwinian sense, he means "evolve" in the everyday-language sense of one thing turning into another. Twistor theory could "evolve" from string theory (or whatever) in the sense that twistor theory could emerge from some set of initial conditions in string theory.
Is the connection you are trying to draw in the OP that once we have defined an appropriate "universality class" theory, we can immediately turn around and
also use that as a meta-theory for evolution of universes (since it may not be
the theory of everything, but it can probably emulate it)? Do you have reason to believe Smolin intends to do this or are you just highlighting this as a possible application?
Or am I missing something altogether...?
Just trying to understand, thanks :)
One more thing, I think Smolin misspelled "Mendel" on page 3. Is there some way to inform him of this? :|
but you know what I mean----built into the fabric everywhere.
