Professor Gibbs,
The new paradigm shift (from one Universe to multiple Universes) is hard even on Western thought. At first I was reticent but then... . It is actually amazing when one thinks about it compared to the concept of the one singular Universe our egocentric minds have somewhat logically been led to believe in (hard to let go). There are hints to the Meta-Laws. Frank Wilczsek stated something to the order that why are the gauge coupling forces unifying (GUT except gravity) at one point in our Universe (I am assuming SUSY makes the unification more exact)? Thinking about this, is it probable that most successful Universes has this form of unification of gauge forces more or less in some tolerant area near a unifying energy (Planck energy type) with gravity? This cannot be attributed to coincidence. You stated in your essay, "It is known that the combination of quantum theory and general relativity imposes tough constraints on the possible range of consistent space-time models." Also, the GUT point being (how much?)variable with other Universe formations this does rule out 'fine tuning" and maybe one should not look at just one number (say the Higgs boson mass) and say it has some 'unnaturalness' because it looks random and especially 'fine tuned'. It is best just to look at the GUT points in any formed successful Universe that has a 4D space-time. It may be hard to trust just a few numbers whereas the GUT points are more of a gestalt of what is going on. Why 4D? It is well know that 4D manifolds are the most interesting manifolds/topologies in mathematics. Even more so than higher dimension topologies. Recently, the Triangulation Conjecture was disproven. Coverings of simplices (triangles or tetrahedrons) cannot completely cover higher dimension topologies (past the 4D) based on some simple rules. This leaves higher dimension coverings 'foamy' or full of holes. Makes one wonder whether this means that higher dimensional Universes can exist in a 'physical' sense. I am not sure that 'all solutions exists'. It is bound to be super variegated (though with 57 varieties ;)). I am thinking that one should not even consider 'fine tuning' anymore but to look at the tolerance or range of solutions in the hierarchal space as a mathematical structure that can eventually be computed in a Scientific framework. All other Universe that have the 4D space-times would somehow have a computational relation to each other (a dictionary?). The GUT point would also be a measure of how fast nuclear rates (and chemistries) and gravity combine to create the Universe. In some Universes (even if 4D) that stars would burn too fast or gravitational collapse only produces black holes where life could not have enough time to form or exist. Or the GUT point is such that stars cannot ignite and that Universe is a cold dead world with not much going on. Where there is no GUT point for a Universe it perhaps collapses to nothing. I think a lot of people misunderstand the Multiverse especially when it is hyped to the point that suggests 'all outcomes are possible' somewhere in a Universe we will never know. And there is no parallel person that is me somewhere else with a different set of beliefs or lifestyle as that is hogwash. I think that the other Universes have some sort of 4D path integral sensibility which produces some similar outcomes but not the same or nearly the same outcomes found in the other Universes. Finally, here is a direct quote from a white paper "Higher-Order Intersections in Low-Dimensional Topology" by Conant, Schneiderman and Teichner, "The Whitney move, sometimes also called the Whitney trick, remains a primary tool for turning algebraic information (counting double points)into geometric information (existence of embeddings). It was successfully used in classification of manifolds of dimension > 4 specifically in Smale's celebrated h-cobordism theorem (implying the Poincare conjecture) and the surgery theory of Kervaire-Milnor-Browder-Novikov-Wall. The failure of the Whitney move in dimension 4 is the main cause that, even today , there is no classification of 4-dimensional manifolds in sight." I quoted this to make the point that there is a lot of work to be done and that perhaps the unreasonable effectiveness of math in physics is really related to the 4D space-time issue of physical-ness.