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Progress in why the universe is 3+1 dimensional?

We live in a 3+1 dimensional world, meaning that to specify the location of some point in space-time requires four coordinates. But why? Fundamental laws of physics such as Quantum Field Theory and General Relativity can be consistently posed in any number of spatial dimensions (though more than one time dimension is generally problematic), and mathematically N dimensions are just about as easy to described as 3.

Relatively few compelling explanations have been put forth to explain this question. One explanation is the "anthropic" one: too few dimensions life is very difficult (e.g. a 2D lifeform can't have a digestive tract without bifurcating!), and in 4+ dimensions orbits and traditional atoms are unstable. (See Max Tegmark's paper for some details.) Another explanation, due originally to Brandenberger and Vafa, has to do with the dimensionality of N-dimensional "branes" interacting as a gas in a higher-dimensional space; see this recent work and this review article.

Recently a new preprint by Julian Gonzalez-Ayala and F. Angulo-Brown appeared making an argument for 3 spatial dimensions on rather general thermodynamic grounds.

Will this explanation prove to be influential?

Question will resolve as positive if (a) this paper appears in a refereed journal by May 1 2017 and (b) if there are at least ten citations on a Google Scholar Search by papers that do not include Gonzalez-Ayala or F. Angulo-Brown as authors.

For reference, in the two papers mentioned above, Tegmark's 1997 paper has been cited 120 times, and Greene et al.'s 2010 paper has been cited 10 times, and the 2006 review has been cited 180 times.

Categories: Physical Sciences – General Relativity and Quantum Cosmology, Physical Sciences – High Energy Physics

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