One of the more intriguing ideas I have seen in some time is summarized at Scientific American, in an article entitled "Using Causality to Solve the Puzzle of Quantum Spacetime." The concept is this:
"To put it differently, if we think of empty spacetime as some immaterial substance, consisting of a very large number of minute, structureless pieces, and if we then let these microscopic building blocks interact with one another according to simple rules dictated by gravity and quantum theory, they will spontaneously arrange themselves into a whole that in many ways looks like the observed universe. It is similar to the way that molecules assemble themselves into crystalline or amorphous solids."
For a number of years, string theory (which evolved into superstring theory, then M-theory...) has been a leading candidate for Einstein's dream of unifying quantum mechanics with relativity, the two pillars of modern physics. However, despite an enormous intellectual effort from hundreds of theoreticians, no testable predictions have been produced. It is mathematically advanced, to say the least, and very difficult to comprehend conceptually with the 11 dimensions it now resides in. Coming from an experimental background, I have always had doubts of such a cumbersome theory which cannot produce physical tests. I would like to think there is something a bit more simple, which does a better job of being able to produce results consistent with quantum mechancs and general relativity, both being well-tested and investigated theories over the past century. This emergent model is 'simple' and has so far, in computer simulated 'experiments' at least, produced interesting results. One of these results is that the number of dimensions being N = 4 naturally arises from the emergence of spacetime (in a nonperturbative model, no less). Adding matter to space leads to naturally warped geometries, consistent with solutions to Einstein's field equations is another result. And yet another result is that at small size scales, spacetime takes on a fractal nature. See the latest technical article if interested. It will be interesting to see where this type of model leads in the next year or two, as work continues to probe the subtleties of the model and find out if actual testable predictions arise from the model.