Causality as a fundamental property of the universe
Browsing the July 2008 Scientific American, I read an article concerning causal dynamical triangulations. I'm ashamed to admit I had not heard of CDT before, as I haven't been following quantum theory much over the last several years.
There are several intriguing aspects to CDT. The first is, it assumes nothing exotic or strange. This sets it apart from string theory, for example. Its basic ingredients are essentially those of Euclidean quantum gravity, an earlier approach that failed to properly predict the basic structure of the universe. CDT adds the concept of causality to the earlier Euclidean quantum gravity approach, and the results are proving to be both robust and accurate.
For instance, it is the first hypothesis to predict the four dimensions of spacetime from first principles. It also conforms to Einstein's general relativity, which is pretty amazing.
The way causality is handled is simply to assume that each simplex has an arrow of time, and that the arrows of time in adjacent simplexes line up, or flow in the same "direction." This means that causality is a first principle, and is not an emergent property of quantum dynamics.
Some other cool features of this approach: if correct, that means that the substance of the universe is fractal below a certain scale, and so there is no lower "resolution" to the universe. Also, at the lowest scales, there are only 2 dimensions, not 4. The dimensionality of the universe increases non-linearly as a function of scale, converging to 4 dimensions at a certain scale. Also, modifying the value of the basic assumptions gives the same final results, making this approach very robust.
This is the only article I've read on the subject, so I have no real opinions, other than to admit a certain amount of excitement. I've thought for years that string theory is too complex, and doesn't seem to do an adequate job of explaining fundamental properties of the universe. I'm glad to see other hypotheses are making headway into the problem of quantum gravity.
Of course, the introduction of causality as a fundamental property of the universe would dig the hole in which we can dump the body of QM woo. But that's just an added bonus.
"Yes, I seriously believe that consciousness is a product of a natural process. I find that the neuroscientists, psychologists, and philosophers who proceed from that premise are the ones who are actually making useful contributions to our understanding of the mind." - PZ Myers