Quantum Physics as Probability Theory

If you feel like stretching your brain today, Philip Ball has a nice little piece at Nature on one of the hottest ideas in theoretical physics, re-imagining quantum physics as a kind of probability theory. A lot of theoretical physics these days is about information, with numerous papers on things like the information content of a black hole or a molecule. One thing about information is that the total amount of information in a system and the amount known to any observer are two very different things. So maybe, some people think, the weirdness of quantum physics less about the world than about the information available to us as observers. This approach, which amounts to treating rigorously an idea that goes back to Niels Borhr, was given a big push by physicist Lucien Hardy in a 2001 paper. Hardy sketched a way to understand quantum physics based on some very simple axioms about probability. Among other things he showed that the equations of quantum theory could have been derived by nineteenth-century mathematicians from their theoretical work on probability without any input from the experimental data that drove physicists to create them.

I, of course, don't really understand this, but I am impressed that somebody is looking for new ways to approach physics instead of banging heads against the same intractable problems or throwing a few thousand more person-years into 11-dimensional string geometry.