Hidden Variables, Statistical Mechanics and the Early Universe

It is argued that our universe happens to be in a state of statistical equilibrium at the hidden-variable level, such that nonlocality is masked by quantum noise. To account for this 'quantum equilibrium', we outline a subquantum statistical mechanics in configuration space, and an H-theorem analogous to the classical coarse-graining H-theorem. Foundational issues in statistical mechanics are addressed, and an alternative explanation based on 'typicality' is criticised. An estimate is given for the relaxation timescale, and an illustrative numerical simulation is provided. Assuming the universe began in quantum non-equilibrium, we sketch a scenario in which relaxation is suppressed at very early times by the rapid expansion of space, raising the possibility that deviations from quantum theory could survive to the present day for relic cosmological particles that decoupled sufficiently early. It is concluded that quantum noise is a remnant of the big bang and, like the microwave background, should be probed experimentally. Possible tests with relic particles are briefly discussed.