A new ensemble interpretation of quantum mechanics is proposed according to
which the ensemble associated to a quantum state really exists: it is the
ensemble of all the systems in the same quantum state in the universe.
Individual systems within the ensemble have microscopic states, described by
beables. The probabilities of quantum theory turn out to be just ordinary
relative frequencies probabilities in these ensembles. Laws for the evolution
of the beables of individual systems are given such that their ensemble
relative frequencies evolve in a way that reproduces the predictions of quantum
mechanics. These laws are highly non-local and involve a new kind of
interaction between the members of an ensemble that define a quantum state.
These include a stochastic process by which individual systems copy the beables
of other systems in the ensembles of which they are a member. The probabilities
for these copy processes do not depend on where the systems are in space, but
do depend on the distribution of beables in the ensemble. Macroscopic systems
then are distinguished by being large and complex enough that they have no
copies in the universe. They then cannot evolve by the copy law, and hence do
not evolve stochastically according to quantum dynamics. This implies novel
departures from quantum mechanics for systems in quantum states that can be
expected to have few copies in the universe. At the same time, we are able to
argue that the centre of masses of large macroscopic systems do satisfy
Newton's laws.Comment: 14 pages, no figure