Physics, Determinism, and Possible Worlds

Posted on November 5, 2014 by

A recent post on the IFL Science page (which I happen to like very much) discusses a new interpretation of quantum physics that was developed by a team led Howard Wiseman of Griffith University in Australia. The team recently published this paper, first authored by Michael Hall, which suggests that Quantum theory is deterministic and that all possible worlds are real worlds. Here is a quote from their abstract:

“quantum theory can be understood as the continuum limit of a mechanical theory, in which there is a huge, but finite, number of classical “worlds,” and quantum effects arise solely from a universal interaction between these worlds, without reference to any wave function. Here, a “world” means an entire universe with well-defined properties, determined by the classical configuration of its particles and fields. In our approach, each world evolves deterministically, probabilities arise due to ignorance as to which world a given observer occupies, and we argue that in the limit of infinitely many worlds the wave function can be recovered (as a secondary object) from the motion of these worlds. We introduce a simple model of such a “many interacting worlds” approach and show that it can reproduce some generic quantum phenomena—such as Ehrenfest’s theorem, wave packet spreading, barrier tunneling, and zero-point energy—as a direct consequence of mutual repulsion between worlds.”


Their understanding of quantum theory allows for multiple versions of our universe to exist and overlap, and even interact with one another on the quantum level. Thus, it seems that this might be some vindication for the realism endorsed by David Lewis, or is there good reason to doubt their interpretation? What bullets must they bite? Fellow philosopher Marcus Arvan also has an eerily similar view (to the view espoused by Hall et. al) on offer and he thinks that the bullets one must bite to adopt such a view are not as bad as one might think. See more on his work here and here. I’d be curious to hear from those better versed with Physics than I am to weigh in on this. This would seem to have interesting ramifications for the free will debate as well

The original IFL post can be found here.