Monthly Archives: December 2016

Amateur Notes on “Quantum Mechanics as Classical Physics”

I am slow to mature. That is why I squandered myself in graduate school. I could have embraced the opportunity to think critically about the philosophy of physics, in which I was at least up to my knees. I instead glibly dismissed philosophy as secondary to prediction. Quantum Mechanics poses the greatest and most interesting philosophical problems and only now, when graduate school is vanishing on the horizon or, at any rate, eclipsed by towering pragmatics racing towards me (mortgages, careers, children), am I taken, with ever more frequency, by thoughts of the philosophy of physics.

Compensating this lack of remit to study is a comparative freedom of choice about how I study. Reading that would have been deemed frivolous by my graduate adviser I am now free to pursue for pleasure. Hence Charles Sebens’ 2013 paper “Quantum Mechanics as Classical Physics,” which develops a purely classical interpretation of Quantum Mechanics of a novel, Bohmian-flavored variety.

Interested readers should read the version on the Archive. I can’t hope to reproduce anything by a quick and probably inelegant if not misleading summary here, but the basic idea is to create a sort of supererogatory interpretative framework for Quantum Mechanics by adding not a single Bohmian particle, but one for many universes in such a way that the dynamics are preserved and then cleverly realizing that the so-called “Pilot Wave,” which corresponds to the Wave Function in more ordinary interpretations, can be completely removed, replaced instead by a regular Newtonian force between the Bohmian trace particles.

This results in a many-universe interpretation of Quantum Mechanics (with the same predictions as any other interpretation) but without a wave function. I’m interested in what I believe to be one aspect of this interpretation: it seems to be that worldlines never cross in this way of thinking, so that, if we jump up and up and up to slightly absurd questions like “Are there me’s in other universes who have made different decisions than I have?” The answer is “no,” in the following sense: because world lines never cross, there was never a time where two universes (and hence two versions of yourself) shared exactly the same state and then diverged. In other words, in each universe, while there may be many beings who resemble any individual in many respects, none of them share identical pasts. If you resent some decision in the past, as I resent not thinking about philosophy more in graduate school, and torture yourself by imagining some parallel person who made different decisions (with the help of some vague thoughts about the Interpretation of Quantum Mechanics) take heart: there is no such moment in the past where you could have chosen differently. You past is fixed and distinct from all those other versions of yourself, none of which were ever identical to you at any point.

At least that seems to be the case when you think about it this way.