Bohmian Mechanics: The Physics and Mathematics of Quantum Theory

Arthur Fine, Sheldon Goldstein, James T. Cushing

Nicolas Gisin

It is usual to identify initial conditions of classical dynamical systems with mathematical real numbers.However, almost all real numbers contain an infinite amount of information.I argue that a finite volume of space can't contain more than a finite amount of information, hence that the mathematical real numbers are not physically relevant.Moreover, a better terminology for the so-called real numbers is "random numbers", as their series of bits are truly random.I propose an alternative classical mechanics, which is empirically equivalent to classical mechanics, but uses only finite-information numbers.This alternative classical mechanics is non-deterministic, despite the use of deterministic equations, in a way similar to quantum theory.Interestingly, both alternative classical mechanics and quantum theories can be supplemented by additional variables in such a way that the supplemented theory is deterministic.Most physicists straightforwardly supplement classical theory with real numbers to which they attribute physical existence, while most physicists reject Bohmian mechanics as supplemented quantum theory, arguing that Bohmian positions have no physical reality.

Detlef Dürr, Sheldon Goldstein, Nino Zanghı̀

Nicolas Gisin

Abstract It is usual to identify initial conditions of classical dynamical systems with mathematical real numbers. However, almost all real numbers contain an infinite amount of information. I argue that a finite volume of space can’t contain more than a finite amount of information, hence that the mathematical real numbers are not physically relevant. Moreover, a better terminology for the so-called real numbers is “random numbers”, as their series of bits are truly random. I propose an alternative classical mechanics, which is empirically equivalent to classical mechanics, but uses only finite-information numbers. This alternative classical mechanics is non-deterministic, despite the use of deterministic equations, in a way similar to quantum theory. Interestingly, both alternative classical mechanics and quantum theories can be supplemented by additional variables in such a way that the supplemented theory is deterministic. Most physicists straightforwardly supplement classical theory with real numbers to which they attribute physical existence, while most physicists reject Bohmian mechanics as supplemented quantum theory, arguing that Bohmian positions have no physical reality.

Sheldon Goldstein, James Taylor, Roderich Tumulka +1 more

We consider the possibility that all particles in the world are fundamentally identical, i.e., belong to the same species. Different masses, charges, spins, flavours or colours then merely correspond to different quantum states of the same particle, just as spin-up and spin-down do. The implications of this viewpoint can be best appreciated within Bohmian mechanics, a precise formulation of quantum mechanics with particle trajectories. The implementation of this viewpoint in such a theory leads to trajectories different from those of the usual formulation, and thus to a version of Bohmian mechanics that is inequivalent to, though arguably empirically indistinguishable from, the usual one. The mathematical core of this viewpoint is however rather independent of the detailed dynamical scheme Bohmian mechanics provides, and it amounts to the assertion that the configuration space for N particles, even N 'distinguishable particles', is the set of all N -point subsets of physical 3-space.

Detlef Dürr, Sheldon Goldstein, Nino Zanghı̀