Bohmian mechanics
Explanation
Bohmian mechanics, also called pilot wave or de Broglie-Bohm theory, was sketched by Louis de Broglie in the 1920s and reformulated by David Bohm in 1952. Its motivation is to recover a realist and deterministic quantum world, in which particles always have well-defined positions and continuous trajectories, in contrast with the radical indeterminacy of the Copenhagen interpretation. What makes the system quantum is how those trajectories are guided.
Two ingredients coexist in this formalism. On one hand, real particles, with concrete positions at every instant. On the other, a pilot wave (the Schrödinger wave function) that, by solving its evolution equation, determines a velocity field guiding the trajectories of the particles. All empirical predictions of standard quantum mechanics are recovered, including interference fringes and non-local correlations, but without collapse and with trajectories defined at all times.
A crucial property is explicit non-locality. The guidance of one particle depends instantaneously on the positions of all others through the joint wave function of the system. This is consistent with Bell's theorems, which show that any theory with local definite outcomes conflicts with quantum mechanics. Bohmian mechanics openly embraces that non-locality and turns it into an ontological feature: the world is deeply interconnected.
For consciousness, Bohmian mechanics is hospitable to holistic interpretations. Bohm combined it with his idea of the implicate order and with a quantum potential that draws information from the global context, affecting each particle. In his vision, mind and matter would be complementary expressions of the same holomovement, and basic non-locality would allow one to think of a deep connection between minds, without having to posit separate substances or violate physics.
Bohmian mechanics avoids some of the extravagances of other interpretations. It needs no collapse (what happens when collapse seems to occur is just that certain branches of the pilot wave function no longer influence the real trajectory), no many worlds, no conscious observers with special powers. In return, it pays the price of an asymmetry between position (really defined) and other magnitudes (which emerge contextually), and of a more complex ontology: pilot wave plus real particles.
Although it was long marginal in the standard curriculum, Bohmian mechanics is still alive as a minoritarian but technically consistent interpretation. It has served as a reminder that no-go theorems against hidden variables were not as conclusive as believed, and as a platform to rethink consciousness in a non-fragmented physical framework. For those interested in the mind-matter problem, it offers an alternative that combines physical realism with a deeply relational structure.
Strengths
- Deterministic, without problematic collapse.
- Empirically equivalent to standard quantum mechanics.
- Coherent with holistic cosmologies.
- Clear articulation of non-locality.
Main critiques
- Explicit non-locality clashes with relativity.
- Posits particles in addition to the wave function (parsimony).
- Extensions to consciousness are speculative.
- Minoritarian in contemporary physics.