[Physics] Flaws of Broglie–Bohm pilot wave theory

Question

I recently learned about an oil drop experiment that showed how a classical object can produce quantum like behavior because its assisted by a pilot wave. How has this not gained more attention? What flaws does Broglie–Bohm pilot wave theory have in explaining particle behavior?

Answer 1

It might help to cite your source: I found this one here - is this what you speak of?

Anyhow, actually this kind of idea has had considerable, if not mainstream attention over the years. Many people who have worked with quantum mechanics will have at least heard of the following: it's just that it doesn't make it into many QM courses (being an equivalent way to think about QM).

The de Broglie / Bohm pilot wave theory has a fairly well known hydrodynamic interpretation, as indeed does Schrödinger's equations. The latter was studied extensively by the German physicist Erwin Madelung (see the Wikipedia page Madelung Equations for more information) and he was doing this almost as soon as Schrödinger put pen to paper: beginning 1926.

So fluid dynamical systems do have analogies in quantum mechanics and contrariwise. That doesn't make them the same physical phenomena. Moreover, the big unsolved mystery in quantum mechanics is the measurement problem and this is not described by the Schrödinger equation. It is not emphasised enough that ALL of quantum mechanics aside from measurement is utterly deterministic. So, without an expert opinion, this is highly interesting work, but it is not relevant to the mysteries of quantum mechanics.

Bohmian mechanics, which is the most mature form of the de Broglie pilot wave theory does explain measurement through the mechanism of hidden variables (i.e. by saying that there is state in a quantum system which is hidden from us). However, it is also known that Bohmian mechanics needs to be nonlocal to make the hidden variable explanation work. Roughly this means that it implies faster-than-light signalling, which in turn makes it very hard to make sense of causality: in a universe where faster than light signalling can be done, effects can come before their causes. So my belief is that most physicists would say that Bohmian mechanics is not a good explanation.