The most common interpretation of quantum mechanics has it describe the world in terms of wavefunctions and probabilities, replacing pure classical determinism. Yet when the Schrödinger equation was first introduced, its meaning was not obvious. Already in 1927, Louis deBroglie suggested a different interpretation of it than the one we know, a deterministic approach in which the wavefunction is merely ‘piloting’ the true particle, which is a classical entity obeying however to weird, unfamiliar laws of motion. This approach was then developed further by David Bohm in the 1950s, thus becoming known as ‘Bohmian mechanics’. While it never gained mainstream popularity, it occasionally provided fertile ground for new developments, such as Bell’s work on the restrictions to hidden variable theories.

In this lecture we will present the fundamentals of Bohmian mechanics as well as the Many Interacting World approach, a new reformulation of it proposed in 2014 that does away with the wavefunction altogether. We will see how these theories recast the same phenomena we’re familiar with in a new light, how they can be useful to gain a deeper understanding of quantum behaviour by visualising it in classical terms, and finally how they can be applied to the field of computational physics, where simplifying assumptions make it a potentially useful method to deal with the problem of quantum effects involving atomic nuclei in matter.