Guidance equation
= Guidance equation
{title2=$\dot{\mathbf X}=\mathbf j/|\psi|^2$}
For a spinless particle without a magnetic vector potential, <Bohmian mechanics> sets $\dot{\mathbf X}=\hbar\nabla S/m$, where $S$ is the dimensionless <quantum phase>. Equivalently the velocity is the <probability current> divided by the <probability density>. This formula is local to nonzero <wavefunction> regions.