Effective wave function in Bohmian mechanics
= Effective wave function in Bohmian mechanics
If $\Psi(q,y)=\psi(q)\Phi(y)+\Psi^\perp(q,y)$ and the actual environmental configuration $Y$ lies in the support of $\Phi$ disjoint from the environmental support of $\Psi^\perp$, then evaluating the <guidance equation> at $(Q,Y)$ gives the velocity generated by $\psi$. This is effective collapse without deleting a universal <empty wave>.