Hrvoje Nikolić derived Q = − − ( 1 / 2 m ) ◻ ◻ R / R as expression for the quantum potential, and he proposed a Lorentz-covariant formulation of the Bohmian interpretation of many-particle wave functions. He also developed a generalized relativistic-invariant probabilistic interpretation of quantum theory, in which | ψ ψ | 2 is no longer a probability density in space but a probability density in space-time.