Something confused me. It is said that non-relativistic Bohmian Mechanics uses multiple-particle wave functions which are functions on a tensor product of N copies of spacetime, one for each particle, which evolve in time. Does it mean for every particle, it really use an entire spacetime for just for it? But then, since spacetime is not object but just a model, no problem about a particle reserving an entire spacetime for it. So in BM, how do different particles interact since each particle uses one spacetime? Non-relativistic theory is said to use parameter time instead of coordinate time. So BM as non-relativistic uses parameter time. Woud it be logically consistent if BM is made to work in coordinate time? What would happen then? For those who are familiar with Tumulka flashy GRW which is supposed to be relativistic... how do multiple particles interact since they are in separate spacetime, but a clue can be given in the following: "The technical apparatus Tumulka uses is a bit unfamiliar- for example, he uses a multi-time wavefunction defined over N copies of space-time (for N families of flashes), and he models the “collapse of the wavefunction” as a change from one multi-time wavefunction defined over the whole multi-time space to a different wavefunction defined over that whole space- but these refinements need not detain us. What we can already see is how Tumulka’s choice of local beable aids in rendering the theory completely Relativistic." What does it mean and how does it differ to Bohmian's? Basically how does multiple particle interaction occur in Bohmian versus that of the above mentioned Tumulka flash GRW? (if you are not familiar with Tumulka, just ignore it and answer the Bohmian part in this message). Happy New Year!! May 2012 be a year of stunning breakthough that will reverberate for generations to come.