While quantum mechanics is an immensely powerful and precise theory which seems to describe everything in the world, its insistence on only predicting what happens when we make "measurements" has left scientists and philosophers alike puzzled - as David Mermin summarized one of Einstein's concerns, "Is the moon there when nobody looks?" Dr.
I shall give an introduction to conceptual ideas and equations of the CSL (Continuous Spontaneous Localization) theory of dynamical wave function collapse. Then, I shall discuss various applications of the theory.
Models of spontaneous wave function collapse make predictions, which are different from those of standard quantum mechanics. Indeed, these models can be considered as a rival theory, against which the standard theory can be tested, in pretty much the same way in which parametrized post-Newtonian gravitational theories are rival theories of general relativity. The predictions of collapse models almost coincide with those of standard quantum mechanics at the microscopic level, as these models have to account for the microscopic world, as we know it.
Given two lattice Hamiltonians H_1 and H_2 that are identical everywhere except on a local region R of the lattice, we propose a relationship between their ground states psi_1 and psi_2. Specifically, assuming the states can be represented as multi-scale entanglement renormalization ansatz (MERA), we propose a principle of directed influence which asserts that the tensors in the MERA’s that represent the ground states can be chosen to be identical everywhere except within a specific, localized region of the tensor network. The validity of this principle is just