Knowledge in Positive Measurements in Quantum Mechanics

Bohr relied on the uncertainty principle as the way to understand Einstein’s 2 hole plate on rollers interferometer experiment where the plate can recoil if the change in momentum of plate in its interaction with the electron is large enough. Bohr acknowledged another way to look at the experiment. For Bohr, the uncertainty principle with an unavoidable and in part uncontrollable interaction between the electron and 2 hole plate allowed one “to escape the paradoxical necessity of concluding that the behaviour of an electron or a photon should depend on the presence of a slit in the diaphragm through which it could be proved not to pass.” What the proof noted by Bohr shows is that the uncertainty principle is irrelevant in the non-classical change in the probability distributions in the measurement. Once we know through a deduction using non-physical quantities that a recoil of the plate in one direction will occur, the wave function component for the electron going through the hole that the electron does not go through vanishes immediately.  Bohr’s proof for a positive measurement is given great support by null measurements where there is only the possibility of a proof. The Einstein experiment begins with the idea that with a 50-50 chance the electron goes through either hole.