Quantum theory of neutrino oscillations for pedestrians: simple answers to confusing questions

A simple rigorous calculation confirms the standard formula and clarifies some confusing difficulties arising in the standard textbook recipe converting the unobserved frequency of time oscillations between neutrino states with different energies to the observed oscillation wave length in space. Including the quantum fluctuations in the position of the detector and in the transit time between source and detector enables the treatment of: (1) The difference in velocity and transit time between neutrinos with different energies. (2) The destruction of all phases between states with different masses by an ideal detector which measures the energy and momentum of the neutrino. (3) The destruction of all phases between states with different energies by a realistic detector in thermal equilibrium with its macroscopic environment. (4) The difficulty for relativistic treatments and relativistic field theory to treat the crucial quantum mechanics of a macroscopic detector at rest in the laboratory.