Solution
= Solution
The nonrelativistic Schrödinger <Hamiltonian> uses $p^2/(2m)$ and therefore has no massless <limit>; massless particles require a relativistic wave equation or quantum field theory.
= Solution
The nonrelativistic Schrödinger <Hamiltonian> uses $p^2/(2m)$ and therefore has no massless <limit>; massless particles require a relativistic wave equation or quantum field theory.