  We discuss some common misconceptions in Unruh effect and Unruh radiation for
the cases of linear and circular uniform acceleration of a charged particle or
detector moving in a quantum field. We point to the need to go beyond Unruh
effect and develop a new theoretical framework for treating the stochastic
dynamics of particles interacting with quantum fields under more general
nonequilibrium conditions. This framework has been established in recent years
using the influence functional formalism and applied to relativistically moving
charged particles. Only with nonequilibrium concepts and methodology applied to
particle-field interaction can one grasp the full complexity of the problems of
beam physics under more realistic conditions, from electrons and heavy ions to
coherent atoms.
