Atomic Physics and Quantum Electrodynamics in the Infinite Momentum Frame*

.Over the past few years it has been shown that the use of an “infinite momentum’7 Lorentz frame1 has remarkable advantages for calculations in elementary particle physics and field theory, especially in the areas of current algebra sum rules, 2 parton models, 3, 4 and eikonal scattering.5,6 One important advantage is that it allows a straightforward application of the impulse and incoherence approximations famil.iar in nonrelativistic atomic and nuclear physics to relativistic field theory and bound state problems.