Charged null fluid and the weak energy condition

Abstract

Uses the Einstein-Maxwell field equations to derive the fundamental equation of motion for charged null fluid. This equation of motion includes a Lorentz force term. Using this equation, it is shown that charged null fluid always satisfies the weak energy condition. This result is in contrast to previous interpretations of the charged Vaidya solution (a special case of a charged null fluid), which produced violations of the weak energy condition. The errors in the previous interpretations are explained. The new interpretation is then applied explicitly to the charged Vaidya solution.