title: Pulsar test of a variation of the speed of light with frequency.
abstract: The sharply defined optical and radio pulses from pulsars make possible a test of the variation of the speed of light with frequency, and of the possible existence of a photon mass. The data indicate that the mass of a real photon is less than 10(-44) gram. Detection of extragalactic pulsars could allow a substantial improvement of this limit.
authors.forename: G
authors.initials: G
authors.lastname: Feinberg