  In the paper Pulsar Electrodynamics, published in 1969, Goldreich and Julian
propose some basic properties of pulsars, such as the oft-cited
Goldreich-Julian density, light cylinder, open and closed magnetic field lines,
corotation and so on. However, inspection of their mathematics reveals three
mistakes: first, the relative velocity is irrelevantly replaced by the
corotation velocity; second, a hypothesis in their theory is contradictory to
Maxwell's equations; and third, their theory neglected a special solution of
the frozen-in field equation which is of particular importance for pulsar
research. We additionally describe the results of a series of
magnetohydrodynamic experiments that may be beneficial to the understanding of
pulsar electrodynamics.
