  We consider strong-field effects in laboratory and astrophysical plasmas and
high intensity laser and cavity systems. Current state-of-the-art laser
facilities are close to reaching energy scales at which quantum electrodynamics
will play a crucial role in the dynamics of plasmas and indeed the vacuum
itself. Developments such as the free electron laser may also give a means for
exploring remote violent events such as supernovae in a laboratory environment.
Here we describe the implications of collective interactions between photons
and photon-plasma systems. We give an overview of strong field vacuum effects
and a set of equations describing the nonlinear propagation of an
electromagnetic pulse on a radiation-plasma is derived. Effects introduced by
QED in pair plasmas is described. Applications to laser-plasma systems and
astrophysical environments are discussed.
