Developments in short pulse laser technology and laser interaction targets have made it possible to explore and apply physical effects in the interaction of extreme amplitude electromagnetic fields with hot plasmas that might have been considered weak, marginal, and difficult to achieve. I will describe two of our recent experiments showing that both quantum effects and finely controlled plasma design can be harnessed to completely dominate the propagation of high intensity laser pulses, leading to exciting applications in remote sensing, directed energy, and relativistic electron acceleration
