Exactly. 10^21 W/cm^2 is actually a little below the threshold of where we expected RR (which is what the second Gemini beam shot at), and hitting 0.5 GeV elect

Exactly. 10^21 W/cm^2 is actually a little below the threshold of where we expected RR (which is what the second Gemini beam shot at), and hitting 0.5 GeV electrons head-on helped alleviate that restriction. With a host of planned laser systems exceeding 10^22 W/cm^2, we can imagine more statistically significant divergences between QRR and Landau-Lifshitz (the "classical" RR model).