Focused Laser -zzzzzzz!

"When laser pulses are slammed into the electron beam, their intensity in the electron's frame of reference will be

boosted by a value of 4y squared, where y is the relativistic Lorentz factor,...with the  v beam velocity and c the speed

of light. When the intensity of light in the boosted frame reaches 4x10 to w9th W/c squared, the stability of the vacuum itself breaks down, and dense clusters of electron and positron pairs are expected to arise ex nihilo."

re: Further outcome of G. Mourou and D. Strickland by Kastalia Medrano, ref: Physics Today.