“Particle-antiparticle pairs fluctuating in the vacuum also permit the fusion of two real photons into a single one, in the presence of an external field.” — Henning Genz Copy Share Image
“Just as photons are scattered off the charged particle-antiparticle pairs fluctuating in the vacuum, electrical charges will interact with the virtual photons of zero-point radiation. Again, the resistance the physical vacuum might be opposing in this way to the propagation… — Henning Genz Copy Share Image
