http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html I am new to physics and have been struggling with the idea that forces are just "action at a distance" and that fields are invisible/incorporeal (can only be detected by the influence they exert) and permeate throughout all of space. The article above describes forces as being mediated by virtual particles, which made me feel more confident that fields were actually some form of matter/energy interaction. The virtual photons are apparently transferring momentum between charged bodies, but I got lost in the physics jargon as to how this ends up working. What are the similarities/differences between photons and virtual photons wrt the em field? I think one deal with a static field and one with a fluctuating field, but I'm not completely sure. Are all forces mediated by virtual particles? What experiments have verified that virtual particles exist? Further down in the article it states that the propagation of the virtual photons is ftl. Does this have anything to do with quantum entanglement? I've also heard of the virtual particles in reference to electron-positron pairs, Dirac sea, and zero point/ vacuum energy. Does this have anything to do with the above description or something completely different? I would greatly appreciate it if anyone could explain this virtual particle subject to me in layman's terms. Thank you.