If strings or membranes are the most fundamental entity that cannot be divided further, where do these "particles" begin? Subatomic particles such as electrons, protons, and neutrons can be further divided into quarks, fermions, leptons, gluons, bosons, ect. Do particle physicists believe that these smaller particles (quarks, ect.) are directly made of strings/membranes? Or do they leave the possibility that strings/membranes can be many particles down? And how far are we from being able to see these tiny membranes which are said to be 10^-20 of a millimeter? How long will it take to actually make a microscope powerful enough to see something this small (so that we can observe and prove it)?