1) In non-mathmatical terms, please correct my description of vitual particles... a) virtual particles are real but too small to be observed directly. i.e. their dimensions are within Plank's values and subject to Heisenberg's uncertainty principles. b) virtual particles are real mathematically in that their presense satisfies the theory but like individual quarks they do not exist individually and independently and cannot be observed. c) virtual particles are real and their role can be deduced by their effect on other elementary particles. 2) How do those in the know explain the concept that the quark is considered an elementary particle which doesn't exist independently? It seems to me frought with contradiction, analogous to a number system in which the number 1 is not defined.