1. I read that the picture of gauge bosons as mediators of interaction originates in and is valid in perturbation theory. But how do we know that picture is correct? We do perturbation theory only because we do not know how to study a system in a fully non-perturbative way. If someday we discover a non-perturbative way of doing all such calculations what will happen to this picture? 2. In quantum electrodynamics a chargeless and massless particle called photon mediates interaction between two electrically charged particles. Then how can such a photon give rise to attraction between oppositely charged particles and repulsion between particles of same charge. I mean how does a chargeless particle cause different effects? 3. Why do we consider 1TeV to be very high energy and difficult to produce while energy of the order of Joule commonplace in daily life? I hope experts here will bear with my elementary doubts in such difficult subjects.