I have a question about the entities in scientific theories and models. The status of some of these objects seems intuitive. Frictionless planes, for example, though they don't exist, seem helpful enough as an abstraction for understanding how actual planes function. My question is about entities which we (non-scientists) know only through the prism of scientific theory--say, photons or electrons. I know what light and electricity are, on some immediate level, through my everyday experience of these phenomena. But I don't know what to make of the entities that physics tells me compose them. My inclination is to take them as "real", not just convenient notions of the purpose of theorizing and mathematical models. I can't help pictures these tiny, planet-like spheres whizzing around. I know there's something importantly wrong about that image, but I'm not sure what. Furthermore, scientists still talk about particles "spinning" and so forth, I am unable to see in what sense this is an analogy in the way a frictionless plane is to an actual one. The point of my question is that science has a kind of authority to inform our understanding of the natural world even though it is too difficult for the non specialist to evaluate its claims. So as a non-scientist, how should I regard the claim that light is composed of "photons" and also "waves" given that these very concepts seem to rest on a great deal of theory that might potentially change such that the entities we now regard, naively or not, as "real" turn out not to "exist" for the purposes of future theories. From the educated lay-person's perspective, aside from considerations of parsimony, and given the way scientists speak to the public, how can we distinguish between theoretical entities which simply turn out to be convenient (for the moment) fictions, like say, Ptolemy's epicycles or "aether", and entities that exist in some more substantial way? This seems kind of important given the authority science has as the arbiter of how to understand the natural world. Thanks!