The Preferred System of Reference Reloaded
  According to Karl Popper assumptions are statements used to construct theories. During the construction of a theory whether the assumptions are either true or false turn out to be irrelevant in view of the fact that, actually, they gain their scientific value when the deductions derived from them suffice to explain observations. Science is enriched with assumptions of all kinds and physics is not exempted. Beyond doubt, some assumptions have been greatly beneficial for physics. They are usually embraced based on the kind of problems expected to be solved in a given moment of a science. Some have been quite useful and some others are discarded in a given moment and reconsidered in a later one. An illustrative example of this is the conception of light; first, according to Newton, as particle; then, according to Huygens, as wave; and then, again, according to Einstein, as particle. Likewise, once, according to Newton, a preferred system of reference (PSR) was assumed; then, according to Einstein, rejected; and then, here the assumption is reconsidered. It is claimed that the assumption that there is no PSR can be fundamentally wrong. 
Israel Perez
physics.class-ph gr-qc physics.ed-ph physics.hist-ph