  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.
