Relative Velocity: A Dichotomy
Zbigniew Oziewicz
Keywords: reference frame, observer, tetrad versus monad, groupoid category, relativity groupoid as a category
The central concept of the (special) relativity theory is a concept of a relative velocity.
Relativity of the velocity means that velocity is not absolute concept. The velocity
of a massive body is not an intrinsic property of this body, but depends on the free choice of
the reference system, it is reference-dependent. The definition of the relative velocity does
not depends on existence or absence of the privileged reference system aether, also the extra
assumption of constant relative velocity is not so important, inertial reference system is also of
secondary relevancy. There is no big difference with this respect among Galilean and Lorentz-
group relativity theories. The concept of a relative velocity depends on the axiom of what it the reference system, the Einsteinian coordinate system versus the Minkowskian fluid vector field.
