The Principle of Relativity as the Equivalence of Inertial Frames with Respect to Local Causal Laws

The principle of relativity is one of the fundamental principles of physics. Since Galileo, it has been undestood as the statement that the local laws of physics are the same in all inertial reference frames. Later, in Newtonian mechanics, this principle was conected to the concept of absolute space, which provided the background allowing inertial frame to be defined. In the late 19th and early 20th centuries, Mach critique Einstein theories of special and general relativity broadened the interpretation of this principle, associating it with coordinate description and the equivalence between inertia and gravitation. However, this traditional interpretation has a weakness - it is often based on kinematical arguments and formal covariance, while the physical essence of the laws remains secondary. This is especially evident in general relativity, where the equivalence principle is essiantially kinematic - it relies on the claim that free fall motion and the effect of gravitation are locally indistinguishabe. In this way, a kinematic phenomenon is declared to by dynamical equivalence. In this paper we propose a different interpretation of the principle of relativity, grounded in the concept of local causal laws.