Volume 60, 2018
Philosophy of Physics
Protophysics and the Meaning of Space-time Geometry
In the orthodox, geometrical interpretation of General relativity, gravitation is regarded as the space-time curvature and space-time as an ultimate, non analyzable reality. This makes the physical meaning of space-time geometry unclear. It’s dynamical, Lorentzian interpretation enables clarifying this meaning by analyzing the space-time geometry in terms of the behavior of physical standards of time and length units related to the absolute spatial geometry and chronometry. However, the absolute spatial and temporal metrics, and absolute simultaneity introduced by this interpretation, are non-physical, as devoid of the unequivocal operational meaning. On the other hand, neither are they metaphysical concepts, since they have some quasi-operational, or conditional operational, meaning. The latter, along with the operational meaning of fundamental physical concepts, is the subject matter of protophysics. Thus, it is protophysics that makes the meaning of the physical geometry of relativistic space-time fully intelligible. Moreover, it clarifies the meaning of the absolute background geometry in bimetric theories and supports introducing such a geometry also into general-relativistic space-time. It also justifies choosing for this role Leibnizian geometry , which has some pleasant features, whereas being capable of solving problems that motivated introducing Minkowskian background geometry in bimetric theories.