New Interpretation of Inertial Force and Natural Existence of Absolute Background

We reinvestigate the formalism of classical particle dynamics according to the basic requirement of causal consistency, and obtain a new particle dynamical equation. In the application of this new particle dynamical equation, the new formula is more in line with the empirical laws from classical mechanics experiments than Newton's second law, but inertial reference frames are no longer required and inertial forces are no longer introduced by hand. The new dynamical equation can be straightforwardly applied in any reference frame which is irrotational with respect to the absolute background of (the whole space of) the universe, namely a moderately general principle of relativity is realized on particle dynamics. The nature of the inertial force is nothing but the real forces acting on the reference object. As far as the framework of classical mechanics is concerned, the essence of this work is nothing but an error existing in the formalism of Newton's second law being corrected. However, it may be more important that the derivation of this new particle dynamics equation strongly suggests the existence of an absolute background for the whole space of the universe. In physical concepts, the absolute background for space must be distinguished from the relative scales of space in order to be mostly compatible with the physical logic in Einstein's special relativity and general relativity. Certainly, the absolute background of space is also able to be understood as the implicit part of Newton's absolute view of space-time, but the former is more natural and more accurate in natural philosophy.