Space and Time in Classical Physics and Relativity
Franjo Sokolić, Ph.D., Professor
Faculty of Science, University of Split, Croatia
Modern physics started with two main principles introduced by Galileo Galilei:
The principle of inertia is the first of the Newton’s laws of motion. The principle of relativity has a less prominent role and is stated as a fifth corollary in his Mathematical Principles of Natural Philosophy. The relativity principle says that all physical laws are the same in all referential frames which move rectilinearly with constant speed one with respect to the other (inertial frames). Newton’s introduction of absolute space and time seems as a regression with respect to Galileo’s theory of motion. For the introduction of these concepts Newton was criticized by Leibniz from the relationist point of view, referring to the principle of sufficient reason and of identity of indiscernibles, claiming that absolute position and velocity are unobservable and unnecessary. Newton’s justified the introduction of these notions by the existence of inertial forces in noninertial referential frames, because these frames are accelerated with respect to the absolute space. This became the central issue in the work of Einstein of the theory of relativity. For the followers of logical positivism (members of the Vienna circle), the theory of relativity was considered as a final refutation of absolute space and time, because space and time depend on the observer’s state of motion. Nevertheless, the special theory of relativity (STR) did not get of the absolute acceleration, which appears in the asymmetry of the two observers in the twin paradox. Although their situation is completely symmetrical from the relational point of view, this is not true in the STR. This was the subject of the contention raised by Herbert Dingle. We are still confronted with with the questions like: