Classical physics rests upon five basic assumptions about the fabric of reality: reality, locality, causality, and determinism. These assumptions were postulated to take place within a framework of an absolute fixed space and time. It was also taken for granted that the mathematical descriptions of physical processes corresponded to the actual behavior of objective events.
The assumption of reality refers to the idea that the physical world is objectively real. That means it exists independently of whether anyone is observing it. The moon is still there even if you aren’t looking at it. Locality refers to the idea that the only way that objects can be influenced is through direct contact. Unmediated action at a distance is prohibited, as this is uncomfortably close to the occult suggestion that invisible spirits can cause things to occur, and the occult concepts are anathema to science.
Causality assumed that the arrow of time points in one direction, and thus that cause → effect sequences are absolutely fixed. Continuity assumes that there are no discontinuous jumps in nature or in that the fabric of space and time is “smooth.” Determinism assumes that, as Einstein once quipped, ‘God does not play dice with the universe,’ meaning that things progress in an orderly, predictable way. We might not be smart enough or know enough to predict everything, but determinism says that in principle we can predict the future completely if we knew all the starting conditions and causal linkages.
