When you are courting a nice girl, an hour seems like a second. When you sit on a red-hot cinder, a second seems like an hour. That’s relativity. ~ Albert Einstein
In 1632, Galileo Galilei stated his principle of relativity: that the laws of physics are the same for all inertial frames. Galilean invariance would underpin Newtonian classical mechanics, which was the mathematic clockwork of classical physics, with an absolute space sharing a universal vector of time.
Galileo and Newton took for granted that reality was circumscribed to the observable dimensions, and that physics could posit properties that were absolute cornerstones of reliance; whence ‘laws of Nature’.
Classical physics modeled the everyday world; a set of rules only for the dimensions we can see. When one’s view veers from the ordinary, onto a path partly paved by Einstein, those rules are rent.