Since Galileo, physics has conventionally described the physical world using four-dimensional coordinates (x, y, z, t), which implies an ontological presupposition that time continuously permeates every point of space. This paper devises a thought experiment to detect temporal effects of absolute vacuum, demonstrates that this presupposition is unverifiable in principle at the operational level. Any detection of temporal effects necessarily takes matter as a constitutive precondition; once a probe is introduced into the vacuum, it is in principle impossible to distinguish whether the detected temporal passage derives from an intrinsic property of space or from intrinsic property of the probe itself. On the basis of Occam’s Razor, “intrinsic time of the absolute vacuum” is a redundant, transcendent presupposition and should be eliminated from physical ontology. This paper further proposes that the essence of simultaneity lies in the equal temporal flow rates, and the physical equivalence between “equal flow rates of each other” and “permanently coinciding time coordinates after convention” cannot be distinguished by physical experiment. It’s highly analogous to Galileo’s principle of relativity. The precise synchronization of mass increase and time dilation in Special Relativity serves as auxiliary corroborating evidence for this position. ( direct link )