Physical Time and Intrinsic Temporality

Physical theories distinguish two notions of time: reversible, homogeneous parameter time (relativity theory and quantum mechanics) and irreversible, directed time (thermodynamics). Both concepts differ fundamentally from what we define implicitly by using the tenses and temporal adverbs in language. The tempora past, present, and future hinge upon one uniquely exposed moment: the now. The now is the moment of actuality in the process of subjective awareness. It proceeds spontaneously and irresistibly in relation to all datable points of time. Without reference to the moving now, past and future only denote directions in time. But there is no physical definition of the now. Physical time, be it reversible or irreversible, differs from subjectively experienced time in that it is atemporal. Because physics has no notion of the now it cannot genuinely treat past and future as temporal regions. As a physicist, Einstein consistently declared the division of time into these regions as illusory. In the first two sections of this paper we reaffirm that Einstein was right on logical grounds. In the third section, however, we insist that the actuality of the now and its movement are truths that logical reason has not the power to question. In the fourth section we shall be looking for a clue to escape the dilemma.