There is a complex interplay between our intuitive understanding of time's transient nature and its representation in modern physics as a dimension. We need to challenge the mainstream view of time as an illusion, and instead seek something that integrates the concept of Becoming into the very fabric of reality, writes Avshalom Elitzur.

It is perhaps the most fundamental ingredient of our experience that reality is constantly changing: Every moment, in its turn, seems to bring new events that did not exist before and that will vanish later. Every event, therefore, has three temporal properties that come one after another: i) before the event takes place it is a potential future event, subject in principle to interference; then, ii) when it actually happens, it is a fleeting present, and finally, iii) after its occurrence, it is a given, unchangeable past. In everyday language, there is a temporal property –– the Now – that continuously moves from one moment to the next, from every event to the following one. Conversely, we may view time itself as passing relative to us, its passage being experienced as the change of the future into present and then into past. Reality, then, seems to be subject to an incessant Becoming.

Trivial statements, one might say, not worth our time. Well, welcome to an ancient realm of paradoxes. Elementary logic proves that these statements are not trivial – they are simply wrong. Any statement like “time flows/passes/moves” is bound to produce gross inconsistencies. For the very concept of movement is based upon that of time; saying that an object “moves” amounts to saying, “it is in one position at one moment and in another position at the next.” But how can such a statement be made on time itself?

To see the absurdity of granting it motion, just ask yourself what is this motion’s velocity! The same contradiction besets the statement “we move in time.” To say so, one must regard time as a sort of “space” in which we move, thereby necessitating another time. Neither shall we avoid absurdities by saying “the future changes into present and then into past.” If “change” denotes different states at different moments, how can the moment itself change its designation from future to past? Would such occurrences not require another time within which the passage or change of time itself occurs?

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We have every reason to think of the passage of time as an illusion.

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It is to physics, the most fundamental of sciences, that we turn in search for an answer. But upon turning to this promising path, let us be prepared to find our problem becoming only worse.

The best introduction to our problem is Newton’s (1686) famous statement:

Absolute true and mathematical time, of itself and by its own nature, flows uniformly, without regard to anything external.

In modern textbooks, this passage is routinely quoted in order to show the inadequacy of the Newtonian assumption of absolute time. This is relativity theory’s seminal point of departure, to which we shall return later. But Newton’s statement contains an even more basic fault, noticed long before relativity: The statement “time flows” is meaningful only if one assumes that there is another, higher order time within which our ordinary time flows. Otherwise we would face an awkward   in our equations. But that additional time, assumed to govern time’s passage, would, by the same reasoning, necessitate introducing a yet higher order time parameter and so on ad infinitum.

Understandably, physics tackles time’s passage simply by ignoring it altogether. A physical law is a function that attaches to each moment a particular state of a given system. The general form of a physical law is: “Under specified conditions, the system is in state S1 at time t1 and in S2 at t2.” Nothing in such a description implies that these states come into being and then vanish, in any temporal order. Recall a geographic map that gives the altitude of each site according to its latitude and longitude: Does the map indicate that these sites come into being and then vanish one after another? Or does it imply that the altitude “moves” up and down? Rather, all sites with all their geographic attributes coexist. Strange as it may seem, physics does not say about time more than the information contained in a map about the geographical dimensions. From the pure physical point of view, all moments, and all the past, present and future states of the universe have the same degree of reality.

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Physics is strikingly alien to our intuitive experience.

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This view, ignoring or even denying time’s passage, seems even more reasonable in view of the tremendous revolutions of special and general relativity. In fact, Einstein’s and Minkowski’s discovery that time is the fourth dimension of “spacetime” is not new, but marks the climax of a centuries-old trend that Whitrow (1980) calls “the elimination of time.” In hindsight, it is safe to say that the realization that time is merely a dimension would have gradually imposed itself upon physics even if relativity theory has never been discovered. For, long before Einstein, it had been noticed that any attempt to render a present moment more “real” than earlier or later moments would mean that this “realness” is moving along time, thereby giving rise to all the paradoxes we encountered above. Hence, a much simpler account of time has been preferred: Let the terms “later” and “earlier” be merely relative, just like “east” and “west.” London is west for the inhabitants of Jerusalem yet it is in the east for the people of New York. These designations depend on the observer’s location and have no absolute status. Moreover, we are aware that these observers sharply differ in the reality they ascribe to their locations. The Londoner feels that “here,” London, is more real than “there,” Jerusalem or New York; but she always remembers that all other cities have the same degree of reality and “hereness” for their inhabitants. Similarly for time, one feels that today is more real than the Middle-Ages or the 25th Century. But this feeling is not more objective than the distinction between the realness of “here” and “there”!

Thus, although the young Einstein was not concerned with time’s transience when he conceived the special theory of relativity, he could have pointed out the paradoxes besetting the presumed passage of time as just another advantage of his theory. We shall later see how the avoidance of time’s transience became even more essential in relativity theory.

This elimination of transience means physics is strikingly alien to our intuitive experience. Einstein himself, as we shall see, has sincerely expressed his unease with this view. Later authors, however, were usually tranquil. It is surprising how often the question of time’s passage is ignored altogether in works dedicated to the physics of time. For example, none of the articles in Landsberg’s volume The Enigma of Time (1982) and in Flood and Lockwood’s The Nature of Time (1986) refers to this problem, let alone discuss it. Nor do Landsberg’s review articles (1972, 1989) refer to it. Hawking’s (1988) best-seller A Brief History of Time – the very title of which implies a paradox by ascribing a history to the parameter of all histories – is mute about the question whether time is really passing. Nor does Price’s (1989) criticism of Hawking touch this point.

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From the pure physical point of view, all moments, and all the past, present and future states of the universe have the same degree of reality.

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Among the physicists who did address the problem of time’s passage, the majority dismissed it as an illusion. Nearly the entire literature on time’s asymmetry (see Chapter ‎2) takes this option. Gal-Or’s lengthy and unorthodox book on the foundations of physics (1987) states: “That time should be endowed with such questionable properties is actually due to the confusion of the objective physical time asymmetry with the subjective illusory forward flow of time” (p. 236). Penrose (1989, 1994), although markedly ambivalent on this point, finally opts for the conventional view and renders time’s transience an illusion. Rucker (1982), following Gödel (1949), stresses that “on the basis of modern physical theory we have every reason to think of the passage of time as an illusion. Past, present, and future all exist together in spacetime” (p. 10). Digressing to personal reflections, he confesses that he even finds this idea relieving from the fear of death (1984, p. 147). Reichenbach (1956) has used a powerful metaphor for challenging our intuitive feeling of transience:

In a film version of Romeo and Juliet, the dramatic scene was shown in which Juliet, seemingly dead, is lying in the tomb, and Romeo, believing she is dead, raises a cup containing poison. At this moment an outcry from the audience was heard: “Don’t do it!” We laugh at the person who, carried by the emotion of subjective experience, forgets that the time flow of a movie is unreal, is merely the unwinding of a pattern imprinted on a strip of film. Are we more intelligent than this man when we believe that the time flow of our actual life is different? Is the present more than our cognizance of a predetermined pattern of events unfolding itself like an unwinding film? (p. 11)

Only a few opted for the possibility that Becoming is a real phenomenon. Among them, surprisingly, was Reichenbach himself (1956). Fraser (1987) is among the modern adherents of this trend. Time, he states, “had its genesis in the early universe, has been evolving, and remains developmentally open-ended (1982, p. 1). Horwitz (1980) and Horwitz, Arshansky & Elitzur (1988) suggested to introduce an additional time parameter in order to resolve some longstanding difficulties in relativistic dynamics. Stapp (1986) has given a lucid exposition of the hypothesis of time’s passage, initiating a lively debate (see Griffin, 1986). Davies (1995) recently voiced a strong opinion favoring the objective nature of transience.

But this is a minority view. Most physicists, apprehensive of the above paradoxes that seem to follow the idea of time-transience, chose to dismiss it altogether. Time’s transience, according to the mainstream of modern physics, is nothing but an illusion. There is no Becoming, as all the events in the past, present and the future have the same degree of reality.

With respect, I beg to sharply differ.

The option I propose is different. We can preserve the essential elements of relativity theory, and still take the ``Now" as a key to a deeper layer of physical reality. The model which I have developed with Shahar Dolev (Elitzur and Dolev, 2005), is the Spacetime Dynamics theory, as it suggests that spacetime itself is subject to evolution. This new approach can make quantum mechanics and relativity theory much more compatible within a new framework in which Becoming is the most fundamental property of physical reality.