The unreality of time and the enfolded past and present 


I've been thinking a lot lately about time and whether it can really be said to exist. Whilst we take the past, present and future to be perfectly normal things that have an existence independent of ourselves (or at least as much as anything else does), it is clear that only one of them is ever actually visible to us. Because we can remember the past and have good reason to suppose that the future will happen, even if we don't know exactly what form it will take, it would appear to make sense to assume that such past and future times exist somewhere 'out there' in an objective sense. However, I think that this belief is mistaken, and that the past and future exist only in as much as they exist within the present which, when all else is said and done, is all that there is. 

There are many philosophical arguments for and against this point of view, also known as presentism, but I would like to explore two particular aspects of the argument. The first is the point that, in one sense of the word at least, to exist is simply to be in the present. We can see this when we think about things coming into existence and ceasing to exist, meaning that they are no longer present. From this, it follows that the past and future cannot exist because, by definition, they are never actually in the present (except in a certain rather obscure sense, as described below). If we take this view about the meaning of existence then we should reject the reality of past and future on purely semantic grounds.

This conclusion is less than convincing because, although it may be incorrect to suppose that the past and future exist 'out there' in some mysterious fourth dimension (the common idea of time being that it is analogous to space, with us moving through it, which explains why things change), it is nevertheless true that aspects of the past and future exist within the present in the form of records, memories, intentions and probabilities. Indeed, the only way that we can know anything about the past is because we can access memories, records and other evidence of it. These traces (or 'time capsules' as Julian Barbour calls them) carry information about past events into the present, making it accessible to us in the here and now, and so giving some kind of present existence to the past.

Another important sense in which the past is present is that the past is what caused the present to be the way that it is. Even though nobody knows how or why the universe began, we can all agree that this event ultimately led to things being the way that they are now, and so in some sense this event is contained in the present by virtue of its consequences, albeit in a highly altered form. We can say that it is true that universe had a beginning because it is possible to know that this is so. Similarly, causal links between the present and future constrain the possibilities for how things will be in the future, suggesting that at the point where the future becomes present, it too will contain what is currently present, which will by then will form part of its past (read this again if it doesn't make sense, or alternatively, this might be a good point to disembark if your plans require that tomorrow really exists!).

At this point I want to draw a distinction between two radically different views of the past and present. The first I will call the dimensional past and future to indicate that they exist separately to now, arranged along a dimension that we call time. An important feature of this model is that each instant of time is an inherently static, unchanging reality, and our impression of change is created by our movement through time (think of a point travelling along a straight line and you get the idea). Indeed, this view is so ingrained in our culture and way of thinking that it's often easy to forget that it is simply an assumption about the way that time operates, as the notions of movement through time and 'moments' pervade our everyday language. Another analogy might be the way that film or television creates the 'illusion' of a moving picture from a series of still images played rapidly one after the other (questions of whether time is quantised or continuous notwithstanding).

The second view of the past and present that I want to present is what I call the enfolded past and future. Here, the idea is that past and future events are only real in so far as they exist within the present. According to this view, the present exists as an ever-changing and dynamic 'now'. It's important to realise that here, unlike the dimensional view, the present is not merely a tiny slice of reality, but is actually all that there is. The past and future are 'enfolded' within the present by means of the traces and potentialities that it contains, and so can be said to have some kind of existence within it, even if that existence is of a rather shadowy and vague nature compared to the view of the dimensional past and present, which exist in exactly the same way as the present moment. Events therefore 'unfold' based on what is happening now to recreate the present in slightly altered form. Things that have happened and that have yet to happen have no independent existence as we can have no knowledge of them except through the present.

This second view leads to some very interesting conclusions about the nature of truth and change. Firstly, we can no longer say that something is true of the past or future, or at least not with the same degree of certainty that we can of the present. As traces of past events decay and change into their consequences, they become in a sense diluted, and so it becomes less certain as to whether that event actually happened or not. Truth about the past is therefore not the same as truth about the present, and this is indicated in ordinary language by our use of tense (I went to the shops, John Lennon was shot, and so on). Note that it is not just our ability to know about the past that is limited in this way, but the very notion of truth itself. Similarly, all knowledge about the future is limited in exactly the same way. We can know with great certainty that certain events are going to happen (I will have muesli for breakfast tomorrow, for example), but others are much less clear (e.g. when and where I will die). This symmetry between past and future truth is an attractive feature of this kind of presentism.

[Digression: I considered and rejected an alternative view in which there simply is no truth about what did or will happen. However, this runs into serious danger of contradiction when we try to make statements about what did or did not happen, e.g. I blinked a particular number of times yesterday, but there is no particular number that matches how many times that I actually blinked. Alternatively: I did not blink any particular number of times yesterday, which is absurd, or there was no yesterday, which is hopelessly sceptical. Hence I conclude that truth about the past is an epistemological rather than metaphysical matter. Many thanks to Tom Baldwin for pointing this out.]

Secondly, the present moment, far from being a frozen, static snapshot of reality is seen as an ever-changing permanent state of 'becoming'. Rather than being an illusion created by our passage through time, change becomes a fundamental feature of reality that is constantly operating upon everything there is. Conversely, it is the idea of the single static moment of time that is illusory, because everything is in a constant state of flux and so even the shortest duration of time would contain at least some slight movement or change. Change and causality, it would seem, are woven into the very fabric of the universe. To revisit the film or television analogy as described by Julian Barbour in his book The End of Time, it is not the illusion of movement that is created by replaying a series of stills in succession, but the reality of movement that is recreated by replaying a series of illusions; in this case, the individual events and moments of time.

In this way, we can reach a definition of what it might mean for an event to be pastly or futurely present, or to put it another way, how the past and future are enfolded within the present. There is a lot more that could be said about this, such as the implications for the way that events unfold, the possibility of free well and non-determinism, and the origin of the ultimate cause of everything: the beginning of the universe. However, this should be sufficient to give some idea of what it might mean to say that time is an illusion, and hopefully give at least some credibility to the idea that the present moment is all that exists, and is the only thing that ever does. 

Posted on Wednesday - February 23, 2005 at 01:10 AM            

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