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Does time pass?

By Adrian Bardon


In the early 5th century BCE a group of philosophers from the Greek colony of Elea formed a school of thought devoted to the notion that sense perception — as opposed to reason — is a poor guide to reality. The leader of this school was known as Parmenides. He left behind scraps of a long prose poem about the true nature of time and change. This work, On Nature, is one of the earliest surviving examples of philosophical argumentation.

Our perception of the world is of a world of change, of motion and transience. Parmenides was convinced that the reality is quite different. He argued as follows. The ordinary notion of change indicates some thing or state of a thing going from being future to being present to being past. Yet we also ordinarily contrast the what is — i.e., the present state of things — with the what is not — i.e., the merely possible or long gone. The future doesn’t actually exist; if it did, then it would exist now! But then nothing can go from actually being future to being present: if the future is not real, then the present state of things cannot come to be from a future state of things. Hence, change is impossible and illusory. Parmenides concluded that the world is really a timeless, static unity. The terms ‘past,’ ‘present,’ ‘future’ do not designate intrinsic properties of things or events.

It would be difficult to come up with a proposition that meets with any less agreement in our everyday experience. How can we even imagine a world without the passage of time? The lived experience of the flow of a river, the enjoyment of a melody, and the decisions we make from moment to moment that depend on what we think is happening now — and what might be coming up — all speak irresistibly in favor of change. Parmenides must have gone wrong somewhere!

Running by Nevit Dilmen, 2006. Creative Commons License via Wikimedia Commons.

Running by Nevit Dilmen, 2006. Creative Commons License via Wikimedia Commons.

And yet the vision of a static universe, with no intrinsic past, present, or future, finds powerful validation in Einstein’s Special Theory of Relativity. According to that well-confirmed theory, two events that are simultaneous to an observer in one inertial reference frame will not be to a different observer moving relative to the first one. Since there is no absolute motion, there is no privileged vantage point that fixes which events are really simultaneous and which are not. This means that the set of events ‘present’ to one observer is different from another’s set; neither is justified in identifying a particular moment that everyone should agree is the present moment. The same goes for pastness and futurity: an event one observer considers past may be present, or even future, for another, depending on its relative distance and their relative velocity. If there is no privileged vantage point from which to determine the ‘truth’ of the matter — and the whole point of relativity is that there is not — then temporal properties like past, present, and future cannot possibly be aspects of reality. They must be subjective and perspectival in nature.

Of all things, whether a loved one’s death occurs in the past or in the future carries immense significance to us. Yet Einstein insists otherwise in a famous letter eulogizing his friend Michele Besso:

Now Besso has departed from this strange world a little ahead of me. That means nothing. People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion.

We know that the designation ‘here’ is purely perspectival: my ‘here’ may be your ‘there,’ and vice-versa. From the universe’s perspective, the designation ‘now’ is no more an objective designation than ‘here.’ (Think what odd consequences follow from treating designations like ‘past’ as real properties of objects and events. This would entail, for example, that something even now is happening to the Battle of Waterloo: it is becoming more past.)

No doubt our biology requires us to think differently. We have evolved as conscious beings who act on the basis of beliefs. Agency requires us to think in terms of what has been accomplished and what is to be done next. Beings like us must think in terms of “now is the time to feed / fight / escape / go to the department meeting.” Even though no moment is privileged, at any given moment we are convinced by our experience, and by that moment’s memories and anticipations, that the time is now. Consciousness of change and the passage of time is irreducible, inescapable. There is no guarantee, however, that even biologically necessary representations of the world speak the truth of the world as it is in itself.

Adrian Bardon is Associate Professor of Philosophy at Wake Forest University. He is the author of A Brief History of the Philosophy of Time.

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3 Responses to “Does time pass?”
  1. [...] closer to me than would appear. My mental faculties have been stretched in this regard lately by this article  – there’s another book on my must-read [...]

  2. Daniel Pech says:

    “Never mind time for the moment. What in the world is space? In reflection of what Jake Gyllenhaal’s character, Homer Hickam, my namesake, said in October Sky, ‘Ah’m goin’ inta spahce’,…

    “Welcome to Quantum Entanglement!, the radio program where we question your intelligence like the Gulag! Our special guest today is space, who is with us in the studio. After some brief words of his own, space will briefly turn the program over to time, who will have just enough time to take one call from among our listening audience. So, without further add-do, let us begin! Welcome, space, to our program today.”

    “Thank you Homer. It’s great to be here.”

    “Well, now, space, I have just one simply question for you: people take you for granted, so what do you have to say for yourself?”

    “Well, Homer, when you have put a pile of firewood on the hearth, what has happened to the empty space where the wood now occupies? I’ll answer that myself:

    “Of course, it seems that the wood has space of its own. So, for example, when you pick up a piece of wood, it seems that its own volume in preserved. Yet, now, there is an equal, but empty volume of space at the location from which you picked up that piece of wood. We even would say that the wood takes up the exact amount of the other, now formerly empty space, that it now occupies.

    “But, given that the wood seems to have its own independent and moveable space, where did the empty space go into which you have now moved the wood? Was that formerly empty space displaced, like water is displaced when we put something it?

    “Well, we do not notice any displacement of the empty spaces into which we put things. In fact, we cannot see to the edges of the universe, to see if it fluctuates like a womb when the baby kicks. Nor can we feel any of the empty space shift around us when we cause something with its own seemingly independent space to be in the place where some empty space was. So, like musk oxen to an as-yet un-bothersome far-off pack of wolves, we assume that the empty spaces from which we take things, and into which we put those things, does not go anywhere, or do anything.

    “And, if we suppose that the empty space does move out when the occupying stuff moves in, then what about the defined location itself where the occupying stuff now occupies? How ‘real’ is a location, as such? Is it to the supposedly displaceable empty space like that empty space is to the occupying stuff? This sounds like a precedent for a meaningless infinite regress, akin to that argued by some thinkers in response to the asserting that God necessarily exists: ‘Then God had no choice in whether he exists or not, which implies that something else made him to be necessarily existent, which, in turn, implies that God depends on something more fundamental than himself.’ So, the odd question, here, is what’s the difference, if any, between location and space?

    “On that odd question, I now turn the moment over to time. Hello time, and welcome to Quantum Entanglement.”

    Time: “Thank you space. It’s good to be here. What’s the caller’s question?”

    Caller: “I’ve been told that you are like an endless flow of hot taffy which flows from the empty future into the cooler room of the ever-present, and from there is shipped out the other side of the room into the endless darkness of the past. Is this true? And, if it is, then what keeps the room cool?”

    Time: “Thank you, caller. Those are interesting questions. To your first question, Am I like hot taffy flowing into a room of the ever-present?, the answer is no. To your second question, What keeps the room cool?, the answer is that it depends on how much work is going on in the room to ‘ship the cooled taffy out into the endless darkness of the past’. The past is just the former states of the work going on inside that room. So, there are no actual past moments. There are only past states. To think that I flow into the room, and that I get shipped out, is like believing in Santa Claus. Though gifts are real, Santa Clause is nothing more than a too-convenient figment of the imagination. After all, to sense that things change means that that sense must have some basis in reality. The problem is when that sense is accorded a kind of independent reality which it does not have. Then it becomes a precedent for an endless series of meaningless precedents. Stick to the present, and figure that out first. That’s where I am. Now, back to you, space.”

  3. zankaon says:

    Perhaps one could consider time as a set of integers, with zero being the now, and negative integers the past, and positive integers the future.

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