Topics Time

Question How can time really exist? If you think about it, threre is an immeasurably short time which is the present which is ever changing. It is commonly accepted that that which cannot be measured cannot physically exsist. I think that we understand the present the way we do because of the past, and predict the future due to the past and present. But, there is effectively no actual past or future. The present doesn't even exist because the point in which it exists is so brief that by the time we perceive its existence, it is part of the past, which is impossible. So, how can time really exist?

Accepted:
March 3, 2008

Comments

There are a number of issues raised here. Let's do a bit of separating out.

Take the sentence "Verdi died over a hundred years ago." That's true. It isn't made true by something happening now. The event whose occurrence makes that sentence true is something that happened in the past, in the 1901. (And this isn't a case like the founding of Rome by Romulus and Remus, a mythical event. Verdi was a real person. His death is an event that actually took place.)

I wonder just what is being said, then, by "there is effectively no actual past". Is it being claimed that really was no such actual event as Verdi's death after all (just as there was no actual event of the founding of Rome by Romulus and Remus)? The past is a blank and all history is a myth? That's absurd. Or is it being claimed that Verdi's death isn't now actual, i.e. isn't now happening. But that is trivial -- no one disputes that! So it is not immediately clear what sensible but interesting view can be expressed by "there is effectively no actual past". Plainly more needs to be said.

Another point: it is too quick to say that "it is commonly accepted that which cannot be measured cannot physically exist". Many would say, for example, that spatial points (or space-time points) exist, even though they have no size to be measured. The present moment could be like that, an extensionless point of time. But note that we can measure the distance between different spatial points -- use a ruler! And equally, we can measure the distance betweeen different "temporal locations" -- use a clock. Thus, the kitchen clock tells me that eight minutes have passed between the past moment when I started writing this response and the present moment as I finish writing this paragraph now.

So some problematic assumptions underlie the question as put. Still, I certainly don't want to suggest that there are no deep and interesting questions in the philosophy of time, including questions about the ontological status of the past and future. One good place to start, if you want to explore these matters, is Robin Le Poidevin's engaging book Travels in Four Dimensions.

I'd go along with Peter Smith's answer, but I figured I'd just take the occasion to point you in the direction of a couple of classic discussions in this area, which you might be interested in following up. First, your question is startlingly close to a problem raised by Saint Augustine at the end of the fourth century AD -- you're in good company! If you're not already familiar with Augustine's discussion, it's in his Confessions, book 11, paragraphs 17 to 38, pages 168 to 174 in this edition. I don't know how much his own solution to the problem would actually appeal to you, which is effectively to say that time only really exists in the mind, the past in memory, the present in sight or consideration, and the future in expectation. But another way around the problem is suggested by J.E. McTaggart's article, 'The Unreality of Time', first published in the journal Mind in 1908 and available online here. McTaggart lays out various alternative ways of thinking about time, and it's up to you to decide which you'd prefer to adopt: but, if you adopt what he calls the 'B-series' view, then the temptation to deny the reality of the past and future will fizzle out altogether. On this view, the present moment, "now", is no more or less real than other temporal moments, past or future, in precisely the same way as the present location, "here", is no more or less real than other spatial locations, in front or behind -- and that's an analogy I'd invite you to ponder.