St. Augustine suggested that when we try to grasp the idea of time, it seems to evade us: "What then is time? If no one asks me, I know what it is.
Nothing seems more basic or real than time. Yet many philosophers, like Zeno of Elea, find it deeply puzzling. Some, like McTaggart, even claim time is unreal. Of course, philosophers often find reasons to doubt the existence of things we take for granted. But with time, it's not just philosophers. It's physicists, too. Like Stephen Hawking, to name just one.
But what does it even mean to say that time is unreal? That there's no such thing as past, present and future? That we're not moving through time?
The best way I have of thinking about the possibility that time might not be real goes like this. Suppose I’ve got this very detailed calendar. It’s basically a list of events --- last week’s pizza party, yesterday’s meeting with the dean, tomorrow’s dentist appointment. Now, no physicist is going to convince me that such things don’t occur. Events happen. Things change. Pizza is real, at least after it is baked and before it is eaten.
But when it comes to the whole structure represented by the calendar, there seems to be a bit of room for maneuver. This super detailed calendar, divided into years, months, weeks, days, hours, and even minutes. Its structure imposes a strict order on the events. And they all fall either into the past or the future, except for this particular moment in time we call now.
But this all goes beyond what we actually experience: things happening. We have this common-sense idea of time as a kind of structure that all events fit into, like on a calendar. But we came up with this framework when we thought the Earth was flat and at the center of the universe. So, would it be too alarming if a physicist were to say… surprise! This is completely the wrong view of time? All these common-sense ideas we have -- like before and after, today, tomorrow, yesterday, and so on -- they’re all just a framework that helps us organize events from a human perspective. But when we look at the vastness of the cosmos and the intricacies of quanta, it could turn out that this framework doesn’t fit.
Well, actually it might be pretty alarming to really believe this, depending on how much of the structure we have to give up. Unless the future is importantly different from the past, for example, we might be faced with fatalism. We shall see what our guest has to say. In the future. Or the past. Depending on when you read this. And how real time is.