From Eternity to Here Read Online Free PDF Page B

and away from the past. We know something about the past, from experience, while the future is more conjectural.
    Common to these perspectives is the idea that time is a thing , and it’s a thing that can change —flow around us, or pass by as we move through it. But conceptualizing time as some sort of substance with its own dynamics, perhaps even the ability to change at different rates depending on circumstances, raises one crucially important question.
    What in the world is that supposed to mean ?
    Consider something that actually does flow, such as a river. We can think about the river from a passive or an active perspective: Either we are standing still as the water rushes by, or perhaps we are on a boat moving along with the river as the banks on either side move relative to us.
    The river flows, no doubt about that. And what that means is that the location of some particular drop of river water changes with time —here it is at some moment, there it is just a bit later. And we can talk sensibly about the rate at which the river flows, which is just the velocity of the water—in other words, the distance that the water travels in a given amount of time. We could measure it in miles per hour, or meters per second, or whatever units of “distance traveled per interval of time” you prefer. The velocity may very well change from place to place or moment to moment—sometimes the river flows faster; sometimes it flows more slowly. When we are talking about the real flow of actual rivers, all this language makes perfect sense.
    But when we examine carefully the notion that time itself somehow “flows,” we hit a snag. The flow of the river was a change with time—but what is it supposed to mean to say that time changes with time? A literal flow is a change of location over time—but time doesn’t have a “location.” So what is it supposed to be changing with respect to?
    Think of it this way: If time does flow, how would we describe its speed? It would have to be something like “ x hours per hour”—an interval of time per unit time. And I can tell you what x is going to be—it’s 1, all the time. The speed of time is 1 hour per hour, no matter what else might be going on in the universe.
    The lesson to draw from all this is that it’s not quite right to think of time as something that flows. It’s a seductive metaphor, but not one that holds up under closer scrutiny. To extract ourselves from that way of thinking, it’s helpful to stop picturing ourselves as positioned within the universe, with time flowing around us. Instead, let’s think of the universe—all of the four-dimensional spacetime around us—as somehow a distinct entity, as if we were observing it from an external perspective. Only then can we appreciate time for what it truly is, rather than privileging our position right here in the middle of it.
    The view from nowhen
    We can’t literally stand outside the universe. The universe is not some object that sits embedded in a larger space (as far as we know); it’s the collection of everything that exists, space and time included. So we’re not wondering what the universe would really look like from the point of view of someone outside it; no such being could possibly exist. Rather, we’re trying to grasp the entirety of space and time as a single entity. Philosopher Huw Price calls this “the view from nowhen,” a perspective separate from any particular moment in time. 13 We are all overly familiar with time, having dealt with it every day of our lives. But we can’t help but situate ourselves within time, and it’s useful to contemplate all of space and time in a single picture.
    And what do we see, when looking down from nowhen? We don’t see anything changing with time, because we are outside of time ourselves. Instead, we see all of history at once—past, present, and future. It’s like thinking of space and time as a book, which we could in principle open to any passage,