Eternalism

Eternalism is a philosophical explanation of the nature of time. It builds on the standard method of modeling time as a dimension in physics, to give time similar properties to that of space. This would mean that time is just another dimension, that future events are "already there", and that there is no objective flow of time. In the view suggested by Eternalism, there is no passage of time; the ticking of a clock measures durations no differently than the marks on a measuring tape measures distances between places.

Consider the relationship the primary three dimensions bear to each other. It helps to imagine our three dimensional world is composed like a pile of paper with infinite discrete two dimensional slices. For instance, a two dimensional slice of a ball would be shaped like a circle. If that two dimensional slice was taken at the exact center of the ball, and it would have lots of increasingly smaller circles above and beneath it. Each slice would be very similar to the one next to it except it would be slightly smaller until eventually they got so small the circle vanished. Every two dimensional slice next to it would be imperceptibly different from the one.

Likewise, every moment in time is another piece of paper in a time stack, the fourth dimension. Every moment is inextricably "next to" every snapshot before of after it. Much like the ball example, every snapshot closely resembles the ones adjacent to it but is slightly different. Conceptually, it's hard for us to imagine a spacial fourth dimension because we 'run out of place' to put things, but by using time as the fourth axis we can store more information. So how is time different than space? time seems to move in only one direction.

Eternalists say time marching forward at a constant pace is merely an illusion because our minds cannot comprehend all things at once. In an eternalist model, time travel is as easy as turning around and walking backwards. One interesting implication of eternalism is that everyone consciousness need not have the same idea of the "present," so although my consciousness exists right now, your conscious could be perceiving the present as twenty years from now. The role the observer plays in a eternalist universe is unfixed.

Eternalism has implications for the concept of free will, in that it proposes that future events are as immutably fixed and impossible to change as past events. Augustine of Hippo wrote that God is outside of time—that time exists only within the created universe. Many theologians agree. On this view, God would perceive something like a block universe, while time might appear differently to us finite beings.