"To get a good mental image of space-time, let us return to 'Flatland' (a 2 dimensional universe populated by sentient 2D geometric forms from Flatland: A Romance of Many Dimensions by the English schoolmaster Edwin Abbott Abbott). Suppose that A. Square is sitting alone in a field. At noon he sees his father, A. Triangle, approaching from the west. A. Triangle reaches A. Square's side at 12:05, talks to him briefly, and then slides back to where he came from. Now, if we think of time as being a direction perpendicular to space, then we can represent the Flatlanders time as a direction perpendicular to the plane of Flatland. Assuming that 'later in time' and 'higher in the third dimension' are the same thing, we can represent a motionless Flatlander by a vertical worm or trail and a moving Flatlander by a curving worm or trail as we have done in Figure 78 <see below>.
We can think of these 3D space-time worms as existing timelessly. We can use them to produce an animated Flatland by take a 2D plane, moving it upwards (forward in time) and watching the motions of the figures formed by intersections of the worms with the moving plane. Try to imagine a picture like Figure 78 which encompassed the entire space-time of Flatland. A vast tangle of worms of varying thickness! Actually each worm would be a tangle of threads, where a thread would correspond to the trail of an atom. Given the fact that every atom in ones body is replaced every 7 years or so, we can see that there is no single thread that goes through the whole length of one's life. A living individual is a persistent pattern rather than a particular collection of particles.
It is an interesting mental exercise to try to see our world in terms of space-time. Walking through a crowd of people for instance, one can try to see the people as trails in space-time rather than as spatial objects moving forward in space-time. Under this view our world consists of is 'worms' in 4D space-time. The universe at any instant is a particular 3D cross section of this 4D structure."
We can think of these 3D space-time worms as existing timelessly. We can use them to produce an animated Flatland by take a 2D plane, moving it upwards (forward in time) and watching the motions of the figures formed by intersections of the worms with the moving plane. Try to imagine a picture like Figure 78 which encompassed the entire space-time of Flatland. A vast tangle of worms of varying thickness! Actually each worm would be a tangle of threads, where a thread would correspond to the trail of an atom. Given the fact that every atom in ones body is replaced every 7 years or so, we can see that there is no single thread that goes through the whole length of one's life. A living individual is a persistent pattern rather than a particular collection of particles.
It is an interesting mental exercise to try to see our world in terms of space-time. Walking through a crowd of people for instance, one can try to see the people as trails in space-time rather than as spatial objects moving forward in space-time. Under this view our world consists of is 'worms' in 4D space-time. The universe at any instant is a particular 3D cross section of this 4D structure."
