I've often heard that time was considered a dimension, but I don't understand how this is possible as it invalidates the idea of motion. Take a simple number line for example. This is considered the first dimension. A point can be at any place on said number line. Moving on up to the second dimension, we have two number lines criss-crossing. The third dimension is to be expected - three lines intersecting. Any person, object, molecule, etc... can be expected to reside in a set of points. Then time is said to be the fourth dimension. If one is willing to go so far as to extrapolate that the fourth dimension is four lines intersecting, then one can imagine time to be a line where each point holds the entirety of the infinite spectrum of the first three dimensions. However, once I get this far, I get stuck. I cannot figure out how motion can come into play. In order to move, one progresses both through time and through space. However, if one were to move along the number line of time, it would not necessitate the movement of any of the particles of the previous three dimensions. Not only that, saying that time is a dimension would mean that everything is pre-ordained: the points that you will occupy, and the neurons that will fire in your brain have already been decided, and we merely move along in pre-determined manner. This is due to the fact that in each point in time, the universe is in a different place than it was before. If one looks at time as a number line, then, assuming zero is the present, there are both points forward and backwards that have the entirety of the previous three dimensions in slightly altered positions. Thus, the points that you are going to occupy can be seen if you are able to jump to that point in time. I have heard theories that we exist in between the dimensions three and four, and that time is a ray rather than a line, but I still come up against problem of how the objects inside of time are capable of movement. And one can't simply say that time is relative because it isn't, at least not unless you're going at different speeds. Therefore, time must be something beyond a dimension. I'm sorry for making this so large, but I wanted to put everything I could down.