by wendy » Thu Jun 02, 2005 4:57 am
If you have, for example, (x,y,z) coordinates, then they can mean anything. There is no particular demand that x or y or z is time.
If you have 2d space-time, then x,y is space, and z is time. This is the metaphor of animation-sheets stacked one on an other.
If you have 3d space, then x,y,z are all space. The metaphor of the skyscraper is this, with x,y as the floor-plan, and z as different floors.
A skyscraper is a sequence of floors: it is not a history of one of them.
In four dimensions, the extra dimension (w), is not a history of the xyz space, but rather a separate sequence of these, all existing at the same time.