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I always understood a dimension as "a variable that you can change to avoid occupying the spot." In 3d space, two objects cannot be in the same spot so either
by aero142 16y ago
I always understood a dimension as "a variable that you can change to avoid occupying the spot." In 3d space, two objects cannot be in the same spot so either their x,y, or z coordinate must be different. If I add time as a fourth dimension then two objects can be at the same x,y and z, but not at the same time. You are right that time is a special dimension, but there are many things it has in common with the 3 spacial dimensions as well, my example being one.
- derefr 16y agoI've always heard dimensions being referred to as "timelike" or "spacelike", similar in vein (though not in concept) to the difference between "flat" and "rolled up" dimensions.
- Jun8 16y agoYou're right, in an intuitive sense. In math, especially dealing with weird stuff like extra dimensions, intuition may break down, though. For example, in the 4D Minkowski space you can have a unit sphere with a radius of -1! One has to understand what is meant when we say that "time is a special dimension". otherwise teh analogies we draw may fail. The Wikipedia article I linked explains these in a simple way.