Guille's time paradox is ultimately misleading (sorry Guille). Time is a congruence of spacial dimensions and measures the relative location and speed of mass carrying objects within the 3-dimensional spatial arena. Saying time is a dimension relies upon the ability of the reader to differentiate between a spacial "dimension" and a "dimension" that is not spatial.
For example... without the time dimension it is possible to give all the information about the position or locality of a mass carrying object within a 3-D space, but it is impossible to say anything about its speed (its change in position over time). When we introduce the time dimension, we can measure more of the speed, but the measurement of location becomes proportionately more difficult to specify (Heisenbergs Uncertainty Principle). The notion of a time dimension must therefore be dependant upon the number of objects relative to the object that is measureing time within a 3-D system. There SHOULD be a quantum mechanical explanation of why time is relative to the amount of matter within a given system (a solar system or planetary system, or even a galaxy), but I would say that the most important principle here is that time can only be measured concerning the relative speed and location of matter (or mass carrying objects). Time dilation and the slowing/speeding of time does not , for example, effect the speed of light. I would argue that this is because light does not actually have speed in the same way that an object with inertia has speed (a mass carrying object). Anomalies travelling at the speed of light simply have a direction vector coupled with a complete lack of location. If you consider the Heisenberg Uncertainty Principle, you should note that a complete lack of location would result in the absolute maximum speed possible, and in one specific direction (vector).
From this standpoint, time is the way that massive objects interact with the spacial dimensions around them. To put it another way.... time is like a perspective dimension of a given 3-D spatial system (galaxy, solar system, planetary system) that has significant amounts of matter.  |