What man generally calls time has nothing to do with the true nature of time itself. What man tends to understand by time is movement - for example, the movement of the earth and the sun, which can only have relevance if it is constant, in the same way that the movement of the earth around the sun is constant.
All of man's perception of reality is based upon his perception of time. For example, when he says, "I won't do this today, I'll do it tomorrow." The whole concept of tomorrow, or next week, or when I retire, creates the illusion of time.
However, the only thing that exists is that the earth moves around the sun, but absolute time does not exist - it is not an absolute value.
Looking at time in terms of awareness, we find in The Toltec Teachings - Volume II the equation:
If t = time, and a = awareness; then t = c/a [where c is a constant (time)].
This implies that full awareness means that one is omnipresent, and that there is zero time.
However, at the moment we think of the end of the universe in terms of light years - not in terms of awareness.
What scientists generally talk about as the 4th dimension is really the 9th - in other words, the World of Sorcerers. The dimension of time exists within what Toltecs call MEST (Matter, Energy, Space and Time). MEST is layered in "tiers" throughout the whole universe and its dimensions, representing the fourfold purpose of the unspeakable, constitute what Toltecs know as the true 4th Dimension. This is explained more fully in The Toltec Teachings - Volume II.