Time, is a dimension in universe that we have come to know over “time”. Time, never stops for anyone, nor does it repeats. That’s philosophical. They time when we were young isn’t going to come back again, we will just keep growing old. 

Time never stops, that’s why we are told not to waste it. Because once a point in your life is gone, once a decision made at that point it rarely goes back to the same. Change is what is constant. Change always happens. Its our choice whether to live it or try to run away from it. That was all philosophical.

Now, if we look through science’s point of view, time is a dimension. Like all other dimensions we know, it can change in space time. Firstly, you should know that, “absolute” means that there is a third object, the “medium” in which the other two interact.

Now, Galileo treats time as “absolute” so the time on any point in space would be the same. Whereas, Einstein, treats time as a “dimension”, in which I agree and follow him. Treating time as a dimension means every point in space can have different time. We cannot go back in time but we can slow it down to such a pace that an hour somewhere in space can be as long as 20 years on earth.

This happens because, gravity, the force of attraction due to the mass of a massive object, can bend and fold space-time fabric. That’s what happens at the event horizon of a black hole, which is that boundary of black hole at which everything becomes infinite. Near black hole, the gravity is so large that it bends the space- time fabric so much its takes “forever” to cross it or any signal to reach us.

But time, it not just an infinitely long dimension like a straight infinity long line. Time is bounded. Its like a circle, there is no start and there is no end. But if it’s a circle then time does repeat?

According to Friedman, who gave Friedman model of universe, “the idea that one could go right around the universe and end up where one started makes good science fiction, but it doesn’t have much practical significance because it can be shown that the universe would re collapse to zero size before one could get round.”

So, use your time wisely, it flies anyway when you tend to enjoy it. 😉

Source for quotes and definitions : The theory of everything by stephan hawking