It has been discussed more and more lately that the notion of time, or what we perceive of time, just doesn’t exist. We set clocks and we plan to meet and do things at a set “time” but what does that really mean. Here is a great writeup that explains scientifically that time itself really doesn’t exist. So far the only real constant in the universe that exists scientifically is the speed of light. I do think that some day we will prove even that is relative.