Time does not exist

First, time is not an object. Time is a dimension, the fourth dimension, and taken with the three spatial dimensions in what is called space-time (I'm sure you've heard of the space-time continuum.) We exist IN time and are swept along by it. While "now" may indeed be all there is, we are aware of past moments via memory, present moments via perception, and future moments via perpetual perception. The past did exist in the present, the present exists in the present, and the future will exist in the present. In temporal terms "now" itself presupposes a "then," much like in spatial terms "here" presupposes a "there." At the very least these are relative terms - relative, that is, to our own individual perspectives. Time is different than space in that it has a permanent direction that is (as far as we know) inescapable. We can't MOVE through time like we MOVE through space; there is no way to have a race, for instance. When we change from one moment to the next, we are not traveling through time - we are all rather stationary in time. Until death and the end of any perception. Time has no speed, as space no size, but both can be quantified and measured arbitrarily by humans (seconds are to inches as hours are to miles.) The present moment is all the time that can exist, but that moment is still time existing and it was preceded by other moments and is constantly being succeeded by additional moments. Second, even if time is an invention of human intuition - a by-product of our set of sense-apparatuses, as you suggest, it still EXISTS in a very real sense - as a way of differentiation between one instance of perception and another, for each instance of experience is different than every other. The sense-perception I am receiving while writing this sentence differs from that of the last sentence. If my "I" couldn't differentiate perception in a temporal manner, everything would truly be a blur. Less technically, even if something is invented, it still exists (at least for us.) Third, as far as time-travel, it is a theoretical possibility. The reason why it can be spoken of is because of the curvature of space-time due to gravity. I am not a physicist or a mathematician, but I'll try to say what is usually meant as best as I understand it: what is the shortest distance between two points? A straight line, right? Wrong. Take a piece of paper and draw two points on it. Now, fold the paper so that the two points line with each other and stick your pencil through the coinciding points; they're right next to each other as opposed to however far apart the points were originally drawn on the paper. This is the basic idea behind high-speed space-travel, and evidently time-travel. Fourth, a thought experiment: Let's say we're going to meet each other for lunch one day. How many coordinates do you need to know to appear at the event of having lunch with me? Or, differently, listen to the Choral Fourth Movement of Beethoven's Ninth Symphony. If time doesn't exist, why do we receive, or rather how can we receive the melody into our ears as it is played and not just all at once, in a single burst of tone? If time did not exist, but other things in our reality remained the same, would anything CHANGE, and if so, how? Change only occurs over OVER TIME, or in time.