Time's a complex matter as it can be defined in several ways:
- As a dimension, it is counted as the 4th, as it can be used to quantify the difference between two seperate entities. For example, length, if yeu have two identical objects, the definition of length can be stated that they have a different value for their Z axis, or that they are located on different locations on the Z axis. Height would correlate to Y axis, and width to the X axis, which's how we can see 3d objects. However, how do yeu define the same identical object, that is in two seperate places? Time is used to quantify that it is not an infinite number of identical objects in an infinite number of locations, but instead the same singular object being moved from one location to another over T amount of time.
- This gets interesting though because various things can affect 'time' so that it's not a steady linear flow... at increasing velocities, approaching the speed of light, time for the observer is slowed proportionately, until at C, light speed, time ceases to function. This can also occur with supermassive gravitational anomalies (black holes). Several other oddities may also change the value of time, such as excessive temperatures down to 0 degrees kelvin, though the effect of that is difficult to ascertain, if any is to be had. As the speed of light is a form of energy, and energy does bleed over in multiple forms, from luminescense to thermal, kinetic and so on, time is often altered in the same way, and may in fact double as both a form of energy, AND as a dimension simultaniously. There's also the possibility it may also have a subatomic particle form, if we go with the current M-theory, the most current form of superstring theory at the present, in which case 'time' is just a string, like any other, vibrating in a particular way.
- There is a quanta of time, as in 'the smallest possible'. This means that yes, there is technically a clock-tick cycle to the universe in a way. The thing is though, that this 'quanta' of time, doesn't truly match the definition, despite that it was called such. In practice, whot was actually done, was assumed the smallest possible relevance of distance (there's a set distance of which beyond this point, standard rules of the universe apply, under this value however, yeu basically are in the realm of quantum mechanics where everything goes a bit screwy), and then assumed that for this set distance, to take the fastest possible velocity (speed of light) and figure out how much time it takes to go this distance at that speed. Essentially, time DOES exist beyond this in smaller increments... yes, yeu can have a half a section of this quanta, but honestly it doesn't matter. If yeu took that half-a-quanta, technically it would be half the time, but during that timeframe, nothing of any relevance could actually occur, because the only things that would occur on that scale would have to be at the quantum level, and then they don't interact with time normally anymore. So yes, there's technically a quantum of time, but it doesn't really exist as a 'hard' fact, it's sort of a soft one because it exists in practice, but not in theory. Or the reverse. It's hard to define because of it's bizzare properties.
- Furthermore we're left with a disturbing question; we have dated the origins of the universe to a particular point in time. Now this means the universe is X years old, I don't know the most current value offhand, and my browser's been crashing alot lately so I'm not going to go looking for the trivial number as it honestly doesn't matter in this context. The point is that the universe is a set value in age. The QUESTION that develops then... is how did time exist before then? It can't just have STARTED and NOTHING existed before, even if we assume the presence of god, then whot? How did god "do" anything without time to allow for something to occur? Or does time 'truly' exist, and everything's instantaneous to a godlike being because they are not constrained by the value of time as we see it, as it only came into existance as a form of energy along with the other particles of the universe? I could go on about this all day, but yeu get the idea, there's alot of complex stuff to start working on, because if time DIDN'T exist before the origin of the universe, then HOW did it ever start in the first place? Time didn't exist, so there was no way for anything to actually OCCUR due to the lack of distinction of a singular object being in two seperate places. In which case either all the matter and energy of the universe was everywheres at all times, which assumes until viewed, in which case one could argue that "god" didn't really 'make' the universe so much as accidentally glance at it and by viewing it, forced it to decide via schrodenger's cat where all the materials in the universe were. But if that were to occur, then there had to've been a point where it HADN'T been viewed... in which case we're stuck with the even more bizzare concept that time MUST exist before the start of the universe in some strange way we can't even begin to grasp.
- Time also is related to the individual, and is not a set value, being able to simultaniously be two seperate values for two individuals at the same time. "Time flies when yeu're having fun" is an easy way to understand this, but on a more complex scale, it can go reaaaaaaally weird... let's say yeu're standing by a railroad track, and a train goes by, traveling just under the speed of light. There's a giant axe attached to the roof of one of the rail cars, and someone was walking through a door just as it swung down at them. As the viewer, motionless from the aside, yeu witness this event (ignore the fact that it's going so fast yeur eyes couldn't even see it), and for yeu, time is traveling at an enormously rapid speed. Due to this, the axe goes faster to yeu, than to the person witnessing it on the train itself, as they're moving relative to the axe itself. Because of this discrepency, it's bizzarely possible for the person on the train to be cleaved in half from yeur perspective, yet at the same time for them to dodge it in theirs. Weeeeeeird stuffs.
- Furthermore on the matter of gravity, or specifically, that of a black hole's event horizon. The event horizon bends time in a strange manner as well, let's say yeu have a ship being fired into the event horizon of a black hole... at some point, to us the viewer, it crosses over that point, light itself can't pass this point, so we are therefore incapable of viewing it ourselves, it just disappears into darkness. But we know that because it disappeared, it has crossed this threshold. The problem is, the person on the ship never actually reaches the event horizon. Time is distorted in such a way that each second is worth half as much, over and over and over, for a simple analogy. Every passing moment, they get 'closer' to the event horizon, but time is extended each step as well, not to mention that space itself is distorted. This means that even though they're getting 'closer', the distance they percieve as having to travel is increased, and the time it takes to reach the next distance is increased as well. They can get closer and closer and closer, but it's just going down halves each time as the easiest way to explain. Yeu go 1 unit, then half, then 1/4, 1/8, 1/16, 1/32, 1/64, getting infinitely closer to 0, but never truly attaining actual nil value. As such, the person percieving it from within the ship, is basically doomed to an eternity of getting closer but never actually reaching the event horizon. They are capable of going through billions of lifetimes watching themselves getting closer, but shall never actually reach it. Whereas to the outside observer, it happens relatively quickly, and there is a difinitive point at which it occurs.
- Due to this, time is a really weird concept, it can have multiple values, at the same time, for multiple people, it can be stopped, slowed, hastened, but as far as we know, not reversed. Toss in such joys as the grandfather paradox (going back in time and shooting yeur own grandfather before he has kids, meaning yeur father isn't born, and subsequently, neither are yeu, which means yeu were never born to commit the act in the first place O.o ) though honestly I don't see why they didn't just call it the father paradox instead of grandfather... but anyways, the thing is that time is capable of many states at the same time, is a particle, energy, and dimension, all at the same time as well, and behaves in ways which just shouldn't be possible of occuring, and even has a quanta value, which isn't even accurate to the description of quanta, it's just the point at which time doesn't have any practical value on the standard view of reality and goes all wonky in quantum physics.
So yeah, time is seriously screwed up beyond imagination. And here is where I point out one of my favorite quotes. "It only makes sense that reality is stranger than fiction, after all, fiction has to stick to possibilities."