What is the Present? The apparent motion of time in one direction, apart from an apparent asymmetry, leads us to the obvious question of how do we describe the past, present and future in a meaningful way. Do these different "times" actually exist as separate things or are they an illusion created by our minds. The best evidence is that the present does exist as an independent physical entity. It must, otherwise there would be no way for our our minds to differentiate between it and other times.
But if it does, what is it? It is the forward edge of the time component of space-time. It contains a perfect record of all past and present events and objects and it constructs the future based on that record. In that sense, the future, while determinable by the present, does not actually exist until it becomes part of the present and then part of the past.
The present is a meta-mechanism. It is a continuously self-revealing feature of the underlying function of the universe. The present is an actual feature of existence, and not a product or bi product of our neural functions. There were photons prior to the evolution of our visual senses, and sound waves before human hearing, and electromagnetism before the invention of the telephone. There was a present prior to the evolution of our present-centric consciousness.The universe can be thought of like a mind. The past is a perfect memory of things that came before. The present is like a consciousness referencing those memories to predict what will come next. As those events pass, the present retains them as new memories with which it constructs the next prediction of the future. The memories themselves are the actual physical states of the objects in the present. They perfectly reflect all the prior events that led to their present state. The present must actually contain all the information of the past or access it in order to allow for determinism and causality.
Time is a fundamental part of our physical universe. We can trace its existence as far back as the big bang. The present takes all the information from the prior moment and constructs or gives expression to the present based on those prior conditions. It then takes the current conditions and produces the new present as the now-former conditions become the immediate past. In that sense, the present and past do exist, but the future does not. It is predictable, but does not actually come into existence until it becomes the present. However, if the universe is deterministic, since the present would be required to contain all the data (or be able to access the data from... somewhere) in order to determine the future, then the future, or at least all the information required to predict it does exist in the present. In this scenario, the present has two functions. The first is the storage of the past and the second is the determination of the present and future.
If the universe is deterministic and if causality is a fundamental feature of the universe, then the present must contain a perfect record of the past or the present and subsequent "presents" would not be coherently connected to the past. The Universe is real. Our observations are not required for things to actually be. They either are or they aren't. If they are, then they arrived at that place at that moment in the universe by a process of successive events. If the information from any one of those events were lost, then the present would not be causally related to the past. Over time, that "gap" in causality would continue to grow until the Universe were grossly unrelated to the past and ultimately causality would cease to control the present. If there is causality, then recording prior events is necessary.
Consider a billiards game. The present sweeps along until all the features of the game's beginning are in place. The players have arrived, the balls have been racked and the cues have been chalked. Now the moment arrives when a ball is struck, it bounces off of one rail, bounces off a second rail and strikes a second ball. The second ball rolls along until it falls into the pocket.
Now breakdown the significant events in this chain. First the cue strikes the first ball (Event A). The ball absorbs the kinetic energy of the cue and begins to roll forward at a speed and direction imparted to it from the interaction between it and the cue. It rolls until it strikes the rail (Event B). Based on the speed and direction that the ball is travelling, it rebounds off the rail, slows as some of the energy in it is absorbed by the rail and continues in a different direction. It then strikes the second rail (Event C) and the same type of interaction as B occurs. The ball continues to roll until it strikes the second ball (Event D). The second ball now begins to roll according to the speed and direction of the first ball toward the pocket. When the ball reaches the lip of the pocket, gravity, which has been continuously trying to pull the ball closer to the earth, but has been continuously foiled by the felt-covered table top, has its moment and pulls the ball down into the pocket (Event E). When a player later looks down into the pocket he or she would see the ball there, where Events A through E have deterministically left it.
Each subsequent event is reliant upon the prior one. If the record of the previous ones were to go "missing" as the present arrived at the time of the subsequent event, the present would be unable to coherently express them. Remove the record of Event A, and ball wouldn't be able to arrive at Event B. The present continues to roll forward, but there is now a causal gap between reality and what causally should be. As we arrive at Event C, now without either A or B, Event C becomes impossible. As each subsequent event is missed, like an unravelling fabric, the gap between what was determined in the first strike of the ball by the cue would grow until the present would be completely unrelated to the past. The only way that determinism and causality to hold is for them to hold completely.
For a contrary view, read Amrit Sorli's piece about time as an illusion, here.
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