Most likely due to my love of Back to the Future at a young age... I have always been fascinated by time and time travel. I read books about it and even tried to "build" a time machine in my closet (at age 7, of course). I even checked out time travel novels from the "Sci-Fi" section at our elementary school library and the local public library (yeah I was a nerd as a kid...).
This interest in time was re-invigorated in my senior physics class in high school when we started to learn about Einstein's Relativity theories... in particular Special Relativity. In a nutshell... one aspect of his theory states that the consequence of the speed of light being constant regardless of reference frame is that time is relative. That is, the rate at which different observers pass through time can be, and in fact is, different.
This effect is all but un-observable in normal-day contexts, but as velocities approach the speed of light, the effects of this "time dilation" become more evident. These effects have been observed in a multitude of experiments and its effects are exploited in modern communication devices like GPS and other satellite systems.
Einstein's theories provide a very predictable and accurate description of time experiments in all domains. But something I've always wondered about is the general perception of time.
Both Newton and Einstein's description of time base it on the fact that time progresses from the past towards the future... and the current point in which we occupy is the present. But what if that description is merely our perception of time, but is completely inaccurate as to the actual description of time?
Reality Check
Before I go any further into this ridiculous entry I think it's important to note the futility of trying to determine the accuracy of perception. The world is what we perceive it to be because that is the only means by which we have to observe. It is by this fact that we will never know whether or not our perception is accurate. This is a weird thought and pretty damn hard to really grasp... but think about simple situations.
If you see a ball on the ground, how do you know it is REALLY there? We perceive it to be there because light bounces off it and is focused to the back of our eyes, causing a chemical reaction that signals our brain to "see" an object. We don't actually see the object but rather the effects of the object (in particular, the chemical reactions to the photons that bounce off of the object).
That being said... let's continue!
Linearly Progressing Time
The way in which we perceive time, and the way in which almost all scientific contexts describe time, is as the independent variable. It progresses continually with our without our permission. One way to describe time in this interpretation is that it is linearly-progressing and single-dimensional.
This "interpretation" of time is the most natural, and is built into our minds intrinsically. Based in this context, the past is over and done with and never to return, the present is right NOW, and the future is unknown and yet to happen.
An Alternative Idea
But what if the concepts of past, present, and future are just manifestations in our mind? Maybe chronological ordering isn't something natural but rather a false construct used by our minds to make sense of something more complicated. It's possible that instead of such definitive descriptions as "before" and "after", that collections of events are far more general.
One could even go further to say that it is possible that time itself is a complete fallacy, that in fact all events exist at once and everything that is to happen, in actuality, already exists. Concepts such as causality and simultaneity dissolve because, in fact, no such framework (i.e, time) is available for these concepts to hold any meaning.
Further consequences of this concept would be that the past, present, and future are all the same: the past is no more gone than the future is unknown, and the concept of the "present" is completely arbitrary.
Pushing Einstein's theories around a little bit seems to even slightly suggest this: another consequence of his theories about relativistic time and length is that the concept of simultaneity is relative as well. That is, the fact that two events are held to be simultaneous is relative to an observer.
Observer A can say Event X happened at the same time as Event Y, and be correct, while Observer B can assert that in fact they happened at different times. Given the relationship between their positions and velocities, they might both be correct, within their own reference frame.
Going a little further, one could suggest that given any two arbitrary events in spacetime, there exists some reference frame from in which those two events can be correctly held to be simultaneous to a given observer. This suggests that both your birth and death can be seem as happening at the same time... given the correct reference frame. Another way to look at this is to realize that an observer in another reference frame could have witnessed events that you hold to be in the "future" before you've witnessed them. This suggests that your death might have already happened within somebody's reference frame.
Combining that extreme perversion of relativity with the notion that time is not what we perceive it to be... we arrive at some interesting conclusions. For example: the future... as much as it might seem "free" an up to you to determine... already exists and in a sense, has happened. In fact... this would mean that every action/choice/decision you seem to make within your own means is already set and is as concrete as something that happened in the "past" and is already done.
This can be thought of as instead of living in the present and determining your own future, your mind is simply trying to digest the universe, and in doing so, creates the illusion of time to better understand it.
What the hell??
The above is posed more as a thought on which to ponder than an actual stating of a theory or anything concrete. It's an interesting example of the complexities associated with time and the concept of perception vs. reality, and just overall some weird shit to think about. So don't flip out about it... just read it over and let it marinate in your mind for a while... or talk to your buddy about it next time you find yourselves jasterbatingly pussy-footing around on an otherwise uneventful evening.
This is all for now, congrats if you made it through my first "deep post"... if you have anything to add feel free to comment... otherwise... I must bid you adieu (thanks geoff).
-B. Valosek, relativistic inquisitor