kronin323
Font of Useless Knowledge
Ok, so I am more than a little out of my league here. Stupid question, but when you say time "moved" at different speeds for the different observers - does time actually move? I am certainly not up to date, but a good while back, I seem to remember that there were several different schools on the concept of time (which I am sure there still are and always will be). Is time linear, as in straight line? Is time cyclical, repeating? I have heard it described as spiral, too. Though we tend to view time as a measuring stick, time is actually much more abstract and complicated. I have heard it theorized that all time actually exists simultaneously - past, present, future. I can't even begin to get my head around that! That to me is up there with trying to imagine nothingness or infinity - simply impossible to fathom.
And as far as quantum mechanics are concerned, we haven't even scratched the surface - parallel dimensions and multiverses and the like...
I see you edited your original post of this - you had originally mentioned a lot more quantum mechanics stuff, which is a whole different beast, incompatible with the Einsteinian stuff...
Don't think of time like a car that you either gas or brake. Think of time like the road you're driving on. Time didn't move at different speeds for the different observers - the observers moved through time at different speeds. But to their own individual perspectives, time seemed to pass like normal.
As far as is time linear, cyclical, etc, I think most discussions along those lines with time as the only consideration are more philosophical than physics. The subject takes a more physical context if you consider all of spacetime (the universe), of which time is only one dimension.
The universe is expanding - there have been different schools of thought on whether that will continue forever (linear), or if it will eventually slow down, reverse and start contracting, eventually compacting down to the "big crunch", and then big-bang all over again (cyclical). If cyclical, that brings up philosophical questions such as, does time run backwards during the contracting phase (no); when it big-bangs all over again, will history repeat itself / are we doomed to repeat our lives with each cycle for eternity (by my understanding of quantum mechanics, no, but that's a longer story).
Those questions appear to be moot, though - in order to answer if it's linear vs. cyclical, scientists turned to observing the universe for answers. If the rate of expansion remains constant, then it would go on forever. If it appears to be slowing, then it will eventually stop, reverse, and crunch. What they found was the answer was neither - the rate of expansion of the universe is not slowing or even remaining constant, it is accelerating! Nobody knows why, but they've labeled the force which is driving the continuing acceleration as "dark energy" (which has absolutely nothing to do with dark matter, by current knowledge). We have zero idea of what dark energy is; the name is really a placeholder until we figure it out, if we ever do. But the point is, the cyclical model looks dead.
If you're asking more about the shape of spacetime itself (flat, circular, torus, etc), I don't feel knowledgeable enough about the subject to speak competently, even in layman's terms.
The idea that past, present, and future all exist simultaneously is also, I believe, more philosophical. It implies that the future is fixed, which brings up the whole "fate vs. free will" debate. We haven't really talked about quantum mechanics yet, but one of my personal takeaways from the subject is that the future is not fixed - quantum mechanics forces one to view things as probabilities, not absolutes. They don't become absolutes until they become observed in the present. I'll leave it at that for now. But for me, it means the future is not fixed; free will is real...
As I mentioned earlier, quantum mechanics is the most counter-intuitive science out there. Things like parallel dimensions and multiverses are attempts to model a reality that explains the "spooky" behavior found in quantum mechanics, but it's all just hypothetical - there's no evidence that anything like that is actually real. Also, with string theory, it requires there to be more spatial dimensions (total of 11 in the original version), but those other spatial dimensions are "curled" up too "tight" for us to move in them. Strings do, within the scale of Plank distance (the smallest measurable distance).
