Interesting thread. I'll drop my piece.
To me time is classified as the motion of existence. Everything has a specific 'rate' at which it happens and we as observers are intrinsically part of that. Energy oscillations moving at different rates cause the different forms of sensations we pick up through the organs attached to our central nervous system. "Time", to me, is an internal abstract tied to our minds construction of sensory input into a subjective perception. Time being the acumulative effect of the collective (or 'relative') rates at which all the different aspects of existence manifest and interact based on causality, as experienced within the axis of causality from an individual perspective. (Time/ordering of events is always
slightly different to two different observers.)
I believe we use the term 'C' (light speed) as we see the rate of light's interaction with physical space as being the most 'instant' aspect of the observable universe, ergo, it as a constant (allthough it may not be). The way of looking at relativity is: If you were traveling along with a single beam of light at the speed of light, you would not see it as a wave, but an oscillating photon. Ergo relativity. Things exist in an observable state relative to the state of the observe, the state of the object of observation being relative to the state of the observer in relation to the thing being observed.
Light emits from a source and bounces off an object, hits your retina, a charge shoots down your optic nerve and triggers an area of your brain adding to your experience. This happens at a specific rate. So fast, we class it as a constant so it is something all sentient beings can relate to and there-for use as a benchmark.
Sound moves slower than light but follows a similar pattern, we have evolved within a system of causality that interacts at specific rates, therefor our sensory instruments have evolved to be tuned into these rates. the internal construct of our experience of existence is based at these specific localities of the rates at which all of these atributes of existence manifest. Be it sound/sight/touch/smell e.t.c.
Space-time comes into the equation by stating that space and time are intrinsically linked, moving faster through physical space would mean altering our experience of the rates of these forms of oscillation of different aspects of existence, this would change our experience of reality. Relativity. (think the doppler effect or Red/blue shift)
Objectively speaking, it takes an amount of time for the light source to hit an object, bounce back and hit you in the face. If we were all moving near the speed of light and all observing the same thing from different localities, moving at different rates and different vectors, we would experiences the order of what we were observing differently because the light essential to our construct of observation would reach us at different times, and would have interacted with different aspects/temporal moments of the observed object as it changes. (Relativity)
Space curvature, to me, can be explained when you look out at the night sky. The further (theoretically) you look 'back' into the sky, the further back in time you are looking because it has taken the light longer and longer to reach you as it has had to travel further and further, but the universe is expanding, so as you look further back in 'time', you are also (theoretically) looking at 'possitions' of space (relative to the axis of time you have observed 'back' into) that don't exist 'in the time they are' in the place you are observing them to be in. Relativistically speaking, If an observer were at the possition of space you were looking at, and at the possition in 'time' you were looking back into, they would experience themselves as being much closer to the center of the universe, and in a much earlier age of the universe. To a point that even though you are looking straight out forward, away from the center of the univers,e you are looking at a part of the universe that is relatively speaking 'behind' the earth, millions of miles in the opposite direction.
The curvature of space time.
This is all obviously my opinion and probably complete bollocks
Now time 'travel' is an odd one. I believe its possible, you have to remember that light is an atribute of the construct of experience and the universe is existing within the axis of causality within the totality of the universe as a whole. Just because we are constrained to observing a finite distance (and time) away from our locale, does that mean that we are too constrained theoretically to physically moving to further points in space and time than we can observe, faster than our current model states is possible? It's not hard for me to believe that theoretically things may be able to move from one place to another faster than the current constant of our modal of understanding the universe. If someone were to time travel, as a human, they wouldn't experience the traveling, but i believe it would be theoretically possible to move 'physically' beyond the constraints of 1 light year of distance for every light year of time. Of course that would mean moving faster than the speed of light, but the way I see it is that you would also inevitably have to move an immensly great distance to carry out that 'time travel'. Time travel to me isn't something you can sit in a pod in one place and do and you certainly can't travel backwards through time, it to me is a movement through physical space beyond the constraints of our current physics model, where you would reach a physcial destination far earlier than you would have having followed current conventions.
I think 'time travel' is miss understood in that respect. Of course, thats just regarding basic conventions. Taking into consideration extreme space-time curvature, worm holes and higher dimmensions, we have a much larger scope of possibility, which of course only strengthens my argument of a decent theoretical possibility of 'time travel', given that the deffinition of that term is of course relative.
