@Alex - while I do condone the action of looking up words in a dictionary it is not necessarily the best way to get definitions of words. Remember, when we discuss time in a "philosophy and humanities" forum we need to define time within that framework. The dictionary definition is a basic, no-frills, everyone-can-understand-it sort of definition.
I think you are confusing physical time with sociological time. Our sense of time passing is indeed subjective, as you point out. Throughout human history, we have learned to measure time as it fits us on our globe, relative to our surroundings (tidal powers, orbits, solar cycles, planetary movements etc).
Yet it has been proven that speed and gravity change time. If you were to live your life on top of Mt Everest, an extremely accurate atomic clock would show that time is passing at a slightly different rate than it is at sea level. The reason for this is that time is relative to the observers speed and place in space.
We have absolutely no evidence that it is impossible to travel back in time, just like we have nothing but theorems stating that it is possible.
@Lord Henry - it is not necessary to point out anyone's age or school grade. Everyone is welcome to have their own point of view and discuss them here. As is you!
Tormod
