The real question is about 'Time' itself; does time exist? Time travel; it either can be achieved, or not - there's no 'sort-of' about it. The larger issue really, is DOES TIME REALLY EXIST as we have been taught? Our sense of 'time' is really nothing more than a name given to our witnessing events in a 'linear' way. TIME (according to the greatest thinkers and physicists) does not really exist in an absolute verifiable way, but is instead a subjective choice of perception that we make from an early age. Mystics and avatars have hinted that upon meditating their minds to stillness and eventual enlightenment that everything that will happen already has happened and that there is no linear progression of time outside of our habitual thinking it to be so. If this is true, there is nothing necessary or missing from ourselves except for the realization that there is nothing we need to find, attain, or become beyond what we already are. Such an overwhelming truth would be more than most of us could handle, thus the 'agreement' we've made to participate in this 'linear' reality (spiritual pre-school) as long as it takes for us to wake up to what is. The idea of going either backwards or forward through a reality that is not truly real is preposterous and full of ego. What would the purpose be of such a journey? Furthermore, if we truly could travel to a distant 'event' or possible future event, our witnessing of such would indeed change that reality, and if we could change such things it would no longer be the 'past' but another present, or a new future that would be opposed to the 'future' that would have presented itself before our journey. Which 'future' would be 'real' and which one would become obsolete? If such travel were possible and one could 'alter' past or future events, future warriors would be running rampant throughout history 'altering' events to suit their political whims. One day we would awaken to a 'reality' that could involve the victory of Nazi Germany and the subsequent world that would entail, the next day we could wake up to the reality that we are now being bred captively as a food source for dinosaurs that did not die out. Time travel through a 'changeable' time-environment would be constantly changing and re-changing, voiding the idea of a true point of reference (past) that was stable. If time travel were possible as many movies have tried to claim it is, nothing would stay the same for long and we would be constantly on the verge of massive upheavals that would feel like a nightmare we could not awaken from. What I believe is more likely is that time is not objectively real, but a subjective experience that can be 'altered' (within our own minds) by our choice or manipulated by outside forces. As postulated by mathemeticians, there MUST be other dimensions, realities and worlds that occupy the same 'time' and space as ours. Rather than travel in a linear fashion through time, it would be thus only possible to 'shift' between these alternate realities either willfully or accidentally so that the observer may mistake an alternate dimension as his 'home' dimension and assume he has traveled to another time/place, instead of sideways, into another dimension entirely. I believe all of us have seen these other worlds during sleep and possibly through mind-altering induced trances. (Of course, meditation offers another way without the chemical side-effects.) The beings in these worlds we've glimpsed would be as 'real' as you or I, and would probably be bound to the same thought-limitations from their upbringings, just as most of us are in this 'world'. If this theory is true and everything that has happened already has and we are already realized fully and completely (as the Buddha realized), then all things, all power, all potential, and all creation is already before us, around us and within us, and we already are complete in all possible ways. A heavy idea, I know, but something tells me it's the truth. JUST BE!