Hi.
One area of this question which hasn?t particularly been touched on, it seems, is the subjective aspect of time. In relation to this my suggestion is basically that time travel, in a real sense, is impossible because we can not return to a previous moment of time in our existence. What this means is that once we have ?lived? a moment, an experience, that moment is gone forever, and can never be retrieved. The consequence of this is that it is meaningless to talk about ?moving? back in time because, for us, there can never be such a return to our past.
Consider, for instance, falling in love for the first time, this is something that we can only ever, it seems, experience once. It is true that we might fall in love a second time, but we can never have that unique experience of a first love again, and there is no possible ?machine? that could take us back to it.
Similarly we can never return in time to a unique moment of artistic appreciation or creation. The reason for this is that, like with love, its uniqueness precludes us from experiencing it again, even if we 'have' other moments which are similar. Furthermore other similar moments will exist in light of the moments already experienced and past, just as a second love might never be like the original precisely because it exists in relation to the first.
Moreover this is not something that just applies to unique moments of love/art but is something that concerns the whole fabric of individual human existence, and is indeed what defines it.
The conclusion of all of this is that, as we know we can never return to past moments of consciousness/existence ?time travel? in any genuine sense is not just an impossibility but, for us, meaningless. Furthermore, we know this not by dissecting the cosmos but by looking at ourselves, and considering what it means to exist in time.
It is imagined that time travel is possible though because time is abstracted from its relation to our subjective existence and therefore viewed, wrongly, as an objective property, like space, which obviously can be traversed. Further the paradoxes associated with time travel, for example someone fathering themselves, seem to arise from such misunderstanding of the idea of time, i.e as something we can move about in.
Moreover there appears to be a psychological desire amongst humans to see time as retrievable, as well as a strange fascination with the idea of time travel itself, hence this discussion. This may be because if we think that once gone each moment is lost forever, and that there is in a sense ?no rehearsal? and no consolation, each moment then assumes a horrendous urgency. In order to avoid this daunting sense of urgency we may construct any number of consoling illusions, one of which can involve viewing time as an objective property.
bye.
David