Those are all very interesting opinion on time travelling! I've had fun reading what's people opinion on this topic.
@ Xyzapy, I agree that it would probably go wrong if human have the ability to travel time, but we've invented many things that was original good but ended up being used against ourselves (for example weapons) because of us human beings. Multi-verse interpretation is a very interesting argument, from my knowledge and talks I been to, multi-verse means that every possibility is possible and happening in different world, apparently they're "parallel" to our time frame as we interpret it, but I certainly think that if every possibility is possible, then surely time travel different in "other universe" too no? But that's just my interpretation and impression of what I get from multi-verse, and I certainly think that there will be infinite amount of those "parallel" world if all those possibility are explored, but I don't strictly know whether that will be "time travelling" in a sense, but with multi-verse it certainly won't cause time paradox as to compare with out time frame as far as I'm concern, it might messed up their's but not ours. To be fair, I guess you're right that mistakes make us how we're and what we're not, correcting the decision will probably change the history completely, but only the one who time traveled will know as he is the only one with that memory. And yes, as I was talking to my friends about this, we did at one point came to the conclusion that it might be too hard to use human being to interpret/process such thing as Time. But anyway, very interesting and thanks for being the first one to reply.
@Ayanochanmk2, well with the situation of time travelling, only that person will know because you'll be the only one who possess the knowledge of what so call future? As for the "world" to be messed up, it is only to your very frame of reference because you have the memory of what "things" should be, but in fact you just created new things, where everyone without that memory will interpret it as a normal whereas you interpret it as "weird" as this and this suppose to happen in your memory. In fact if you alter history, or more precisely rewrite history, the world won't mess up, it will just carry on in a different way. But no, you can only rewrite history to a certain extent as once you change one event, another might be different follow from that event, as let's say CaoCao did win RedCliff, then other battles might not follow on which lead to the dead of certain generals such as Zhou Yu might not have to face Zhuge Liang which won't ultimately causes his death, so therefore you will only be able to change a couple of events in "history" but the rest will be a new future to you as well.
@Corocoro, Yes, but I believe that's wrong as well, because multi-verse traveling, you're technically strictly speaking not time travelling, but just travelling to a "parallel" world where same history might have happen with minor changes that you don't recognizes, so therefore having say that with multi-verse setting won't cause time paradox not exactly a valid reason, as you're not even dealing with time. But I doubt it would be dimension travelling? As you're not travelling to a different dimension, in a sense it is technically impossible for a "lower" dimension existence to travel to a "higher" dimension as there will be an extra "plane" that the "lower" existence doesn't possess, so therefore rendering the idea of dimension travelling a bit weird in my opinion. But you're right about you won't know the future anymore, as it will completely be rewritten, but you're the one who write the story, so if so then you can talk about all those knowledge that is yet to be discovered, so you could even possibly advance human race in a much quicker pace than we do now, we probably will be able to have a much higher understanding of science if we start with what we got now in two thousand years ago, then our interpretation of time might be a lot different in year 2010. (or equivalent time spent)
@Neo-Exile, Haha, fair enough that you don't really want to travel into the future and find certain things out, some thing are meant to be kept untouched. Well to be fair, you might have a different point of view in the future if you happen to really regret yourself, you might enjoy your life style now but you might really hate it in the future want to change certain decision you have, but that's just a possibility, as many of us have agreed that it will not effect you, but most likely everyone surrounding you or in worse case everyone in the world. It certainly won't make sense if you go back and kill your ancestor, actually just you going back will probably be enough to rewrite the history and create a time paradox the moment you travel "backward". But it is interesting that how do we "travel" back into the history that doesn't actually exist? I mean taking from the point that this second I'm writing this post, but next second I might be not writing this post anymore, so how exactly do we go back to that second that is already lost? It is technically impossible unless somehow those history is contained in storage device to "contain" those information, otherwise how do you suppose to see something that doesn't exist anymore? xD But it is a nice idea to think about going backward. Well what will be the fun you ask? Well I should probably rephrase the question as I don't really mean "Near future", but future where your age won't let you to see, like 200 years from now, do you want to know what happen? I don't know, certainly you probably won't live that long with the technology and life cycle human have at the moment, but who knows where technology will be in fifty years time when average life expectancy is probably 200 years plus? Though I would like to ask you this, how do you time travel into the future when it doesn't exist yet? Like the next second of me doesn't actually exist yet, then how do we even travel into the future let just a years time when technically it doesn't exist? So won't it be true that if we can time travel, then there will be no future but you're travelling into the past of what it happened already? Is like reading a book, you cannot read page 301 when the book only goes up to 300 can you? So there must be something there for you to "Read" before you can "read" it. Haha, I won't call you old school, is your opinion and I respect it, I think it is a perfectly valid opinion just like everyone else because this is what make use unique, the way we think and the way we express to certain thing that is propose to us.
@Kou, Well because we know little about it, we can't really say whether we like it or not I guess. It will certainly effect other people if you change what happen in time, not just yourself as people you interact with is part of that "time". Technically no matter what you do, the moment you time travel you have likely to have effected someone already, even if you might not realize it, you've. I like your answer on whether there will be a future or not, certainly a lot different to people, but if possible I would ask whether you could expand on that a bit more please? Well like I said again that I phased the question really badly, and I should be talking about future where your age won't allow you to get to, will you want to see the future in about 200 years time? I personally would want to see that my body won't allow me to see. Is good to be happy with what you got, and appreciate it, otherwise you probably won't be the Kou we know now. I'll be watching out for that anime, thanks for the suggestion.
@Paladinoras, True true, we might not want to change it, but it is just a question where at the end of the day, you kind of ask yourself, have I done it to the best that I could moment in your death bed. You know, I'm just curious of what people's opinion on it, there is certainly no right or wrong answer, but matter of opinion. Well I don't know, we learn from experience and if we just keep going back to change it, we'll never learn will we? You'll make that terrible mistake again because you'll know you can change it, just like how we write in pencil, if we know we can change it, we're more likely to make mistakes where as if you're using pen, when you know you can't change it then you'll be a lot more careful and make a lot less mistakes. Emiya Shiro regretted his life because what he saw as an ideal was nothing but an ideal in the end, but his opinion did change in the end, so our opinion might change just like him. I don't think so, you'll create a different thing if Multi-verse were to exist, because will only be able to mess with the current time frame and not other time frame unless you're universe travelling, because you've just introduced a possibility of new option to this universe, it will certainly impact the other universe as new possibility will probably also happen there, but in a different time, so you don't effect the time flow of different multi-verse but only this one, as multi-verse suppose to be separate to our one. Well like I said again, I do mean travelling in 200 years time where you're unlike to see the that time when you have died already, not near future (if we forget time paradox of course, but time paradox just makes things more confusing xD). Is good to hear that you're please with yourself, not a really greedy person, hopefully there is more in this world but then the economy might get upset xD as we rely on people to make and spend money in order for the economy to flow.
@Firev1 Interesting idea compare with the rest, but why so may I ask? I don't think you'll have created a parallel world, you've just wrote a new history where you will be part of that time's history, but like I said, how do you go back to someone that disappear and long gone already? But this is just intended to be theoretical discussion so it is fine for your opinion to be theoretical.
Thank you everyone again for reading and think about this post, I appreciate it and had fun reading and commenting everyone's post, it makes me think of things that I might have missed out and trigger me to think in a different way. Hopefully my opinion have not offended you and I just gave it to the best of my knowledge, so if I'm wrong then point it out and we can discuss.