1. Traveling forward in time is actually quite easy and not impossible by any means. Just go very fast and relativity takes care of the rest.

Traveling backwards in time is trickier, but there are many suggested ways to how this would be accomplishable. For example through a wormhole which not only is connected by to points in space, but also by two points in time. To be able to pass and also return, you'd need a transversable wormhole, which would require negative energy. This the most promising design for an actual time machine. Sadly it requires so much energy (like that of an entire galaxy) that we aren't even close to be able to construct one. This kind of time machine would also only work back to the point in time when it was built. This would solve the problem of time travelers not visiting us all the time.

Stephen Hawking said "time travel may be possible, but it's not practical".

2. This kind of time machine would also only work back to the point in time when it was built. This would solve the problem of time travelers not visiting us all the time.
You're talking about making a bigger one?
You're talking about making a bigger one.

Anyway, I see time travel as like 3D television: The novelty would wear off.

3. But it's not 1900 anymore and it's not television it's time travel
I think you're missing his point.

Like, entirely.

4. Can you scientificly prove that it is impossible? No. Therefore, the possibility of time travel exsisting, is there.

5. Can you scientificly prove that it is impossible? No. Therefore, the possibility of time travel exsisting, is there.
Can you scientifically prove that it is possible? No. Therefore, the possibility of the possibility that time travel can't exist, is there.

6. Can you scientifically prove that it is possible? No. Therefore, the possibility of the possibility that time travel can't exist, is there.
No. With proving something impossible, there is still the WHOLE universe(s) to explore. Trillions upon billions of things to invent and discover that could render something that we once thought was impossible, possible.

7. Just because X can, doesn't mean it does. It's a possibility, not proof.

8. We can already timetravel, the thing is, we can't go that far. We can only go about 0.000001 seconds ahead in time.

9. Can you scientifically prove that it is possible? No. Therefore, the possibility of the possibility that time travel can't exist, is there.
..What? Our known scientific laws and principles allow for the possibility of time travel, therefore, time travel is possible.

10. We could find out who messes up the future and shoot them now. But seriously, I think they have to create reference point first, you can't just go back to any time you want like 1955.
Are there any physicists that help here?

11. That's backwards thinking. Do you also believe in ghosts and unicorns and other things that haven't been disproved?
Narwhals. As for ghosts, no.

12. Can you scientifically prove that it is possible? No. Therefore, the possibility of the possibility that time travel can't exist, is there.
Can't as of right this second, but it's the same principle of flight. People thought it impossible, but now we have planes.

13. Can't as of right this second, but it's the same principle of flight. People thought it impossible, but now we have planes.
You do know birds fly right

14. Replace the word time travel with television back in the 1900's and you'd get the same replies.
What paradoxes would occur from Television?
With time travel, you could cause things to happen that you know would happen because you went back in time to cause them. Like, let's say when I was little, I was given a book by a stranger, and I used the information in the book to better my life immensely. Later on, I get a time machine, so I take the book back in time and give it to the younger version of me. Where does the book come from?

Not only that, but what about going back in time to say, stop Hitler? It's doomed to fail since Hitler did what he did. If you succeed, then Hitler would have always been stopped by a time traveler, and you would have no need to go back in time to stop him, because someone did it for you, meaning you would not go back in time to stop Hitler, meaning Hitler never got stopped, and so on and so forth.

15. What paradoxes would occur from Television?
With time travel, you could cause things to happen that you know would happen because you went back in time to cause them. Like, let's say when I was little, I was given a book by a stranger, and I used the information in the book to better my life immensely. Later on, I get a time machine, so I take the book back in time and give it to the younger version of me. Where does the book come from?

Not only that, but what about going back in time to say, stop Hitler? It's doomed to fail since Hitler did what he did. If you succeed, then Hitler would have always been stopped by a time traveler, and you would have no need to go back in time to stop him, because someone did it for you, meaning you would not go back in time to stop Hitler, meaning Hitler never got stopped, and so on and so forth.
That's why you shouldn't give something that can travel time to an idiot.
Besides, it's amazingly easy to go fowards in time/accelerate the passage of time, I can think of many ways. Traveling backwards would obviously be much, MUCH harder.

16. Backwards, no. Forwards... plausible.

I personally believe in the theory of Cyclical time. That is: When this universe dies another one which is exactly the same takes it's place, with all the same happenings and events. The theory sounds ridiculous but, hey, it clears up time travel paradoxes if you only travel forwards.

17. Isn't it possible to go back in time by going faster than the speed of light? (Which seems to be easier said than done.)

18. Yes, although as far as we know that's impossible for massive particles (barring the neutrino incident which has not been thoroughly analyzed yet) but using general relativity it's also possible without even having to go the speed of light.

19. I think it'd be possible to travel forward in time. But to me, backwards time travel is incomprehensible and I therefore don't think it's possible.

20. Stephen Hawking performed an experiment to "prove" his time travel paradox (if backwards time travel is possible, why are there no time travelers that have come back) by holding a time traveler party at his house, then advertising it in the newspaper the following day.

No-one came.

21. Stephen Hawking theorized, that if you were in a train, which went in a big circle, one meter/per second away from the speed of light, and if you started running up and down the train for two weeks, a year or so would pass for everyone else, but not you.

As well as this, he said that time travel backwards is impossible, because nobody from the future has ever came back to our times, and some other reasons as well.

22. Stephen Hawking theorized, that if you were in a train, which went in a big circle, one meter/per second away from the speed of light, and if you started running up and down the train for two weeks, a year or so would pass for everyone else, but not you.
Somehow I think you're remembering this wrong because A) Einstein theorized that, B) you don't need to run up and down the train. You can just sit there, and C) If you were on a train going 1 m/s slower than the speed of light relative to some observer for two weeks, over 400 years would actually pass outside the train.

23. Time travel is possible.

We are travelling through time right now.

*EDIT*

I dont quite understand the whole train thing.

If you put someone on a train and sent it at light speed, you would have to put them on it for 400 years, then they would feel like two weeks had passed?

So if you were to put them on the train, set it off, then stopped it in 2-3 days, it would feel to them like they just got on it, then it would stop seconds later?

24. I believe backwards time travel is impossible because if people in the future really use it, wouldn't it mean that they would live in the here and now? And if someone confesses that he/she is a "future person" wouldn't it cause panic and pretty much jeopardize all, formerly secret, efforts?

I also doubt the technology would be developed enough to prevent the user from aging backwards and maybe die of ..."young age"?

25. I don't think something in the universe constantly saves "states" of the entire universe so that we can access "the past" by travelling to it.

Where/how would these states be saved anyways?

26. I don't think something in the universe constantly saves "states" of the entire universe so that we can access "the past" by travelling to it.

Where/how would these states be saved anyways?
Alternate/Parallel Universes.

I think that the only way for backwards time travel to be possible, would be if there were parallel universes that you went to when you time travelled that were slightly behind. It would also mean you could kill your younger self without disappearing and a lot of stuff.

27. If time travel is or ever will be possible, where are there no time travelers walking around the Earth today from the future?

28. I've concluded that it would be possible if there was a machine that could take a snapshot of all particle positions and another machine that could arrange all particle positions. This would of course be impossible for obvious reasons, but my argument is essentially that all a time machine would be doing would be rearranging particles to a previous state. I'm in the works of writing up a piece that goes into the details of this.

I also get a bit into the idea of alternate universe, though I've only been using this phrase because I'm not sure what would fit. I try to define an alternate universe as any arrangement being outside the probability. A way to think of it is any arrangement that could not possibly occur within the past timeline would be a creation of an alternate universe. What if the particle arranger randomizes all particle positions. That would obviously not be within the same scope of the same universe we are currently we living in and in my definition of the word would be an alternate universe. If you were to take a snapshot of last week and go back then, but manage to include your current self in this, that would also be going back into an alternate universe. This is harder for people to agree with, but I'll make the point more clear in the piece I write up.

I don't at all keep up with this kind of stuff so my thoughts may be old, but they are original to myself at least.

29. No-one knows yet, this isn't a debating topic, it's a wait till we get more facts and see what happens topic. Nothing disallows it in our current understanding of the laws of nature, but that doesn't mean there isn't a rule against it that we don't know.

Edited:

Heck, we don't even know what time is.

30. I think the famous paradox of time travel can be avoided with a simple theory that is also relatively known.

The fact that if you were to time travel back in time, something would change, thus it must have always been like that, but if it's always been like that, then nothing would have ever changed which means you would have not gone back in time and changed it. Follow me? Of course you do.

Famous example: You go back in time to kill your grandpa. You kill him. But how? You wouldn't be able to exist if you killed him, therefore you would have never been born, and thus unable to kill him, but if you never killed him, there again you would be alive to go back and kill him.

Reasoning around paradox: When time traveling, you are not jumping back in time, rather still on a continuous forward moving stream of time.

Think of it this way. You are walking down a road. You walk into a restaurant. The place you are at/in changed, but time never rewound or shifted.

This being said, time travel would simply be a changing of position in dimensions or universe.

My conclusion: I don't think it's really possible to truly travel back in TRUE time.

31. As time flys, we all travel in to the future, that is a fact. Einstein's theory of relativity can provide us with a short cut trough time.

Lets say we have two twins. One is left back on Earth living a normal life, the other is blasted to space with almost the speed of light. Einstein's theroy mentined earlier, teels us that faster the object movies, the slower time passes for that object – this phenomenon is known as time dialation. Years later when the twin returns, she has not aged much, but her sister left back on earth is in her mid 70's by now.

32. Theoretically time travel, to the future is possible. I remember reading a borrowed book some time ago on this subject. It explained the entire process in a simple to understand matter.

There were two twins the same age, one was blasted into space with 99.9% speed of light, the ship she was on was programmed to return to earth after 3 years. She aged by 3 years, while her twin back on Earth was in her mid 70's.
I read about a REAL story similar to that. But there was a man who orbited the Earth in a satellite for like a year (not really a year, I just forget the actual amount of time) going at thousands of miles per hour. Supposedly he was like .5030 minutes or something ahead of everyone else or in the future.

I know that (theoretically) wormholes attach to the nearest point of gravity but w/e.

34. I've been thinking alot about this, but I think time will only ever go forward, and that nothing can be reversed.

35. The faster you get to the speed of light the faster times goes around you, then what happens if you have something (Or are) going at exactly the speed of light?

36. The faster you get to the speed of light the faster times goes around you, then what happens if you have something (Or are) going at exactly the speed of light?
Going at the speed of light is impossible. Therefore your answer doesn't have any practical answer. But mathematically, what would happen is that the moment you hit light speed, you would travel infinitely into the future. I.e. time would stop for you and the universe would age infinitely.

37. "Time travel" going forwards in time is entirely possible due to relativity and time dilation. It's a fact that satellites we drop into space need to have their internal clocks adjusted to compensate for time actually being slower for the satellites relative to our time down on Earth. Time gets faster the closer you are to a large gravitational mass (such as the Earth) and slower the farther you are from one as well. In theory, this means that we can ship someone out into space orbiting Earth from a very far away distance for say 10 years for them and when they come back 15 years would've passed on Earth. Those numbers are just examples of course, I know not how the actual ratio, but the concept should still be true. I do not, however, think you can ever go back in time under any circumstances. Similar to how its impossible to have a negative value for temperature in Kelvin, it's impossible to have a negative value for the progression of time. Even if you did find a place in space with absolutely no gravitational influence, you would never be able to go back in time, you'd only be able to slow it down (for you relative to Earth) enough that time would appear to be at a standstill. This does bring an interesting idea along though, a what if: If you found a place where time stood still, would time still seem normal to you or would you be trapped, moving so slowly you are unable to escape? Interesting concept, but unrelated. The point is: Time dilation could mean traveling forwards in time is possible, but never backwards.

38. Going at the speed of light is impossible. Therefore your answer doesn't have any practical answer. But mathematically, what would happen is that the moment you hit light speed, you would travel infinitely into the future. I.e. time would stop for you and the universe would age infinitely.
Wait, so if light travels at the speed of light then wouldn't the universe age infinitely around a photon travelling at the speed of light?

39. I recall my physics teacher explaining me, that because of thermodynamics, specifically the theory of entropy and how it can only fall or remain unchanged, time could only move forward.

Edited:

Wait, so if light travels at the speed of light then wouldn't the universe age infinitely around a photon travelling at the speed of light?
If you were a proton, time would seem not to pass at all.

40. Wait, so if light travels at the speed of light then wouldn't the universe age infinitely around a photon travelling at the speed of light?
The reason photons travel at the speed of light is because they're massless which coincidently means they are not subjects of time dilation.

Furthermore photons are not sentient and they cannot "experience" time in such a fashion. :)