Time Travel Possible?

I think no. If time travel is possible, creating a time paradox would be possible and crash all of time. Example, killing your own Grandpa. However, something I personality think is that going in the past alone would in itself create a time paradox. If you travel back 500 years ago, stand in the middle of an empty grassy field, you just existing in that time would create a time paradox.

People think time paradoxes would only occur if something of great change were to occur. Where is the line drawn according the universe of big change? I think the universe wouldn't have consideration of how big the change is, and therefore all the big and small changes in time traveling, even if its as small as moving your hand and pushing air around in the middle of a 500 year old field.

I used to think time travel was awesome a kid but now I can't enjoy when the story mechanic is placed anywhere because they usually don't do it correctly. In short, I think time travel would not be possible and just crash upon doing so.

 

Why would you kill your grandpa? D:

 

The main reason I think time travel would be impossible is the fact that matter cannot be created nor destroyed. To travel through time would pretty much be removing matter from one "time" and creating it in another, though I could be wrong and traveling through time would essentially negate the pre-existing matter from ever existing...which I have no clue if it's possible to do so.

 

It's an example. Here's a better one.

What if you went back in time and killed an evil, evil person because he killed a lot of people, but (unbeknownst to you) one of those killings led to your parents meeting for the first time? In other words, if none of those people had been killed, your parents would never have met and you would never have been born. If you hadn't been born, would you have been able to go into the past to kill the man whose evil deeds caused your parents to meet?

 

If we were to time travel--wouldn't it disrupt the balance of time--as to say--everything would be pretty messed up?

 

Not necessarily. For time travel to work, we'd have to assume that everything we have now has happened because or in spite of whatever time travel related interference has occurred in our past.

Regardless, you're not answering my question. What happens to you if you go back in time and kill a person who caused your parents to meet?

 

Well--why would I go back in time to kill a person? I wouldn't have any reasons to and I think murder is very--how should I put it? Uncivilized. I think that things can be solved without murder--wouldn't you think?

 

That's not the point. The point is that in this hypothetical situation, you did kill that person because he killed a bunch of other people, and the fact that he wasn't around to kill those people means that your parents didn't meet. Maybe you didn't even kill him. Maybe you just saved all of his victims. Regardless, your parents didn't meet because you went back in time and saved those people. What happens to you now?

 

Aren't all these theories based on fiction? I only wonder if anyone has any coherent articles, any readable articles for country bumpkins like me who lack knowledge in tough scientific concepts or terms, of you would please.

Time travel is such a... distant thing to base on logical concept or more that we have no... Truths about it? I'm grasping for words to explain but can't.

 

I don't think time travel is possible, it just seems like too far-fetched of a thing to actually exist. However I know nothing about the things surrounding it.


I would like to add that I think for the good of humanity that it should never be possible, or if it would be possible it should never be allowed or used.
If time travel were possible then we as a society would cease to learn from our mistakes, because we could go back and change them to whatever suited us best, and we would not be able to grow as people because the experiences that made us who we are would be decided by ourselves. Things like regret would no longer be relevant because there would be nothing to drive us to better ourselves.

 

Time travel rules aside you' re assuming :

- That we' d actually be willing to use it to change the past, but I dare hope our scientists would be smart enough not to experiment with this all wily-nilly, even less to make it available to citizens. I' d see it as a way to expand our knowledge, not as a practical tool in itself.

- That we' d be good at it, but many of the stories allowing time travelers to rewrite their own time-line are used as cautionary tales. They don' t show a world rid of mistakes, they show a world where mistakes can have monumental consequences. Fringe or The Butterfly Effect for instance.

 

I didn't mean to imply that every citizen would be free to use it, or that a time machine would be a household standard. I meant more as an idea that became possible, rather than something that would be put to a practical use.

If that makes any sense.

 

Stop me if this doesn't make since but I would love it if time travel was real. It would be a mistake though one tiny error equals huge paradox. Even if you only change one little thing about your life it won't end well and its though mistakes that makes us human. The one thing I would use it for would to see my grandpa one last time. Of course I would pick a day where I wasn't around.

 

I found this one : http://arstechnica.com/science/2012...cts-results-of-measurements-taken-beforehand/
It seems to do a better job at vulgarizing it, but I don' t know nearly enough about quantum physics and entanglement in particular to fully grasp what it says ... ^^''

 

I do believe time travel is possible, there is a series called "Stephan Hawking's universe" and the second episode is about time travel,and the stuff that he says is actually really believable. Stephan Hawking if you don't know is a cosmologist.

 

Time travel.

Time. What is time? There is no proper answer to what "time" is. Is time actually a component of the universe? Is time a component of all "universes" that may exist in a multiverse? Is time just something in our heads?

Time travel into the future is possible, but not in a conventional sense.

Now, I am no physics expert but I have read a few things so here I am carefully attempting to explain, I suppose. However, because I am not a physics expert I would generally appreciate it if others may help clarify and correct this rather heavy-handed and slightly confusing explanation of what "time" is, if it is necessary.

To put it simply, time is generally relative and is heavily based on the frame of reference. Let us say you have two people -- Arch and Patman. Both of them have fine Swiss watches that correspond as accurately to the time as a cesium-electron clock. Arch flies off to space because he feels he is too cool for Earth, while Patman remains on the planet. Both of them keep their watches, but use an ansible to stay in contact with each other, so they can theoretically relate the exact time they perceive to each other instantly.

Using Patman as a reference, Patman is stationary per his perspective, while Arch is accelerating close to the speed of light (while this is reversed for Arch -- under special relativity, there is no such thing as absolute space and time, and thus to Arch it would be Patman who is moving away from him). Arch blasts off into space with his rate of acceleration while Patman is accelerating at his own rate on a moving Earth. However, Arch misses his home and decides to return back to Earth, adding additional acceleration to his already present acceleration. When he returns to Earth, he has found that Patman is much older than he is. Rather, he has not aged as fast as Patman has, back on Earth. This is known as the "twin paradox" which is not exactly a paradox in the first place.

There are two explanations for this. One is that Arch's perception of time did not make him age at the same rate as Patman, because of the acceleration -- specifically, the extra acceleration needed for his return trip of his space ship. It was the acceleration that affected his frame of time, very much because time is relative! Thus, the amount of acceleration appears to have a definite effect on time frame in some ways.

The second is gravitational time dilation. The basic example used for this concept was placing two clocks on Earth -- one very, very close to the surface, and one high, high up in the sky. Although the clocks seem to be observed as fine when looked at individually, one notices that one clock is actually slower than the other. The times are different, what in the world even is this! This is gravitational time dilation -- the gravity of a mass in space affects time itself.

So how does this apply to time travelling into the future? Loriah hijacks Arch's spaceship and his fine Swiss watch and decides to fly over to a black hole because she is cool enough to straddle the event horizon without spaghettification. Arch is left on the planet Earth in the present day era -- in, let us say a city currently dominated by Justin Bieber and skyscrapers built by I. M. Pei. She moves at an acceleration close to the speed of light, which is also in turn affected by the black hole. She is catapaulted away towards Earth, with extra acceleration, and reaches the planet once again. All this time, Loriah has kept time using her fine Swiss watch. As has Arch (who stole one from Patman). However, when Loriah returns to Earth, everything has changed! No more Justin Bieber. No more glass skyscrapers. Now Peace and War is the biggest star with his face plastered all over the twisty, amorphous futuristic buildings made by the child of Zaha Hadid and Frank Gehry or something. Loriah has just "travelled to the future".

But what does that mean? It means that she travelled to a time she ordinarily would not have theoretically reached if she stayed on Earth, because of the very fact that her perception of time was changed due to the acceleration of her space craft.

Now, what about time travel to the past?

To do so would require the very possibility of exceeding the speed of light. Doing so means that you can effectively change the order of events that occur in your perception. But the problem? The speed of light is the very speed limit of the universe -- a product of spacetime itself, as we know it so far anyway. Nothing, (not even the neutrinos which did not actually pass the speed of light and that was actually just a major calculation error) is known so far to pass the speed of light; to be the mythical "tachyon" post-lightspeed particle.

That being said, it is not necessarily out of the question. For example, quantum physics is an extremely, extremely bizarre field. Uncharted territory that seems to show that the normal rules of relativistic space rarely, if ever truly apply at all, as if you brought US dollars into the middle of a Kazakh colony on Mars. It is entirely possible that the answer to time travel to the past may lie within the field of the very small. However, even relativity holds the possibility of time travel to the past -- the concept of closed time-like curves, very, very simply meaning that the positions of particles in four-dimensional spacetime will return to their previous state.

Time travel backward also gives us a few questions. Where are the tourists from the future -- a variation of the Fermi Paradox? What would happen if we were to change the past so significantly? There are a few theoretical explanations, of course, and I believe Arch covered a few of them earlier. A few comments about changing the past were brought up in the thread, however, so it gives rise to two interesting little ideas involving paradoxes.

The first one is Igor Novikov's self-consistency principle. This means that, if you were to go back in time with the probability of getting involved in a situation that would result in a temporal paradox (such as killing your own grandfather), spacetime would allow the very probability of this event to be zero. This is basically a physics hand-wave to all sorts of paradoxes, though it works for the universe game-breaking ones such as the grandfather murdering (who would even want to do that anyway). However, it also limits actions and poses a few questions/situations. Is it perhaps the reason why we are unable to see any person from the future -- the very possibility of our perception to do so is also at a zero? Does this imply that the universe by nature ensures its own stability and existence by the very fact its physical laws would prevent such a paradox from occurring? Would we be able to change anything under this principle if small changes resulted in big ones -- chaos theory, or the "butterfly effect" of small changes equaling large ones that would eventually result in temporal paradoxes?

But it is that very idea of small changes and large effects that brings us to the second possibility. Parallel universes generally stem off from each other depending on the changes made, and these parallel universes are the result of changes in time travel. It may not necessarily help with paradoxes, but if parallel universes would exist, what is to say the collapse of one universe does not mean immediate change to the other? Getting back into quantum physics again (oh boy here we go), the idea of quantum immortality -- you surviving anything even if there is a marginal chance of escape from death by your particles switching universes to one in which you reach the probability margin of not dying -- could support the parallel-universes-on-top-of-paradoxes argument. Time loops, the idea of ensuring your past self shall do things that will make sure that the act of travelling to the past is ensured by your future self, is typically a logical way (mostly tackled in fiction) that gets rid of the paradox of not making your future self travel back into the past.

Or perhaps Norikov and parallel universes could exist simultaneously. Who knows?

This most likely has a proper name to it like good ol' Novikov up there, but I am too tired to find it so I shall simply call it the Quantum superposition universe line hypothesis (which is a gosh-darned mouthful). In layman's terms, parallel universes of these alternate timelines that exist simultaneously at all states at the same time. I was researching things for a story involving time travel and I found this concept rather intriguing because it implies that all possibilities in time exist together but time is only perceived through our perspective due to wavefunction (time perspective?) collapse. All times -- past, present, future -- exist in their personal lines simultaneously but under our observations we perceive the current time. It sounds a bit silly, but quantum physics in general is crazier than a horse on bath salts.

Time travel to the future? Generally possible, but not in the conventional sense.
Time travel to the past? We have as just as good a clue as any major hints towards a unified theory of physics, honestly.

But remember one thing: when dealing with time travel in actual physics, there is still typically motion involved. No immediate change to the past while staying stationary. Well, yet, anyway.

 

i say it's possible because if there is time then there can be a time travel

 

Would you care to elaborate your meaning exactly?

Just because time exists doesn't necessarily mean it can be travelled on. Can you ride a supernova, or the suns rays just because they are there, untouchable but existing?