Lets put this in a way that easy to understand.
If timetravel is ever invented, we would likely all be dead already.
I mean, what's there to stop some dickhead from going back and say, aiding the Nazis to win WWII? How about a barrier to keep them from coming and enacting a nuclear holocaust in the cold war?
Fanatics, militants, terrorist, and just assholes could and likely would have gotten their hands on this by now if it ever gets invented.
However, time-travel is achievable (and already has been achieved) through different means. If something is going really, really fucking fast then whatever that item is will not age as fast as the world around it. It would technically warp to the future, but visiting the past is impossible.
And that "already achievable" thing, guess what, astronauts go so fast when travelling in rockets that scientists have verified that they are a fraction of a second younger then if they had merely stayed on Earth. of course, it's not like that makes a difference, but it shows it's possible.
Let's say we're in timeline A.
We invent the machine, a person goes back in time, changes something and that person is now in timeline B while we're still in timeline A.
I once thought of that theory. It's plausible, but the required power to do so will likely be forever beyond mans reach.
We also know so little about time-travel. It's all still restricted to theories (largely String Theory and the Theory of Relativity), and theories are not official. At any moment, a new discovery could change science as we know it and re-invent how we view things.
That's why I say science isn't ever really official, but we are still restricted right now as to what we know.
Time travel is absolutely possible. I'm time traveling right now. Everybody time travels.
Backwards time travel, is another story. I'm no physicist, but from my understandings (watching science channel, NOVA, etc.) it's mathematically possible.
Maybe there's an edge of our universe that when crossed takes you back in time to our universe. Like a mirror. Who knows? Nothings for sure.
But if we went back in time we still wouldn't be able to change anything, would we?
Theoretically, if you went fifty years back in time you couldn't change anything because then you would already have been a part of that time. You were obviously there fifty years ago already, since you travelled back in time later on. You've already done everything you will do as that has already happened, fifty years ago.
I might be horrible at explaining, but I think it makes sense.
I think there is an alternate universe for every possibility of everything, how we get to each universe is dependent on our decisions. If we were to go back in time, it would not be to the universe we came from, it'd be to one very similar if not exactly the same. We'd just be re-creating the situation at that point in time, not necessarily going back to it. *Shrug*
If you don't want things fucked up, just make sure that events in the future cannot entangle with those in the past and you're set.
By the way entangle as in quantum mechanics, not a verb.
Still a verb, bro.
And also that doesn't really make sense.
I would have thought we may have seen evidence of time travel by now, some stupid prick from the year 3000 accidentally getting caught.
although this does not eliminate the possibility of time travel forwards.
I have never seen so many duplicate posts in my life. Why does everyone feel the need to repost the same thing over and over again? I'm referring to the "Hey guys, an object in space will age more slowly than one near a gravitational mass like Earth!"
I personally don't think backwards time travel will work in the way people want it to if it ever comes to light. If it's even possible that is. I really don't see how you can undo billions of years of energy movement and matter interaction. Multiple dimensions are a nice possibility, but then it's not really time travel so much as inter dimensional travel. Forward time travel is a nice loophole that might be our saving grace to allow us to actually leave this solar system (assuming we can ever create a ship that can go near the speed of light). Lightyears would only take two decades or so, and we'd be able to travel to other star systems.
I think perhaps time travel can possibly exist (in the future, unlikely can go back). A lot of theoretical physicists are starting to consider the universe and big bang as a cyclical and repeating event, exploding and compacting back into energy. The big bang encompasses e=mc^2, pure energy becoming first dimensional subatomic particles accelerating at high velocity, smashing into other particles creating energy and higher generations of elementary particles and then matter. Perhaps when the universe begins to concave onto itself, time goes backwards and as it becomes a singlarity it preforms to e=mc^2 against and translates all the universe's matter into pure energy.
Considering spacetime exist on the same dimension, and can be skewed by mass, speed and energy in motion, it would be reasonable to go further in time by going the speed of light. I don't know however if you could go back, the idea of the time going backwards as the universe concaves is pure observational. But time being skewed is a reality, being shown in black holes and in planetary bodies with high mass. Neutron stars experience light refraction and bends light as it travels past it because high mass object have higher gravitational fields, creating the effect you see when looking at a metallic marble and distort time. Black holes also suck in light and distort surrounding spacetime. Time doesn't exist in a black hole, meaning you wouldn't age. Theoretical scientists believe the centers of black holes may take you into a parallel universe, which makes some sense in my head.
Imagining time and how fragile it and perception is, is difficult. If you have done drugs, and felt time slow down, it's kind of like that. The reason we age is because we're in motion, we are expanding from the point our big bang occurred. We also live in the third dimension, and because we don't experience life in the fourth dimension, we see a very constant linear timeline of aging (as it occurs). Time is a very fascinating concept, because it is distorted by mass/energy.
If you had a twin, and the span of life is determined by heartbeats. Then if you and your twin's life consisted of 50,000 heartbeats and you moved to Jupiter and your twin stayed on Earth. Because Jupiter has a higher mass, you would experience time slower and would return to Earth to learn you had outlived your twin.
The simple fact that you are going through time one second at a time into the future is time travel, not to mention relativistic effects.
I asked a physicist once about relativity, might be of use here.
I've read that observing the neutrino going faster than the speed of light is just an optical illusion.
It's very cool though.
Well.. they are blasting neutrinos and other things that are like split atoms to light speeds, and we humans need to get to that speed, in some vehicle. So that's a other whole new story
Okay, So this may just be my 2 cents but, Most theory's state that time is like a river, going back and changing something would produce an alternate future, but we are already living in the future, were our past happened. If someone from our future went into the past it would create a completely different timeline. Also time isn't linear, people haven't appeared in the past yet because we would need to make the machine then go back, again effectively creating a timeline we haven't experienced.
I'm just going to chime in and say that time travel is an animal that humans just shouldn't ever mess with. We're too sentimental about past events and we all think we know what's best for everyone. Shit would get fucked up so quickly with that kind of power.
Of course, this is assuming it will affect the present, which is baseless and unlikely, but still. I just don't see any value in a technology like this, because even if you use it to "better humanity", at the end of the day you have man (or men) deciding what is "better".
You can travel to the future.
But IMO we can never travel to the past.
It seems we've already kind of made this concrete with our current understanding of the universe.
In the dimension we experience time, is completely linear. Only going forward, not backwards.
Maybe someday we'll have the technology and understanding to embrace a higher dimension and unlock new possibilities.
But I don't see that happening soon.
We only perceive time in one direction: forward. But in reality, it could be three-dimensional: there could be multiple time "tracks" sweeping back and forth, up and down. And we don't perceive changes in time, because we exist in it, if time goes faster, our thought processes go faster, and we perceive time as normal. Same if time goes slower. Hell, you could make a graph with a sine wave and say "that's the speed of time", you could be damn right.
And time travel could very well be possible. You might say "well if someone 500 years from now went back and changed things and fucked it all up, we'd notice". But perhaps some kind of "time police" 700 years from now will exist and will fix these sort of things, so we'd never notice.
So we don't know until we find out how.
People said powered, heavier than air flight was impossible. People said real-time face-to-face communication over vast distances was impossible. People said space flight was impossible. People said walking on another orbital body was impossible.
Every single one of those things has been done. So who's to say time travel won't be done either? Scientists have this strange habit of taking "x is impossible" as a challenge rather than a fact, and in doing so I believe we'll figure it out.
Perhaps if we were to expand to the 4th dimension or something. Then perhaps.
I understand time isn't actually linear. It just is for us in the third dimension.
Considering string theory is based on different timelines and possibilities occurring, then I guess you could say it is possible.
I don't think it's very likely that we will be able to travel back in time, but traveling forward in time at increased speeds might be.
As I see it, if you want to go back in time you'd need to reverse Entropy for the entire universe or something.
That would require a lot of energy.
Okay guys rate me all your dumbs.
Timetraveling back in time is probably possible.
But like some posts state, it would probably create a new universe if one would go back to time since
the dimension you came from should by logic(according to me) continue on without you and as you go back in time you form a new universe since it needs to continue with you.
Or you'll just vaporize.
It makes sense though.
"A closed timelike curve can be created if a series of such light cones are set up so as to loop back on themselves, so it would be possible for an object to move around this loop and return to the same place and time that it started. An object in such an orbit would repeatedly return to the same point in spacetime if it stays in free fall. Returning to the original spacetime location would be only one possibility; the object's future light cone would include spacetime points both forwards and backwards in time, and so it should be possible for the object to engage in time travel under these conditions."
I've always viewed time as entropy. As entropy can't be reversed, so can't time.