is time travel possible?

Question

i am watching through the wormhole with Morgan Freeman and in it there is a theory that there is a 4th dimension that works with time. I don't really know how to explain this because it is a new theory and it is a very complex kind of maths.
but what i did get is that there are different types of dimensions 9 or 11 and we are the 3rd. we see in the 3rd dimension the 2nd is where everything is flat i am not sure what 1 dimension is.
there are a few theories on what a 4th dimension would look like because to us it would be so hard to exactly know. it would be like explaining what green blue and other colors look like. one theory is that it is more time based in a way we would find hard to understand since people who believe this theory claim we look at time the wrong way.
anyway they said in this dimension it could be possible to go back in time like if you drop a pencil the pencil could just go back up and this is one idea of what started the big bang if energy could go back in time back to the point where there was nothing because everything comes from energy. it could take thousands millions or billions of years but if there is energy a particle will just randomly appear out of nowhere.
could this be possible.

again i am not sure i explained it right and this is still a theory but then again no one can really understand where the big bang came from.

Answer 1

The ghost isn't right.



The bottom line is we know so little about physics, the universe and dimensions we couldn't possibly say what is possible and what isn't.



We know that going forward in time is definitely possible - according to physics as we know it - not saying we will ever find a way to successfully do this though.



As for going back in time, well that could definitely cause a paradox and is something I don't think many people could comprehend but as we know so little and are learning so much in recent years that blows past theories out the window there is currently know way to know if it is possible.



Bottom line - travelling into the future is definitely possible but by how much and how long will it take?



Travelling backwards we can not see how at the moment but I doubt any physicist would doubt it could be possible.



We know very little about dimensions that may or may not exist past the 3rd but other dimensions could give us answers to so many confusing questions. String theory is interesting but a complete mind ****



*edit* Just read Kyle's. Again talks very much about physics as we currently know it but there is no reason it won't ever be possible for something to travel the speed of light. Afterall isn't parts of the universe thought to be travelling faster? I think we have done an experiment and had something go a tiny fraction faster, almost certain of it but can't remember exactly how but 90% sure that is true. Wouldn't have been an object but a neutrino or something

Answer 2

Most all theoretical physicist agree that time travel to the past is not possible. It violates the basic fundamental law of the universe. Cause must come before effect.



However, any object with motion is technically time traveling. Because light speed, c (3*10^8 m/s) is the universal speed limit, any time anything has motion and comes closer to c, time will slow down for that thing such that c can never be reached by that thing. This can be expressed mathematically through the addition of parallel velocity vectors with regard to special relativity:

w = [u + v] / [1 + (uv)/c^2]

Where w is combined velocities, u is one velocity vector, v is another, and c is the speed of light.

So if you are going very fast, say 50% light speed, time for you will be moving very slowly with respect to everyone else. Technically, sending you into the future with respect to anything that has a smaller velocity than you.

Answer 3

I remember watching a program by Hawkins where he states that time travel is possible but only forward , the paradoxes would prevent you travelling backwards - he states if a time traveller went back in time and shoot his past self it would prevent him from travelling back to kill himself and create a paradox , the universal laws would prevent this.