explain in detail, why is it possible in quatum theory, to travel through time?

Question

Relativists have been trying to come to terms with time travel for the past seven years, since Kip Thorne and his colleagues at Caltech discovered -- much to their surprise -- that there is nothing in the laws of physics (specifically, the general theory of relativity) to forbid it. Among several different ways in which the laws allow a time machine to exist, the one that has been most intensively studied mathematically is the "wormhole". This is like a tunnel through space and time, connecting different regions of the Universe -- different spaces and different times. The two "mouths" of the wormhole could be next to each other in space, but separated in time, so that it could literally be used as a time tunnel.

Building such a device would be very difficult -- it would involve manipulating black holes, each with many times the mass of our Sun. But they could conceivably occur naturally, either on this scale or on a microscopic scale.

The worry for physicists is that this raises the possibility of paradoxes, familiar to science fiction fans. For example, a time traveller could go back in time and accidentally (or even deliberately) cause the death of her granny, so that neither the time traveller's mother nor herself was ever born. People are hard to describe mathematically, but the equivalent paradox in the relativists' calculations involves a billiard ball that goes in to one mouth of a wormhole, emerges in the past from the other mouth, and collides with its other self on the way in to the first mouth, so that it is knocked out of the way and never enters the time tunnel at all. But, of course, there are many possible "self consistent" journeys through the tunnel, in which the two versions of the billiard ball never disturb one another.

Answer 1

My friend you are talking about mathematically there are no reasons to forbid it, though I think there are but I'll get to that later. As every physicist is brought up on the presupposition of the arrow of time there automatically is this nonmathematical axiom built into their thought frame from which time travel (beyond the fact that we are all journeying through time) is not possible. Mathematicans also have such axioms too. These are things that are just taken to be true because if they weren't then we couldn't prove anything.
Now general relativity (particularly as espoused by american universities like caltech) is a mathematicians description of the universe. The universe is described geometrically such that spacetime has a certain topology, e.g. wormholes (by the way the whole two black hole thing is just popular science. there is no reason why a connect the dots approach would be able to make wormholes. The formation of entangled particles is wormhole like. If you were to make a wormhole with black holes it would probably be done by the simultaneous collapse of two stars that had a high degree of phase correlation... not gonna happen).
The topology used in general relativity to describe spacetime is that of a differential manifold. This manifold has an underlying algebraic structure, of which one of its properties is that it is a hausdorf space. i.e. it is non-self-intersecting or alternatively that no two things can be at the same place at the same time.
Let us assume that a finite number of wormholes exist. Now secondly I'll make a further assumption that the universe is closed in all 4 dimensions. This I make because if it was open then I could move my centre of reference somewhere else pushing the wormhole(s) to infinity. At infinity they are no longer my problem; there would then be no point in having made that first assumption; what good is a wormhole if you can't reach it?
I have a ball. It is a 3 dimensional object tracing out a surface in my closed 4 dimensional spacetime that has a dimensionality of somewhere between 3 and 4. As such there must be some point in time when it enters a wormhole. Now the ball can never re-enter this wormhole because if it did the hausdorf requirement of spacetime would be violated (the wormholes are a contraction of spacetime to zero dimensions due to the singularity. there is also the possibility of donut type wormholes but I won't go into them now). With only a finite number of ins and outs the shape created by the trajectory of the ball cannot be fractal and must therefore reach the critical value of being 4 dimensional where it self intersects hence there is a violation.
In summary if there are wormholes allowing time travel then either:
1. They don't matter (i.e. they are at infinity)
2. There are infinitely many of them (and so probably should be a regular part of our reality)
3. They are donut shaped (equivalent to infintely many but not necessarily needing to be a regular part of our life)
So that probably makes donut shaped ones the favoured pick but then such a thing CANNOT be fabricated (the topological issues are a lot more obvious than the case for point wormholes) so unless someone finds one there won't be any time travel.

Now from a physicists view of reality there are many theorems and laws that exclude its possibility: arrow of time, 2nd law of thermodynamics, causality, etc.
Quantum theory doesn't really have anything to do with it save that the laws of physics work just as well by viewing antiparticles as regular particles which travel backward in time.

Answer 2

Time is a dimension just like any other dimension. The only difference is that we are moving at a constant rate in the time dimension.

All things in the universe exist only at one point in time. If you had a method of acting on our transition in time you could move backward and forward in the time dimension. This however is not moving forward to the future or past of the universe. The universe only exists in the present and the present position in the time dimension.

As you can see there is no possible paradox with time travel.

Answer 3

Quantum Mechanics preserves causality. So it doesn't introduce any time paradoxes. (Time travel.)

What you may be thinking about is the EPR paradox or "spooky action at a distance." This is very interesting and is commonly popularized as Quantum Teleportation. It is a real phenomena and not a paradox as the name suggest. It was originally introduced by Einstein-Poldesky-Rosen (EPR) as a paradox in QM and proof that QM was not complete. It has since been experimentally verified.

You may also be thinking about the famous explanation of anti-matter as moving backwards in time.

Answer 4

It is not possible in the sense you are describing. Time is relevant only to the observers and not to the traveler. If you are traveling to a distance star and you exceed the speed of light, then theoretical, you are going backwards in time. That means that you are back to where you were seconds ago..... can't you see.... you are not traveling to the distant star. You are going back to base.

Answer 5

The details are not necessary. You are traveling through time at a constant rate constantly. It is only the rate which can be fiddled with when you start talking about relativity and all that.

Answer 6

From what I understand one could theoretically only travel forward in time and not backwards so the paradox, although interesting, is irrevalent.

Answer 7

there is not any would desire to bash you and people who do are only afraid of their own god( here comes the genuine bashing). easily the bible means that hell is a bad place yet maximum appropriate me if i'm incorrect i don't think of it easily is going out and says it is all eternal suffering. each and every of the perspectives of hell are all very eccentric. think of roughly it if hell wasn't so undesirable might anybody quite have faith in it. in my view heaven could be worse. In heaven you become one with a god you in no way quite met on earth and you're compelled into eternal happiness. in case you lose all your different emotion are you quite your self anymore? despite if hell became a terrible place eternal suffering is a few thing that seems impossible while you're already lifeless what's discomfort? and after awhile would not you get used to it besides. yet from my atheist attitude particular hell is religions device to scare human beings into faith. The vulnerable minded are truthfully tricked via this because of the fact they think of that they'd desire to already be entitled to an after existence and desire for it to be as exhilaration finished as available. To me it quite is boastful thinking. think of the statistical improbability of somebody being born. the prospect of anybody who posts here even being alive is rather slender. maximum intercourse cells will in no way become a functioning human so shouldent us fortunate few be pleased with 1 existence and not bypass searching for yet another?

Answer 8

No.Time travel is Not possible. So no explanation in any theory

Answer 9

I have no idea.....but I have seen the movie Donnie Darko...does that count?..lol