Time travel not logical according to current laws

[Ihcisphysicist]

Its obivious that time travel is something that fascinate scifi geeks and not really applicable with current laws of physics but if physics could be viewed from a different point of observation, then it won't be hard for anyone to understand that 'events', past, present and future can all be directly viewed by an advanced particle code breaking computer (apcbc).

[ajb]

... not really applicable with current laws of physics

But I think this is the point; it is not obvious why within our current understanding of physics why time travel is not allowed. This is not to say that it is allowed, but rather if it is not allowed then this should be explained within physics. Trying to understand physics in such extremes can give insight into what we do know as well as pointing towards new physics.

[WWLabRat]

I'm far from being an expert on the subject, but don't the theories behind physics, general and special relativity, and QM allow for a flow of time to be forward or backward without any distinction between the two except for entropy going from a high state to low? Why would one have to "observe" physics from a different point? The laws of physics apply everywhere, it's only when you get into relativity and approximation to large/dense mass that who's viewing matters. Right?

 

The common problem that comes up with time travel theory is when moving to the past and the possibility of creating paradoxes as well as self fulfilling prophecies. Sorry Doctor Who fans, paradoxes are a bit more complicated than the newer series shows. Despite the paradoxes created, theories have arisen to sidestep these possibilities. There's the multiverse which would allow for any changes made to exist in a slightly alternate reality. There's the theory (don't know the name) about something happening to prevent the paradox from being created. Example of that would be if you went back to kill your grandfather, before your father was conceived, someone would kill you first. And finally every action you take in the past was how things happened originally and you can't change anything.

[ajb]

At the fundamental level the laws of physics are time reversible. You can let t-> -t and it still all works out fine. Macroscopic physics does not seem like that and we have an arrow of time, which seems to be tied in with the notion of entropy and the laws of thermodynamics. The possible exception here is the quantum mechanical arrow of time which is related to wavefunction collapse.

[Deidre]

In theory, time travel is possible, and maybe someday we will be able to, but hard to say because it would be incredibly unsafe, even with the best of technology. A really big time ‘warp’ requires an intense gravitational field. Black holes are ideal but they are quite dangerous (for humans to be hanging around) and only ‘represent’ traveling into the FUTURE. If you want to go BACK in time, a wormhole is your best bet, but also dangerous. So, it’s not out of the question but it just hasn’t been something anyone can test yet, and not sure due to the risk, if we ever will be able to. But, if anyone here wants to build a really cool SAFE spaceship and give it a try, I’ll tag along for the ride.

[Ihcisphysicist]

But fellas in reality what goes around doesn't come back around and so will time and the motion of universe.

[Deidre]

we're all not ''fellas'' here.

[gabrelov]

But fellas in reality what goes around doesn't come back around and so will time and the motion of universe.

 

Even in most mathematical formula it states so there is always entrophy they say. That is for macroscopic scale.

[Ihcisphysicist]

About the grandfather paradox, the simplest way to understand the concept is that given the 'killer' is from your reality if he managed to travel back to time then definetly he would land in an alternate universe of that time and killing your grandfather would only prevent you from taking birth in that universe and little will it affect the 'you' of this universe. If this is not so then it's the same paradox of which came first, 'egg' or 'chicken', 'Kyle Reese' or 'John Conner', good luck solving that.

This conclude that you can never go back or forward the actual reality of any universe because, assume that there is no time and that you are and have always been you and since you can't divide yourself into another 'you' through you like the single celled beings, how can another you regardless of the appearance with reference to age appear before you out of this same universe.