Timemachines ... causality problem

[coolVariable]

The most often "imagined" working time machine consists of two wormholes (actually one connected to the other) with one parked in a gravity free environment and one parked in the vicinity of a neutron star/gravity-heavy-object.
Wormholes supposedly transport one instantaneously between the two ends.
Because time moves slower around the neutron star a traveler entering the gravity-free wormhole would emerge in the past at the other end because time had passed slower there.

Link to Scientific American Article


What if he didn't appear at the other end right away?
Supposedly an object entering one end of the wormhole exits the wormhole at the other end at the same time!
Now if the two wormholes are seperated by ten years of time what if the traveler enters the wormhole and appears ten years later at the other end (AT THE SAME TIME HE ACTUALLY ENTERED IT!)
Now that would take care of the causality problem of timetravel because it would make time travel impossible (at least using this method).

 

[TNTrulez]

What if this actually works? Would time be the normal time when he steps out of the gravity zone or would he stay in the past? Hmm. . .

 

[budice]

Time travel is great for science fiction but is not possible. There is the here and now that's all there is. The 30 seconds I took to type this is gone.

 

[guyver01]

Actually the best way to travel between two points is to use a retaining magnetic field to focus a narrow beam of gravitons. These in turn fold space-time consistent with Weyl tensor dynamics until the space-time curvature becomes infinitely large and you produce a singularity.

 

[MacBaine]

Originally posted by: budice
Time travel is great for science fiction but is not possible.

How many times have we heard this inthe last 5 years alone? "____ is only possible in science fiction". The point is that there are plenty of things in this universe that we cannot and may not ever understand. that's not to say it's impossbile.

Nothing is impossible. It may seem like we can't do it, but it's only a matter of time.

 

[guyver01]

Originally posted by: budice
Time travel is great for science fiction but is not possible.

i think someone told Orville & Wilbur the same thing back at Kitty Hawk...

 

[coolVariable]

Well actually Einsteins theory of relativity specifically allows time travel (that's why Einstein never really liked his own theory)

 

[MacBaine]

Originally posted by: guyver01
Actually the best way to travel between two points is to use a retaining magnetic field to focus a narrow beam of gravitons. These in turn fold space-time consistent with Weyl tensor dynamics until the space-time curvature becomes infinitely large and you produce a singularity.

Damn, you beat me to it.

 

[guyver01]

Originally posted by: MacBaine
Damn, you beat me to it.

Dr Weir would be proud of this thread

 

[dman]

Time travel for humans is impossible. Otherwise, we would insist that any future time travelers MUST travel back in time and prove it's possible (through multiple methods acceptable to the scientific community). Thus, we'd already know about it.

Yeah, that's it, that's the ticket.

 

[Ladies Man]

actually time travel is possible

but you can only go forward in time.... not go back

the closer you get to the speed of light the slower time goes by... it actually goes the same for you but lets say back home on earth time seems to you to be more rapid....

in short if you could travel near the speed of light in space you could return to earth lets say in a month and it could actually be 10 years later

my head hurts trying to explain it

 

[Moonbeam]

I've heard some say that you can only travel back in time to the time when time travel is invented.

 

[guyver01]

Originally posted by: Moonbeam
I've heard some say that you can only travel back in time to the time when time travel is invented.

i would tend to believe that...

because time is fluid... you wouldn't know what 'future' to travel to... since there is a multiverse of possibilities... however the past HAS already occurred... so there's only one perfectly possible past.

 

[Iron Woode]

Originally posted by: Ladies Man
actually time travel is possible

but you can only go forward in time.... not go back

the closer you get to the speed of light the slower time goes by... it actually goes the same for you but lets say back home on earth time seems to you to be more rapid....

in short if you could travel near the speed of light in space you could return to earth lets say in a month and it could actually be 10 years later

my head hurts trying to explain it

Actually it would be more like 100 years. If you went to the nearest star (alpha centauri) and back at 99% the speed of light, 50,000 years would go by on Earth.

 

[Shantanu]

actually time travel is possible

but you can only go forward in time.... not go back

the closer you get to the speed of light the slower time goes by... it actually goes the same for you but lets say back home on earth time seems to you to be more rapid....

in short if you could travel near the speed of light in space you could return to earth lets say in a month and it could actually be 10 years later

my head hurts trying to explain it

That's not time travel, anymore than "freezing" yourself and being woken up at a later date (if possible) would be.

I've also heard that "open up a wormhole, and put one end where time passes slow (like a spaceship or a black hole)" theory. I don't believe it though. Even though time might be passing more slowly at one end of a wormhole, if you jumped in at the other end, you would come out at the same time, you'd just witness time move more slowly after you come out. I don't see how a time differential would be created between the two ends.

 

[Joemonkey]

I always like explaining time travel to people at work (we are constantly messing with each other, saying we'll kill each other... yes we're weird) this way:

You're lucky i don't want to invent a time machine... if i did, i'd go back in time and kill you when you were a baby... but then, i would have never known you as you are now, and since me wanting to kill you is the reason i want to make the time machine, i would then have no reason to make it... SO, you would in fact still be alive, and i'd be working on the time machine...

 

[zephyrprime]

I've never bought into the worm hole thing either. I believe that coolVariable's idea may be true, that the wormhole has length. Plus, I think gravity may be able to pass through the worm hole so that you wouldn't have a situation where there was gravity on one end but none on the other. After all, if people are able to pass through the worm hole, why not gravity? Also, if gravity is really caused by curved spacetime like einstein says, wouldn't a worm hole have a stupendous gravitation field of its own?

 

[SithSolo1]

My roommates and I discussed this for about an hour tonight. None us of had a clue what we were talking about and I'm the only one that has had a physics class. Anyway, I described it how I though it would work.(which is probably wrong) as follows.

I said that it was only possible to go forwards in time if you had gone backwards to begin with. The closer to the speed of light the slower time goes, once you hit the speed of light time stands still. Once you surpass the speed of light you ar traviling faster than time and you can catch up to things that have already happened, effectively going backwards in time(now that I think about this, no way could this ever happen. It goes against everything we know). Also matter cannot be created or destroyed as far as we no, but if you travel through time aren't you effectively adding matter to whatever point in time you arrive in? And if the same matter can't occupie the same space at the same point in time how do you know that the matter that is you wasn't an air molecule back then? All you would have to do is breath the wrong air and *!poof!* there goes the universe as we know it. My roomates also asked about the streching thing with getting closer to the speed of light ala StarTrek's Warp. i said it had to do with the lag time between one atom and the next as they accelerate, is this correct?