The problem with time travel is space travel.

[Sidhe]

There's a very simple way to tell that time travel will never be invented: there are no people from the future visiting our time.

Would you believe some nut who traveled back in time? Especially if current physics notions are correct and it's a one way experience, ie as soon as you do the future is non existent and you can't return and time progresses differently. Even if some guy got some guesses right we'd most likely dismiss it as nonsense. Are prophets who got it right time travellers? Not that I believe we might it's just a bit difficult to say absolutely that it couldn't happen. Also if you believe in a many worlds intepritation you may well end up in a completely different reality and thus anything you say would be meaningless about the future. Think the episode of The Simpsons with Homer and his miraculous toaster experience

OP to explain what I said more clearly if anti matter particles do in fact travel back in time to anihilate there corresponding matter particle(completely speculative) They also either know where they are or are tied to them in a corellatory way. Isn't complete unscientific speculation fun?

 

[Masquerouge]

I don't, but wouldn't it be kinda obvious if there was?

Well, if you could go in the past, would you advertise yourself as a man of the future all over the place?

 

[Bozo Erectus]

Its only in the movies that they wear shiny silver suits and have white pompadour haircuts.

 

[Gladi]

Now please what?

Time Travel does that, Time Travel works this way... it is really tiring and I am already sick.

don't, but wouldn't it be kinda obvious if there was?

I have it from the good source that there was time-traveler on Titanic. He warned captain that the ship will sink if it travels at full speed. So captain ordered full-steam ahead to show the madmen.

 

[homeyg]

I dont know that it would be. Theyd just be people, right? Why would anyone think they were from the future?

Different clothes, or using things that haven't been invented yet?

 

[North King]

Time Travel does that, Time Travel works this way... it is really tiring and I am already sick.

Calm down, kind sir. I'm just trying to inject what I understand of time into the discussion; I don't claim to be a physics PhD., nor do I claim to have a time machine in my back yard (because of course you wouldn't believe me; it's cleverly disguised as a tree!). I'm just inputting what I think of the matter. Since this is all speculation anyway, I would think that putting "IMO", or "IMHO" before all of the things I say would be kind of pointless, since everything in here is obviously opinion--even if it was from physicists, since we don't HAVE experimental data.

 

[Gladi]

Calm down, kind sir. I'm just trying to inject what I understand of time into the discussion; I don't claim to be a physics PhD., nor do I claim to have a time machine in my back yard (because of course you wouldn't believe me; it's cleverly disguised as a tree!). I'm just inputting what I think of the matter. Since this is all speculation anyway, I would think that putting "IMO", or "IMHO" before all of the things I say would be kind of pointless, since everything in here is obviously opinion--even if it was from physicists, since we don't HAVE experimental data.

Oh sorry, as I said I am already sick and somehow increased temperature does not lend itself to incresed temperamence.

 

[Bozo Erectus]

If you guys are going to be using this technical jargon, the rest of us wont be able to follow.

 

[Masquerouge]

Different clothes, or using things that haven't been invented yet?

That would not be very smart of a time-traveler.

 

[Sidhe]

Not sure if you meant me Bozo, but here you go.

http://en.wikipedia.org/wiki/Many-worlds_interpretation

In other words for every event in quantum mechanics, there are all possibilites, all futures. Basically it's sci-fi's wet dream about parallel possible universes, in that every single event both quantum and real can become apparent and nothing is preset.

http://arxiv.org/html/physics/9812021

Antimatter should in theory have not only the opposite spin, charge etc of mater but also move backwards in time.

If you reverse events they reverse accordingly in space, so move yourself back and you reverse the particles in you in the same way leaving you in the same position in space if you travel back. In other words causality works in both directions of time.

R. P. Feynman (3, 4, 5) developed earlier work by Stueckelberg (6) to produce the Feynman-Stueckelberg Interpretation of antimatter. This interpretation states that all the properties of antimatter are consistent with the view that antimatter and matter are identical except that their particles move in opposite directions in time. This view has never been refuted, but it is seldom discussed

 

[Thorgalaeg]

Well, according to theoretical physicists a necessary "law" for time machines says that you never could go to a time before your time machine was built. That answers the originial thread question since time travel destination point in space would be where the time travel machine or system was in that moment.

 

[Bluemofia]

For me, it is always the associated space travel that is the problem. Suppose for a moment that I invented a machine that would take me back one year in time (or forward, same issue). The problem is that if I wanted to be "here" in my mad scientist lab one year ago, my lab wasn't "here" one year ago. The Earth has rotated, and moved within the solar system, and the solar system within the galaxy, and the galaxy within the universe (which is expanding). So how do I accelerate through space in such a way as to go back one year and remain "here"?

On the micro level, to get from now to one year ago, at some point I have to move through a river of quantum time units. More simply explained, to get to one year ago, I have to pass through one second ago, two seconds ago, etc. As I pass through the instant of one second ago, the world/universe has shifted around me, and I am now in existence at that time occupying the same space as the matter that was there. No matter which direction the world shifts relative to me, I will be taking up the same space as the ground below me, or the air above me, or the table beside me. I'm sure that is not healthy for me, and probably will cause some weird subamotic event as my atoms try to take up the same space as other atoms.

That's thinking in absolutes. You will be relitive to the gravitational source, because there is no absolutes really. (is a person walking on a train really moving at 4 mph, or 104 mph?)

Ahh... The butterfly effect. Going into the past leads to nasty consequences. And with the problem of the air taking up space before the machine went there, and is now in the way. Most easily solved by having the machine clear the area of atoms before entering. (by some sort of time rift that defines an area that allows matter to leave, but not enter? So the random walk would then take effect, and the space would then empty out. Eh. It's fiction.)

 

[MrCynical]

Of course you could always time it precisely to end up in a position where the Earth was

Given that the galaxy is rotating and the universe expanding, will the Earth ever actually be in exactly the same place as it has previously been? At a solar system level it would appear that the Earth would return to roughly* the same place each year. Looking at the galactic level Earth would presumably return to the same point relative to the rest of the galaxy with a much longer cycle, far too long to be of much use for time travel, but with the expanding universe, will this ever be the case?

*-This "roughly" seems extremely important. Earth's orbit is not perfectly consistent and the tiniest variation would be catastrophic to a time machine on its surface. Even a shift of a few metres could leave the machine reappearing in mid air, or worse below ground level, neither of which seems likely to do it much good.

 

[Sidhe]

Given that the galaxy is rotating and the universe expanding, will the Earth ever actually be in exactly the same place as it has previously been? At a solar system level it would appear that the Earth would return to roughly* the same place each year. Looking at the galactic level Earth would presumably return to the same point relative to the rest of the galaxy with a much longer cycle, far too long to be of much use for time travel, but with the expanding universe, will this ever be the case?

*-This "roughly" seems extremely important. Earth's orbit is not perfectly consistent and the tiniest variation would be catastrophic to a time machine on its surface. Even a shift of a few metres could leave the machine reappearing in mid air, or worse below ground level, neither of which seems likely to do it much good.

Yeah stupid idea, I wasn't thinking But I think the reverse causality stuff means you end up in the same place anyway, assuming that's true.

 

[TheBladeRoden]

Maybe time travelers are just really responsbile and discreet people. Or maybe this one guy went back a few thousand years ago and talked to Abraham and friends with his telepathic megaphone.

Or maybe when you travel back in time, the matter you displace is also sent forward in time, like in TMNT III.

 

[North King]

If you can tunnel through TIME, why do people assume that the inventor will be stupid enough not to create something that tunnels through SPACE as well?

 

[Elta]

Now please, SIR!

LMAO I don't knowwhy I found that so funny but I did.

 

[BasketCase]

For me, it is always the associated space travel that is the problem.

Actually, movement in space may be REQUIRED in order to go back in time.

If you're trying to walk across the room, you have to go around the sofa; no other object can occupy the same point in space (well, spacetime actually) as the sofa. If you want to put a table there, you have to move the sofa.

Now, suppose you stand in one spot (say, right in front of the sofa) and try to go back in time from 3:15 to 3:13. The problem with this is that you're going to bump into something--namely, you. You can't stand in front of the sofa and go back from 3:15 to 3:13, because you were already standing in that very spot at 3:14.

The solution: go around the obstacle--i.e. move sideways while you're going backwards in time.


The above is proof that I got way too much free time on my hands.

 

[North King]

Actually, movement in space may be REQUIRED in order to go back in time.

If you're trying to walk across the room, you have to go around the sofa; no other object can occupy the same point in space (well, spacetime actually) as the sofa. If you want to put a table there, you have to move the sofa.

Now, suppose you stand in one spot (say, right in front of the sofa) and try to go back in time from 3:15 to 3:13. The problem with this is that you're going to bump into something--namely, you. You can't stand in front of the sofa and go back from 3:15 to 3:13, because you were already standing in that very spot at 3:14.

The solution: go around the obstacle--i.e. move sideways while you're going backwards in time.


The above is proof that I got way too much free time on my hands.

I completely disagree. If you pluck something out of a certain time and reinsert it in another time, then you won't have any of this nonsense about moving back through time, you'd be in the future time, then immediately thereafter in the past time.

Furthermore, to suppose that one has to move back through time as though one was moving forward in time would completely negate the point of time travel, as the person would be dead. Our body's survival completely depends on time moving forward.

 

[NKVD]

The Earth has rotated, and moved within the solar system, and the solar system within the galaxy, and the galaxy within the universe (which is expanding). So how do I accelerate through space in such a way as to go back one year and remain "here"?

time is not the same dimension as space positions. Time has nothing to do with your local coordinates. So being elsewhere while travelling time have nothing to do.

the error in movies though is when the hero goes in future like MacFly in Back to the future 2 to visit his kids. He's there standing in the closet hiding while he ,himself now as a grand-pa, enter the house and doesnt know there is someone in the closet...how come he dont remember 20 years ago that he was in that closet ?! Back to the future was really good though. That parallel universe thing is in accordance with Heisenberg's principle and quatum theory . anyway I have yet to see a movie without chronological errors