Time Travel

[Anthropomorphic]

This thread may be an oversimplification of the issue of time travel, but I think it's worth a nerd's shot at discussion.

We could disregard the idea of HOW we would time travel, and instead focus on IF. What I'm wondering is your view on this:

Theoretically, in order to go back in time, you must exceed the speed of light. Besides the fact that light is the fastest moving entity (or so we know of), shouldn't it be impossible anyway? If I go back in time and kill my own grandfather, doesn't that negate my own existence (therefore making it impossible for me to exist, go back in time, and kill my grandfather) and create a temporal paradox? Or does it simply create an alternate reality in which I did not exist because my grandfather died?

I'm sorry if I'm not explaining this very well. It's kind of an abstract subject, and many people wouldn't even consider it to be science. I just want your thoughts/views on it.

[John 6:29]

From my understanding, with advances in string theory, time travel may very well be possible in the near future.

[Reverie.]

I understand what you're saying. I suppose all of it is possible. With the killing your own grandfather bit, of course you'd have to be extremly careful about time travel anyway as to eliminate the dangers of these things happening. But yes, I've never considered the you not exsisting to kill him thing actually. I suppose time would, potentially, be as if it was stuck on some sort of a loop. All of this seems pretty logical, if you did not exists, your grandfather would not die. But if you did exsist, you would thus travel back and kill him, so nothing will ever move on.

We will never reallly know until it happens I don't think. Good thread though, good to get people thinking

[Anthropomorphic]

Originally Posted by Safe-inside-my-head

I suppose time would, potentially, be as if it was stuck on some sort of a loop. All of this seems pretty logical, if you did not exists, your grandfather would not die. But if you did exsist, you would thus travel back and kill him, so nothing will ever move on.

We will never reallly know until it happens I don't think.

I'm pretty sure that if we ever found a way to do it, I wouldn't want to be the first one to try it. The grandfather idea is probably the most basic paradox, but there are other possibilities that would either negate the history of one (or all) of the creators of the time travel device, OR otherwise change the course of history in a way that would alter our own existences.

One problem with going back in time is that everything can be so interconnected, we don't know if us doing something (or, theoretically, not doing something) would negate our ability to go back in time in the first place.

And so the endless loop continues.

[Xujhan]

I'm rushed for time, but note that travelling forward in time and travelling back in time are as different as night and oranges. It's very plausible that one is possible and the other is not. In a sense, we travel forward in time all the time, at a constant rate of approximately one second per second. Accelerating and slowing that are things that demonstrably possible through gravity and velocity, but actually reversing it is a very different story.

[Kryptonite]

Fletcher - well said.

Traveling a bit in the future is potentially possible. Accelerate beyond the speed of light, you should in theory move faster than time. But reversing events already occurred, I believe, will not be possible in our, or our children's, or our grandchildren's lifetime...if at all.

[Epsilon]

I don't see how time travel is possible at simply because it is impossible for anything with mass to travel at the speed of light. Even the act of building some advanced technology that could move that fast would still have mass by the very nature of it being an object. With that said it would be conceivable to create a vehicle that could travel almost as fast as the speed of light, which would seemingly send it into the future, when it fact time would just be passing by for this vehicle so fast that it would only seem like time traveling to the future.

[Boobies]

Surely if you go back in time and do something nothing would change because it would of already have happened, since you're going to the past, and the past has already happened?

[aranel05]

Well, we are technically traveling through time on a daily basis. We just aren't traveling backwards or very far into the future. hah.

[dr2005]

Fletcher said it pretty well - the mechanics of travelling in different directions with regard to time are so completely different it's not even funny. It would take completely new physics and technology well beyond our own to even contemplate such endeavours, and would also require a departure from the idea that the speed of light cannot be exceeded (which may well be possible for all we know - it was once thought that the speed of sound was an absolute limit so you never know). Regarding the temporal paradox question, quantum theory as currently understood would mean a different reality would be created in which you would not exist, although you would continue to exist in that reality were you not to travel back. The reality you came from would continue in the meantime. I think. I'm not 100% sure on that one but that's vaguely how I remember it.

[Reverie.]

Originally Posted by God.

Surely if you go back in time and do something nothing would change because it would of already have happened, since you're going to the past, and the past has already happened?

If the past has already happened, and you alter what happened, wouldn't it affect your ability to alter it in the first place? If something dramatic that never happened, turned out happening, firstly, it would make history that had never before been made, and secondly, it could change the future (or present) by the events that took place.

[BDF]

My brain short circuits and explodes out of my nose when I think about this. I believe anything is possible, but common sense tells me some things in time travell make it impossible. Like I said though... I'm gona spare my braincells.

[Anthropomorphic]

Originally Posted by aranel05

Well, we are technically traveling through time on a daily basis. We just aren't traveling backwards or very far into the future. hah.

This is true, but as far as I know, we have no way to manipulate it to travel slower, faster, or in reverse.

Think of a car using speed control. You set a certain speed on the highway, and it will maintain that speed. Assuming you do not touch the brake or clutch, and don't hit anything, what would make it go faster or slower, or stop altogether? Probably nothing.

Someone stated that we can manipulate time by use of gravity. I could understand this argument in terms of the black hole theory (gravity so strong that not even light can escape), but I hope that's the limit to their argument. If I drop a ball from a height of 10 meters on Earth, and then drop a ball from a height of 10 meters on the moon, the ball on the moon will drop more slowly. But that's simply the rate at which it descends; it takes more time, time does not slow down for it to happen.

[BDF]

Originally Posted by Hyperion

This is true, but as far as I know, we have no way to manipulate it to travel slower, faster, or in reverse.

Think of a car using speed control. You set a certain speed on the highway, and it will maintain that speed. Assuming you do not touch the brake or clutch, and don't hit anything, what would make it go faster or slower, or stop altogether? Probably nothing.

Someone stated that we can manipulate time by use of gravity. I could understand this argument in terms of the black hole theory (gravity so strong that not even light can escape), but I hope that's the limit to their argument. If I drop a ball from a height of 10 meters on Earth, and then drop a ball from a height of 10 meters on the moon, the ball on the moon will drop more slowly. But that's simply the rate at which it descends; it takes more time, time does not slow down for it to happen.

I read an article years ago, where it described an experiment. Two identical timers. One left on earth, one taken by satelite round the earth. A year later or so the timers showed different times. I think the one in orbit was slower, but I don't remember. The one in orbit would be different because of weaker gravity.

I wish I could find that article but I've totally lost it. So you would age slower in space, relative to someone on earth I think. But that wouldn't make any difference to you as such, because everything about you would be slower. Brain functions, reflexes, your whole life, so to you it would appear the same. But if there really was no gravity whatsoever, in theory perhaps you'd be able to outlive someone on earth by infinite time. But I'm only saying that assuming that less gravity means slower time... and I don't remember if that's the case.

Anti-gravity (lol wtf I just made that up) would then allow you to go back in time. I honestly dont know if this makes any sense.

[Anthropomorphic]

Originally Posted by BDF

[/color]So you would age slower in space, relative to someone on earth I think. But that wouldn't make any difference to you as such, because everything about you would be slower. Brain functions, reflexes, your whole life, so to you it would appear the same. But if there really was no gravity whatsoever, in theory perhaps you'd be able to outlive someone on earth by infinite time. But I'm only saying that assuming that less gravity means slower time... and I don't remember if that's the case.

Yeah, I don't think it works like that. This precludes the idea that escaping all (or almost all) forces of gravity would allow a person to live for hundreds or thousands of years, if not indefinitely. As I said, the only thing that can truly manipulate time in such a strong way (as far as we know) is a black hole, and I don't think we want to get too close to those.

What I'm getting at here is that I understand what you're saying, but I don't think it's possible on the scale that you describe. Time will pass no matter how it is measured or what the gravitational forces are in its given environment.

Also, just out of curiosity.... If anti-gravity is real, if it could be contained and controlled, would it be used as a fuel for traveling back in time, or as a vehicle? This question isn't based in fact, I just want to know what you think.

[BDF]

Originally Posted by Hyperion

Yeah, I don't think it works like that. This precludes the idea that escaping all (or almost all) forces of gravity would allow a person to live for hundreds or thousands of years, if not indefinitely. As I said, the only thing that can truly manipulate time in such a strong way (as far as we know) is a black hole, and I don't think we want to get too close to those.

What I'm getting at here is that I understand what you're saying, but I don't think it's possible on the scale that you describe. Time will pass no matter how it is measured or what the gravitational forces are in its given environment.

Also, just out of curiosity.... If anti-gravity is real, if it could be contained and controlled, would it be used as a fuel for traveling back in time, or as a vehicle? This question isn't based in fact, I just want to know what you think.

I don't know what I was thinking... lol. It's too confusing. It doesn't exactly make sense thinking of it. I don't get it myself. It was purely theoretical. If it could be contained though... well I imagine it would work similar as anti-matter does somehow. I really dono how to explain it though. Nothing would exist really if antigravity was reall... everythin would explode and move apart at an ever accelerating pace.

But the way I think about the less gravity = time passing more slowly, is that beyond the "edge" of the universe (which is constantly expanding), there is no gravity, and no time, effectively time is frozen. Everywhere within our universe there is at least a little gravity acting on everything.