[RagnaToad]

EDIT: I deleted the original post, and decided to restart this thread with a more general and less hypothetical "let's-say-you-CAN" approach.

-What's your opinion on timetravel?
-Is it possible?
-What are the effects/dangers of altering the past? (e.g. the Butterfly effect)
-Would it be a good thing to be able to travel to (and thus see) "the future"? (If there is such a thing...)
-What would actually happen if a true paradox were created? (e.g. imploding universe theories)

Discuss topics like this thread's title and knock yourselves out

[Moogable]

I do not think that Time Travel to the future or the past is possible. The reasoning is farily simple in this case.

PAST: One cannot travel to the past, because the past has already been set in stone. If one were to travel back in time, it would fundamentally alter the timeline. Even if that person stood still and spoke and did nothing, that would STILL have a ripple effect, like all actions do. This would change that with is already certain, and as such everything in the present could be changed. Since the past is solid, one can't alter the rock without shattering it.

FUTURE: One can't travel to the future, because the future has not been set yet. You could die tomorrow, next week, or in two hours. To travel anywhere beyond that would, in theory, kill you. And once you've crossed the barrier between life and death you can't come back. Likewise, traveling to the future would bring few results, again, because it's fluid. And, even if travel to the future Were possible, you wouldn't be able to come back to the present. Since the present is set in stone, already, and your return would again alter that which is set in stone.

[Sinister]

Technically, time travel is a natural occurrence. People are convinced that time is iron-clad. That it is as a clock. One second is one second for everyone. But the truth is that Time and Space are relative to certain degrees of speed.

In theory time should slow the closer you get to a black hole, for instance...or the closer you get to the speed of light. Such speeds are not available to humans, of course. But then, as you rejoin normal speeds you would rejoin normal time. And thus having achieved a...form of time travel.

But if you're referring to Back to the Future or other Sci-Fi mediums. I have nothing to contribute.

Most everything that can be said about Time travel, has been. The bottomline is, it's not possible at the moment... But it's not impossible.


As for Paradoxes. Paradoxes are often flaws in logical conceptualization. But until someone has tried it, who can say?

-Sin

[RagnaToad]

Originally Posted by Sinister

In theory time should slow the closer you get to a black hole, for instance...or the closer you get to the speed of light. Such speeds are not available to humans, of course. But then, as you rejoin normal speeds you would rejoin normal time. And thus having achieved a...form of time travel.

I don't quite understand what you mean with "time should slow...".
It's not because you move faster through space, that everything else moves faster through time.

Personally I don't believe in the matter of "time". There is only this moment that is real, not the moment 1/1000.000th of a second ago, that is a moment gone forever. Neither is there something as a "future".

Many people see "time" as a timeline on which we are but one little dot. The thing is, time is just an abstract term for us to use to easily refer to situations "in the past" i.e. situations that are no more. The term "future" is used to describe what will happen according to someone's logic, but it's not written in stone or anything. There is no destiny.

The native Americans believed that the people "in the past" were still alive, but just in the past. I disagree. You would have to see time as a timeline on which there is no absolute "now". If you know what I mean? We would simply be the past's future and the future's past. It's just weird to assume that this situation is not more existent than a situation which is no more...

I do believe looking back in time is possible.
In fact, we already do, don't we? What is the ability of sight? Light reflects on an object, e.g. a person you're talking to, travels a meter to your eye and falls into your eye and voila, sight is a fact.
Light may be incredibly fast, but it still has A speed. So it takes a while for the light, reflecting on something, to reach your eye.

Why don't we notice it? Because light is extremely fast. We WOULD notice the "delay" if, say, light were somewhat slower than our thinking.
Imagine someone moving in front of you, you try to hit him, and you can, because what you see may not be what happens when the light reaches your eye, but the difference in time between something actually happening and you being able to see it, is not noticeable by our brains.
(Whereas for sound, which can be slowed down in thin air or various curcimstances, you often see something happening, only for the sound to arrive later. Think about an F-16 flying over, flying faster than the speed of sound. You hear him being a couple of hundred yars behind where he actually is, right?)

Just to illustrate "looking" back in time is what we already do, but travelling is a totally different thing. I wouldn't want to know how easily a paradox could be created...

[Clint Eastwood]

Is it possible?
Scientists have found, using both the theory of relativity and quantum theory, that time travel isn't necessarily physically impossible. It's been stated that wormholes, so to speak, exist in a sense, in black holes, and can take a person to another time. This same theory has been used in many famous science fiction works over the years. The thing about it is, normal black holes just sit in space, with no rotation. These black holes just destroy anything in it's path, because inside, everything essentially gets crushed. However, if the black hole were to rotate, it would open up sort of a ring through it's center, allowing for possible passage through. It's also been noted that time runs slow when an object is moving. Therefore, if one were to hypothetically fall into one of these wormholes inside of the black hole, he or she would be transported at a rate of speed impossible to record by human beings, and therefore, be sent out the other end sometime in the future.

With quantum theory, on the other hand, it's a bit different. That theory suggests that every decision that every entity of matter is up against, the universe splits into multiple different universes in order to make every decision possible, creating parallel multiverses, not exact, but closely related to one another.

What are the effects/dangers of altering the past? (e.g. the Butterfly effect)
Altering the past wouldn't be too dangerous, because going by the quantum theory perspective, if you were to go back in time and, for example, kill one of your parents, then two separate futures would be created for you; one where you don't exist, and the one where you come from, where you do exist. You'd just have to make sure that when traveling back to the present, that you end up in the reality where you do exist.

Would it be a good thing to be able to travel to (and thus see) "the future"? (If there is such a thing...)
If humans had the ability to travel through time, it wouldn't be good. Humans are known for destruction. They can't get along because they think they're so superior, even over other humans. So if the ability of time travel was possible for humans, they would find which countries would grow strong, and when they get back to the present, they would take those countries out before they had a chance to grow into a superpower. Or at least that's what I think would happen.

What would actually happen if a true paradox were created? (e.g. imploding universe theories)
The imploding universe theories are just that; theories. Quantum theory, which is much more researched than the exploding universe theories, states that if one were to create a paradox, all it would do is create a separate reality than your own, but not necessarily a replacement reality. One that sits next to the original reality in the spacetime continuum.

[PurpleDiamond]

Wow, Dr. Egon Spengler I like the whole idea of multiple different universes in order to make every decision possible O.O...I personally believe that people could probably travel to the future if enough science was researched..However I don't believe travelling to the past is possible because whats done is done and I don't believe we can change that...
I would never though like to travel to the future because I'd rather wait tell it happens as opposed to knowing ahead of time and changing it if I didn't like it :]

[RagnaToad]

I dont see how travelling to something that is not yet existent is more plausible than travelling to something that used to be existent?

And the alternative worlds theory is a common theory, but I think it's rather hypothetical. You can't go to another world. You couldn't change the past and then go to the world in which everything is different. The "other worlds" which is spoken of are hypothetical, theoretical, call it what you want.
I don't think there is an actual physical reality other than ours, but there are many possible worlds.
As I said, the concept of "time" is in our heads, as are these other worlds.


kind of off-topic but also kind of not:

I love it when novels/films are not set in the future, but instead, set in an alternative world. E.g. 'V for Vendetta', a world in which the Nazis won the war and the whole(/European?) world has gone fascist.

[Clint Eastwood]

Originally Posted by RagnaToad

I dont see how travelling to something that is not yet existent is more plausible than travelling to something that used to be existent?

It would logically be easier to go forward in time than backwards in time, due to the fact that the faster that an object moves, the slower time moves around that object, but only around that object. Time everywhere else is moving faster, and therefore, when that object stops moving, it will be some time in the future. I have no idea how anybody could physically go back in time. I can't seem to think of anything that would seem believable, unless if somebody were to somehow travel to a parallel universe in the technical past, considering that with quantum theory, all parallel universes, past, present, and future, exist at exactly the same moment in time.

[RagnaToad]

Originally Posted by Dr. Egon Spengler

[...]considering that with quantum theory, all parallel universes, past, present, and future, exist at exactly the same moment in time.

That is exactly what I believe not to be true

I see your point though. The problem with discussing about this subject, is that the discussion already begins at the basics on which theories should be based. There is no proof for certain basic rules, like paradoxes making one possible world disappear, or the "timeline" splitting up, which makes it even harder to convince someone of your idea, when there are no general facts from which you can work everything out.

Since it's all hypothetical and all

[H.U.N.K]

So here's what im thinking.

If we could theoreticly timetravel, then I dont think we could do that without creating a paradox. To not create a paradox you would have to stay compleatly annonomos to everyone and everything. I think if someone in the past knew you then it would, at that point in time, screw up everything that is going to be related to you and your family(a.k.a, your ancestors).

Here is somthing, what if you went to the past...and died. What do you think would happen? Would you simply die there and seem to everyone in your time that you just dissapeared? Or would you mess up the rest of the world in your time? Would it effect the time you are in or just your time?

Due to how little can be proven, im pretty sure its safe to say its an answere to a question we should not yet ask.

However I dont accually look up and information or anything so I really am just speaking of what I know, which is not that much

[RagnaToad]

Originally Posted by H.U.N.K

If we could theoreticly timetravel, then I dont think we could do that without creating a paradox. To not create a paradox you would have to stay compleatly annonomos to everyone and everything.

Indeed. That's why I named this thread this way.

Although you should think about at what point the paradox would be established. Is it only when you meet someone that plays a role in your life? I believe it would automatically be created, because any small thing that changes, would make you a "different" person, even though nothing would be actually different, if you know what I mean. It's not because a person is the same in a world were some unknown guy fell off a tower, that he is the same person, you see? Since there would suddenly be a world where a guy fell off a tower, including a "you", right?
But the from what world are you?

The present splitting up in 2 presents seems to be giving me the least headaches at the moment, so I'm going with that right now .

But then there is no purpose of going to the past in order to change something. Plus, it's not hard to imagine you disappearing, cause from where would you have come, right? Since the future of the past you have changed (= alternative present created) is totally different from your present... So your either stuck in another world (umm... what?) or you just vanish, cause you don' exist anymore. (But then who made the changes? ---> paradox. yeah ^_^)

[Clint Eastwood]

Originally Posted by RagnaToad

So your either stuck in another world (umm... what?) or you just vanish, cause you don' exist anymore. (But then who made the changes? ---> paradox. yeah ^_^)

I realize that it doesn't matter what theories any of us throw out there concerning time travel and paradoxes, because in the end, everything is just really confusing. I would just like to add to that confusion a little bit.

It's impossible for somebody to just vanish, even if they don't technically exist any more in that one timeline, because the person already exists. That was probably the thinking when the time travel part of quantum theory was being established, because if a person doesn't exist in a certain timeline, yet still exists, doesn't that mean that there has to be another timeline in which that person does exists?

[Sinister]

Originally Posted by RagnaToad

I don't quite understand what you mean with "time should slow...".
It's not because you move faster through space, that everything else moves faster through time.

Personally I don't believe in the matter of "time". There is only this moment that is real, not the moment 1/1000.000th of a second ago, that is a moment gone forever. Neither is there something as a "future".

Many people see "time" as a timeline on which we are but one little dot. The thing is, time is just an abstract term for us to use to easily refer to situations "in the past" i.e. situations that are no more. The term "future" is used to describe what will happen according to someone's logic, but it's not written in stone or anything. There is no destiny.

The native Americans believed that the people "in the past" were still alive, but just in the past. I disagree. You would have to see time as a timeline on which there is no absolute "now". If you know what I mean? We would simply be the past's future and the future's past. It's just weird to assume that this situation is not more existent than a situation which is no more...

I do believe looking back in time is possible.
In fact, we already do, don't we? What is the ability of sight? Light reflects on an object, e.g. a person you're talking to, travels a meter to your eye and falls into your eye and voila, sight is a fact.
Light may be incredibly fast, but it still has A speed. So it takes a while for the light, reflecting on something, to reach your eye.

Why don't we notice it? Because light is extremely fast. We WOULD notice the "delay" if, say, light were somewhat slower than our thinking.
Imagine someone moving in front of you, you try to hit him, and you can, because what you see may not be what happens when the light reaches your eye, but the difference in time between something actually happening and you being able to see it, is not noticeable by our brains.
(Whereas for sound, which can be slowed down in thin air or various curcimstances, you often see something happening, only for the sound to arrive later. Think about an F-16 flying over, flying faster than the speed of sound. You hear him being a couple of hundred yars behind where he actually is, right?)

Just to illustrate "looking" back in time is what we already do, but travelling is a totally different thing. I wouldn't want to know how easily a paradox could be created...

I simply stated time slows in relation to speed. "In relativistic contexts, however, time cannot be separated from the three dimensions of space, because the rate at which time passes depends on an object's velocity relative to the speed of light and also on the strength of intense gravitational fields, which can slow the passage of time." That is relativity. How I choose to word what we all know happens, isn't relevant. Time travels in different frequencies at certain speeds, on which assertion I am correct according to most astrophysicists. The twin that is flying around the galaxy near the speed of light for ten years, could well stop and come back home to a brother who has aged twenty years.

Not only time, but matter as well. A meter stick going the speed of light will be shorter than a meter stick I hold in my hand on earth, by principle.


As to expound on the rest of your post... I quite agree. We, Taoists have a saying that the man who comes home and sits down in his chair, is not the same man who woke up and left home in the first place. There is no future. No one has ever lived two days at once, so how can their be a tomorrow.

People like to look at time the way they look at music, dragging the past to make sense of the present and assuming the future to establish a pattern. If the music doesn't follow the pattern set by the past, it's just a lot of jumbled noises. You have to follow the flow of notes to catch the greater meaning. Taoists don't live like this. We live only second to second.

[RagnaToad]

Hmm.

Some interesting points

[M16]

Originally Posted by Dr. Egon Spengler

Is it possible?
Scientists have found, using both the theory of relativity and quantum theory, that time travel isn't necessarily physically impossible. It's been stated that wormholes, so to speak, exist in a sense, in black holes, and can take a person to another time. This same theory has been used in many famous science fiction works over the years. The thing about it is, normal black holes just sit in space, with no rotation. These black holes just destroy anything in it's path, because inside, everything essentially gets crushed. However, if the black hole were to rotate, it would open up sort of a ring through it's center, allowing for possible passage through. It's also been noted that time runs slow when an object is moving. Therefore, if one were to hypothetically fall into one of these wormholes inside of the black hole, he or she would be transported at a rate of speed impossible to record by human beings, and therefore, be sent out the other end sometime in the future.

With quantum theory, on the other hand, it's a bit different. That theory suggests that every decision that every entity of matter is up against, the universe splits into multiple different universes in order to make every decision possible, creating parallel multiverses, not exact, but closely related to one another.

What are the effects/dangers of altering the past? (e.g. the Butterfly effect)
Altering the past wouldn't be too dangerous, because going by the quantum theory perspective, if you were to go back in time and, for example, kill one of your parents, then two separate futures would be created for you; one where you don't exist, and the one where you come from, where you do exist. You'd just have to make sure that when traveling back to the present, that you end up in the reality where you do exist.

A lot about this post is incorrect.

Black holes, for one, don't just "sit in space" and "destroy anything in their path." Black holes rotate. Anything with gravity that massive is going to rotate around its center of gravity. And they can't "destroy anything in their path" because they don't really have a path, relative to the objects around them. The objects around a black hole have a path relative to the black hole. Not vice versa. However, you are right about the ring at the center. The ring, however, would be so (infinitesimally) thin that it would have no physically evident volume.

Your quantum theory is also a little bit off. While I guess it can technically be classified as quantum theory, it's mostly the sci-fi authors and theoretical thinkers that consider this type of scenario. Most scientists don't really bother to study that possibility because there's really no feasibility in studying it.

A few people have also mentioned "time slowing down as you move faster." This is called time dilation. "Time slowing down" is an elementary way to look at it, but it's a pretty good way to look at it, too. A good example can be found in 'muon decay.' Muons are sub-atomic particles that travel through the universe. They have a decay time of two microseconds. Traveling through the universe, they travel with the speed of light. As such, they should only be able to travel about 600 meters. And yet, we are able to detect them as far as ~1800 meters below the earth's atmosphere, where they are thought to be created. This occurs due to this time dilation. At higher velocities, space-time obeys different laws. Things always get pretty funky at relativistic velocities.


As to the actual topic of time travel, I don't really think it's too possible. It's always a lot of fun to think about, but I just can't see it. Time isn't always necessarily linear, but there's just no real reason to consider the possibility of seeing into the future or past.

EDIT: I missed the real question. Do I think it would really create a paradox? I would say that if it could actually occur, no, I don't think it would necessarily create a paradox. I don't think the universe would blow up. I think instead, a series of small events would add up to alter the future to match up with the past. However, I do not think all changes would necessarily be detrimental.

[Clint Eastwood]

Originally Posted by M16

Black holes, for one, don't just "sit in space" and "destroy anything in their path." Black holes rotate. Anything with gravity that massive is going to rotate around its center of gravity. And they can't "destroy anything in their path" because they don't really have a path, relative to the objects around them. The objects around a black hole have a path relative to the black hole. Not vice versa. However, you are right about the ring at the center. The ring, however, would be so (infinitesimally) thin that it would have no physically evident volume.

There are two types of black holes, actually. The non-rotating Schwarzschild black holes, which essentially just suck up and destroy everything that crosses it's path, and the rotating Kerr black holes, which create a ring in the center, allowing for possible transport.

[M16]

Originally Posted by Dr. Egon Spengler

There are two types of black holes, actually. The non-rotating Schwarzschild black holes, which essentially just suck up and destroy everything that crosses it's path, and the rotating Kerr black holes, which create a ring in the center, allowing for possible transport.

So then again, even if the non-rotating black hole bit is true, I'll state that the black hole does not have a "path." It has a gravitational pull, but it doesn't just float around sucking things up.

[Clint Eastwood]

Originally Posted by M16

So then again, even if the non-rotating black hole bit is true, I'll state that the black hole does not have a "path." It has a gravitational pull, but it doesn't just float around sucking things up.

Whichever direction it moves in, that's it's path. As long as it's moving, which black holes do, then it has a path. And yes, it does just float around sucking things up. Due to the intensive amount of gravity surrounding a black hole, anything that gets close enough to it will literally be sucked into it.

[T.G. Oskar]

Well, think of it this way: measure the speed at which the planet Earth rotates. Now, travel upon a craft (an airplane, for example) which travels roughly twice that speed, so that eventually you move at the same speed by which the Earth rotates, either exactly at the same direction or at the opposite direction. Now, exceed that speed so that you theoretically move faster than the Earth. In theory, you're traveling through time.

Now, this may seem as a joke, but it's mostly to challenge the notion of time. Time, physics speaking, is used mostly as a measure; time as a concept is highly ignored, if not blatantly disapproved. If you consider time as a form of measure, then you can't travel through time, either forward or backward, because time does not exist. If you were to consider it a concept upon which you travel through "photo stills", then it might be possible (essentially, you'd have to transcend the dimensions of space and remain "still" on time, or have time perfectly go "still", to move through the "stills" of time and return. The idea is pretty bizarre, but impractical. It's mostly how you "perceive" time; do you perceive it as a measure, dividing activity in precise 1-second stills (or for greater precision, 1-picosecond or 1-femtosecond stills) in order to gather information about said activity, or as snapshots of activity as if cosmical frames per second?

Those sound similar, but are different when you think about them. The first meaning implies that, once that "still" passes, you can't return to it. Because it never existed at all; it's an arbitrary measure to gather information on what you really want (the activity). The latter is a conception upon which you consider what you do as part of a movie, or a sequence upon which you could turn back and forth.

In a nutshell: if time is a measure, then you can't return to the earlier activity of the Universe; universal activity is irrelevant to the time period (for purposes of returning to such event), and you can't even think of a paradox. If time is a concept, then universal activity is tied to the time frame, and you could theoretically (by any kind of Applied Phlebotinum) return to such a frame. If that happens, then you could either:

a) Alter the course of time (thinking of time as a progressing current, aka a river) and find nothing happened except that a new course opened. Then, there's no paradox; you just simply expand the multiverse, but you recall the specific point in time and space where you are.
b) Alter the course of time (thinking of time as a progressing current, aka a river), and finding you changed the events in time, hence cutting the current course, taking the changes, and creating a new course. In this case, there would be no possible multiverses or so forth; you altered time and space permanently.
c) Alter the course of time (thinking of time as a progressing current, aka a river), and finding you changed nothing. If only because your change did nothing, or changed ever so slightly it's ridiculous. Sure, you killed yourself on the womb, but lo and behold, there was another one in the uterus, and you just couldn't change yourself. Or said person was born only a second later. Or things like that.

Note that, each explanation is increasingly ridiculous as there is no empirical evidence on the matter. The closest thing there is to empirical evidence is that time is a measurement invented by men to measure activity. So, until further evidence is found that time is a real thing, that you can travel back and forth through real time, then probably you can think of its repercussions.

And about that "sensation" of time dilation...well, it's the only way the brain can assimilate traveling at speeds beyond light (assuming you can survive such an event); time "passes" slowly because your brain can't measure that amount of information at the same time, much as how you rewind or fast-forward something while playing it. The theoretical results of time "slowing" or "speeding up" are mostly ways to compensate, nothing of interest since you can't survive a black-hole anyways. Your body would die just by the intense pull of gravity; just trying to reach escape velocity is dangerous to a human being untrained to resist such speeds, imagine that multiplied by a thousand, or a million. Your brain would shut down before experiencing that event.

But if it were possible, then it's depending on how you consider it. Is it an inalterable stream, that compensates for any ripples done? Is there one timeline, or many which you might access just as easy as you can change channels? Depending on what you believe will be the answer you take. But, if you believe time is a measurement, then it's ridiculous to even speculate. Have a nice day.

[RagnaToad]

Originally Posted by T.G. Oskar

Well, think of it this way: measure the speed at which the planet Earth rotates. Now, travel upon a craft (an airplane, for example) which travels roughly twice that speed, so that eventually you move at the same speed by which the Earth rotates, either exactly at the same direction or at the opposite direction. Now, exceed that speed so that you theoretically move faster than the Earth. In theory, you're traveling through time.

huh?

No...

Why would you be travelling through time if you flew faster than earth? Since when is being fast the same as travelling through time?

If you fly around the earth faster than the earth rotates, the things that happen on earth will still take place in the same way as they would when you're on earth too.

Or are you saying that the earth's rotation speed is the norm for travelling through time? That really doesn't make sense. And I'm not saying that the speed of light being the norm is more logical or anything.

But the earth's surface has a speed of a little over 1000 miles/hour. And there is a plane which can go up to 1900 miles/hour. So with what you're saying, we could travel through time?

Don't think so, pal.