[GTA_stu]

What about if you go to a point when your father has already been born. Then you'd still eventually be born so you couldn't erase yourself, and you could still kill your grandad. Hooray!

[Irviding]

QUOTE (GTA_stu @ Friday, Apr 13 2012, 11:59)

What about if you go to a point when your father has already been born. Then you'd still eventually be born so you couldn't erase yourself, and you could still kill your grandad. Hooray!

That is the solution. Are you good at puzzles?

[Icarus]

I thought Fry (from Futurama) already demonstrated that if you kill your grandfather back in time, you have a limited window to impregnate your grandmother and thus, become your own grandfather.

[Gtaman_92]

Lay of the drugs dude.

[zoo3891]

Almost all of Piers Anthony's books that I've read (all two of them!) discuss his thoughts on time paradoxes (and because I can't create any theories about them due to my lack of education on metaphysics I'll share his).

Actually no, I don't even really understand what he has to say, if you want to explore time paradoxes though I suggest "Dead Morn."

[d0mm2k8]

QUOTE (Icarus @ Friday, Apr 13 2012, 20:47)

I thought Fry (from Futurama) already demonstrated that if you kill your grandfather back in time, you have a limited window to impregnate your grandmother and thus, become your own grandfather.

I did do the nasty in the pasty.

[Irviding]

QUOTE (Gtaman_92 @ Friday, Apr 13 2012, 16:51)

Lay of the drugs dude.

The original topic wasn't about robots, though the topic change made me laugh when I woke up this morning. Apparently what I posted about is a serious phenomenon debated in numerous intellectual circles. So perhaps, you sir, are the one who needs to start doing drugs.

[K^2]

There are no paradoxes in time travel. If you go into the past, and you kill your grandfather, you simply end up living in a time line where you were never born. You don't alter your own past, just the history. Pretty straight forward, really. All you need to understand time travel are introductory Quantum Physics and General Relativity.

[Irviding]

QUOTE (K^2 @ Friday, Apr 13 2012, 18:50)

There are no paradoxes in time travel. If you go into the past, and you kill your grandfather, you simply end up living in a time line where you were never born. You don't alter your own past, just the history. Pretty straight forward, really. All you need to understand time travel are introductory Quantum Physics and General Relativity.

So the "you" that went back in time would just exist in that time with the grandfather?

Is the timeline of the "you" that went back in time still in existence?

[jackass2009]

At least you're not going by Star Trek rules. If I remember right, it's some of the most confusing sh*t ever. One person has their own timeline, doing something to alter it creates a new timeline, and you can't interact with other peoples' timelines. So, hypothetically, going back in time creates a new timeline, and killing your grandfather has it's own timeline, and so forth. How did I just explain all that without getting a migraine?

[lil weasel]

People confuse themselves. You do what you do. You exist, you have always existed, you will continue to exist. Time is a fixed line, picture a rubber band nailed at the beginning of time and the end with Major events tacked along it. When you move the 'line' to one side the ends stay the same as the 'time line' tries to reestablish itself. Major events never change, but the people who affect it might.

[K^2]

QUOTE (Irviding @ Friday, Apr 13 2012, 21:43)

Is the timeline of the "you" that went back in time still in existence?

That's open to interpretation. Problem is, you cannot conduct an experiment to see if a time-line you're not in exists or not. So there are two alternative interpretations to quantum mechanics. One says the alternative time-line exists regardless. The other says that only the time-line you're in exists. And there is no way to distinguish between the two.

[rodneythesavior]

QUOTE (lil weasel @ Friday, Apr 13 2012, 23:02)

Time is a fixed line, picture a rubber band nailed at the beginning of time and the end with Major events tacked along it. When you move the 'line' to one side the ends stay the same as the 'time line' tries to reestablish itself. Major events never change, but the people who affect it might.

I don't mean to call you out on this, but I don't think that time is linear.
Time is perceived differently depending on the person. An hour to me, may be longer than an hour to you. Even though an hour is 60 minutes, we don't interpret them equally.

It's a common belief that Time is linear, but I think that's because it's much easier to wrap our minds around that.
Again, I'm not calling you out on anything.

QUOTE (Irviding @ Friday, Apr 13 2012, 21:43)

Is the timeline of the "you" that went back in time still in existence?

Maybe somewhere, but I'll keep it simple and say. No, that timeline would be destroyed, gone forever.

This post has been edited by rodneythesavior on Saturday, Apr 14 2012, 11:38

[El Zilcho]

QUOTE (K^2 @ Saturday, Apr 14 2012, 00:50)

There are no paradoxes in time travel. If you go into the past, and you kill your grandfather, you simply end up living in a time line where you were never born. You don't alter your own past, just the history. Pretty straight forward, really. All you need to understand time travel are introductory Quantum Physics and General Relativity.

And you've done this? Unless you have, that degree of certainty is absurd. While we can be pretty sure backwards time travel is impossible, we can't be certain that if it was, we'd simply magic up a new timeline. This isn't Back to the Future 2 guys.

And for you fellas bawing about "let me haev mah fantasy fun!", why aren't we discussing Santa Claus' existence?

[finn4life]

QUOTE (El Zilcho @ Sunday, Apr 15 2012, 00:41)

QUOTE (K^2 @ Saturday, Apr 14 2012, 00:50) There are no paradoxes in time travel. If you go into the past, and you kill your grandfather, you simply end up living in a time line where you were never born. You don't alter your own past, just the history. Pretty straight forward, really. All you need to understand time travel are introductory Quantum Physics and General Relativity. And you've done this? Unless you have, that degree of certainty is absurd. While we can be pretty sure backwards time travel is impossible, we can't be certain that if it was, we'd simply magic up a new timeline. This isn't Back to the Future 2 guys. And for you fellas bawing about "let me haev mah fantasy fun!", why aren't we discussing Santa Claus' existence?

El Zilcho, i dunno if i detect sarcasm when you ask K^2 if he has done this, i suspect you were being sarcastic, i don't like you so far but you're not an idiot.
-
The reason we are not discussing Santa Claus is because time travel is more interesting, besides, as if you have never once thought of a what if and pondered on it.

QUOTE

'Why' isn't part of the discussion. I believe in the rubber band theory. You may change bits but the line of time will return to the central points. Kill Bush and the war will still carry on by someone else. Kill your 'grandparent' and someone else will become 'your' grandparent. This one is something I read many years ago. Basically saying no matter what is done Major points in time will happen. "Blow up the Iceburg that would have sank the Titanic, and Mr. Greenberg will do something to cause it to sink."

Look i tend to disagree here, in some instances your idea works, in others it kinda does but not so specifically, read my example on page 2.

[El Zilcho]

QUOTE (finn4life @ Saturday, Apr 14 2012, 14:56)

QUOTE (El Zilcho @ Sunday, Apr 15 2012, 00:41) QUOTE (K^2 @ Saturday, Apr 14 2012, 00:50) There are no paradoxes in time travel. If you go into the past, and you kill your grandfather, you simply end up living in a time line where you were never born. You don't alter your own past, just the history. Pretty straight forward, really. All you need to understand time travel are introductory Quantum Physics and General Relativity. And you've done this? Unless you have, that degree of certainty is absurd. While we can be pretty sure backwards time travel is impossible, we can't be certain that if it was, we'd simply magic up a new timeline. This isn't Back to the Future 2 guys. And for you fellas bawing about "let me haev mah fantasy fun!", why aren't we discussing Santa Claus' existence? El Zilcho, i dunno if i detect sarcasm when you ask K^2 if he has done this, i suspect you were being sarcastic, i don't like you so far but you're not an idiot. - The reason we are not discussing Santa Claus is because time travel is more interesting, besides, as if you have never once thought of a what if and pondered on it.

Of course I'm being sarcastic. What I'm trying to say with Santa Claus is that this is highly improbable and in fact predicted impossible by Einstein's theories and common sense - paradoxes aren't just a by product of this fictitious process, but also the very reason that it wouldn't work. By creating a paradox you've done something that is impossible; called such because it is impossible, not improbable. We can speculate as to what would happen if it was possible, but so far a few people in here have passed judgement on this in a serious matter, as if time travel backwards could happen, and how we could circumvent these paradoxes. That's why I was saying what I did.

[Irviding]

QUOTE (K^2 @ Saturday, Apr 14 2012, 04:12)

QUOTE (Irviding @ Friday, Apr 13 2012, 21:43) Is the timeline of the "you" that went back in time still in existence? That's open to interpretation. Problem is, you cannot conduct an experiment to see if a time-line you're not in exists or not. So there are two alternative interpretations to quantum mechanics. One says the alternative time-line exists regardless. The other says that only the time-line you're in exists. And there is no way to distinguish between the two.

What exactly would happen to all the people of that time line? If I went back in time to kill my grandfather at age 40, would my wife and kids just disappear, my kids never having existed and my wife being somewhere completely different since we never met?

I honestly had no idea this has to do with actual quantum physics and such. You have a PhD in physics right?

[El Zilcho]

QUOTE (Irviding @ Saturday, Apr 14 2012, 15:21)

QUOTE (K^2 @ Saturday, Apr 14 2012, 04:12) QUOTE (Irviding @ Friday, Apr 13 2012, 21:43) Is the timeline of the "you" that went back in time still in existence? That's open to interpretation. Problem is, you cannot conduct an experiment to see if a time-line you're not in exists or not. So there are two alternative interpretations to quantum mechanics. One says the alternative time-line exists regardless. The other says that only the time-line you're in exists. And there is no way to distinguish between the two. What exactly would happen to all the people of that time line? If I went back in time to kill my grandfather at age 40, would my wife and kids just disappear, my kids never having existed and my wife being somewhere completely different since we never met? I honestly had no idea this has to do with actual quantum physics and such. You have a PhD in physics right?

That isn't a hard and fast rule - at the very best a tenuous theory. There is no way to know if that would happen. He's speculating.

[K^2]

QUOTE (Irviding @ Saturday, Apr 14 2012, 10:21)

What exactly would happen to all the people of that time line? If I went back in time to kill my grandfather at age 40, would my wife and kids just disappear, my kids never having existed and my wife being somewhere completely different since we never met? I honestly had no idea this has to do with actual quantum physics and such. You have a PhD in physics right?

I'm working towards a Ph.D., but it's in particle physics, so time travel is normal order of business. Of course, with particles, it has completely different consequences.

Anyways. As far as new timeline is concerned, nothing from your time line has ever existed. Your own existence starts the moment you step out of "time machine"*, basically. The fact that you have memories of an entirely different time-line might as well be a delusion as far as everything else goes.

* I'm oversimplifying concept of time-machine. It's not a little blue box or a Delorean. The only way we know how to time-travel is via certain space-time geometries. It'l like a corridor built out of space and time itself that has its exit before its entrance. However, it's not something you can just create in the future to return to the past. It needs to exist. And here is another twist. We can tell what happens to history if you change it. But if changing history results in change to the "time-machine", we don't know what will happen. It's Ok if going into the past makes it impossible for you to go to the "time-machine" and travel to the past. But if going to the past changes where the "entrance" point is, or prevents it from existing all together, you still have a grandfather paradox, and you need quantum gravity to resolve it. We simply don't know the answer.

QUOTE

That isn't a hard and fast rule - at the very best a tenuous theory. There is no way to know if that would happen. He's speculating.

General Relativity predicts time travel as possibility. We have actual solutions to space-time geometry. In other words, I can do math to it and see what actually happens. Quantum Mechanics covers the rest. The reason QM is necessary is because it's the only theory we have that allows an object to interfere with itself, which is what grandfather paradox is all about. So as long as conditions you set up for time-travel are such that you can use GR and QM, this is not just a "tenuous theory". It's a strong prediction of standard theory.

However, there are situations where GR and QM are fundamentally incompatible. What I describe above with stronger version of grandfather paradox taps into that incompatibility. We simply have no theory to treat situations where GR depends on QM.

[AtomicPunk]

QUOTE (Irviding @ Friday, Apr 13 2012, 05:23)

I'm sh*tfaced and high right now and we were having a debate on time travel. One of us is saying that it could never happen because if you went back in time and killed your grandfather, then you would not have existed to go back in time and kill him in the first place. So basically you would just end up in some alternate universe and you wouldn't be killing YOUR grandfather, but the grandfather of another YOU. My head hurts now probably not just from the liquor but from this discussion. It's actually pretty intriguing. Do you guys think you could go back in time and kill your grandfather? TO me it's not as simple as just "yes and you'd be dead". I mean you can't just disappear or anything.

Out of place time travelers is good to google. Then you have John Titor. Also, I wouldn't worry too much about people being robots as I would about there being reptilians among us. Youtube reptilians and watch. David Icke believes so and there is some footage that is actually creepy to watch. Do I believe it? IDK. A lot of things are possible, I guess.