A Solution to the Grandfather Paradox

[RuroumiKenshin]

[SOLVED] A Solution to the Grandfather Paradox

For those who don't have a clue of what the grandfather paradox is, here is the definition:

Time travel is impossible as exemplified by the famous grandfather paradox. Imagine you build a time machine. It is possible for you to travel back in time, meet your grandfather before he produces any children (i.e. your father/mother) and kill him. Thus, you would not have been born

Okay, so my solution:
My solution is enitirely based on Richard Feymann's multiple history idea.
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This idea implies that there are multiple histories. For each decision that is ever made, (i.e. should I wear a white shirt or a black shirt today) there is another universe in which the decision is made differently. It is possible that in another universe, you wear a white shirt every single day of your life. This idea, however, is very difficult to prove. By definition, it would be impossible for us to go to these other universes and see for ourselves.



Feynman histories allow for closed-loop time as well as spacetimes which are warped enough for travel into the past. Keep in mind that we are talking about really small particles here, not spaceships or even people. As Hawking points out, due to these quantum fluctuations in spactime "quantum theory allows time travel on a microscopic scale" (p. 150). We cannot talk to hydrogen atoms and ask them if they travel in closed loop histories, but we can observe that there is a shift in the light given off by hydrogen atoms, which indicates that their electrons are moving in closed loops. Maybe, time travel takes place in front of us everyday according to Feynman histories, yet it happens on such a small scale that we don't even notice it.
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So, you go to the past, kill your grandfather. This automatically creates a new history. (sort of like a branch, so to speak)You would still be in existence in the original history, but not in the new one. This causes me to ask, can you exist twice? If your grandfather's twin becomes your grandfather, would you still be the same person(genetically speaking, and not referring to personality traits, as that gets quite a bit complicated)?

 

[zk4586]

well, this isn't really your solution; I've seen this (or variations thereof) in other places. Basically, when you go back in time and kill your grandfather it causes a rift whereby in one universe your grandfather is dead and you don't exist and in another universe your grandfather is still alive and so you do still exist (and this would be the universe you'd be in when you travel "back to the future.")

This causes me to ask, can you exist twice?

Well, if you subscribe to the multiple history idea (or the multiverse theory) than you exist a near-infinite amount of times.

 

[zimbo]

I agree that a multiple universe model avoids time-travel paradoxes. But 'time-travel' becomes impossible (apart from physical limitations) because it would be pretty hard to select the 'correct' past - a past that is exactly like the one you lived through except that you actually existed earlier than you are 'meant' to.

Each time you disturb a subatomic particle, the universe 'branches' because of quantum indeterminacy. So it's not just about conscious decisions that create branching, and that the number of possible universes is utterly, mindbogglingly, astronomical.

So if this is true, then there are an infinite number of universes where 'you' exist - where the different 'yous' have identical genes, but different life experiences. And there are a greater infinite number of universes where 'you' are almost genetically identical to your current self, save for a gene or two. Would that be the 'same' you?

So when you go to the 'past', it can't be the 'same' past that you actually lived through (because 'you' weren't there with your teenage grandfather!). In that alternative universe, your grandfather's only grandchild may be genetically identical to you, but there is a good chance that it won't be - either because your grandfather may end up having children with someone other than your 'grandmother', or that a different sperm may fertilise the ovum etc. So if you killed your grandfather in that alternative universe, you won't instantly disintegrate because that 'grandfather' isn't your grandfather anyway.

 

[RuroumiKenshin]

yeah, zimbo brings up a good point. So, when you go back in time, do you, in a sense, appear in a "future past" since the universe branches? I know this sounds very confusing, so if anyone can ask me where it's confusing, I'll fill in the spaces!

 

[zimbo]

Originally posted by MajinVegeta
yeah, zimbo brings up a good point. So, when you go back in time, do you, in a sense, appear in a "future past" since the universe branches? I know this sounds very confusing, so if anyone can ask me where it's confusing, I'll fill in the spaces!

Pretty much so. We would need to evolve a new range of verb tenses to deal with time-travel. Like when you want to talk about what you 'will' do once you get to the past, or what you 'did' before you 'left' the future, or what would 'had' already happened when you go back 100 years next week.

 

[RuroumiKenshin]

Yeah, I agree with you. So do you understand what I said?

 

[Iacchus32]

If time travel is "going to happen" -- in the future -- then it already has ...

Of course it would all depend on whether or not you could go backwards. If, the other hand you could only go forward, then you could pretty much create any scenerio you wanted (without worrying about the future), becasue it hasn't happened yet.

 

[CJames]

Wouldn't your sudden appearance in the "past" or the parellel universe (if such QM universes really exist) violate the second law of thermodynamics? Or would you somehow suck up energy from the entire universe to be created?

 

[wuliheron]

Although many physicists are loath to admit it, QM is a paradoxical magical theory of existence that permits anything and everything. The many worlds theory is just one of the more paradoxical magical interpretations.

A somewhat less magical theory, if that isn't an oxymoron, that attempts to overthrow the grandfather paradox involves the concept that the past cannot be changed. Thus, instead of requiring the paradoxical infinite universes of the many worlds theory, it involves self-referential time loops.

For example, because the past cannot be changed it is impossible to go back in time and kill your grandfather or yourself because, obviously, you are here and did not do so. However, it is possible in this theory to go back in time and save your grandfather's life because, obviously, you are here and did so. Similarly, you could not go further back in time than when your time machine was first turned on.

Again, these are very much magical theories. There is one serious attempt in progress I am aware of to build the first time machine. It uses counterrotating concentric circular laser beams that have been first sent through a Bose-Einstein condensate. The condensate slows the light to a crawl and, in doing so, increases its inertial mass.

The hope is that inside the rings of light a small area of spacetime can be distorted enough for light and particles to pass through. However, most physicists don't believe it is possible to get enough energy to do the trick or if spacetime is distorted enough to do this the result will be a feedback that will explode in the experimenters faces and destroy the machine.

http://www.rexboothill.com/RBDSite/timemachine.shtml

 

[RuroumiKenshin]

For example, because the past cannot be changed it is impossible to go back in time and kill your grandfather or yourself because, obviously, you are here and did not do so. However, it is possible in this theory to go back in time and save your grandfather's life because, obviously, you are here and did so. Similarly, you could not go further back in time than when your time machine was first turned on.

Yeah, but then the universes' history of that time period branches out. So, hypothetically speaking, (and assuming time travel to the past is possible), a history would branch out. You could change the past, and when you do so, you create a parallel universe, so to speak, or rather a new history. The original history would still exist.

 

[RuroumiKenshin]

??

Wouldn't your sudden appearance in the "past" or the parellel universe (if such QM universes really exist) violate the second law of thermodynamics?

How would it violate entropy?

 

[wuliheron]

Yeah, but then the universes' history of that time period branches out. So, hypothetically speaking, (and assuming time travel to the past is possible), a history would branch out. You could change the past, and when you do so, you create a parallel universe, so to speak, or rather a new history. The original history would still exist.

No, it is not a branching out of history. It is a temporal loop, the temporal version of a wormhole shortcut through space. Einstein's spacetime implies the past, present, and future all coexist in a static state. That is why we can travel into the future and experience different rates of the passage of time.

 

[STAii]

Mainly, this can be solved by saying that the peson going to the past is only an observer, and cannot change anything (don't ask me how )

Originally posted by Iacchus32
If time travel is "going to happen" -- in the future -- then it already has ...

I don't see your point.
If time travel will happen in far future, it is possible that the person that will go to past will reach our near future, therefore 'time travel' wouldn't have happened yet !

 

[chosenone]

I beg to differ that time travel is not possible but not time changing.let me see hear and you make your own judgement,but as you will see all you can say is you can prove it wrong and you can prove it right.if telepathy existed and it may,people have precognitive experiences all the time.when they do they believe it was a warning of a possible future,and they saw what would have been.so when the event happens they change what would have been to what was.in time travel paradoxs.this would be explain as the future was already suppose to be what happened and the alternate future never was going to happen.so what happens if you accidently kill someone by making a mistake.you couldn't live with there death on your hands and wanted to change it.see where this is going!you sent a telepathic message to your self in the past.in the past you receive the signal.to you it was a precognitive experience,so when you came up to when you made the mistake that killed the person you wouldntr do it.thus the paradox is avoided and the universe does blow up.all the one could assume at the moment you changes time.time just keeps going.like i said can't say it can can't say in can't.so what happens next when you try to argue what happens in the time line if this happens and you come up to the first event before it looped around to change time.ahh haa.what do you know.you had a premonition and you kept yourself from killing someone.so how would you know if that was time changing or the real thing.like I said.try to bet that arguement!

 

[RuroumiKenshin]

Originally posted by chosenone
I beg to differ that time travel is not possible but not time changing.let me see hear and you make your own judgement,but as you will see all you can say is you can prove it wrong and you can prove it right.if telepathy existed and it may,people have precognitive experiences all the time.when they do they believe it was a warning of a possible future,and they saw what would have been.so when the event happens they change what would have been to what was.in time travel paradoxs.this would be explain as the future was already suppose to be what happened and the alternate future never was going to happen.so what happens if you accidently kill someone by making a mistake.you couldn't live with there death on your hands and wanted to change it.see where this is going!you sent a telepathic message to your self in the past.in the past you receive the signal.to you it was a precognitive experience,so when you came up to when you made the mistake that killed the person you wouldntr do it.thus the paradox is avoided and the universe does blow up.all the one could assume at the moment you changes time.time just keeps going.like i said can't say it can can't say in can't.so what happens next when you try to argue what happens in the time line if this happens and you come up to the first event before it looped around to change time.ahh haa.what do you know.you had a premonition and you kept yourself from killing someone.so how would you know if that was time changing or the real thing.like I said.try to bet that arguement!

I have thought about that too. BUT it is entirely incorrect, at least not in modern theory. If you would be so kind as to look at the first post, you'll see that there are such things as "alternate universes" as you call them(and I like the name). When you started talking about sending telepathic messages to yourself in the past, I wondered if you were making this up as you went along, to fill in the spaces? Can you provide some data to substantiate your telepathy-related statements?
First off, everything you said is hypothetical, and not an inference. You can't send a message to your past self, because that would require time travel, and not telepathy. Telepathy is still hypothetical(and it doesn't make too much sense to me). In alternate universe, two probable choices are made, separately (one in one universe, another in the second unvierse) and each have there own consequences. Also, what you said sounds a lot like De Ja vu. Your apperent explanation is that you talk to yourself from the past. This is simply not possible...i don't see how it is.
Anyhow, the fact is that there are myriads of probabilities that don't neccasserily(sp?!) have to do with something that's "bad"(like murder, as you suggested). Whether or not I wear a pink or green t-shirt with blue or bedge pants is a probable situation. If I pair my pink t-shirt with bedge (ahh! fashion disaster! ) or if I wear a green shirt instead with the bedge pants and so on. These are all different probabilities, and thus multiple histories.

 

[RuroumiKenshin]

Originally posted by wuliheron
No, it is not a branching out of history. It is a temporal loop, the temporal version of a wormhole shortcut through space.

yeah, sort of like a branch? I feel like I'm taking this too literally. I mean, I imagine that there really are parallel/alternative universes. This further implies that Hawking's idea of multiple universes may be true.

Einstein's spacetime implies the past, present, and future all coexist in a static state. That is why we can travel into the future and experience different rates of the passage of time.

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okaay...
so how does that relate with the multiple history theory [?]

 

[wuliheron]

Mainly, this can be solved by saying that the peson going to the past is only an observer, and cannot change anything (don't ask me how )

No, that isn't quite it. This newer theory incorporates a kind of temporal uncertainty principle. The more you learn about your future, the less control or free will you appear to have over it. For example, if I found out from my future self that my father was going to die in a car accident I could warn him but the universe would still arrange for him to die that way or my future self might have been lying to me or whatever.

The same kind of thing works in reverse, future and past, have strange meanings when it comes to such discussions. Essentially if I went into the past to try and kill myself the universe would arrange things somehow so I would fail. In addition, when I use the word "universe" in this context it is just a convenience due to the difficulty of talking coherently about such things.

Sorry if that isn't much clearer. Just remember this is a theory based on Relativistic ideas where the past, present, and future all coexist in some sense. In other words, even causality is a slave to fate.

 

[RuroumiKenshin]

No, that isn't quite it. This newer theory incorporates a kind of temporal uncertainty principle. The more you learn about your future, the less control or free will you appear to have over it. For example, if I found out from my future self that my father was going to die in a car accident I could warn him but the universe would still arrange for him to die that way or my future self might have been lying to me or whatever.

So is death involved with multiple histories? I mean, can the probabilities of preventable deaths differ from history to history? Are all deaths preventable?

 

[wuliheron]

So is death involved with multiple histories? I mean, can the probabilities of preventable deaths differ from history to history? Are all deaths preventable?

Again, what I am talking about are not multiple histories, but a single continuous history. It just has loops in it similar to the way wormholes might work. If you go into the past and meet yourself as a child, for example, this is not a new event from your point of view. You remember your future self meeting you as a child but now you are experiencing the event from the other side as the adult.

Just as when we might travel through a wormhole from one part of the universe to another and the universe is still the same universe, theoretically it might be possible to travel back in time and still remain in the same universe. It just requires a rather healthy stretch of imagination and the laws of causality.

 

[RuroumiKenshin]

Oh, I see now!I have a much better view of it...I think it just might even correspond with the multiple histories theory.

 

[CJames]

Sorry earlier when I said second law of thermodynamics. (See my signature.) What I meant was conservation of energy. Your sudden creation, your appearance from nobody, appears to violate the law of conservation of energy. One second, there is nothing there. The next second, you are there. Where did that energy come from?

Considering all the paradoxes, the requirements for negative energy, the violations of fundamental physical laws, it seems to me that time travel is most likely impossible. I'm not saying it is for sure, but the odds appear low.

The many worlds view of QM isn't even that widely accepted, certainly not proven. I don't understand why people are talking about it as though it is a certain outcome of QM.

 

[chosenone]

since telepathy,or if it exists, the telepathic particles, teletrons can travel faster than light ,and can instanteniously appear anywhere in the universe at will.who's to say they are bound by the laws of physics and travel foward it time only.tacheons are hypothesised to be traveling faster than light by traveling backwards in time,so why not teletrons?

 

[STAii]

Originally posted by CJames
Sorry earlier when I said second law of thermodynamics. (See my signature.) What I meant was conservation of energy. Your sudden creation, your appearance from nobody, appears to violate the law of conservation of energy. One second, there is nothing there. The next second, you are there. Where did that energy come from?

Good point.
Maybe your energy (and matter) kind of travels with you (okz, i know, no one will buy this one ).
But the other idea could be that you get formed in the past from the matter that happens to be near the place where you come up, it is also not really logical but it can solve the problem for a second .

 

[CJames]

Originally posted by chosenone
since telepathy,or if it exists, the telepathic particles, teletrons can travel faster than light ,and can instanteniously appear anywhere in the universe at will.who's to say they are bound by the laws of physics and travel foward it time only.tacheons are hypothesised to be traveling faster than light by traveling backwards in time,so why not teletrons?

What are teletrons? Any reason why they would exist? Any evidence? Any theoretical predictions for them? I'm sorry but this is a moot point.

 

[chosenone]

if energy is what stops matter from going faster than light,then teletrons at particles without mass but have form.teletrons just carry information on them.so if a black holes singularity has gravity and is a forces spacetime bubble.then matter has gravity and its structure is energy inside a spacetime bubble.then teletrons are forced spacetime bubbles woith no energy,allowing them to travel faster than light,just like gravity does,the same type of hypothetical particle I am talking about

 

[RuroumiKenshin]

Originally posted by CJames
Sorry earlier when I said second law of thermodynamics. (See my signature.) What I meant was conservation of energy. Your sudden creation, your appearance from nobody, appears to violate the law of conservation of energy. One second, there is nothing there. The next second, you are there. Where did that energy come from?

I'm sorry, I don't quite understand your point.

 

[CJames]

Matter is engergy. If you show up in the past, matter is emerging in an area where there previously was no matter. Energy is coming from nowhere. This violates the conservation of energy.

 

[RuroumiKenshin]

The matter is not comming from no where. The matter is comming from the future(if you are going to the past). The matter exists in a different space time.

 

[zk4586]

I agree that a multiple universe model avoids time-travel paradoxes. But 'time-travel' becomes impossible (apart from physical limitations) because it would be pretty hard to select the 'correct' past - a past that is exactly like the one you lived through except that you actually existed earlier than you are 'meant' to.

I don't know if anyone responded to this because I'm too lazy to go through and read everyone else's responses right now, but you wouldn't be traveling back in time into a different universe. It would still be 'your' universe that you go back into, but other universes would be created from changes that were made as a result of your trip back in time. You never leave your own universe, but other universes are necessarily created by your trip.

 

[RuroumiKenshin]

Well, according to the "Pretzel" universe, in a way, you do "leave" your own universe. When you go back to the past, then just that simple action is changing the past because there'd be 2 of you. The U2 (the one that traveled to the past) would have not existed in the past. So, U2 would have entered a parallel unvirse which has an alternative universe. Wait, would it be an alternative universe?