The Grand Father paradox is flawed.

[frankinstein]

The “Grand Father” paradox is flawed.

The time travel cliché of the “Grand Father” paradox is logically flawed and has driven the notion of the multiverse theory. In fact matter as information can be proven to be persistent through time travel and indifferent to events that created it. The fact that a woman and man spawn a child is a form of instancing an object, albeit to the degree of abstraction of a human being is more of instancing a configuration of matter, none the less the information stands on its own within the universe. If such a child where to travel to the past and kill his grand father preventing his birth it would not destroy the information that structures the child. You could find this analogous to a virus that persists in a computer memory. If the computer memory is never purged and the operating system is replaced and all executables that created the virus destroyed but the virus itself is in the memory and never touched then when the operating system is started again the virus still persists. In a similar fashion the child is never destroyed by the child going back in time and killing his grand father. What does happen is the child is preserved in the changed time line even though it is never born.

So why do experts need a parallel universe to solve this paradox?

 

[Dmitry67]

There should be no paradox and time does not 'flow' or 'move'.

As 'block time' is commonly accepted: http://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time )

As time does not flow then all the events in Closed time-like loop must be consistent from the very beginning. In another words, when you try to kill you father, you suddendly change your mind, or it does not work, or forget the gun, get arrested before you kill him etc.

Here is more detailed ananlysis:
http://en.wikipedia.org/wiki/Novikov_principle

 

[frankinstein]

There should be no paradox and time does not 'flow' or 'move'.

As 'block time' is commonly accepted: http://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time )

As time does not flow then all the events in Closed time-like loop must be consistent from the very beginning. In another words, when you try to kill you father, you suddendly change your mind, or it does not work, or forget the gun, get arrested before you kill him etc.

Here is more detailed ananlysis:
http://en.wikipedia.org/wiki/Novikov_principle

The notion that the time-line exerts a force to preserve past events is a supersitious belief. If the oportunity for an event exists and can happen by physical processes then nothing can stop it from happening. So if the child is stead fast in testing this paradox he or she can kill the grand father. Because the information or mattter in the form of the child is not physically destroyed it will be preserved in the new time line, whether that be returning to the future or remaining in the past.

Frank

 

[frankinstein]

The real problem of time travel is the increase in the universe's mass when you travel back in time. Think about it, if you go back in time the stuff you're made of exists in some other form in a body of water, mineral, plant or animal. So when you go back in time effectively there is more mass in the universe!

So the increase in gravitational influence described by astronomers in the galaxy isn't from dark matter but from all the time travelers from other planets in the universe.

 

[Dmitry67]

The real problem of time travel is the increase in the universe's mass when you travel back in time. Think about it, if you go back in time the stuff you're made of exists in some other form in a body of water, mineral, plant or animal. So when you go back in time effectively there is more mass in the universe!

So the increase in gravitational influence described by astronomers in the galaxy isn't from dark matter but from all the time travelers from other planets in the universe.

Lets talk not about the hypotetical 'time machine' which does not exist
but about the Closed Timelike loops - they exist, at least inside the rotating black holes

In CTR mass is preserved and there are no paradoxes.

 

[Dmitry67]

The notion that the time-line exerts a force to preserve past events is a supersitious belief. If the oportunity for an event exists and can happen by physical processes then nothing can stop it from happening. So if the child is stead fast in testing this paradox he or she can kill the grand father. Because the information or mattter in the form of the child is not physically destroyed it will be preserved in the new time line, whether that be returning to the future or remaining in the past.

Frank

The key point of block time is that there is only one time line.
In order to talk about 'other timelines' you need to literally rework the whole physics.

 

[S.Vasojevic]

The time travel cliché of the “Grand Father” paradox is logically flawed and has driven the notion of the multiverse theory. In fact matter as information can be proven to be persistent through time travel and indifferent to events that created it.

You should acknowledge that, as there is spatial structure of object, there is also time structure as well. Your arguments are that there is no past, and that it does not matter what happened in past, present remains as it is. That is ok, but then there is no past to travel to.

 

[superpaul3000]

The time travel cliché of the “Grand Father” paradox is logically flawed and has driven the notion of the multiverse theory. In fact matter as information can be proven to be persistent through time travel and indifferent to events that created it. The fact that a woman and man spawn a child is a form of instancing an object, albeit to the degree of abstraction of a human being is more of instancing a configuration of matter, none the less the information stands on its own within the universe. If such a child where to travel to the past and kill his grand father preventing his birth it would not destroy the information that structures the child. You could find this analogous to a virus that persists in a computer memory. If the computer memory is never purged and the operating system is replaced and all executables that created the virus destroyed but the virus itself is in the memory and never touched then when the operating system is started again the virus still persists. In a similar fashion the child is never destroyed by the child going back in time and killing his grand father. What does happen is the child is preserved in the new time line even though it is never born.

So why do experts need a parallel universe to solve this paradox?

You make some serious contradictions in your statement. First of all, this paradox doesn't drive the idea of a multiverse. It simply states that only considering relativity, this thought experiment would violate causality. At the end of your argument you assert that a new timeline is created, which is consistent with a multiverse view (which you seem to be adamantly against). So you literally answered your own question. You need a parallel universe to solve this paradox for the new timeline (preserving the child) to exist.

 

[yuiop]

So why do experts need a parallel universe to solve this paradox?

How about this scenario. It is 2009 and John decides to travel back in time to 1909 and kill his grandfather. Let's say he succeeds does that mean his mother and brother that did not travel back in time magically dissolve when John kills his grandfather and do not exist in the year 2010 in the original timeline? If not, then we have 2 time lines, one in which his mother and brother exist in 2010 and another branching off at 1909 in which John will never meet his mother or brother again. Two timelines requires two parallel universes or we have to include some magic such as his mother and brother mysteriously disappearing in the future without any apparent cause or mystical coincidences conspiring to prevent John killing his grandfather.

So as I see it, we have 4 choices:

1) Parallel universes.
2) Mystical disappearances. (Cause without observable effect)
3) Mystical coincidences.
4) Time travel is not possible.

[EDIT] I posted about the same time as SuperPaul and it seems we are drawing similar conclusions.

 

[Dmitry67]

0) Novikov's self consistency principle and 1 timeline

 

[yuiop]

0) novikov's self consistency principle and 1 timeline

0) = 3)

 

[Dmitry67]

On the low level (solution of the wavefunctions of QM particles) it is not mystical. Just extra boundary conditions.

On the macroscopic level yes, it probably looks mysterious. It is interesting - if I really decide to change the past at some point how soon the 'environment' reacts? Should I change my mind month or days before? Or something happens at the very last moment? Would nature try to minimize the 'intervention' - like, moving few milligrams of matter in my brains would be probably enough to cause severe illness or brain damage, instead of spending energy on creation of earthquake?

 

[yuiop]

Does Novikov's self consistency principle require a strictly deterministic universe?

 

[frankinstein]

You make some serious contradictions in your statement. First of all, this paradox doesn't drive the idea of a multiverse. It simply states that only considering relativity, this thought experiment would violate causality. At the end of your argument you assert that a new timeline is created, which is consistent with a multiverse view (which you seem to be adamantly against). So you literally answered your own question. You need a parallel universe to solve this paradox for the new timeline (preserving the child) to exist.

No I do not since I am accerting that the universe is not deterministic. So a new time line in this context means the past was manipulated. I guess I should have stated that the time line is changed, this way you get the point that there is only one time line.

 

[frankinstein]

You should acknowledge that, as there is spatial structure of object, there is also time structure as well. Your arguments are that there is no past, and that it does not matter what happened in past, present remains as it is. That is ok, but then there is no past to travel to.

You're right in a scenario where a time machine could reach any time period of the past, there is no past to return to. But in the scenario where the time machine is a wormhole taking advantage of time dialation, according to many theorist, time travel to the point of opening the wormhole is possible, since the past is preserved by time dialation.

 

[superpaul3000]

No I do not since I am accerting that the universe is not deterministic. So a new time line in this context means the past was manipulated. I guess I should have stated that the time line is changed, this way you get the point that there is only one time line.

Well guess what a indeterministic universe implies. Path space (or parallel universes as some call it). If you only have one timeline, the universe is set, and the future is unchangeable. This is the very definition of deterministic. However, quantum mechanics shows us that reality is fundamentally indeterministic. Why do you have such a deep philosophical objection to multiple universes?

 

[frankinstein]

Actually in the idea that killing your grandfather prevents ones birth is really good to a certain degree of probability. After all the conditions by which one is born is subject to many influences and since such influences would probably still be in the changed time line that someone like you could be born since your mother would have tastes for men similar to what was to be your father. In a similar notion the prevention of birth may not stop scientific or social trends from happening. While Newton was on the verge of inventing calculus so too was Gottfried Leibniz who in fact was attributed with the invention of calculus. The universe is so complicated that simply preventing one event does not deterministically prevent other events that followed the event that was prevented. Of course if you destroy enough of the past to be certain of preventing an event, like WWI by destroying the human race, then there is enough certainty.

 

[frankinstein]

Well guess what a indeterministic universe implies. Path space (or parallel universes as some call it). If you only have one timeline, the universe is set, and the future is unchangeable. This is the very definition of deterministic. However, quantum mechanics shows us that reality is fundamentally indeterministic. Why do you have such a deep philosophical objection to multiple universes?

No, one time line does not mean that the time line can not be changed, it actually implies that information forming the time line can be changed. In effect redirecting the universe by changing information within the universe does not require multiple time lines or parallel univirses.

 

[S.Vasojevic]

You're right in a scenario where a time machine could reach any time period of the past, there is no past to return to. But in the scenario where the time machine is a wormhole taking advantage of time dialation, according to many theorist, time travel to the point of opening the wormhole is possible, since the past is preserved by time dialation.

Or look at it this way: Take any spatial dimension. You can go left, you can go right, but any change that you made will influence whole space-time. There is no reason to suspect that same is not true for the time. If you are, somehow able to move through time any way you want, any change you make must have influence, but in the case of time consequences can be dramatic, completely nonlinear, and probably instant. I strongly suspect that traveling to past is possible for any kind of information from future. Whole thing would end up in complete chaos.

 

[Dmitry67]

However, quantum mechanics shows us that reality is fundamentally indeterministic.

No, it does not
There are some deterministic interpretations and some non-deterministic

 

[superpaul3000]

No, it does not
There are some deterministic interpretations and some non-deterministic

Seriously. A deterministic interpretation of quantum mechanics is one that says the theory is wrong. Go back to your undergraduate QM textbook and take a look at Bell's theorem. QM happens to be a very accurate theory. Saying that it is wrong is like saying relativity is wrong.

 

[Dmitry67]

Looks like you know nothing about the interpretations.
All of them (except some, like objective collapse theories) are 100% compatible with the experiment. For that very reason they are called interpretations - not theories

Check column: Deterministic?
http://en.wikipedia.org/wiki/Interpretation_of_quantum_mechanics#Comparison

 

[superpaul3000]

Looks like you know nothing about the interpretations.
All of them (except some, like objective collapse theories) are 100% compatible with the experiment. For that very reason they are called interpretations - not theories

Check column: Deterministic?
http://en.wikipedia.org/wiki/Interpretation_of_quantum_mechanics#Comparison

You are correct. All interpretations are 100% compatible with the RESULT of the experiment. The difference between them comes before the measurement. So maybe I'm wrong about the other interpretations. I don't think so, but please enlighten me. What happens before the measurement? If for instance, the wave function describes an ensemble of equally prepared experiments. This seems to imply that (in the context of the double slit experiment) the electron actually travels along a certain path. If this were true we would not see the interference pattern but we do see it. So if quantum mechanics says that the electron travels through both slits at the same time how are the other interpretations not throwing QM in the trash? So again I ask, what happens before the measurement?

 

[Dmitry67]

Well, we have very long threads about the Interpretations, and of course it is difficult to cover that subject here. So I will try just to provide the motivation for having other interpretations.

In Copenhagen Int. "measurement" is a magical process. It causes "wavefunction collapse". Historically, it was the very first interpretation and the most covered in popular literature.

The deepest problems with Copenhagen are not things like EPR, but Shroedinger Cat. What makes a measurement device different? It is made of the same atoms, and yet - it behaves differently in Copenhagen.

Then happened 2 things: at first, in Quantum computing the 'measurement devices' could be as small as few atoms. On the other hand, billions of electrons can be put in superposition on a superconductive ring. So the answer ‘measurement device is big (macroscopically)’ was no longer accepted as an answer

The second thing was a discovery of Quantum Decoherence in 199x. So it appeared that in order to explan how classcal world emerges from quantum rules, we don’t need any 'collapse' at all! Quantum Decoherence suggests MWI, but other people might have other opinions.

As a result, here there are almost no people how seriously defend Copenhagen (I remember only one), while others prefer MWI, BM, and of course most of the posters do not participate in the "Interpretation Wars".

P.S.
Replying to your question, in MWI there are no particles. Tracks, light splashes are the result of Quantum Decoherence with the macroscopic states of the observer. So electron is a wave in MWI, and there is nothing but unitary evolution.
In BM you can not, in principle, have a sequence "equally prepared experiments" because there are hidden variables, which you can not measure but which affect the result.

 

[SASGood]

energy time lines.
energy (and mas is energy) creates it own time in which to exist.
All the stuff that makes up the man is already traveling through time at many different speeds, at least if you look at the man as energy.

 

[jakesee]

I think the grandfather paradox is more like a result of say, quantum teleportation in the time dimension rather than time travel in relativity sense.

Somehow, it seems that discussions have omitted the possibility that going back into time also changes our age (5th dimension), conciousness (6th dimension), or for that matter, any higher dimensions I call "states-of-being".

In everyday life, it is obvious that all the x,y,z,t dimensions alter our "state-of-being", I think we should not assume that we can retain our evolved state when we travel on the time axis. Just as x,y, z, t are all interdependant.

May I propose that perhaps time travel also reverts our state of being back to the same point on the x,y,z,t location? Hence, if the man intending to kill the grandfathe returns to the past, we would find it will not be possible since he would lose all the plans of doing so from his state-of-being.

 

[A.T.]

going back into time also changes our age (5th dimension), conciousness (6th dimension), or for that matter, any higher dimensions I call "states-of-being".

Did you read the second sticky thread?
https://www.physicsforums.com/showthread.php?t=17355

 

[jakesee]

Did you read the second sticky thread?
https://www.physicsforums.com/showthread.php?t=17355

Yes I did, but I figured if someone could argue "Grand Father" paradox as flawed and offer alternative explanation, I think I could casually do so, for this thread only, as well? No? I don't see how we can have a discussion if we can only agree? Not that my opinion is any valuable but I just hope to see responses to my own understanding and maybe some experimental results to show that my thinking has been proven wrong or otherwise. Please advice. Thanks.

 

[A.T.]

maybe some experimental results to show that my thinking has been proven wrong or otherwise

Experimentally prove that consciousness is the 6th dimension? Unless you explain how to measure the value of consciousness, you are not even talking about physics here.

 

[jakesee]

Experimentally prove that consciousness is the 6th dimension?

I think you misunderstood. I really just meant states. But it's ok, please get back to the point and just respond to the topic starter.

 

[SASGood]

I don't accept that consciousness is a sixth dimension because people with alzheimer's loose there consciousness gradually. By the time they actually die all of their ability to think has gone.

 

[frankinstein]

I think the grandfather paradox is more like a result of say, quantum teleportation in the time dimension rather than time travel in relativity sense.

Somehow, it seems that discussions have omitted the possibility that going back into time also changes our age (5th dimension), conciousness (6th dimension), or for that matter, any higher dimensions I call "states-of-being".

In everyday life, it is obvious that all the x,y,z,t dimensions alter our "state-of-being", I think we should not assume that we can retain our evolved state when we travel on the time axis. Just as x,y, z, t are all interdependant.

May I propose that perhaps time travel also reverts our state of being back to the same point on the x,y,z,t location? Hence, if the man intending to kill the grandfathe returns to the past, we would find it will not be possible since he would lose all the plans of doing so from his state-of-being.

As I explained in the first post because information in the form of the child is never destroyed the child continues "as is" preserved in the changed time line, this would include its memories, which is inclusive of behaviors.

The preservation of memories in the child subtly relates to the issue of time itself which is a contextual measure, so by the child's frame of reference the pre-changed time line is still a vivid memory...

Frank

 

[jambaugh]

The time travel cliché of the “Grand Father” paradox is logically flawed and has driven the notion of the multiverse theory.

Firstly the "Grandfather paradox" is not "flawed" it is a set of mutually inconsistent assumptions. Given they are not mutually consistent then one of the assumptions must be false. Which is a matter of opinion.

But this paradox is not the motivation behind parallel universes theories. In so far as parallel universes are taken seriously at all they are invoked by certain interpretations of quantum mechanics to preserve certain other desired assumptions which the interpreter wants to keep.

In fact matter as information can be proven to be persistent through time travel and indifferent to events that created it.

You can't "prove" anything until you have a working time machine to test. You can at best "prove" what a given theory predicts. Within what theory are you working? Classical Einsteinian GR?

So why do experts need a parallel universe to solve this paradox?

The paradox is "solved" by invalidating anyone of the assumptions used in its formulation. The most obvious is "cosmic censorship" i.e. time travel is impossible.

If you like I'll give you my "resolution". Consider say water freezing around a sphere of ice. Think of the patterns of defects in the ice as the sphere grows as "objects". There is a certain randomness to their formation but they also propagate according to some definable rules as the ice forms. Think of these rules as "dynamics" think of the ice as "the past" and think of the liquid as "the future". Now building a time machine is simply a matter of going back and melting down to a point inside the ice. Doing so "erases" all the future after this event point. The ice will refreeze consistent with the "rules" but possibly with a few artifacts from the act of resetting and using the leeway given by the randomness.

The time traveler will have whatever memory he carried with him but his history will be rewritten including his appearance in his recalled past. He must integrate himself back in the time line consistently with the laws of nature (i.e. he appearance must still conserve energy, charge, momentum etc.) so his appearance must look like a very very unlikely random accident (allowed by quantum uncertainty).

I am of course invoking a form of "meta causality" and "meta-time" in which the dynamics of the water and ice and freezing process is defined along with the dynamic physical time defined by the radius of the sphere of water and propagation of "material" defects. One then must ask the meta-question of whether a meta-time machine is possible and a meta-grandfather paradox needs resolution.

So really it doesn't resolve anything except, as with Everett's many worlds interpretation of QM, providing the speculator with a meaningless world picture into which he can integrate the assumptions he wants instead of sticking to operationally meaningful science.

 

[frankinstein]

Firstly the "Grandfather paradox" is not "flawed" it is a set of mutually inconsistent assumptions. Given they are not mutually consistent then one of the assumptions must be false. Which is a matter of opinion.

But this paradox is not the motivation behind parallel universes theories. In so far as parallel universes are taken seriously at all they are invoked by certain interpretations of quantum mechanics to preserve certain other desired assumptions which the interpreter wants to keep.

You can't "prove" anything until you have a working time machine to test. You can at best "prove" what a given theory predicts. Within what theory are you working? Classical Einsteinian GR?

The paradox is "solved" by invalidating anyone of the assumptions used in its formulation. The most obvious is "cosmic censorship" i.e. time travel is impossible.

If you like I'll give you my "resolution". Consider say water freezing around a sphere of ice. Think of the patterns of defects in the ice as the sphere grows as "objects". There is a certain randomness to their formation but they also propagate according to some definable rules as the ice forms. Think of these rules as "dynamics" think of the ice as "the past" and think of the liquid as "the future". Now building a time machine is simply a matter of going back and melting down to a point inside the ice. Doing so "erases" all the future after this event point. The ice will refreeze consistent with the "rules" but possibly with a few artifacts from the act of resetting and using the leeway given by the randomness.

The time traveler will have whatever memory he carried with him but his history will be rewritten including his appearance in his recalled past. He must integrate himself back in the time line consistently with the laws of nature (i.e. he appearance must still conserve energy, charge, momentum etc.) so his appearance must look like a very very unlikely random accident (allowed by quantum uncertainty).

I am of course invoking a form of "meta causality" and "meta-time" in which the dynamics of the water and ice and freezing process is defined along with the dynamic physical time defined by the radius of the sphere of water and propagation of "material" defects. One then must ask the meta-question of whether a meta-time machine is possible and a meta-grandfather paradox needs resolution.

So really it doesn't resolve anything except, as with Everett's many worlds interpretation of QM, providing the speculator with a meaningless world picture into which he can integrate the assumptions he wants instead of sticking to operationally meaningful science.

Your analogy of water in different states fails to realize that the information of water as a liquid is not stored in the configuration of water as ice, albiet water has behaviors which are stored in the form of subatomic particles and processes, the state of water as ice is not a point of stasis for water as a liquid. In fact the ice is a different state of water and is a form of instanced information. It doesn't matter if at some infintesimal time dt the ice was a liquid or gas for the state of water to remain as ice. So information is persistent without the need for a past. In the end the information going back in time is preserved by the mechanics of physical properties of matter, not the past that created the situation to configure the state of matter.

The whole point is once information is instanced it has no need for the past to persist, no more than a computer virus needs the initial deployment scheme to persist in your pc from past OS configurations...