Dr. Seth Lloyd, an MIT professor and self-described “quantum mechanic,” describes the quantum mechanics behind time travel during a guest lecture at the Institute for Quantum Computing, University of Waterloo. Recorded on Nov. 4, 2010, this is the entire lecture entitled “Sending a Photon Backwards in Time.”
Wheeler has the physics theory that positrons are electrons going backwards in time.
The early part of the talk is a lot about the many time travel stories.
Lloyd indicates that all the stories fall into either the many worlds version or the consistent history version. The consistent history version is that you cannot alter the past in ways that you know are not true.
Here is where he starts talking about his theory and the theoretical basis in more detail.
Quantum teleportation experiments had 80% fidelity but this was post selected for success. Overall fidelity was 11%.
Here is where he talks about their particle quantum experiments.
In a post selected sense this is time travel.
They create a singlet and then make measurements.
The photon never manages to kill itself in the past.
y Seth Lloyd approach to time travel is based upon post-selection and path integrals. In particular, the path integral is over single-valued fields, leading to self-consistent histories. He assumed it is ill-defined to speak of the actual density state of the CTC itself, and we should only focus upon the density state outside the CTC.
No solution exists due to destructive interference in the path integral. For instance, the grandfather paradox has no solution, and leads to an inconsistent state. If a solution exists, it is clearly unique. Now, quantum computers using time machines can only solve PP-complete problems.
Arxiv – The quantum mechanics of time travel through post-selected teleportation (2010)
The paper discusses the quantum mechanics of closed timelike curves (CTCs) and of other potential methods for time travel. We analyze a specific proposal for such quantum time travel, the quantum description of CTCs based on post-selected teleportation (P-CTCs). We compare the theory of P-CTCs to previously proposed quantum theories of time travel: the theory is physically inequivalent to Deutsch’s theory of CTCs, but it is consistent with path-integral approaches (which are the best suited for analyzing quantum field theory in curved spacetime). We derive the dynamical equations that a chronology-respecting system interacting with a CTC will experience. We discuss the possibility of time travel in the absence of general relativistic closed timelike curves, and investigate the implications of P-CTCs for enhancing the power of computation.
Just out of curiosity, what kind of science guy are you, that judges a book by it’s cover? I am 71 years old and know better than that. 🙂
Bald guy with ponytail? LOL. With style choices like that his other opinions are suspect.
Just out of curiosity what kind of science guy are you that judges a book by it’s cover? I am 71 years old and know better than that. 🙂
Bald guy with ponytail? LOL. With style choices like that his other opinions are suspect.
I agree. It’s always seemed odd to me that something would randomly stop you from killing good ol’ grandpa, or anyone else, or from altering time in any way. That presupposes that time is a single fixed stream, which goes against rationality (to me). I lean toward multiple timelines and universes that are created by the slightest action. Besides, we know what happens if someone kills Hitler. Anyone who’s played Command and Conquer Red Alert knows that. 😉 “Hitler… is out of the way.
Agreed. Even displacing a few air molecules and your eyes absorbing a few photons that were not affected before, is still a change… *And* given the chaotic nature of historical events, it may *take* only a small change in the right time and place, to have large effects downstream. (One guy gets sloppy in quality control of a certain ammunition manufacturer at the right moment, and various historical figures live another day,)
Agreed. Even displacing a few air molecules and your eyes absorbing a few photons that were not affected before is still a change…*And* given the chaotic nature of historical events it may *take* only a small change in the right time and place to have large effects downstream.(One guy gets sloppy in quality control of a certain ammunition manufacturer at the right moment and various historical figures live another day)
There’s a third option.First of all ANYONE who traveled back in time would alter the past. Eben if all they did is pop up in a the woods apart from humanity and then never ate drank or sought shelter when they quickly died they would become food for some animal and thereby alter the timeline of that animal. Why do we think that only alterations to human timelines matter? Why do we think that only things that are recorded in history public or personal matter?So anyone who travels back in time would alter events.They would also create a new timeline slightly different to moderately different if they killed their own grandfather to majorly different if they killed Hitler in 1932.And this is why we never hear about them. Since the timeline has been altered subsequent events unfold elsewhen and any time traveler’s past and subsequent future would not be OUR past.In those other timelines there may indeed be records of time travelers in the past if they did something noteworthy enough to record but it would have to be understood that whatever they did they had first started out from elsewhen in A future just not the future of those who recorded that history.Got that? Have I changed the future? Of course in some small way everything we do always does.
So in layman’s terms: ALL of the Terminator films need to be redone. None of the Back To The Future films need to be. Got that? Pretty easy, eh?
I tend to think of it as a game of Chinese checkers (which should actually be called German checkers) where every marble has a spot painted on top. At the beginning of the game they are all divided by color and every spot is facing up (a state of low entropy). Pass your hand across the marbles and some get moved to new slots and a lot of them get spun so the spots are every which way, then do it again, and again. This is the universe. To travel backwards in time you will have to move every marble back to the exact way it was at the point in time you wish to return to. Even if you could do this with the entire universe (the Laws of Thermodynamics say you can’t, although it might be possible on a much more local scale), and somehow stand outside of it as you did this, you wouldn’t be traveling in time, you would merely be destroying the universe and using it to create an exact copy of what it was like at an earlier point in time. Same deal if you did it on a more local scale, like just your planet or your neighborhood. The thing is, I believe the universe (multiverse) is a single expanding wave of space-time. There is no ‘past’ to go back to, it’s all still here, just changed. I don’t like that thought, but it’s what I’ve come to believe is the most likely truth.
You basically described an old idea of mine what the idea of ‘time travel’ really represents :)) . What we call a point in history a the specific and unique state of the wave function of the whole universe or multiverse. So, to ‘restore’ a state that you believe was the case in ‘the past’, you would have to have complete knowledge of that state of the universe. Basically, a harddrive image file of the universe. Full universal state knowledge of all ‘points in time’ is equivalent to omniscience that we would associate with the mightiest imaginations of deities – ‘God’ who created this universe. To create a specific state of the universe, you would need what I call ‘full admin rights’. The reception of ‘time’ is basically an artifact of the inner workings of our brains. As external sensory inputs and internally circulating excitations of our neural network race along the immensely long pathways, they always take a specific neural route that is formed by repeated identical or very similar inputs traversing and enforcing pathways, like a bulldozer having created a stable, easy to traverse pathway through the previous wild neural jungle. When we experience inputs A, B and C in that excitation order a couple of times, the neural ‘bulldozer’ creates and reinforces a specific path in the N-dimensional neural matrix for this input triplet (A,B,C). As excitations can only travel along paths with limited speed, they activate the memories in these pathways in exactly that order (A,B,C). We physiologically experience these activations in order, and so we believe that there is a ‘temporal’ order of (A,B,C). It’s misleading and makes understanding quantum mechanics very difficult or impossible. Well, our brains have evolved to survive ice ages and wild boars. So, I believe this: ‘Time travel’ requires omniscience and omnipotence. Won’t happen.
That’s the butterfly flapping in the rainforest concept. The other idea is that small changes are like ripples in a stream – it’s just random noise, and adding or removing a pebble won’t affect the ripples in any discernible way to an observer just a few yards downstream. But put in a big rock, or even take out a pebble that’s holding up a rock in a bend of the river, and things could soon change in a noticeable way. As it’s described in Dr. Who, there are “Fixed Points” that he(she) cannot change, or cannot allow to change, while the rest of it is just noise in the stream and won’t matter.
You basically described an old idea of mine what the idea of ‘time travel’ really represents :)) .What we call a point in history a the specific and unique state of the wave function of the whole universe or multiverse. So to ‘restore’ a state that you believe was the case in ‘the past’ you would have to have complete knowledge of that state of the universe. Basically a harddrive image file of the universe. Full universal state knowledge of all ‘points in time’ is equivalent to omniscience that we would associate with the mightiest imaginations of deities – ‘God’ who created this universe. To create a specific state of the universe you would need what I call ‘full admin rights’. The reception of ‘time’ is basically an artifact of the inner workings of our brains. As external sensory inputs and internally circulating excitations of our neural network race along the immensely long pathways they always take a specific neural route that is formed by repeated identical or very similar inputs traversing and enforcing pathways like a bulldozer having created a stable easy to traverse pathway through the previous wild neural jungle.When we experience inputs A B and C in that excitation order a couple of times the neural ‘bulldozer’ creates and reinforces a specific path in the N-dimensional neural matrix for this input triplet (ABC). As excitations can only travel along paths with limited speed they activate the memories in these pathways in exactly that order (ABC). We physiologically experience these activations in order and so we believe that there is a ‘temporal’ order of (ABC). It’s misleading and makes understanding quantum mechanics very difficult or impossible. Well our brains have evolved to survive ice ages and wild boars.So I believe this: ‘Time travel’ requires omniscience and omnipotence. Won’t happen.
That’s the butterfly flapping in the rainforest concept. The other idea is that small changes are like ripples in a stream – it’s just random noise and adding or removing a pebble won’t affect the ripples in any discernible way to an observer just a few yards downstream. But put in a big rock or even take out a pebble that’s holding up a rock in a bend of the river and things could soon change in a noticeable way.As it’s described in Dr. Who there are Fixed Points”” that he(she) cannot change”” or cannot allow to change”” while the rest of it is just noise in the stream and won’t matter.”””
all the stories fall into either the many worlds version or the consistent history version.” Your theory falls under the many worlds category. It’s not a third option.
all the stories fall into either the many worlds version or the consistent history version.””Your theory falls under the many worlds category. It’s not a third option.”””
Time only exists at the level of Thermodynamics – it doesn’t exist at the Quantum level
I don’t think there is a past or future to go to. I think there are only present moments that are infinite “bread slices” in a multiverse. You can “travel” to, or exist in another bread slice. That bread slice may look completely identical to the one you are used to living in, except maybe the slightest difference (e.g, a single strand of hair), or it can be completely unrecognizable. But it will not be the same as “your” bread slice of that moment. Ever. It means you can “travel” back to a time to prevent your parents from meeting, but that is a separate bread slice from your present slice so there is no dilemma. You can “travel” “forward” to a bread slice in the future to see – potentially – what your life might be like out of an infinite number of permutations, but it will not “be” the future (not from your own bread slice at least). I think all this is permissible in quanta theory. The trick I guess is finding the “present” bread slice again. There would need to be some kind of identifier. That could be a math equation that has all the universes’ information about it available, down to sub-atomic level, for that moment in time, a GPS-type locator. If all the data about all the universes was known, you could have path integrals?
Time only exists at the level of Thermodynamics – it doesn’t exist at the Quantum level
I don’t think there is a past or future to go to. I think there are only present moments that are infinite bread slices”” in a multiverse. You can “”””travel”””” to”” or exist in another bread slice. That bread slice may look completely identical to the one you are used to living in except maybe the slightest difference (e.g a single strand of hair)”” or it can be completely unrecognizable. But it will not be the same as “”””your”””” bread slice of that moment. Ever. It means you can “”””travel”””” back to a time to prevent your parents from meeting”””” but that is a separate bread slice from your present slice so there is no dilemma. You can “”””travel”””” “”””forward”””” to a bread slice in the future to see – potentially – what your life might be like out of an infinite number of permutations”””” but it will not “”””be”””” the future (not from your own bread slice at least). I think all this is permissible in quanta theory. The trick I guess is finding the “”””present”””” bread slice again. There would need to be some kind of identifier. That could be a math equation that has all the universes’ information about it available”” down to sub-atomic level for that moment in time a GPS-type locator. If all the data about all the universes was known”” you could have path integrals?”””
The kind with a sense of humor. ; )
If the universe is a simulation then time travel also has no paradoxes. In fact it would be easy to do if you could hack into the control code.
The kind with a sense of humor. ; )
If the universe is a simulation then time travel also has no paradoxes. In fact it would be easy to do if you could hack into the control code.
good point, as long as you are hacking the actual code and not the sim code.
good point as long as you are hacking the actual code and not the sim code.
Yep, especially if, as I suspect, at some level we primitive humans aren’t even close to, omniscience and omnipotence probably become mutually exclusive, in that any more progress towards one state requires a corresponding reduction in the other.
Yep especially if as I suspect at some level we primitive humans aren’t even close to omniscience and omnipotence probably become mutually exclusive in that any more progress towards one state requires a corresponding reduction in the other.
It’s not that “something random would stop you”, it’s that the probability function destructively interferes with itself *because* there is a Closed Timelike Curve. You can change anything so long as that doesn’t make it impossible to have you go back in time to change things. It’s OK if this doesn’t make sense to you: very little in quantum mechanics makes sense to anyone. The math checks out, though. Check out authors DOT library DOT caltech DOT edu SLASH 3737 SLASH.
It’s not that something random would stop you””” it’s that the probability function destructively interferes with itself *because* there is a Closed Timelike Curve. You can change anything so long as that doesn’t make it impossible to have you go back in time to change things.It’s OK if this doesn’t make sense to you: very little in quantum mechanics makes sense to anyone. The math checks out”” though. Check out authors DOT library DOT caltech DOT edu SLASH 3737 SLASH.”””
It’s not that “something random would stop you”, it’s that the probability function destructively interferes with itself *because* there is a Closed Timelike Curve. You can change anything so long as that doesn’t make it impossible to have you go back in time to change things. It’s OK if this doesn’t make sense to you: very little in quantum mechanics makes sense to anyone. The math checks out, though. Check out authors DOT library DOT caltech DOT edu SLASH 3737 SLASH.
It’s not that something random would stop you””” it’s that the probability function destructively interferes with itself *because* there is a Closed Timelike Curve. You can change anything so long as that doesn’t make it impossible to have you go back in time to change things.It’s OK if this doesn’t make sense to you: very little in quantum mechanics makes sense to anyone. The math checks out”” though. Check out authors DOT library DOT caltech DOT edu SLASH 3737 SLASH.”””
Yep, especially if, as I suspect, at some level we primitive humans aren’t even close to, omniscience and omnipotence probably become mutually exclusive, in that any more progress towards one state requires a corresponding reduction in the other.
Yep especially if as I suspect at some level we primitive humans aren’t even close to omniscience and omnipotence probably become mutually exclusive in that any more progress towards one state requires a corresponding reduction in the other.
It’s not that “something random would stop you”, it’s that the probability function destructively interferes with itself *because* there is a Closed Timelike Curve. You can change anything so long as that doesn’t make it impossible to have you go back in time to change things.
It’s OK if this doesn’t make sense to you: very little in quantum mechanics makes sense to anyone. The math checks out, though. Check out authors DOT library DOT caltech DOT edu SLASH 3737 SLASH.
Yep, especially if, as I suspect, at some level we primitive humans aren’t even close to, omniscience and omnipotence probably become mutually exclusive, in that any more progress towards one state requires a corresponding reduction in the other.
good point, as long as you are hacking the actual code and not the sim code.
good point as long as you are hacking the actual code and not the sim code.
The kind with a sense of humor. ; )
The kind with a sense of humor. ; )
good point, as long as you are hacking the actual code and not the sim code.
If the universe is a simulation then time travel also has no paradoxes. In fact it would be easy to do if you could hack into the control code.
If the universe is a simulation then time travel also has no paradoxes. In fact it would be easy to do if you could hack into the control code.
The kind with a sense of humor. ; )
Time only exists at the level of Thermodynamics – it doesn’t exist at the Quantum level
Time only exists at the level of Thermodynamics – it doesn’t exist at the Quantum level
I don’t think there is a past or future to go to. I think there are only present moments that are infinite “bread slices” in a multiverse. You can “travel” to, or exist in another bread slice. That bread slice may look completely identical to the one you are used to living in, except maybe the slightest difference (e.g, a single strand of hair), or it can be completely unrecognizable. But it will not be the same as “your” bread slice of that moment. Ever. It means you can “travel” back to a time to prevent your parents from meeting, but that is a separate bread slice from your present slice so there is no dilemma. You can “travel” “forward” to a bread slice in the future to see – potentially – what your life might be like out of an infinite number of permutations, but it will not “be” the future (not from your own bread slice at least). I think all this is permissible in quanta theory. The trick I guess is finding the “present” bread slice again. There would need to be some kind of identifier. That could be a math equation that has all the universes’ information about it available, down to sub-atomic level, for that moment in time, a GPS-type locator. If all the data about all the universes was known, you could have path integrals?
I don’t think there is a past or future to go to. I think there are only present moments that are infinite bread slices”” in a multiverse. You can “”””travel”””” to”” or exist in another bread slice. That bread slice may look completely identical to the one you are used to living in except maybe the slightest difference (e.g a single strand of hair)”” or it can be completely unrecognizable. But it will not be the same as “”””your”””” bread slice of that moment. Ever. It means you can “”””travel”””” back to a time to prevent your parents from meeting”””” but that is a separate bread slice from your present slice so there is no dilemma. You can “”””travel”””” “”””forward”””” to a bread slice in the future to see – potentially – what your life might be like out of an infinite number of permutations”””” but it will not “”””be”””” the future (not from your own bread slice at least). I think all this is permissible in quanta theory. The trick I guess is finding the “”””present”””” bread slice again. There would need to be some kind of identifier. That could be a math equation that has all the universes’ information about it available”” down to sub-atomic level for that moment in time a GPS-type locator. If all the data about all the universes was known”” you could have path integrals?”””
all the stories fall into either the many worlds version or the consistent history version.” Your theory falls under the many worlds category. It’s not a third option.
all the stories fall into either the many worlds version or the consistent history version.””Your theory falls under the many worlds category. It’s not a third option.”””
If the universe is a simulation then time travel also has no paradoxes. In fact it would be easy to do if you could hack into the control code.
Time only exists at the level of Thermodynamics – it doesn’t exist at the Quantum level
I don’t think there is a past or future to go to. I think there are only present moments that are infinite “bread slices” in a multiverse. You can “travel” to, or exist in another bread slice. That bread slice may look completely identical to the one you are used to living in, except maybe the slightest difference (e.g, a single strand of hair), or it can be completely unrecognizable. But it will not be the same as “your” bread slice of that moment. Ever. It means you can “travel” back to a time to prevent your parents from meeting, but that is a separate bread slice from your present slice so there is no dilemma. You can “travel” “forward” to a bread slice in the future to see – potentially – what your life might be like out of an infinite number of permutations, but it will not “be” the future (not from your own bread slice at least).
I think all this is permissible in quanta theory. The trick I guess is finding the “present” bread slice again. There would need to be some kind of identifier. That could be a math equation that has all the universes’ information about it available, down to sub-atomic level, for that moment in time, a GPS-type locator. If all the data about all the universes was known, you could have path integrals?
“all the stories fall into either the many worlds version or the consistent history version.”
Your theory falls under the many worlds category. It’s not a third option.
You basically described an old idea of mine what the idea of ‘time travel’ really represents :)) . What we call a point in history a the specific and unique state of the wave function of the whole universe or multiverse. So, to ‘restore’ a state that you believe was the case in ‘the past’, you would have to have complete knowledge of that state of the universe. Basically, a harddrive image file of the universe. Full universal state knowledge of all ‘points in time’ is equivalent to omniscience that we would associate with the mightiest imaginations of deities – ‘God’ who created this universe. To create a specific state of the universe, you would need what I call ‘full admin rights’. The reception of ‘time’ is basically an artifact of the inner workings of our brains. As external sensory inputs and internally circulating excitations of our neural network race along the immensely long pathways, they always take a specific neural route that is formed by repeated identical or very similar inputs traversing and enforcing pathways, like a bulldozer having created a stable, easy to traverse pathway through the previous wild neural jungle. When we experience inputs A, B and C in that excitation order a couple of times, the neural ‘bulldozer’ creates and reinforces a specific path in the N-dimensional neural matrix for this input triplet (A,B,C). As excitations can only travel along paths with limited speed, they activate the memories in these pathways in exactly that order (A,B,C). We physiologically experience these activations in order, and so we believe that there is a ‘temporal’ order of (A,B,C). It’s misleading and makes understanding quantum mechanics very difficult or impossible. Well, our brains have evolved to survive ice ages and wild boars. So, I believe this: ‘Time travel’ requires omniscience and omnipotence. Won’t happen.
You basically described an old idea of mine what the idea of ‘time travel’ really represents :)) .What we call a point in history a the specific and unique state of the wave function of the whole universe or multiverse. So to ‘restore’ a state that you believe was the case in ‘the past’ you would have to have complete knowledge of that state of the universe. Basically a harddrive image file of the universe. Full universal state knowledge of all ‘points in time’ is equivalent to omniscience that we would associate with the mightiest imaginations of deities – ‘God’ who created this universe. To create a specific state of the universe you would need what I call ‘full admin rights’. The reception of ‘time’ is basically an artifact of the inner workings of our brains. As external sensory inputs and internally circulating excitations of our neural network race along the immensely long pathways they always take a specific neural route that is formed by repeated identical or very similar inputs traversing and enforcing pathways like a bulldozer having created a stable easy to traverse pathway through the previous wild neural jungle.When we experience inputs A B and C in that excitation order a couple of times the neural ‘bulldozer’ creates and reinforces a specific path in the N-dimensional neural matrix for this input triplet (ABC). As excitations can only travel along paths with limited speed they activate the memories in these pathways in exactly that order (ABC). We physiologically experience these activations in order and so we believe that there is a ‘temporal’ order of (ABC). It’s misleading and makes understanding quantum mechanics very difficult or impossible. Well our brains have evolved to survive ice ages and wild boars.So I believe this: ‘Time travel’ requires omniscience and omnipotence. Won’t happen.
That’s the butterfly flapping in the rainforest concept. The other idea is that small changes are like ripples in a stream – it’s just random noise, and adding or removing a pebble won’t affect the ripples in any discernible way to an observer just a few yards downstream. But put in a big rock, or even take out a pebble that’s holding up a rock in a bend of the river, and things could soon change in a noticeable way. As it’s described in Dr. Who, there are “Fixed Points” that he(she) cannot change, or cannot allow to change, while the rest of it is just noise in the stream and won’t matter.
That’s the butterfly flapping in the rainforest concept. The other idea is that small changes are like ripples in a stream – it’s just random noise and adding or removing a pebble won’t affect the ripples in any discernible way to an observer just a few yards downstream. But put in a big rock or even take out a pebble that’s holding up a rock in a bend of the river and things could soon change in a noticeable way.As it’s described in Dr. Who there are Fixed Points”” that he(she) cannot change”” or cannot allow to change”” while the rest of it is just noise in the stream and won’t matter.”””
So in layman’s terms: ALL of the Terminator films need to be redone. None of the Back To The Future films need to be. Got that? Pretty easy, eh?
So in layman’s terms:ALL of the Terminator films need to be redone. None of the Back To The Future films need to be. Got that? Pretty easy eh?
I tend to think of it as a game of Chinese checkers (which should actually be called German checkers) where every marble has a spot painted on top. At the beginning of the game they are all divided by color and every spot is facing up (a state of low entropy). Pass your hand across the marbles and some get moved to new slots and a lot of them get spun so the spots are every which way, then do it again, and again. This is the universe. To travel backwards in time you will have to move every marble back to the exact way it was at the point in time you wish to return to. Even if you could do this with the entire universe (the Laws of Thermodynamics say you can’t, although it might be possible on a much more local scale), and somehow stand outside of it as you did this, you wouldn’t be traveling in time, you would merely be destroying the universe and using it to create an exact copy of what it was like at an earlier point in time. Same deal if you did it on a more local scale, like just your planet or your neighborhood. The thing is, I believe the universe (multiverse) is a single expanding wave of space-time. There is no ‘past’ to go back to, it’s all still here, just changed. I don’t like that thought, but it’s what I’ve come to believe is the most likely truth.
I tend to think of it as a game of Chinese checkers (which should actually be called German checkers) where every marble has a spot painted on top. At the beginning of the game they are all divided by color and every spot is facing up (a state of low entropy). Pass your hand across the marbles and some get moved to new slots and a lot of them get spun so the spots are every which way then do it again and again. This is the universe. To travel backwards in time you will have to move every marble back to the exact way it was at the point in time you wish to return to. Even if you could do this with the entire universe (the Laws of Thermodynamics say you can’t although it might be possible on a much more local scale) and somehow stand outside of it as you did this you wouldn’t be traveling in time you would merely be destroying the universe and using it to create an exact copy of what it was like at an earlier point in time. Same deal if you did it on a more local scale like just your planet or your neighborhood. The thing is I believe the universe (multiverse) is a single expanding wave of space-time. There is no ‘past’ to go back to it’s all still here just changed. I don’t like that thought but it’s what I’ve come to believe is the most likely truth.
Agreed. Even displacing a few air molecules and your eyes absorbing a few photons that were not affected before, is still a change… *And* given the chaotic nature of historical events, it may *take* only a small change in the right time and place, to have large effects downstream. (One guy gets sloppy in quality control of a certain ammunition manufacturer at the right moment, and various historical figures live another day,)
Agreed. Even displacing a few air molecules and your eyes absorbing a few photons that were not affected before is still a change…*And* given the chaotic nature of historical events it may *take* only a small change in the right time and place to have large effects downstream.(One guy gets sloppy in quality control of a certain ammunition manufacturer at the right moment and various historical figures live another day)
You basically described an old idea of mine what the idea of ‘time travel’ really represents :)) .
What we call a point in history a the specific and unique state of the wave function of the whole universe or multiverse. So, to ‘restore’ a state that you believe was the case in ‘the past’, you would have to have complete knowledge of that state of the universe. Basically, a harddrive image file of the universe. Full universal state knowledge of all ‘points in time’ is equivalent to omniscience that we would associate with the mightiest imaginations of deities – ‘God’ who created this universe. To create a specific state of the universe, you would need what I call ‘full admin rights’.
The reception of ‘time’ is basically an artifact of the inner workings of our brains. As external sensory inputs and internally circulating excitations of our neural network race along the immensely long pathways, they always take a specific neural route that is formed by repeated identical or very similar inputs traversing and enforcing pathways, like a bulldozer having created a stable, easy to traverse pathway through the previous wild neural jungle.
When we experience inputs A, B and C in that excitation order a couple of times, the neural ‘bulldozer’ creates and reinforces a specific path in the N-dimensional neural matrix for this input triplet (A,B,C). As excitations can only travel along paths with limited speed, they activate the memories in these pathways in exactly that order (A,B,C). We physiologically experience these activations in order, and so we believe that there is a ‘temporal’ order of (A,B,C). It’s misleading and makes understanding quantum mechanics very difficult or impossible. Well, our brains have evolved to survive ice ages and wild boars.
So, I believe this: ‘Time travel’ requires omniscience and omnipotence. Won’t happen.
That’s the butterfly flapping in the rainforest concept. The other idea is that small changes are like ripples in a stream – it’s just random noise, and adding or removing a pebble won’t affect the ripples in any discernible way to an observer just a few yards downstream. But put in a big rock, or even take out a pebble that’s holding up a rock in a bend of the river, and things could soon change in a noticeable way.
As it’s described in Dr. Who, there are “Fixed Points” that he(she) cannot change, or cannot allow to change, while the rest of it is just noise in the stream and won’t matter.
There’s a third option. First of all, ANYONE who traveled back in time would alter the past. Eben if all they did is pop up in a the woods apart from humanity, and then never ate, drank or sought shelter, when they quickly died, they would become food for some animal and thereby alter the timeline of that animal. Why do we think that only alterations to human timelines matter? Why do we think that only things that are recorded in history, public or personal, matter? So, anyone who travels back in time would alter events. They would also create a new timeline, slightly different, to moderately different if they killed their own grandfather, to majorly different if they killed Hitler in 1932. And this is why we never hear about them. Since the timeline has been altered, subsequent events unfold elsewhen, and any time traveler’s past and subsequent future would not be OUR past. In those other timelines, there may indeed be records of time travelers in the past, if they did something noteworthy enough to record, but it would have to be understood that whatever they did, they had first started out from elsewhen in A future, just not the future of those who recorded that history. Got that? Have I changed the future? Of course, in some small way, everything we do always does.
There’s a third option.First of all ANYONE who traveled back in time would alter the past. Eben if all they did is pop up in a the woods apart from humanity and then never ate drank or sought shelter when they quickly died they would become food for some animal and thereby alter the timeline of that animal. Why do we think that only alterations to human timelines matter? Why do we think that only things that are recorded in history public or personal matter?So anyone who travels back in time would alter events.They would also create a new timeline slightly different to moderately different if they killed their own grandfather to majorly different if they killed Hitler in 1932.And this is why we never hear about them. Since the timeline has been altered subsequent events unfold elsewhen and any time traveler’s past and subsequent future would not be OUR past.In those other timelines there may indeed be records of time travelers in the past if they did something noteworthy enough to record but it would have to be understood that whatever they did they had first started out from elsewhen in A future just not the future of those who recorded that history.Got that? Have I changed the future? Of course in some small way everything we do always does.
Just out of curiosity, what kind of science guy are you, that judges a book by it’s cover? I am 71 years old and know better than that. 🙂
Just out of curiosity what kind of science guy are you that judges a book by it’s cover? I am 71 years old and know better than that. 🙂
So in layman’s terms:
ALL of the Terminator films need to be redone.
None of the Back To The Future films need to be.
Got that? Pretty easy, eh?
I tend to think of it as a game of Chinese checkers (which should actually be called German checkers) where every marble has a spot painted on top. At the beginning of the game they are all divided by color and every spot is facing up (a state of low entropy). Pass your hand across the marbles and some get moved to new slots and a lot of them get spun so the spots are every which way, then do it again, and again. This is the universe.
To travel backwards in time you will have to move every marble back to the exact way it was at the point in time you wish to return to. Even if you could do this with the entire universe (the Laws of Thermodynamics say you can’t, although it might be possible on a much more local scale), and somehow stand outside of it as you did this, you wouldn’t be traveling in time, you would merely be destroying the universe and using it to create an exact copy of what it was like at an earlier point in time. Same deal if you did it on a more local scale, like just your planet or your neighborhood.
The thing is, I believe the universe (multiverse) is a single expanding wave of space-time. There is no ‘past’ to go back to, it’s all still here, just changed. I don’t like that thought, but it’s what I’ve come to believe is the most likely truth.
Bald guy with ponytail? LOL. With style choices like that his other opinions are suspect.
Bald guy with ponytail? LOL. With style choices like that his other opinions are suspect.
I agree. It’s always seemed odd to me that something would randomly stop you from killing good ol’ grandpa, or anyone else, or from altering time in any way. That presupposes that time is a single fixed stream, which goes against rationality (to me). I lean toward multiple timelines and universes that are created by the slightest action.
Besides, we know what happens if someone kills Hitler. Anyone who’s played Command and Conquer Red Alert knows that. 😉 “Hitler… is out of the way.”
Agreed. Even displacing a few air molecules and your eyes absorbing a few photons that were not affected before, is still a change…
*And* given the chaotic nature of historical events, it may *take* only a small change in the right time and place, to have large effects downstream.
(One guy gets sloppy in quality control of a certain ammunition manufacturer at the right moment, and various historical figures live another day,)
There’s a third option.
First of all, ANYONE who traveled back in time would alter the past. Eben if all they did is pop up in a the woods apart from humanity, and then never ate, drank or sought shelter, when they quickly died, they would become food for some animal and thereby alter the timeline of that animal. Why do we think that only alterations to human timelines matter? Why do we think that only things that are recorded in history, public or personal, matter?
So, anyone who travels back in time would alter events.
They would also create a new timeline, slightly different, to moderately different if they killed their own grandfather, to majorly different if they killed Hitler in 1932.
And this is why we never hear about them.
Since the timeline has been altered, subsequent events unfold elsewhen, and any time traveler’s past and subsequent future would not be OUR past.
In those other timelines, there may indeed be records of time travelers in the past, if they did something noteworthy enough to record, but it would have to be understood that whatever they did, they had first started out from elsewhen in A future, just not the future of those who recorded that history.
Got that? Have I changed the future? Of course, in some small way, everything we do always does.
Just out of curiosity, what kind of science guy are you, that judges a book by it’s cover? I am 71 years old and know better than that. 🙂
Bald guy with ponytail? LOL. With style choices like that his other opinions are suspect.