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New Model Solves Grandfather Paradox
goldfishy writes "If you went back in time and met your teenage parents, you could not split them up and prevent your birth - even if you wanted to, a new quantum model has stated. Researchers speculate that time travel can occur within a kind of feedback loop where backwards movement is possible, but only in a way that is 'complementary' to the present. In theory, you could go back in time and meet your infant father but you could not kill him." From the article: "Quantum behaviour is governed by probabilities. Before something has actually been observed, there are a number of possibilities regarding its state. But once its state has been measured those possibilities shrink to one - uncertainty is eliminated."
I am my own grandfather!
Farnsworth: Oh, a lesson in not change history from Mr. I'm my own Grandpa!
Sounds like the Novikov self-consistency principle to me.
Please, for the good of Humanity, vote Obama.
"OK, McFly, here's the gun. If you can kill your own father and thus erase yourself from existence, we'll know the theory was wrong."
Lawrence Person (lawrencepersonh@gmailh.com (remove all "h"s to mail)
http://www.lawrenceperson.com/
In other words, even if you take a trip back in time with the specific intention of killing your father, so long as you know he is happily sitting in his chair when you leave him in the present, you can be sure that something will prevent you from murdering him in the past
This means that you cannot be killed when you go back in time, nor can you kill or destroy anything! That's just perfect!!
Go back in time and be able to observe, only... no ability to interact with anyone either... it should be kinda like ghosts... we go back in time and observe and be like ghosts in the sense that we cannot interact and change anything that has already happened but only observe!
Imagine the possibilities of history classes of the future... maybe there are already a lot of ghosts watching us right now... the future students studying history!!
Destiny, it had to happen. Which now make me realize the importance the several episodes of time travel in Futurama had to the plot. It miss it....
And the knowledge that they fear is a weapon to be used against them...
"Clearly, the present never is changed by mischievous time-travellers: people don't suddenly fade into the ether because a rerun of events has prevented their births - that much is obvious."
That's not clear at all. If I went back in time and killed the baby George W Bush, it's like he would disappear in the middle of a speech. Rather the entire course of history branching from that moment would be changed, so that in the "present" no one would ever know GW had existed.
-Alex
Couldn't you go back in time to kill your grandfather, only to have him rematerialize out of quantum randomness 5 minutes later? It's not impossible, just really improbable... maybe that's the protection mechanism.
Comment removed based on user account deletion
How can that even be remotely possible? Anything and EVERYTHING (no matter how small or big of an event it is) will change SOMETHING in the future.
Sci-fi writers have had two main theories for a long time. Either you can go back in time and change things, or you can go back in time and "fulfill" the past you expireinced. Just because you have an influence on the past doesn't mean your influence didn't shape time into the way you remembered it.
Anyone who thinks any differently needs to go back to school.
Yes, because I'm sure these quantum physicists haven't spent any time in school...
By doing the nasty in the pasty.
---- El diablo esta en mis pantalones! Mire, mire!
Clearly, the present never is changed by mischievous time-travellers: people don't suddenly fade into the ether because a rerun of events has prevented their births - that much is obvious.
;)
So either time travel is not possible, or something is actually acting to prevent any backward movement from changing the present.
So let me get this straight, BBC reporter. Your proof that time can't be changed, is simply that you don't remember it happening?
There are just so many flaws in that reasoning.
First, time changes could be happening everywhere, but perhaps you have not witnessed one. Wait! How about this? How about time changing, and altering your memory at the same time?
What's the matter with you? Do you believe that it is impossible for something to occur, without you being aware of it?
Is this a God complex?
What unmitigated self-importance, BBC reporter!
Now sure, I know this reporter was likely trying to parse some marlaky that they were told, but this has to be the worst use of logic I have seen.
not to mention the best-selling novilization of the movie that followed shortly there after!
1) Your analysis is based on bad assumptions so your result is way off. 2) You're a sick bastard for fucking a horse.
The one thing that always bothered me about those time travel movies (besides the ridiculous timetravel part) like "Back To the Future", is that you wouldn't have to go to extremes to prevent your birth. All you would have to do is bump into your Mom or Dad to delay them for 1 second; that slight change in the timeline would guarantee that it would be a different sperm that won the race to impregnate your mom.
Power to the Peaceful
It could be happening all the time and you wouldn't be aware of it (by definition).
Sounds like bad fiction to me.Sounds like the techno-babble "justification" in the bad fiction.And the easiest way to not change it is for time travel to be impossible.If, for example, you knew a picture would be taken, you could reflect light from your body and appear in that picture, thereby altering the future.
So, travelling back in time, you cannot reflect light, and, by the same token, you cannot absorbe light.
And it just moves up from there for all other physical effects. Nothing touched, no air breathed, no light disturbed, nothing.
So, how would you even know you were in the past?
"Anyone else having difficulty imagining a scenario where it would be "impossible" to kill somebody?"
*cough* Bin Laden *cough*
To avoid contradictions in time travel, two simple rules must apply:
1) You can observe, but not alter the past.
2) You can alter, but not observe the future.
Well, I, for one, will never enjoy a pasty ever again.
It's still hard to grok what this "prevention" means to the time traveller. If you go back, are you physically prevented from firing the gun or will the gun misfire? Or if you make a change, does the timeline establish a new universe with the old one running along merrily as a parallel universe.
When we use our senses, we only see things in the typical 4D realm, so is it possible that all those other postulated dimensions (to 11) give the degrees of freedom to allow bifurcations in the timeline? Geez this is confusing.
If you saw your buddy killed before your eyes, you would leave the scene immediately, and avoid examining the body in any way. Instead, you'd go get a dummy that looks like your buddy, then return to the time just before your buddy died, rescue him, and leave the dummy behind to "fool" your past self. I was delighted later on to see that in the game Chrono Trigger it was possible to use exactly this mechanism to save the life of one of the characters in spite of their onscreen "death".
What this sounds like to me: If you have directly or indirectly observed something occur, then there is no uncertaincy of it occuring. If you haven't directly seen something happen or been informed that it happened, then it may not have happened. Why do we need scientists to tell us this?
Nope. I can prove it to you.
Lets say that at t = 0 your father is alive. And you go back to t = -10 to kill him. Let's say, further, that you kill him. So at t = -10 your father is dead. Then at t = 0 your dad is dead. This is a contradiction by hypothesis. The logic here is valid, so some premise must fail.
So it is logically impossible to kill your own father, given a relatively naive understanding of causation and fatherhood. A more nuanced understanding of causation and space-time might include things like "branching universes" and the like. Which is perfectly fine. But then there's the philoshical issue whether the person killed is actually your father or "merely" your "parallel universe father."
After all, I am strangely colored.
Apparently the BBC can report on this new model, but they can't seem to say where these papers are being published or what scientists are working on it or at which universities this research is taking place. Michio Kaku posited this might be the case in his book Hyperspace (excellent book) and to my mind, this is on the same level. It is defenitly some interesting stuff to talk about after burning a J, but it hardly rises to the level of scientific model. The Standard Model is a model; this is just fluff, albeit somewhat interesting fluff.
exceptio probat regulam in casibus non exceptis
One of the major problems encountered with time travel is not that of accidentally becoming your own father or mother. There is no problem involved in becoming your own father or mother that a broadminded and well adjusted family can't cope with. There is also no problem about changing the course of history - the course of history does not change because it all fits together like a jigsaw. All the important changes have happened before the things they were supposed to change and it all sorts itself out in the end.
Douglas Adams, The Restaurant at the End of the Universe
This is another case of science fiction being well ahead of science.
I often don't like the choices people make, but I like the fact that people make choices. That's why I'm a conservative.
Something I don't think a lot of people really grok is that the laws of physics are time symmetric (actually the full symmetry is CPT, charge+parity+time, an electron going back in time would be a positron for example) so the fundamental weirdness is why we perceive time to flow in one direction in the first place. That's why I've always loved Feynman's absorber theory and it's associated spin-off the transactional interpretation of quantum mechanics. Those theories don't discard the so-called "advanced" (that is, backwards in time)solutions and work out how in a universe with appropriate boundary conditions you get an arrow of time. The advanced solutions actually exist but because of the boundary conditions they cancel each other out except where they "count". So according to the theory, when you go to push an electron every other particle in the universe sends waves back in time in response to push back on the electron at the exact instant you push it! The advanced waves only manifest themselves as the normal radiation resistance we observe when accelerating charged particles. The transactional interpretation takes this line of thinking with regards to the collaspe of the wave function. When one particle of a two particle entangled system wave function collapses it sends an advance wave back in time to collapse the wave function of the other particle. So in the EPR experiment there is no instanteous "spooky action at a distance" but travel exactly at the speed of light but in the opposite direction in time.
Just because you have an influence on the past doesn't mean your influence didn't shape time into the way you remembered it.
For this to work, there would have to be no beginning and no end. In other words, no free will.
The NSA: The only part of the US government that actually listens.
The thing about time travel is that by nature, it has to be discovered simultaneously at all points in time. So, if we're not doing time travel right now, we never will. (At least random-access time travel. Someone might come up with a short term 'rewind' ala Superman or "Prince of Persia.")
The reason is...as soon as the first time machine is invented, then everyone from the future will jump back into the past and invent it first.
--Welcome to the Realm of the Hawke--
Doesn't work. At some point you would have had to decide to go to the past or not. What you are saying is that the past already contains whatever decision you made. If so that would mean you had no real choice. There has to be a beginning in order to have free will. If the past already contains all of our decisions of the present then we couldn't have really decided anything.
You are also thinking of the future as something undetermined but the past as determined and unchangable. Our present is the past of the future. For the past to be unchangable our present would also have to be unchangable. Again, we are back to no free will.
The whole point of time travel presenting us a paradox is because we think we have free will. If there is no possibility of a paradox then we have no free will.
The NSA: The only part of the US government that actually listens.
This story is a dup. The original will be published next week.
--
make install -not war
> Couldn't you go back in time to kill your grandfather, only to have him rematerialize out of quantum randomness 5 minutes later? It's not impossible, just really improbable... maybe that's the protection mechanism.
The actual protection mechanism is that you discover your grandfather to still be a young stud rather than a cranky old man, and he gives you a good ass-beating before sending you back where you belong.
Sheesh, evil *and* a jerk. -- Jade
They can talk about quantum probabilities till they're blue in the face, but until they accept the fact that there are more measurable dimensions beyond time, we'll remain stuck in this stupid mindset that you can't travel back in time and kill your grandfather.
By this rationale, the very act of time travel will destroy you, because it will cause two copies of yourself to occupy the same three-dimensional space at the same time!
A better theory would be one that proposes "cause" as another dimension, where all objects have specific properties at a point of length, with, height, time, and cause.
Cause provides a kind of branching decision point, where one "reality" diverges from all the rest. By going back in time and killing your grandfather, you alter your "cause" from that point forward. If you travel forward in time, you'll find that the "you" that would exist through your father in that "cause" reality does not exist, but you can still exist since you travelled there from a forward point in the "cause" that created you.
Expand your mind.
Actually, philosophers have had the theories, but time-travel sci-fi is, like most sci-fi, just a futuristic take on one philosophical idea or another.
:p.
The "new" model is actually called the "B theory" of time and isn't new at all (although this scientific explanation of it is I guess). The B theory is that every instance in time exists somewhere and it is always "now" in that instance, so there is no real past, present or future. In the B theory if you were to go back in time you would merely fulfil the events that happen in that instance of time, always as the way they were intended.
So if you went back in an attempt to kill the parents of the bully who harassed you in school you would find out that your attempts failed, and that they didn't change your "present" at all. In fact, they would have helped created your present. A good example of this theory in effect is the sci-fi series "Andromeda", which follows the B theory of time in its time-travel episodes. A more well known example is the movie 12 Monkeys.
Star Trek on the other hand follows the multiple futures theory, whereby if you go back in time and change something you actually from that point on move down a different branch of time into an alternate future. The Butterfly Effect is another movie example of this.
The problem with the B theory of time is that it requires a deterministic universe, which is an unpleasant who isn't a materialist (ie. you believe you're made up of more than just matter). Of course the alternate timeline theory also has its own problems in that regard, wherein if you can exist in multiple timelines then which one is really you and where is your soul? If you're a materialist then no worries
My own theory on the matter is that time is nothing more than a human construct. Matter changes, and one change takes place before another, and we measure the order in which these changes occur and call that 'time'.
I forget the name of the short story, but the female character ended up being her own great grand-daughter, as a result of a letter she received from her husband/great-grand-father.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
That sounds like a wager.
Free of Flash! Free of Flash!
Hereforth, I propose that all mass in our universe is comprised of elaborate boolean operations on chicken. After all, it is a well-known truth that chicken tastes like everything, and it also helps explain why so much of DNA is the same throughout species.
Unfortunately, I don't have a concise mathematical model to support this hypothesis yet, but I'm sure there's someone resourceful out there who can take care of all that hand-waving stuff.
Ahhh, someone who's willing to ask. :) Thanks. :)
While trying to avoid sounding like a complete lunitic, I'll try to explain the best I can. I'm no expert in paranormal events, so some of my phrasing may be a bit off. I was corrected on my experience of "Deja Vu" a few months ago, being told it's really "Precognition".
I was told when I was a kid that if I live through an event a second time, where I'm sure it couldn't have happened before, it was a "Deja Vu". This was clarified by someone more into paranormal phenomena to be a precognition. A deja vu is where you've lived it once, and you're living it again, even though you probably weren't able to have lived it once before. Use the example from the Matrix, where he sees a black cat run by, and then turns to see the same black can run by the same way again.
My precognitions usually happen years before the real event. They come in dreams. Usually they're very clear events, as viewed from my own eyes. Hollywood never portrays them like that, usually to show the stars involved in the scenes.
The most notable one was a conversation I had with 4 complete strangers. I went to a city I hadn't been to before, with a new friend. We met 4 of his friends there, and through the evening, we were having a conversation. We ended up in a library, and for 10 seconds through the conversation, I knew exactly what everyone was to say. At the point where I was suppose to say something, I didn't say a word. By not saying my part, the next person to speak didn't say anything, because I had changed the chain of events. They continued talking, it was just that it changed subtly.
Another changed event was visiting a strange house as a child. We went to a house, and I asked to play downstairs. I named very specific details of the downstairs of the house, because I **KNEW** I had been there before. They corrected me in that I had never been there before, because they had just moved in, but my details of the basement were absolutely correct, including an item of furnature which was left there by the previous owner. I may have changed this event by mentioning it too early, or it may have been changed by someone else changing plans.
My precognitions come more frequently when "something" is going to happen. The precognitions never have anything to do with the event that is going to happen, they're just like warnings that it will happen. The event isn't necessarly important to me, about half the time they are. I may get precognitions several times a day when the event is coming close. After the event, they can completely go away for a while. Sometimes it's weeks, sometimes it's years.
I can usually remember when the dreams are from. Usually they don't make sense at all, because of the time that I have the vision. I pass them off as a weird dream, until it really happens.
For example, I was dating this really nice girl. I dated her for years. While I was dating her, I had this dream. I was with this other girl in my car. This was a nice car, which at the time I didn't have anything like. I was at a particular intersection in a city I had never been in. I was messing with the air conditioning controls, because this girlfriend had changed something while I was driving. She was also talking on a cell phone to my ex-girlfriend (the girl I was dating when I had the dream), and their conversation was exactly from the dream.
When I had the precognition, I didn't see the girlfriend in the dream, because I was looking out at the traffic, which was a very specific part of the precognition. I didn't know what she'd look like, and I didn't realize what it was until it all happened. That dream was about 4 years previous to the event.
I spoke with someone who does remote viewing professionally. He's described some of his work. One that he told me about was an event that he was asked to view where something important to the investigat
Serious? Seriousness is well above my pay grade.
Why do we need scientists to tell us this?
/. saying "I could have told you that, who's paying these guys?" And all it really is, is that there was actual good scientific research going on, and the press got ahold of the simplest sound bite they could and presented THAT. There's usually a lot more than meets the eye.
Because this is a horribly simplified and popularized version of actual scientific work. It happens all the time: you hear "Study says: People would be happier if they chose jobs they liked." Everyone posts to
If we arbitrarly set time as a 4th dimension, which encompasses some arbitrary number of 3 dimensional states, space, then can't probability be a 5th dimension that contains all the different possible timelines?
We unintentionally move forward through the 4th dimension of time right now. Let's say we can move through time freely with a time machine, but by doing so there is an unintentional movement 5th dimensionally through possibility.
We see no time travelers because in our timeline the time machine is never created, but we might eventually create one, but every time we go back in time with it, we travel unintentionally through probability and there's probably already a bunch of time travellers there, we can't ever go back to our own original histories.
... so there's no chance of stopping Lucas from making Episodes I-III?
Let the commencement BEGINULATE!
This is hardly a "new" theory. At best it is a restatement of the decades old theories that are expressed here:http://plato.stanford.edu/entries/time-travel -phys/
Non sequitur: Your facts are uncoordinated.
I get tired of people being so limited in their thinking. A quantum wave function does not need to collapse. It can vibrate between all possible futures. When we observe it, it is our interaction with it at whatever point it is in its vibration that changes what universe we are in. The wave appears to collapse as we have now changed our own location in the multiverse relative to the quantum wave we were observing. Notice that we ourselves can act like quantum waves and that we like the wave we were observing are vibrating between possible realities. We simply made an observation or in other words we engaged in action that caused a quantum level interaction that pushed us away from another quantum waves location givings us the appearance of its collapse into one certain reality. As to what happens when you kill your grandfather in the past. In the universe you leave you would appear to vanish forever having engaged in a action that moved that reality away from you. In the past you do kill the man whose particles participate in the multiversal wave that your Grandfather participates in. The result is that you have now moved yourself into a universe in which the matter making up your dad's structure is dead. You still exist because you came from the future at a point in a another universe in which he still exists in the living form of your to sire you. So, ironically, the answer is that you cannot kill your actual father but you can go back and kill a version of your father and in so doing remove yourself forever from the universe in which your father exists. :-)
In the many-worlds theory, if you alter the past a new timeline is created, with your changes in place. If you kill your mother, then the other you doesn't exist, but since he's not the one who went back in time, no problem.
In the self-consistent theory (there might be a better name, but I don't know it), any alterations you make in the past have already been made. They are part of the history that led up to your time travel in the first place. Paradoxes are impossible - the probability of such an event is zero, as it assumes multiple, inconsistent events occur. One way to think of this is as similar to many-worlds, except with no branching - every world which is self-consistent exists, and every one with a paradox does not. While it appears to you you're going back in time to meet/kill/observe your mother, you're in fact just following a closed timelike curve through spacetime. The eventualities in which there is a paradox do not exist - even if you get to the past with killing intent, you will not be able to carry it out. Something will happen to prevent you carrying out your mission, from a simple attack of conscience to a sudden meteor strike.
We, existing in this universe, are on a crash course toward the future.
There's no stopping it or slowing down of time, in the traditional sense. However, it might be possible (with the help of absolute zero) to stop all things in the area of the absolute zero. This would be akin to stopping time, as nothing could be happening within that area.
Unbaking a cake or uncracking an egg is a good example of going back in time. Hey, if you can take a fully-baked cake, reverse the steps, and make it back into cake-mix-egg-and-milk-inna-bowl, that's good enough time travel for me.
Job? I don't have time to get a job! Who will sit around and bitch about being broke and unemployed then?
Actually it is proven that time travel forward is indeed possible (Einstein proved that in 1905 with his special relativity). It is happening all the time [sic]. Relative motion in spacetime in accordance with the absolute spacetime is what we perceive. This relative motion's duration is different for every observer.
So in fact, yes, time travel is possible. It just only proven for forward time travel. Backwards... We'll see about that...
... being one's own father is not going to be nearly as messy as being one's own mother?
There are numerous problems with your "proof". Here are some assumptions that you gloss over:
- You assume that t automatically progresses from -10 to 0, with all other values in tact. That is, you assume that if father is dead at t=-10, then father will be dead at t=0. Pretty wild assumption, considering that you assume just the opposite is true (that if father is dead at t-10, it's possible for father to be alive at t-11). It's a much more logical assumption that if father's state can change from dead to alive going in the negative direction (from t=-10 to t=-11), then father's state can also change from dead to alive in the positive direction (from t=-10 to t=0).
- You assume that it is impossible for father to be dead at t=0 and father to also be alive at t=0. Since parallel universes and probabilistic realities are two hotly debated ideas (by people smarter than you), I'd say that this assumption cannot be relied upon.
You can't just apply math where you want to, and gloss over these huge assumptions. Nice try, though.
- A/C #12345
I've always wondered why that sort of view isn't more popular or at least widely recognized as a reasonable alternative to the "quantum magic" view of the world. It's philosophically more reasonable while being mathematically identical.
When I was taking undergraduate quantum mechanics (about 8 years ago), I recall feeling elated when I ran across a single paragraph in the textbook that referred to the possibility that one day someone might develop a non statistical theory for the workings of the sub quantum world.
It probably would be pure fantasy since there's no way such a theory could ever be tested (right?), but I was happy to see that it was at least acknowledged that the statistics are just a tool and not a philosophical statement about what the universe is.
Cow Cube
You're thinking of "--All You Zombies--". "By His Bootstraps" is a similarly structured story about a man who is visited by future versions of himself, who give him advice. It is also a closed time loop, but I think the one in "All You Zombies" is considerably more convoluted.
The circumstances of the protagonist's conception and birth are an elaborate setup which can exist only because of the interference of the protagonist as an older man in his own past - he is his own mother and father, and in various other ways responsible for his own existence. He feels as if he is the only real person in the world, hence the title: "I know where I came from, but where did all you zombies come from?"