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This is original research - don't delete it - this is a talk page. Just for the record.
So the exception to the "can't change the past" rule, is where the past is ambiguous (example: Bible prophecy, memory, perception, etc.) and that ambiguity might be used as a "buffer" (as in Chemistry) at some future juncture where a dominant teleological outcome exists. In that case the past might be changed sufficiently, having no other consequence, until the "tipping point." That's it.
If you think this is nuts, based on the typical apologetic level of non-theoretical criticism, you wouldn't pass the class entrance test, and you should recuse yourself from making comments.. If you have something constructive to add, or a question to ask, please do. We are dealing with unknown reality here. If it makes you uncomfortable, don't take it as an excuse to foul the drinking water
-- Xgenei ( talk) 01:35, 20 August 2017 (UTC) — Preceding unsigned comment added by Xgenei ( talk • contribs) 01:30, 20 August 2017 (UTC)
I was wondering if any research into how this concept relates with the concept of an "uncaused paradox" has ever been done by anyone notable. By "uncaused paradox" I mean something similar to the following:
- I receive instructions on building a time machine from the future - I follow the instructions and build a time machine - I go to the past and deliver the instructions to my past self
Simply saying that that has a zero chance of happening seems to be a little axiomatic in this case. The reason for it not happening, would be that it would be a paradox. But "paradox" could be defined in a way consistent with both the Novikov principle and the uncaused event simply by stating axiomatically that a universe where the first event occurs exists; in this way, the second and third events would have to exist, and no "paradox" would have occured, despite the time machine itself having no history or origin. Or to put it another way, the fact that the time machine has no history or origin would, pardon me for indulging, paradoxically be considered to not be a paradox by the model Novikov's principle presupposes.
Or to put the concept I'm trying to address in Lostie terms, "Whatever happened, happened" would neatly avoid addressing this sort of paradox at all in a "not even wrong" fashion.
I'm trying to do a decent enough summary to enable googling, but I'm probably not doing the idea justice. My googling attempts were simply in vain, and if anyone has done anything, it would make a really great addition to the article. And, of course, while it would probably abuse the purpose of the talk page to discuss this kind of stuff right here for fun, I'd nonetheless be game. — Preceding unsigned comment added by 173.22.35.171 ( talk) 01:56, 19 January 2013 (UTC)
The opening paragraph implies that if an event has probability zero then it cannot occur. A counterexample is choosing the number "3" out of all of the integers. The probability is zero but choosing "3" is not at all impossible. —Preceding unsigned comment added by 18.248.5.194 ( talk) 04:42, 19 July 2010 (UTC)
The original commenter is correct, and IO Device is wrong. Probability 0 is not the same as impossible. See http://en.wikipedia.org/wiki/Almost_surely . — Preceding unsigned comment added by 65.254.127.187 ( talk) 21:54, 16 September 2012 (UTC)
Yes, I also agree, IO is wrong. Probability of zero does not imply the impossible event. The wording of this should be corrected. — Preceding unsigned comment added by 114.244.190.98 ( talk) 07:18, 30 December 2012 (UTC)
this article need more clarification i think. does it simply means that it time is unchangeabe and you cannot go back in time and marry you mother because you haven't done it already? No paradoxis are possible beacause everything has already happened?
then it should say so. -- Alexandre Van de Sande 17:19, 5 Aug 2004 (UTC)
Novikov didn't use an example ("Rather than consider the usual models for such a paradox, such as the grandfather paradox..."), he used a mathematical/quantam model. Salasks 21:29, Aug 5, 2004 (UTC)
This quote from the article makes no sense: "if an event exists that could give rise to a paradox, then the probability of that event happening is zero"
Some philosophers like Richard Hanley claim that the self-consistency principle is just non-contradiction which philosophers have used for thousands of years. gren 05:02, 18 Jun 2005 (UTC)
This principle has a major flaw: one travelling into the future to pick up some object and take it back shall get the object, whatever it may be (including non-adherence to physical laws), because relatively to them, the people giving one the object have already recieved it from him when one returned.
The "time loop logic" program must be impossible, as it provides an easy way to create a machine that can fabricate any desired object from nothing. To wit:
The resolution to this paradox is clear: Nothing will ever be received at step 3. 71.178.183.147 ( talk) 05:58, 21 October 2009 (UTC)
This principle is very straightforward if you look at the universe with certain assumptions:
Consequences:
—The preceding unsigned comment was added by Spoon! ( talk • contribs) .
The principle is based upon an assumption that if time travel were possible the time traveller could return to an earlier state of the universe. The following explanation shows that asumption to be wrong, and as a consequence makes the principle redundant. Every particle in the universe, including those that make up me, travels on a trajectory through spacetime. Suppose I was to travel back through time to a point in spacetime that used to be occupied by the atoms that comprised my grandfather (say the year 1906): I would find that the atoms which comprised my grandfather were not there, as they were 'still' in 2006 where I had left them at the start of my travels. The only atoms that travel back in time are the ones that constitute the body of the traveller- all of the other atoms in the universe continue on their spacetime trajectories as before, and so are not found by the traveller when he/she arrives in the past. Given this, none of the supposed paradoxes arise, and so the self-consistency principle (in this context at least) is redundant. This seems pretty self-evident to me- am I missing something?
DoctorDen 1 April 2006 17.44 GMT (not logged in).
Doctor Den says: Thank you- that is very helpful. Can you recommend any references that explain how atoms have a definite constant position in spacetime, as I would like to read more.
DoctorDen 7 April 2006 20.35 GMT (not logged in).
Arn't the strongest arguments for the self-consistency principle all based upon quantum mechanics? For example, if your billiard ball was a quantum particle, then its interfearing with itself merely makes those trajectories rediculously improbable? I don't know enough about it to add this intelligently, but please get some input from someone who knows about quantum mechanics. JeffBurdges 19:35, 20 June 2006 (UTC)
Seems that way to me as well, in classical (non-quantum) physics if you know the position + velocity of the billiard-ball precisely the system is entirely deterministic and there is no probalility involved at all; so talking about the probability of when happens when the billiard ball hits itslef makes no sense unless you invoke quantum mechanical ideas (i.e. the unceratintly principle). Tomgreeny 18:24, 5 September 2006 (UTC)
So if someone would be to travel through time, their actions would have no effect?
But time travel itself affects the past -- you're taking something from the present and putting it in a different point in time, thus, for the context of the earlier point in time you travel to, introducing matter/energy/whatever that didn't exist there before, thus (as per chaos theory) possibly screwing up everything. Any successful travel through time would have an effect, otherwise it wouldn't be time travel.
With that in mind -- does the principle boil down to "time travel is only possible if it has no effect, thus time travel (the possibility of which necessitates having an effect) is not possible"?
The matter and energy of which the time traveller (and his clothing, etc) consists would (if the universe is a closed system) have been in use by something else at an earlier point in time and thus a re-allocation of matter and energy already existent at that earlier point in time to recreate the time traveller doesn't seem to be a viable alternative either. But if the time traveller can neither be composed of matter and energy that didn't exist, nor of that which already existed but was "in use" already, what does he consist of?
Even if the universe is not a temporally closed system (i.e. matter/energy can vanish and re-appear at future points in time), for something to vanish in the present and re-appear in the past, it would have to vanish before its original appearance unless it can't exist twice at the same point in time (i.e. if atom A was sent back in time from a point Z to a point X, it would vanish at point Z (now) and appear at point X (back then) as A', but have to vanish again as time advances closer to the point Y (somewhere before point Z) where it was originally introduced as A, otherwise A and A' (which should be identical) would exist at the same point in time, which would definitely be an alteration of past events and thus incompatible with the principle.
I'm assuming the principle isn't based on the simplification of the idea that the only thing that "matters" is the action/inaction of humans (as in the interpretation of Schroedinger's experiment that the cat is in an unknown state where it is both alive and dead until the human interacts with it -- which implies the human's perception determines the state of reality). If that is true, then the example from Twilight Zone where someone goes back in history to start the fire he travelled back in time to prevent is clearly contradictory as it introduces a paradox (a time travel having to have occurred in order for the time travel to occur) unless it actually changed the events (i.e. originally the fire would have been caused by something else), which would still be inconsistent with the principle which doesn't allow for any changes of the past.
I'm aware this post is getting a bit rant-y, but I'm seriously at a loss here. How does time travel NOT change the past, regardless of whether it has any consequences in the grand scheme of things or not? The very concept of travel backwards through time is that one appears at an earlier point of time, thus changing the past.
The only possibility I can think of for time travel not to change the past is a paradox in which the time travel happens because it has already occurred (i.e. the future representation (person A') of someone (person A) appears in the present and at some future point in time the same events cause person A to travel back in time that "already" caused person A' to go back in time, i.e. both of their time lines are identical), but in which there is no "other" time line in which the time traveller didn't already appear before travelling back in time (i.e. there is no time line in which person A travels back in time without person A' having travelled in time already, i.e. where person A doesn't eventually become person A', the time traveller).
All of this is obviously rendered null and void if the laws of physics are inconsistent and random stuff does appear out of thin air for no reason. — Ashmodai ( talk · contribs) 18:14, 20 December 2006 (UTC)
So the person learned that the fire had existed well before time traveling, so that person was already a part of history and didn't change anything. I suggest rereading the "Potential implications for free will" section in the article. -- Brandon Dilbeck 18:37, 20 December 2006 (UTC)In another example, taken from an episode of The Twilight Zone, first referenced by Henry James, a person travels back in time to discover the cause of a famous fire. While in the building where the fire started, he or she accidentally knocks over a kerosene lantern and causes a fire, the same fire that would inspire him or her, years later, to travel back in time.
Yeah, this doesn't make any sense. By: Ron Francis —Preceding unsigned comment added by 99.245.249.223 ( talk) 01:41, 26 November 2008 (UTC)
There are so many problems with Novikov's self consistency principle. Time travel is unphysical [1]. Here are some of the serious problems of the self consistency principle:
1. The Polchinski paradox [2]: a billiard ball falls through a wormhole, travels back in time, collides with its younger self and prevents its falling in the wormhole in the first place. The supporters of time travel explain this by rejecting the initial conditions leading to this scenario. In classical physics there is no such mechanism, and regular quantum mechanics cannot enforce this either.
2. The self-consistency principle demands that free-will is only an illusion I. D. Novikov, Notion of the past & can we change it?, On Time.-Suppl. to EAS Newsletter 18.. This is wrong in so many ways. Leaving the physics arguments, let us observe that this is very similar with the utopia of totalitarian arguments The Open Society and Its Enemieswhere human rights (local physics) are trampled by the totalitarian state demands (global self-consistency condition).
3. With no claim of exactness, Godel’s second incompleteness theorem shows that an axiomatic system can prove it is consistent if and only if it is inconsistent. First let us clarify this statement. If a theory is inconsistent, then it can prove anything, like the sky is pink, and therefore it can certainly prove that itself is consistent and correct. The reverse is not trivial, and what Godel showed was that if a theory can arrogantly state about itself that is infallible (starting from its axioms, or original assumptions), then the theory is garbage. If Novikov’s self-consistency principle is part of the axioms of the Universe, then the Universe can be proven consistent, and thus it will be inconsistent. If on the other hand the principle is not part of the axioms of the Universe, than it is ad-hoc, no more than wishful thinking to avoid the paradoxes of time-travel. Therefore the self-consistency principle is either too arrogant (and wrong) or is just a statement with no physical consequences. This criticism is in regards to the tautology comment on the main argument.
There are also other very significant arguments against the principle (involving deeper knowledge of physics).{{[[ Florin Moldoveanu 20:09, 28 December 2006 (UTC)]] 18:37, 28 December 2006 (UTC)}}
~~~~
) --
intgr
15:58, 27 December 2006 (UTC)This is a fairly crappy article, peppered with original research. Perhaps a philosopher who understands the subject of time travel could patch it up? Ben Finn 15:56, 16 April 2007 (UTC)
The "The Logic, or otherwise, of time travel - in simple language" link is biased and offers no information. It only asks the basic questions about time travel paradoxes, and offers no answers or even theories. Bredd13 21:14, 8 July 2007 (UTC)
"Horwich also argued that it was possible to affect the past, but not to change it." What is the difference? 86.164.186.238 ( talk) 12:10, 20 January 2008 (UTC)
So taking an imaginary look at this in four dimensions, where one can see all of time like a strip of film: According to the NSCP, there is no paradox because the time travel is built into the film in the first place. Then events just happen. The film is already extant, sans paradox. Applejuicefool ( talk) 15:06, 11 March 2008 (UTC)
So you could travel back in time but you would be constrained from carrying out any event that would change the past. It's difficult to see exactly what form this constraint would take - if you went back with the intention of changing the past would you find your efforts thwarted at every turn, or would you simply lose the intention? Of course this principle might be upheld just as firmly if going back in time caused you to arrive dead, comatose, amnesiac or paralysed. But of course the most surefire way to uphold it would be for time travel to be impossible in the first place. Lee M ( talk) 19:37, 21 March 2008 (UTC)
There should be a mention of Heinlein's short story "All you zombies..." imho. 85.28.87.67 ( talk) 19:53, 17 June 2009 (UTC)
Indeed, one of the major themes of Doctor Who is the Blinovitch Limitation Effect (discussed on another wikipedia page). Kuitan ( talk) 16:14, 19 September 2011 (UTC)
At some point the results from Aaronson and Watrous' refereed paper should be considered for the Time loop logic section. It extended Deutsch's result currently on the page and established that quantum computers are no more powerful than classical computers if CTCs are included in the model for computation (both can efficiently solve PSPACE problems). One potential link is here.-- Adam Wolbach ( talk) 04:25, 18 June 2009 (UTC)
I find it strange that the article doesn't mention the problem of entropy, since that would seem to be a major issue with the Novikov self-consistency principle. If the billiard ball collides with its earlier version, then that must have some physical effect on the atomic makeup of the earlier ball, even if very slight. If you collided a billiard ball with another billiard ball a thousand times, would it crack? How about a billion times? How about an infinite amount of times? We can say positively that anything that experiences physical stress an infinite amount of times would be damaged at some point. Since this billiard ball is travelling back in time and colliding with itself an infinite (literally) number of times, the ball will at some "point" crack. Actually for a crack to occur after x amount of collisions, each individual collision must have some effect. For each collision the ball will be slightly more damaged internally. Therefore it's not the exact same ball that travels back for each iteration. Since the point of the principle is that it applies to a one-timeline model, there is actually only one iteration, a closed loop, so the billiard ball has be physically the exact 100% copy of the ball it's hitting. Since that is clearly not the case, the principle fails after just one iteration. 193.91.181.142 ( talk) 10:50, 20 June 2009 (UTC) (Nick)
Damage to the balls, and any other entropy increase, is not inevitable, just overwhelmingly probable, on statistical grounds. Self-consistency requirements can force the entropy increase to be zero. In essence, this is because the number of ways of having an undamaged ball is vastly increased, so much so that it becomes overwhelmingly probable that a randomly chosen microstate will correspond to an undamaged ball.. This should really go on the page, but I don't have a cite immediately to hand. —Preceding unsigned comment added by 91.107.199.68 ( talk) 07:24, 20 August 2009 (UTC)
You're both wrong. Entropy poses no problem to the principle, as there is only a single collision, and the two balls that collide are not required to be atom-for-atom identical. To see this, imagine that each time a ball is involved in a collision, it acquires one new crack. The sequence of events is then:
71.178.183.147 ( talk) 13:00, 21 October 2009 (UTC)
I suspect that we can deduce existence of God (defined as a function solving any mathematical problems in physical reality) from existence of time machine.
See this my Usenet message for details.
I however (yet) not found any way to prove this conjecture. VictorPorton ( talk) 00:45, 18 February 2010 (UTC)
There was this example in the article about a time traveler saving passengers of Titanic and replacing them with fake corpses, but I think it would violate the self-consistency principle.
The time traveler and his/her actions would cause a butterfly effect that would affect to nearly everything in the Earth and it's future light cone (more entropy) and therefore his/her actions would affect to the time traveler himself/herself.
So this example would actually break the self-consistency principle (if we accept the butterfly effect).
If the time traveler would be outside the Titanic's future light cone the operation would be possible, but the time traveler would know nothing about the incident.
(Sorry if there is any flaws in my English.)
-- MrZalli ( talk) 11:45, 3 May 2012 (UTC)
I am confused by the sentence "Physicist David Deutsch showed in 1991 that this model of computation could solve NP problems in polynomial time [...]." Is this not completely obivous? You receive an answer, then you check it in polynomial time, if it was correct you send it back, if not you send back something different (which is an impossible outcome because of self-consistency). Or am I making a mistake here? -- 80.219.253.238 ( talk) 22:37, 7 May 2012 (UTC)
Suppose you have essentially complete knowledge of how something happened, and thus you went back in time to affect it. That is to say, all the examples given only prove that no one seems to know anything about the past for certain (for example, going back in time to meet Jesus only to end up being Jesus himself, etc). As such, if you KNOW FOR A FACT that something happened in a very specific way--like no one dropped trousers and stuck their bare-butt into JFK's face just before he got shot--then there's no way reality could end up being the same... there's no way history can continue on "unaltered".
But here inlies the rub: if the ONLY way for history to actually be altered is due to just KNOWING that it will be altered--as in, one's ignorance is the only thing that kept history from being altered in the stated examples--then I think this whole principle falls apart; the human mind alone is not that powerful as to be able to alter time itself. -- 71.141.121.26 ( talk) 02:36, 14 June 2012 (UTC)
Another thing to keep in mind is that your memory is an unreliable record of the past. If you use known facts about the past (eye witness being the most reliable) to go back and take an action that clearly contradicts that record (assuming circumstances/the universe don't prevent it), then the NSCP would imply that your record of the past is wrong. Given that record is your brain then you should probably be worried. Hallucinations don't tend to come out of no where, so you might want to get checked for tumours. 155.63.200.55 ( talk) 02:36, 30 October 2020 (UTC)
"then some event will prevent the execution of step 3 that receives the value F from the future. "
Outside of closed time loops, under NSCP, there is no way to affect the past from the future. Prior to any incoming time travel (the future affecting the past), the universe is perfectly consistent and in most normal computer architectures, there shouldn't be a way for an insoluble problem to cause a computer failure or similar improbable event.
Since NSCP is an assertion of "no new physics", just because we are about to feed Time Loop Logic an insoluble problem does not affect at all the probability of computer failure/spontaneous violations of thermodynamics 2nd law/events of extreme improbability (eg. freak cosmic rays). Prior to any time travel, the computer executing the algorithm on the given problem is not a special computer and normal computers do not spontaneously combust if given an insoluble problem.
Therefore, it seems obvious to me that the only thing that can prevent of execution of the algorithm will be an incoming time travel event that must get itself sent. Clearly, we are not about to engineer a computer system that will refuse to execute our algorithms, so it will be overwhelmingly likely to execute and result in paradox if something doesn't stop it and the only thing that can stop it is the time travelling event.
If need be, this event may indeed cause spontaneous violations of the 2nd law of thermodynamics or other exceedingly improbable events simply by being arranged "just so". But outside any time travel event with "just so" arrangements (which is allowed and even likely under Time Loop Logic), exceedingly improbable events remain just that. — Preceding unsigned comment added by 175.156.215.144 ( talk) 16:41, 5 November 2012 (UTC)
If the Novikov self-consistency principle was valid, and using time loop logic, could an "infinite improbability drive" (apologies to Douglas Adams) be created? If so, would this not disprove the principle? Msiminski ( talk) 22:57, 24 January 2013 (UTC)
The Novikov Principle does not allow a time traveler to change the past in any way at all, but it does allow them to affect past events in a way that produces no inconsistencies—for example, a time traveler could rescue people from a disaster, and replace them with realistic corpses if history recorded that bodies of victims had been found.
What it has to do with physics? Physics should not be concerned whether history recorded the corpses or not; it should not be concerned with collective knowledge of humanity. And I think I won't be far off if I say it should not be concerned with individual people's knowledge or opinions, either. - 89.110.17.174 ( talk) 19:49, 4 August 2013 (UTC)
I agree that the Novikov principle is nothing to do with physics. It is just a conjecture. The reference to a presentist view, above, makes the principle entirely redundant. for a good explanation see http://essaydensushing.blogspot.co.uk/2013/10/bye-bye-dr-who.html 62.232.115.50 ( talk) 05:52, 11 October 2013 (UTC)EDS
Isnt the simplest solution simply to have a generalized property that BLOCKS All Timetravel ???? Because if you allow some mechanism which blocks the formation of local individual paradoxes (article talks about either inherent modifications to the results of backward traveling actions (mutating the actions) or just not allowing those specific backward traversals of actions which WOULD create a paradox - and you must now account for subsequent/additional backward (time travel) effects which could put the original paradox back on course (or a whole infinite sequence of attempted corrections -- all materializing before/after/simultaneously with the first (paradox potentialed) time travel event).
The simplest solution by far, is to just not have ANY Timetravel be possible - a general blockage that now has no worries about infinite complications (and possible breaking of who knows how many actually real physical laws).
in his early 1980's book "Thrice upon a Time?" — Preceding unsigned comment added by 71.190.176.128 ( talk) 01:45, 14 June 2015 (UTC)
As this conjecture was written in the mid 80's, it's not better to reference Novikov as soviet and not russian? -- Canopus49 - Replies here 00:59, 4 August 2015 (UTC)
I recently added "Bill & Ted's Excellent Adventure" to the "See Also" section of this page, and user: IsaacAA removed it, commenting: "Bill & Ted has 'timelines' that don't follow the single-self-consistent-history idea. Movie has nothing to do with the principle." But the movie is paradox-free, and there is no explicit mention of alternate timelines as far as I recall.
And elsewhere on this talk page, in the "Potential implications for free will" section, it is remarked: "Well, how about Bill & Ted's Excellent Adventure? Both in the scene where they met their future selves (which was shown twice, from both points of view) and in the scene where they broke various historical figures out of jail by using helpful items (like the dad's keys, which had been missing since the start of the movie) that they planned to go back and plant in the right spots later using the time machine, the movie was actually a pretty good illustration of the idea of a single unchangeable timeline which already incorporated the actions of the time travelers." Hypnosifl (talk) 00:10, 28 March 2008 (UTC)
Can anyone point to a sequence of events in the movie that would violate the Novikov self-consistency principle on its face (without reference to any hypothetical paradoxes that may have arisen from kidnapping a variety of historical figures and later presumably depositing them back in their own time), or is it logical to conclude that the movie is a most excellent portrayal of a self-contained, self-consistent, Cauchy Horizon-bounded universe which is ultimately harmonized across time and space by the righteous majesty of Wyld Stallyns music? — Preceding unsigned comment added by Zwitterbiel ( talk • contribs) 00:08, 7 August 2015 (UTC)
Fair enough, but what I'm hearing now is that the Novikov self-consistency principle page itself is in dire need of an entire section on this most radical and historical adventure which is faithful to the laws of physics as this Russian time-traveling dude understood them. — Preceding unsigned comment added by Zwitterbiel ( talk • contribs) 00:38, 7 August 2015 (UTC)
Hi, I might have experimental evidence that time travel also explains ball lightning. Recall some of the early conjecture by Feynman that suggests antimatter is matter traveling back in time. As thunderstorms seem to generate antimatter in quantity, this could be responsible as radio signals *might* be able to pass through a BL and back in time by hours or even days provided they are within range. Its also possible that if my hypothesis is correct it can be tested experimentally, if the spatial and temporal coordinates of an event is known then a signal can be sent back through time on purpose.
I also had some limited success (unable to replicate) generating a CTC on a small scale; the effect was strong enough to knock over a radio inside a sealed cupboard and other researchers suggest that larger scale effects could account for reports of strange activity near certain geographical areas. I'd be happy to share the experimental configuration but not sure if publishing it in an open journal is such a good idea for any number of reasons. As the person sent part of the experimental setup hasn't been seen since! — Preceding unsigned comment added by 185.3.100.3 ( talk) 06:45, 6 September 2018 (UTC)
This article does not explain how the NSCP tackles the law of conservation of energy / thermodynamics / entropy of the universe. Self consistency can not over ride these. If I have a machine that can send a message to the past and I use it to send a message to myself of 10 minutes ago. I suddenly receive a message from my future self and print it out. 10 minutes pass and the moment arrives where I should send the message to myself of 10 minutes ago (the message I had received). But I suddenly refuse to send the message. I do not send it. Yet I have the printout of the message my future self had sent back in my hands.
If I don't send it the NSCP suggest that due to self consistency that message will be sent of its own accord. This violates conservation of energy / entropy of the universe. 85.148.213.144 ( talk) 21:31, 29 September 2021 (UTC)
The picture of Echeverria and Klinkhammer's resolution of Polchinski's billiard ball paradox, looks like simple moving the 'entrance' of the wormhole to the left so that it can 'catch' the ball whose path was altered by its past self.
But in the text it seems that the wormhole just stays where it always was and the reason that the billiard ball can still enter it despite being hit by its future self is that when the billiard ball exits the wormhole it does so under a different angle than in the first picture, allowing it to touch its younger self in a more gentle manner that does not prevent it from entering the wormhole, but just makes it enter the wormhole under a different angle, which then in turn explains why it had exited the wormhole under a different angle in the first place.
Which description of E & K's resolution (the one in the pictures or the one in the text) is the correct one? I hope the one in the text and not the one in the picture, because that would be much more interesting. But if so, could some one perhaps edit the picture to match the true solution? Octonion ( talk) 22:15, 15 February 2023 (UTC)
The Novikov self-consistency principle offers a concise interpretation of the so-called paradoxes related to Closed timelike curve's, Problem of time, and Hugh Everett's many-worlds interpretation (MWI), Multiverse. The clever idea of Igor Dmitriyevich Novikov is the realization that the pseudo-contradictory logic of these paradoxes can be eliminated by incorporating event observability likelihoods, i.e., chance or probabilities. In a nutshell, we can certainly postulate the theoretical existence of paradoxical events, however the intrinsic event-inconsistencies (the paradox itself) suggest that they are measure-theoretically trivial. In other words, an event causing a paradox is almost surely of zero probability. Here are two examples of this idea:
The diagram captioned "Echeverria and Klinkhammer's resolution" incorrectly shows the wormhole as being moved.
It should instead show the angle of the ball as being changed 2600:1002:B033:C99:6304:2793:9226:625B ( talk) 15:24, 30 September 2023 (UTC)
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This is original research - don't delete it - this is a talk page. Just for the record.
So the exception to the "can't change the past" rule, is where the past is ambiguous (example: Bible prophecy, memory, perception, etc.) and that ambiguity might be used as a "buffer" (as in Chemistry) at some future juncture where a dominant teleological outcome exists. In that case the past might be changed sufficiently, having no other consequence, until the "tipping point." That's it.
If you think this is nuts, based on the typical apologetic level of non-theoretical criticism, you wouldn't pass the class entrance test, and you should recuse yourself from making comments.. If you have something constructive to add, or a question to ask, please do. We are dealing with unknown reality here. If it makes you uncomfortable, don't take it as an excuse to foul the drinking water
-- Xgenei ( talk) 01:35, 20 August 2017 (UTC) — Preceding unsigned comment added by Xgenei ( talk • contribs) 01:30, 20 August 2017 (UTC)
I was wondering if any research into how this concept relates with the concept of an "uncaused paradox" has ever been done by anyone notable. By "uncaused paradox" I mean something similar to the following:
- I receive instructions on building a time machine from the future - I follow the instructions and build a time machine - I go to the past and deliver the instructions to my past self
Simply saying that that has a zero chance of happening seems to be a little axiomatic in this case. The reason for it not happening, would be that it would be a paradox. But "paradox" could be defined in a way consistent with both the Novikov principle and the uncaused event simply by stating axiomatically that a universe where the first event occurs exists; in this way, the second and third events would have to exist, and no "paradox" would have occured, despite the time machine itself having no history or origin. Or to put it another way, the fact that the time machine has no history or origin would, pardon me for indulging, paradoxically be considered to not be a paradox by the model Novikov's principle presupposes.
Or to put the concept I'm trying to address in Lostie terms, "Whatever happened, happened" would neatly avoid addressing this sort of paradox at all in a "not even wrong" fashion.
I'm trying to do a decent enough summary to enable googling, but I'm probably not doing the idea justice. My googling attempts were simply in vain, and if anyone has done anything, it would make a really great addition to the article. And, of course, while it would probably abuse the purpose of the talk page to discuss this kind of stuff right here for fun, I'd nonetheless be game. — Preceding unsigned comment added by 173.22.35.171 ( talk) 01:56, 19 January 2013 (UTC)
The opening paragraph implies that if an event has probability zero then it cannot occur. A counterexample is choosing the number "3" out of all of the integers. The probability is zero but choosing "3" is not at all impossible. —Preceding unsigned comment added by 18.248.5.194 ( talk) 04:42, 19 July 2010 (UTC)
The original commenter is correct, and IO Device is wrong. Probability 0 is not the same as impossible. See http://en.wikipedia.org/wiki/Almost_surely . — Preceding unsigned comment added by 65.254.127.187 ( talk) 21:54, 16 September 2012 (UTC)
Yes, I also agree, IO is wrong. Probability of zero does not imply the impossible event. The wording of this should be corrected. — Preceding unsigned comment added by 114.244.190.98 ( talk) 07:18, 30 December 2012 (UTC)
this article need more clarification i think. does it simply means that it time is unchangeabe and you cannot go back in time and marry you mother because you haven't done it already? No paradoxis are possible beacause everything has already happened?
then it should say so. -- Alexandre Van de Sande 17:19, 5 Aug 2004 (UTC)
Novikov didn't use an example ("Rather than consider the usual models for such a paradox, such as the grandfather paradox..."), he used a mathematical/quantam model. Salasks 21:29, Aug 5, 2004 (UTC)
This quote from the article makes no sense: "if an event exists that could give rise to a paradox, then the probability of that event happening is zero"
Some philosophers like Richard Hanley claim that the self-consistency principle is just non-contradiction which philosophers have used for thousands of years. gren 05:02, 18 Jun 2005 (UTC)
This principle has a major flaw: one travelling into the future to pick up some object and take it back shall get the object, whatever it may be (including non-adherence to physical laws), because relatively to them, the people giving one the object have already recieved it from him when one returned.
The "time loop logic" program must be impossible, as it provides an easy way to create a machine that can fabricate any desired object from nothing. To wit:
The resolution to this paradox is clear: Nothing will ever be received at step 3. 71.178.183.147 ( talk) 05:58, 21 October 2009 (UTC)
This principle is very straightforward if you look at the universe with certain assumptions:
Consequences:
—The preceding unsigned comment was added by Spoon! ( talk • contribs) .
The principle is based upon an assumption that if time travel were possible the time traveller could return to an earlier state of the universe. The following explanation shows that asumption to be wrong, and as a consequence makes the principle redundant. Every particle in the universe, including those that make up me, travels on a trajectory through spacetime. Suppose I was to travel back through time to a point in spacetime that used to be occupied by the atoms that comprised my grandfather (say the year 1906): I would find that the atoms which comprised my grandfather were not there, as they were 'still' in 2006 where I had left them at the start of my travels. The only atoms that travel back in time are the ones that constitute the body of the traveller- all of the other atoms in the universe continue on their spacetime trajectories as before, and so are not found by the traveller when he/she arrives in the past. Given this, none of the supposed paradoxes arise, and so the self-consistency principle (in this context at least) is redundant. This seems pretty self-evident to me- am I missing something?
DoctorDen 1 April 2006 17.44 GMT (not logged in).
Doctor Den says: Thank you- that is very helpful. Can you recommend any references that explain how atoms have a definite constant position in spacetime, as I would like to read more.
DoctorDen 7 April 2006 20.35 GMT (not logged in).
Arn't the strongest arguments for the self-consistency principle all based upon quantum mechanics? For example, if your billiard ball was a quantum particle, then its interfearing with itself merely makes those trajectories rediculously improbable? I don't know enough about it to add this intelligently, but please get some input from someone who knows about quantum mechanics. JeffBurdges 19:35, 20 June 2006 (UTC)
Seems that way to me as well, in classical (non-quantum) physics if you know the position + velocity of the billiard-ball precisely the system is entirely deterministic and there is no probalility involved at all; so talking about the probability of when happens when the billiard ball hits itslef makes no sense unless you invoke quantum mechanical ideas (i.e. the unceratintly principle). Tomgreeny 18:24, 5 September 2006 (UTC)
So if someone would be to travel through time, their actions would have no effect?
But time travel itself affects the past -- you're taking something from the present and putting it in a different point in time, thus, for the context of the earlier point in time you travel to, introducing matter/energy/whatever that didn't exist there before, thus (as per chaos theory) possibly screwing up everything. Any successful travel through time would have an effect, otherwise it wouldn't be time travel.
With that in mind -- does the principle boil down to "time travel is only possible if it has no effect, thus time travel (the possibility of which necessitates having an effect) is not possible"?
The matter and energy of which the time traveller (and his clothing, etc) consists would (if the universe is a closed system) have been in use by something else at an earlier point in time and thus a re-allocation of matter and energy already existent at that earlier point in time to recreate the time traveller doesn't seem to be a viable alternative either. But if the time traveller can neither be composed of matter and energy that didn't exist, nor of that which already existed but was "in use" already, what does he consist of?
Even if the universe is not a temporally closed system (i.e. matter/energy can vanish and re-appear at future points in time), for something to vanish in the present and re-appear in the past, it would have to vanish before its original appearance unless it can't exist twice at the same point in time (i.e. if atom A was sent back in time from a point Z to a point X, it would vanish at point Z (now) and appear at point X (back then) as A', but have to vanish again as time advances closer to the point Y (somewhere before point Z) where it was originally introduced as A, otherwise A and A' (which should be identical) would exist at the same point in time, which would definitely be an alteration of past events and thus incompatible with the principle.
I'm assuming the principle isn't based on the simplification of the idea that the only thing that "matters" is the action/inaction of humans (as in the interpretation of Schroedinger's experiment that the cat is in an unknown state where it is both alive and dead until the human interacts with it -- which implies the human's perception determines the state of reality). If that is true, then the example from Twilight Zone where someone goes back in history to start the fire he travelled back in time to prevent is clearly contradictory as it introduces a paradox (a time travel having to have occurred in order for the time travel to occur) unless it actually changed the events (i.e. originally the fire would have been caused by something else), which would still be inconsistent with the principle which doesn't allow for any changes of the past.
I'm aware this post is getting a bit rant-y, but I'm seriously at a loss here. How does time travel NOT change the past, regardless of whether it has any consequences in the grand scheme of things or not? The very concept of travel backwards through time is that one appears at an earlier point of time, thus changing the past.
The only possibility I can think of for time travel not to change the past is a paradox in which the time travel happens because it has already occurred (i.e. the future representation (person A') of someone (person A) appears in the present and at some future point in time the same events cause person A to travel back in time that "already" caused person A' to go back in time, i.e. both of their time lines are identical), but in which there is no "other" time line in which the time traveller didn't already appear before travelling back in time (i.e. there is no time line in which person A travels back in time without person A' having travelled in time already, i.e. where person A doesn't eventually become person A', the time traveller).
All of this is obviously rendered null and void if the laws of physics are inconsistent and random stuff does appear out of thin air for no reason. — Ashmodai ( talk · contribs) 18:14, 20 December 2006 (UTC)
So the person learned that the fire had existed well before time traveling, so that person was already a part of history and didn't change anything. I suggest rereading the "Potential implications for free will" section in the article. -- Brandon Dilbeck 18:37, 20 December 2006 (UTC)In another example, taken from an episode of The Twilight Zone, first referenced by Henry James, a person travels back in time to discover the cause of a famous fire. While in the building where the fire started, he or she accidentally knocks over a kerosene lantern and causes a fire, the same fire that would inspire him or her, years later, to travel back in time.
Yeah, this doesn't make any sense. By: Ron Francis —Preceding unsigned comment added by 99.245.249.223 ( talk) 01:41, 26 November 2008 (UTC)
There are so many problems with Novikov's self consistency principle. Time travel is unphysical [1]. Here are some of the serious problems of the self consistency principle:
1. The Polchinski paradox [2]: a billiard ball falls through a wormhole, travels back in time, collides with its younger self and prevents its falling in the wormhole in the first place. The supporters of time travel explain this by rejecting the initial conditions leading to this scenario. In classical physics there is no such mechanism, and regular quantum mechanics cannot enforce this either.
2. The self-consistency principle demands that free-will is only an illusion I. D. Novikov, Notion of the past & can we change it?, On Time.-Suppl. to EAS Newsletter 18.. This is wrong in so many ways. Leaving the physics arguments, let us observe that this is very similar with the utopia of totalitarian arguments The Open Society and Its Enemieswhere human rights (local physics) are trampled by the totalitarian state demands (global self-consistency condition).
3. With no claim of exactness, Godel’s second incompleteness theorem shows that an axiomatic system can prove it is consistent if and only if it is inconsistent. First let us clarify this statement. If a theory is inconsistent, then it can prove anything, like the sky is pink, and therefore it can certainly prove that itself is consistent and correct. The reverse is not trivial, and what Godel showed was that if a theory can arrogantly state about itself that is infallible (starting from its axioms, or original assumptions), then the theory is garbage. If Novikov’s self-consistency principle is part of the axioms of the Universe, then the Universe can be proven consistent, and thus it will be inconsistent. If on the other hand the principle is not part of the axioms of the Universe, than it is ad-hoc, no more than wishful thinking to avoid the paradoxes of time-travel. Therefore the self-consistency principle is either too arrogant (and wrong) or is just a statement with no physical consequences. This criticism is in regards to the tautology comment on the main argument.
There are also other very significant arguments against the principle (involving deeper knowledge of physics).{{[[ Florin Moldoveanu 20:09, 28 December 2006 (UTC)]] 18:37, 28 December 2006 (UTC)}}
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) --
intgr
15:58, 27 December 2006 (UTC)This is a fairly crappy article, peppered with original research. Perhaps a philosopher who understands the subject of time travel could patch it up? Ben Finn 15:56, 16 April 2007 (UTC)
The "The Logic, or otherwise, of time travel - in simple language" link is biased and offers no information. It only asks the basic questions about time travel paradoxes, and offers no answers or even theories. Bredd13 21:14, 8 July 2007 (UTC)
"Horwich also argued that it was possible to affect the past, but not to change it." What is the difference? 86.164.186.238 ( talk) 12:10, 20 January 2008 (UTC)
So taking an imaginary look at this in four dimensions, where one can see all of time like a strip of film: According to the NSCP, there is no paradox because the time travel is built into the film in the first place. Then events just happen. The film is already extant, sans paradox. Applejuicefool ( talk) 15:06, 11 March 2008 (UTC)
So you could travel back in time but you would be constrained from carrying out any event that would change the past. It's difficult to see exactly what form this constraint would take - if you went back with the intention of changing the past would you find your efforts thwarted at every turn, or would you simply lose the intention? Of course this principle might be upheld just as firmly if going back in time caused you to arrive dead, comatose, amnesiac or paralysed. But of course the most surefire way to uphold it would be for time travel to be impossible in the first place. Lee M ( talk) 19:37, 21 March 2008 (UTC)
There should be a mention of Heinlein's short story "All you zombies..." imho. 85.28.87.67 ( talk) 19:53, 17 June 2009 (UTC)
Indeed, one of the major themes of Doctor Who is the Blinovitch Limitation Effect (discussed on another wikipedia page). Kuitan ( talk) 16:14, 19 September 2011 (UTC)
At some point the results from Aaronson and Watrous' refereed paper should be considered for the Time loop logic section. It extended Deutsch's result currently on the page and established that quantum computers are no more powerful than classical computers if CTCs are included in the model for computation (both can efficiently solve PSPACE problems). One potential link is here.-- Adam Wolbach ( talk) 04:25, 18 June 2009 (UTC)
I find it strange that the article doesn't mention the problem of entropy, since that would seem to be a major issue with the Novikov self-consistency principle. If the billiard ball collides with its earlier version, then that must have some physical effect on the atomic makeup of the earlier ball, even if very slight. If you collided a billiard ball with another billiard ball a thousand times, would it crack? How about a billion times? How about an infinite amount of times? We can say positively that anything that experiences physical stress an infinite amount of times would be damaged at some point. Since this billiard ball is travelling back in time and colliding with itself an infinite (literally) number of times, the ball will at some "point" crack. Actually for a crack to occur after x amount of collisions, each individual collision must have some effect. For each collision the ball will be slightly more damaged internally. Therefore it's not the exact same ball that travels back for each iteration. Since the point of the principle is that it applies to a one-timeline model, there is actually only one iteration, a closed loop, so the billiard ball has be physically the exact 100% copy of the ball it's hitting. Since that is clearly not the case, the principle fails after just one iteration. 193.91.181.142 ( talk) 10:50, 20 June 2009 (UTC) (Nick)
Damage to the balls, and any other entropy increase, is not inevitable, just overwhelmingly probable, on statistical grounds. Self-consistency requirements can force the entropy increase to be zero. In essence, this is because the number of ways of having an undamaged ball is vastly increased, so much so that it becomes overwhelmingly probable that a randomly chosen microstate will correspond to an undamaged ball.. This should really go on the page, but I don't have a cite immediately to hand. —Preceding unsigned comment added by 91.107.199.68 ( talk) 07:24, 20 August 2009 (UTC)
You're both wrong. Entropy poses no problem to the principle, as there is only a single collision, and the two balls that collide are not required to be atom-for-atom identical. To see this, imagine that each time a ball is involved in a collision, it acquires one new crack. The sequence of events is then:
71.178.183.147 ( talk) 13:00, 21 October 2009 (UTC)
I suspect that we can deduce existence of God (defined as a function solving any mathematical problems in physical reality) from existence of time machine.
See this my Usenet message for details.
I however (yet) not found any way to prove this conjecture. VictorPorton ( talk) 00:45, 18 February 2010 (UTC)
There was this example in the article about a time traveler saving passengers of Titanic and replacing them with fake corpses, but I think it would violate the self-consistency principle.
The time traveler and his/her actions would cause a butterfly effect that would affect to nearly everything in the Earth and it's future light cone (more entropy) and therefore his/her actions would affect to the time traveler himself/herself.
So this example would actually break the self-consistency principle (if we accept the butterfly effect).
If the time traveler would be outside the Titanic's future light cone the operation would be possible, but the time traveler would know nothing about the incident.
(Sorry if there is any flaws in my English.)
-- MrZalli ( talk) 11:45, 3 May 2012 (UTC)
I am confused by the sentence "Physicist David Deutsch showed in 1991 that this model of computation could solve NP problems in polynomial time [...]." Is this not completely obivous? You receive an answer, then you check it in polynomial time, if it was correct you send it back, if not you send back something different (which is an impossible outcome because of self-consistency). Or am I making a mistake here? -- 80.219.253.238 ( talk) 22:37, 7 May 2012 (UTC)
Suppose you have essentially complete knowledge of how something happened, and thus you went back in time to affect it. That is to say, all the examples given only prove that no one seems to know anything about the past for certain (for example, going back in time to meet Jesus only to end up being Jesus himself, etc). As such, if you KNOW FOR A FACT that something happened in a very specific way--like no one dropped trousers and stuck their bare-butt into JFK's face just before he got shot--then there's no way reality could end up being the same... there's no way history can continue on "unaltered".
But here inlies the rub: if the ONLY way for history to actually be altered is due to just KNOWING that it will be altered--as in, one's ignorance is the only thing that kept history from being altered in the stated examples--then I think this whole principle falls apart; the human mind alone is not that powerful as to be able to alter time itself. -- 71.141.121.26 ( talk) 02:36, 14 June 2012 (UTC)
Another thing to keep in mind is that your memory is an unreliable record of the past. If you use known facts about the past (eye witness being the most reliable) to go back and take an action that clearly contradicts that record (assuming circumstances/the universe don't prevent it), then the NSCP would imply that your record of the past is wrong. Given that record is your brain then you should probably be worried. Hallucinations don't tend to come out of no where, so you might want to get checked for tumours. 155.63.200.55 ( talk) 02:36, 30 October 2020 (UTC)
"then some event will prevent the execution of step 3 that receives the value F from the future. "
Outside of closed time loops, under NSCP, there is no way to affect the past from the future. Prior to any incoming time travel (the future affecting the past), the universe is perfectly consistent and in most normal computer architectures, there shouldn't be a way for an insoluble problem to cause a computer failure or similar improbable event.
Since NSCP is an assertion of "no new physics", just because we are about to feed Time Loop Logic an insoluble problem does not affect at all the probability of computer failure/spontaneous violations of thermodynamics 2nd law/events of extreme improbability (eg. freak cosmic rays). Prior to any time travel, the computer executing the algorithm on the given problem is not a special computer and normal computers do not spontaneously combust if given an insoluble problem.
Therefore, it seems obvious to me that the only thing that can prevent of execution of the algorithm will be an incoming time travel event that must get itself sent. Clearly, we are not about to engineer a computer system that will refuse to execute our algorithms, so it will be overwhelmingly likely to execute and result in paradox if something doesn't stop it and the only thing that can stop it is the time travelling event.
If need be, this event may indeed cause spontaneous violations of the 2nd law of thermodynamics or other exceedingly improbable events simply by being arranged "just so". But outside any time travel event with "just so" arrangements (which is allowed and even likely under Time Loop Logic), exceedingly improbable events remain just that. — Preceding unsigned comment added by 175.156.215.144 ( talk) 16:41, 5 November 2012 (UTC)
If the Novikov self-consistency principle was valid, and using time loop logic, could an "infinite improbability drive" (apologies to Douglas Adams) be created? If so, would this not disprove the principle? Msiminski ( talk) 22:57, 24 January 2013 (UTC)
The Novikov Principle does not allow a time traveler to change the past in any way at all, but it does allow them to affect past events in a way that produces no inconsistencies—for example, a time traveler could rescue people from a disaster, and replace them with realistic corpses if history recorded that bodies of victims had been found.
What it has to do with physics? Physics should not be concerned whether history recorded the corpses or not; it should not be concerned with collective knowledge of humanity. And I think I won't be far off if I say it should not be concerned with individual people's knowledge or opinions, either. - 89.110.17.174 ( talk) 19:49, 4 August 2013 (UTC)
I agree that the Novikov principle is nothing to do with physics. It is just a conjecture. The reference to a presentist view, above, makes the principle entirely redundant. for a good explanation see http://essaydensushing.blogspot.co.uk/2013/10/bye-bye-dr-who.html 62.232.115.50 ( talk) 05:52, 11 October 2013 (UTC)EDS
Isnt the simplest solution simply to have a generalized property that BLOCKS All Timetravel ???? Because if you allow some mechanism which blocks the formation of local individual paradoxes (article talks about either inherent modifications to the results of backward traveling actions (mutating the actions) or just not allowing those specific backward traversals of actions which WOULD create a paradox - and you must now account for subsequent/additional backward (time travel) effects which could put the original paradox back on course (or a whole infinite sequence of attempted corrections -- all materializing before/after/simultaneously with the first (paradox potentialed) time travel event).
The simplest solution by far, is to just not have ANY Timetravel be possible - a general blockage that now has no worries about infinite complications (and possible breaking of who knows how many actually real physical laws).
in his early 1980's book "Thrice upon a Time?" — Preceding unsigned comment added by 71.190.176.128 ( talk) 01:45, 14 June 2015 (UTC)
As this conjecture was written in the mid 80's, it's not better to reference Novikov as soviet and not russian? -- Canopus49 - Replies here 00:59, 4 August 2015 (UTC)
I recently added "Bill & Ted's Excellent Adventure" to the "See Also" section of this page, and user: IsaacAA removed it, commenting: "Bill & Ted has 'timelines' that don't follow the single-self-consistent-history idea. Movie has nothing to do with the principle." But the movie is paradox-free, and there is no explicit mention of alternate timelines as far as I recall.
And elsewhere on this talk page, in the "Potential implications for free will" section, it is remarked: "Well, how about Bill & Ted's Excellent Adventure? Both in the scene where they met their future selves (which was shown twice, from both points of view) and in the scene where they broke various historical figures out of jail by using helpful items (like the dad's keys, which had been missing since the start of the movie) that they planned to go back and plant in the right spots later using the time machine, the movie was actually a pretty good illustration of the idea of a single unchangeable timeline which already incorporated the actions of the time travelers." Hypnosifl (talk) 00:10, 28 March 2008 (UTC)
Can anyone point to a sequence of events in the movie that would violate the Novikov self-consistency principle on its face (without reference to any hypothetical paradoxes that may have arisen from kidnapping a variety of historical figures and later presumably depositing them back in their own time), or is it logical to conclude that the movie is a most excellent portrayal of a self-contained, self-consistent, Cauchy Horizon-bounded universe which is ultimately harmonized across time and space by the righteous majesty of Wyld Stallyns music? — Preceding unsigned comment added by Zwitterbiel ( talk • contribs) 00:08, 7 August 2015 (UTC)
Fair enough, but what I'm hearing now is that the Novikov self-consistency principle page itself is in dire need of an entire section on this most radical and historical adventure which is faithful to the laws of physics as this Russian time-traveling dude understood them. — Preceding unsigned comment added by Zwitterbiel ( talk • contribs) 00:38, 7 August 2015 (UTC)
Hi, I might have experimental evidence that time travel also explains ball lightning. Recall some of the early conjecture by Feynman that suggests antimatter is matter traveling back in time. As thunderstorms seem to generate antimatter in quantity, this could be responsible as radio signals *might* be able to pass through a BL and back in time by hours or even days provided they are within range. Its also possible that if my hypothesis is correct it can be tested experimentally, if the spatial and temporal coordinates of an event is known then a signal can be sent back through time on purpose.
I also had some limited success (unable to replicate) generating a CTC on a small scale; the effect was strong enough to knock over a radio inside a sealed cupboard and other researchers suggest that larger scale effects could account for reports of strange activity near certain geographical areas. I'd be happy to share the experimental configuration but not sure if publishing it in an open journal is such a good idea for any number of reasons. As the person sent part of the experimental setup hasn't been seen since! — Preceding unsigned comment added by 185.3.100.3 ( talk) 06:45, 6 September 2018 (UTC)
This article does not explain how the NSCP tackles the law of conservation of energy / thermodynamics / entropy of the universe. Self consistency can not over ride these. If I have a machine that can send a message to the past and I use it to send a message to myself of 10 minutes ago. I suddenly receive a message from my future self and print it out. 10 minutes pass and the moment arrives where I should send the message to myself of 10 minutes ago (the message I had received). But I suddenly refuse to send the message. I do not send it. Yet I have the printout of the message my future self had sent back in my hands.
If I don't send it the NSCP suggest that due to self consistency that message will be sent of its own accord. This violates conservation of energy / entropy of the universe. 85.148.213.144 ( talk) 21:31, 29 September 2021 (UTC)
The picture of Echeverria and Klinkhammer's resolution of Polchinski's billiard ball paradox, looks like simple moving the 'entrance' of the wormhole to the left so that it can 'catch' the ball whose path was altered by its past self.
But in the text it seems that the wormhole just stays where it always was and the reason that the billiard ball can still enter it despite being hit by its future self is that when the billiard ball exits the wormhole it does so under a different angle than in the first picture, allowing it to touch its younger self in a more gentle manner that does not prevent it from entering the wormhole, but just makes it enter the wormhole under a different angle, which then in turn explains why it had exited the wormhole under a different angle in the first place.
Which description of E & K's resolution (the one in the pictures or the one in the text) is the correct one? I hope the one in the text and not the one in the picture, because that would be much more interesting. But if so, could some one perhaps edit the picture to match the true solution? Octonion ( talk) 22:15, 15 February 2023 (UTC)
The Novikov self-consistency principle offers a concise interpretation of the so-called paradoxes related to Closed timelike curve's, Problem of time, and Hugh Everett's many-worlds interpretation (MWI), Multiverse. The clever idea of Igor Dmitriyevich Novikov is the realization that the pseudo-contradictory logic of these paradoxes can be eliminated by incorporating event observability likelihoods, i.e., chance or probabilities. In a nutshell, we can certainly postulate the theoretical existence of paradoxical events, however the intrinsic event-inconsistencies (the paradox itself) suggest that they are measure-theoretically trivial. In other words, an event causing a paradox is almost surely of zero probability. Here are two examples of this idea:
The diagram captioned "Echeverria and Klinkhammer's resolution" incorrectly shows the wormhole as being moved.
It should instead show the angle of the ball as being changed 2600:1002:B033:C99:6304:2793:9226:625B ( talk) 15:24, 30 September 2023 (UTC)