...don’t take this the wrong way, but even Harry knows better than that.
There is NO DOWN SIDE!
It may be best to hand over the time turner but you do so after having a chance to think it through. Time turner. Plan. Decide that it is better to hand over the device for now. Write your analysis down. Give it to yourself at the appropriate time. (And give it to yourself again to make the loop stable.)
If you genuinely think this is a smart thing to do in real life, it makes me seriously worry about your safety and the safety of people around you.
I have offended you by questioning the rationality of your fictional persona. My own safety is not in any danger. Every other exceptional use that Harry put the device to is risky and I would not do any of them. But giving himself a chance to think through his options in a way that would not be detected by anyone else is the trivially correct strategic option.
My own safety is secure in the short term, and medium term (human life span) but for the long term the threats to my life are human mortality and existential risk. And that’s kind of what I’ve been counting on you to take care of (with any contribution that I could hope to make purely financial). That being the case, this conversation is quite literally scaring me. I’m not quite there yet, but the key quote from Snape is at least springing to my mind: “And I no longer trust your cunning.”
Examples of stupid things to do with a Time Turner:
Throw pies at people through misguided altruism. It would be better to let them break your finger. You’re at Hogwarts… a 5th year Luna could fix it.
Have a dramatic stand off over a rememberall. If it is so important… use the time turner to find and or steal the thing beforehand and leave it somewhere Neville will find. I mean seriously… using a time turner in a way that is detectable is for emergencies!
Disappearing acts from a class room. Of all the things to do with a Time Turner in that situation making a bigger scene is not one of them. At the very least, if you must refuse to be bullied, write yourself a note telling yourself to not attend potions and make another arrangement. It would be much easier to convince Dumbledore to allow Harry to hire potion tutors than have a full on confrontation.
Not using the time turner to go back and prevent the entire situation, after writing a great big essay to your past self on what happens if you mess with those in power.
Now, all the above mistakes are credible for Harry to make. At least, they fit the needs of the story. But using the turner to give yourself time to think at a critical moment… not on the list. And make no mistake, giving up one of the most powerful super-powers (even in the weakened 6h form) is an extremely critical moment.
But now another lesson from Harry Potter: MOR occurs to me: Always be sure you know exactly what you are both talking about. I may well be missing Eliezer’s real message.
If you genuinely think this is a smart thing to do in real life, it makes me seriously worry about your safety and the safety of people around you.
What are we really talking about here? Being as EY may be several levels ahead of me the intended ‘this’ could be “implying that a respected authority is obviously wrong without a clear benefit to yourself”. That would make for extremely good advice, and a valid concern. Fortunately I for most part avoid that in real life. It does cost me and I do limit my options such that my environment doesn’t put me in that situation too often. One way to ensure my safety is to not put myself in situations that prompt risk taking. It isn’t optimal, except in the bounded sense, but it does work.
It may be best to hand over the time turner but you do so after having a chance to think it through. Time turner. Plan. Decide that it is better to hand over the device for now. Write your analysis down. Give it to yourself at the appropriate time. (And give it to yourself again to make the loop stable.)
You seem to misunderstand how the time-turner works (or at least, how it’s been suggested it works). You don’t get to overwrite anything; the universe doesn’t “end up in” a stable state that results from using it; there isn’t any meta-time (or at least, we’ve seen nothing to suggest such). If he were going to use the time turner to give himself advice, he would have already gotten the advice. And having used the time-turner right there and visibly, he couldn’t use it “later not use it there” and have his going back in time undetectable.
A possible way he could use the time turner to help himself in this case would be to ask to go to the bathroom or somesuch, use the time turner, use the extra time to think, and then return to the room shortly after he left having thought about things.
(Edit: But this would be pretty obvious, and McGonagall probably wouldn’t let him leave the room with the time turner in any case.)
You seem to misunderstand how the time-turner works (or at least, how it’s been suggested it works). You don’t get to overwrite anything; the universe doesn’t “end up in” a stable state that results from using it
My interpretation of the “DO NOT MESS WITH TIME” incident was that you can try setting things up so that temporal consistency implies the result you want, but actually ruling out every other possibility whatever, including vast classes of outcomes you never even imagined, is next to impossible, at least for an 11-year-old boy, however smart. It hadn’t even occurred to him that there was a problem in his reasoning when he tried the experiment that gave him “the scariest result ever in the history of science”. Temporal consistency in the presence of time loops is another blind idiot god, far more swift and powerful than evolution.
Anyway, he still has the Time-Turner. All that stands between him and it is a magical lock. How difficult can that be for him to get around? No, actually what stands between him and it is the author’s necessity not to unbalance the plot by giving him a get-out-of-jail-free card.
Harry’s error in the experiment was responding to “DO NOT MESS WITH TIME” with the same. If he didn’t have the property of responding to that message with the same, that message wouldn’t appear.
Actually, this whole consistency-based time travel seems to be an extremely expressive thought experiment infrastructure for thinking about Newcomb-like problems and decision theories able to deal with them. Maybe I should do a top-level post on that (I don’t have a sufficiently clear picture of the setting, so I might be wrong about its potential)… Though I consider that happening unlikely, so other people who understand UDT are welcome to try.
I was thinking exactly the same thing. After getting my head around the implications it seems to be an extremely intuitive way of handling such problems. I didn’t write a post myself since I have yet to look close enough at UDT to be able to explain the difference between UDT and TDT.
My interpretation of the “DO NOT MESS WITH TIME” incident was that you can try setting things up so that temporal consistency implies the result you want, but actually ruling out every other possibility whatever, including vast classes of outcomes you never even imagined, is next to impossible, at least for an 11-year-old boy, however smart. It hadn’t even occurred to him that there was a problem in his reasoning when he tried the experiment that gave him “the scariest result ever in the history of science”. Temporal consistency in the presence of time loops is another blind idiot god, far more swift and powerful than evolution.
I think you summed that up perfectly. I would have liked to see a little more of that explanation in the Fan Fic. It would make the story feel more natural and also be a perfect excuse to include the ‘blind idiot god’ kind of message.
Anyway, he still has the Time-Turner. All that stands between him and it is a magical lock. How difficult can that be for him to get around?
Without Hermione backing him up? I think he’d struggle. Harry just isn’t that smart! He really should be spending more time sweet talking her. Well intentioned genius with ambition that doesn’t involve gaining power… just the kind of ally Harry needs.
No, actually what stands between him and it is the author’s necessity not to unbalance the plot by giving him a get-out-of-jail-free card.
Uh huh. It’s even worse than if Harry had actually gone and made himself rich on day 1!
once McGonagall sees Harry disappear, he can’t undo it.
Sounds like UDT might be applicable here. Here’s a time-traveling version of Counterfactual Mugging:
Harry appears to McGonagall and tells her, “If you give me 1 Galleon now, I’ll go back in time and hand you 100 Galleons an hour ago.” Suppose McGonagall does not recall being handed 100 Galleons an hour ago. What should she do?
Here’s my analysis. Suppose McGonagall decides not to give Harry 1 Galleon, then there are two possible consistent timelines for this universe. One where McGonagall gets 100 Galleons, and one where she doesn’t. How does the universe “choose” which one becomes reality? I don’t know but let’s say that the two possibilities have equal chance of being true, or get equal amount of “reality juice”.
Given the above it seems clear that McGonagall would prefer to have pre-committed to “give 1 Galleon even if not handed 100 Galleons an hour ago” since that would make the “not get 100 Galleons” timeline inconsistent. I think that’s also UDT’s output (although I haven’t written down the math to make sure).
ETA: I didn’t follow the previous discussion closely, so this might not apply at all to it. Hopefully, in that case the above is of interest in its own right. :)
Seems straightforward to me. McGonagall knows that she does not recall being handed 100 Galleons an hour ago, so the three states of the world with high probability are: 1) She is not in a universe where she will hand Harry 1 Galleon, 2) She is in a universe where she hands Harry 1 Galleon and Harry breaks the agreement, or 3) She is in a universe where she hands Harry 1 Galleon and Harry keeps the agreement in a way that leaves her unable to recall this happening. By not handing Harry a Galleon, she will ensure that she is in universe 1. By handing Harry a Galleon, she will find herself in universe 2 or 3. She should therefore give Harry a Galleon if she judges it less than 99 times more likely that Harry will break the agreement than fulfil it in a way consistent with her experience.
As Harry has access to a time machine, he doesn’t need to decide to give her 100 Galleons before he gets the 1 Galleon, so the situation is quite different to one based on predicting her actions, as Omega does in the Counterfactual Mugging. Rather it has most of the properties of the forward-time version of the gambit: “If you give me 1 Galleon now, I’ll hand you 100 Galleons in one hour”, except that McGonagall has a big piece of evidence that the promise will be broken, namely that she doesn’t remember it being kept.
ETA: I didn’t follow the previous discussion closely, so this might not apply at all to it. Hopefully, in that case the above is of interest in its own right. :)
Vladmir and I agree with the applicability of UDT and have suggested time-travel-with-consistency is a good way to consider Newcomblike problems and the the decision theories that can handle them.
Suppose McGonagall does not recall being handed 100 Galleons an hour ago. What should she do?
Precommit, give him the Galleon, then reach in her bag to get the 100 Galleons. (She must have been Obliviated; otherwise, she would remember.)
You can actually get around a lot of the problems with time travel by taking advantage of the difference between observation and reality. For instance, if you see one of your friends die, you can go back in time, save him, then plant a fake double so you still have the same observations.
Though Godel was interested in time travel loops, that’s not the type of consistency that his Second Incompleteness Theorem discussed (it’s limited to formal axiomatized systems that can describe arithmetic).
It seems we can’t rely on setups, which include decision making inside time loop, because it is not clear who or what makes decisions (agent? consistency law? agent’s preferences?).
It seems I can’t rely on setups, which include decision making inside time loop
If you say ‘we’ you invite contradiction as your stance implies magical thinking about decision making which not many people would want to admit to. Decisions are not a special case. If gravity works you can build a gravity powered mechanical device that makes a decision.
Either you treat decisions exactly as you usually would or nothing works at all.
Can I be in the one where the ‘created information’ is a a freak quantum conversion of graphite into diamond and not the one where the created information is freak quantum effects making my neurons fire in a way that they normally wouldn’t?
You can be there, no problem. The problem is to setup everyting to get there. I’ve just considered the question of setting up, and found that I can’t say even what causes existence of time loop. Can you say what should I do to be sure that no matter what after 1.01 hour I will timeturn 1 hour back? Being the person that will do that is important, but it will not help if in 20 minutes someone will steal my timeturner.
Returning back to 6(grand)parent, I can say, that imposing any condition on a stable state of time loop (but initial conditions before time loop) seems unphysical. All in all, thought experiments with time loops are interesting, but their validity is highly questionable.
Eliezer can do that, because he is consistency law of Harry’s universe.
You can be there, no problem. The problem is to setup everyting to get there. I’ve just considered the question of setting up, and found that I can’t say even what causes existence of time loop. Can you say what should I do to be sure that no matter what after 1.01 hour I will timeturn 1 hour back? Being the person that will do that is important, but it will not help if in 20 minutes someone will steal my timeturner.
Go think about it some more from the perspective of an integrated physics that happens to include time travel of this kind and not as a special case. That seems to be confusing you.
Eliezer can do that, because he is consistency law of Harry’s universe.
Eliezer can have Harry become a Hari Krishna if he really wants. Or he could artificially select for extremely improbable quantum events either inside or outside of time loops. Neither of those would make for an especially good story in this instance.
A trolley is running out of control down a track. In its path are 5 people who have been tied to the track by a mad physicist. Fortunately, if trolley ran down different track, it would activate timeturner that would send it 10 seconds back in time and then trolly would flip a switch, which will lead the trolley down a different track to timeturner. And also a bystander runs to flip a switch.
Possible stable states.
Bystander stops and wait for trolley to appear from nowhere. Trolley kills 5.
Bystander stops and wait for trolley to appear from nowhere. Trolley appears from nowhere and flips the switch, then original trolley runs to timeturner and disappears.
Trolley appears from nowhere kills bystander, which almost managed to reach the switch, and flips the switch, then original trolley runs to timeturner and disappears.
Bystander appears from nowhere and flips the switch, then original bystander runs to timeturner and disappears. Trolley run past deactivated timeturner.
Bystander appears from nowhere shouts “watch your step!” and fails to flip switch in time, original bystander looks on timetraveller, missteps and falls, then manages to activate timeturner and disappears. Trolley kills 5.
Bystander appears from nowhere shouts “careful!” and flips switch, original bystander looks on timetraveller, missteps, but manages to not fall, then activates timeturner and disappears. Trolley run past deactivated timeturner.
Bystander appears from nowhere looks on trolley, shouts “damn! too late” and fails to flip switch in time, original bystander hearing that tries to run faster, missteps and falls, then activates timeturner and disappears. Trolley kills 5.
Bystander appears from nowhere, shouts “Shout, what I shouting now, it is very important!” and flips switch, original bystander activates timeturner and disappears. Trolley runs past deactivated timeturner.
Even in those rigid conditions stable states can be numerous without any improbable events. But yes, maybe you are right, because amount of information-from-nowhere must be limited by communication channel bandwidth (spoken or written speach, nonverbal actions of future-agent, agent’s memory throughput), thus rendering stable states in principle analyzable.
In a time loop do things still fall down? Is there gravity? And if I implement a decision making mechanism using a gravity powered system of gears and pulleys where is the magic thing that makes reason no longer apply?
Information from future will affect any kind of decision making. This information is a consequence of consistency law, it even doesn’t need to have cause.
...don’t take this the wrong way, but even Harry knows better than that.
If you genuinely think this is a smart thing to do in real life, it makes me seriously worry about your safety and the safety of people around you.
There is NO DOWN SIDE!
It may be best to hand over the time turner but you do so after having a chance to think it through. Time turner. Plan. Decide that it is better to hand over the device for now. Write your analysis down. Give it to yourself at the appropriate time. (And give it to yourself again to make the loop stable.)
I have offended you by questioning the rationality of your fictional persona. My own safety is not in any danger. Every other exceptional use that Harry put the device to is risky and I would not do any of them. But giving himself a chance to think through his options in a way that would not be detected by anyone else is the trivially correct strategic option.
My own safety is secure in the short term, and medium term (human life span) but for the long term the threats to my life are human mortality and existential risk. And that’s kind of what I’ve been counting on you to take care of (with any contribution that I could hope to make purely financial). That being the case, this conversation is quite literally scaring me. I’m not quite there yet, but the key quote from Snape is at least springing to my mind: “And I no longer trust your cunning.”
Examples of stupid things to do with a Time Turner:
Throw pies at people through misguided altruism. It would be better to let them break your finger. You’re at Hogwarts… a 5th year Luna could fix it.
Have a dramatic stand off over a rememberall. If it is so important… use the time turner to find and or steal the thing beforehand and leave it somewhere Neville will find. I mean seriously… using a time turner in a way that is detectable is for emergencies!
Disappearing acts from a class room. Of all the things to do with a Time Turner in that situation making a bigger scene is not one of them. At the very least, if you must refuse to be bullied, write yourself a note telling yourself to not attend potions and make another arrangement. It would be much easier to convince Dumbledore to allow Harry to hire potion tutors than have a full on confrontation.
Not using the time turner to go back and prevent the entire situation, after writing a great big essay to your past self on what happens if you mess with those in power.
Now, all the above mistakes are credible for Harry to make. At least, they fit the needs of the story. But using the turner to give yourself time to think at a critical moment… not on the list. And make no mistake, giving up one of the most powerful super-powers (even in the weakened 6h form) is an extremely critical moment.
But now another lesson from Harry Potter: MOR occurs to me: Always be sure you know exactly what you are both talking about. I may well be missing Eliezer’s real message.
What are we really talking about here? Being as EY may be several levels ahead of me the intended ‘this’ could be “implying that a respected authority is obviously wrong without a clear benefit to yourself”. That would make for extremely good advice, and a valid concern. Fortunately I for most part avoid that in real life. It does cost me and I do limit my options such that my environment doesn’t put me in that situation too often. One way to ensure my safety is to not put myself in situations that prompt risk taking. It isn’t optimal, except in the bounded sense, but it does work.
You seem to misunderstand how the time-turner works (or at least, how it’s been suggested it works). You don’t get to overwrite anything; the universe doesn’t “end up in” a stable state that results from using it; there isn’t any meta-time (or at least, we’ve seen nothing to suggest such). If he were going to use the time turner to give himself advice, he would have already gotten the advice. And having used the time-turner right there and visibly, he couldn’t use it “later not use it there” and have his going back in time undetectable.
A possible way he could use the time turner to help himself in this case would be to ask to go to the bathroom or somesuch, use the time turner, use the extra time to think, and then return to the room shortly after he left having thought about things.
(Edit: But this would be pretty obvious, and McGonagall probably wouldn’t let him leave the room with the time turner in any case.)
My interpretation of the “DO NOT MESS WITH TIME” incident was that you can try setting things up so that temporal consistency implies the result you want, but actually ruling out every other possibility whatever, including vast classes of outcomes you never even imagined, is next to impossible, at least for an 11-year-old boy, however smart. It hadn’t even occurred to him that there was a problem in his reasoning when he tried the experiment that gave him “the scariest result ever in the history of science”. Temporal consistency in the presence of time loops is another blind idiot god, far more swift and powerful than evolution.
Anyway, he still has the Time-Turner. All that stands between him and it is a magical lock. How difficult can that be for him to get around? No, actually what stands between him and it is the author’s necessity not to unbalance the plot by giving him a get-out-of-jail-free card.
Harry’s error in the experiment was responding to “DO NOT MESS WITH TIME” with the same. If he didn’t have the property of responding to that message with the same, that message wouldn’t appear.
Actually, this whole consistency-based time travel seems to be an extremely expressive thought experiment infrastructure for thinking about Newcomb-like problems and decision theories able to deal with them. Maybe I should do a top-level post on that (I don’t have a sufficiently clear picture of the setting, so I might be wrong about its potential)… Though I consider that happening unlikely, so other people who understand UDT are welcome to try.
I was thinking exactly the same thing. After getting my head around the implications it seems to be an extremely intuitive way of handling such problems. I didn’t write a post myself since I have yet to look close enough at UDT to be able to explain the difference between UDT and TDT.
I think you summed that up perfectly. I would have liked to see a little more of that explanation in the Fan Fic. It would make the story feel more natural and also be a perfect excuse to include the ‘blind idiot god’ kind of message.
Without Hermione backing him up? I think he’d struggle. Harry just isn’t that smart! He really should be spending more time sweet talking her. Well intentioned genius with ambition that doesn’t involve gaining power… just the kind of ally Harry needs.
Uh huh. It’s even worse than if Harry had actually gone and made himself rich on day 1!
He has been rich since day 1, it just that all his money is tied up in a variety of non-liquid “investments.”
I should say “insanely rich”, not merely ‘well off heir’.
Time travel in this universe has a consistent single line; once McGonagall sees Harry disappear, he can’t undo it.
Sounds like UDT might be applicable here. Here’s a time-traveling version of Counterfactual Mugging:
Harry appears to McGonagall and tells her, “If you give me 1 Galleon now, I’ll go back in time and hand you 100 Galleons an hour ago.” Suppose McGonagall does not recall being handed 100 Galleons an hour ago. What should she do?
Here’s my analysis. Suppose McGonagall decides not to give Harry 1 Galleon, then there are two possible consistent timelines for this universe. One where McGonagall gets 100 Galleons, and one where she doesn’t. How does the universe “choose” which one becomes reality? I don’t know but let’s say that the two possibilities have equal chance of being true, or get equal amount of “reality juice”.
Given the above it seems clear that McGonagall would prefer to have pre-committed to “give 1 Galleon even if not handed 100 Galleons an hour ago” since that would make the “not get 100 Galleons” timeline inconsistent. I think that’s also UDT’s output (although I haven’t written down the math to make sure).
ETA: I didn’t follow the previous discussion closely, so this might not apply at all to it. Hopefully, in that case the above is of interest in its own right. :)
Seems straightforward to me. McGonagall knows that she does not recall being handed 100 Galleons an hour ago, so the three states of the world with high probability are: 1) She is not in a universe where she will hand Harry 1 Galleon, 2) She is in a universe where she hands Harry 1 Galleon and Harry breaks the agreement, or 3) She is in a universe where she hands Harry 1 Galleon and Harry keeps the agreement in a way that leaves her unable to recall this happening. By not handing Harry a Galleon, she will ensure that she is in universe 1. By handing Harry a Galleon, she will find herself in universe 2 or 3. She should therefore give Harry a Galleon if she judges it less than 99 times more likely that Harry will break the agreement than fulfil it in a way consistent with her experience.
As Harry has access to a time machine, he doesn’t need to decide to give her 100 Galleons before he gets the 1 Galleon, so the situation is quite different to one based on predicting her actions, as Omega does in the Counterfactual Mugging. Rather it has most of the properties of the forward-time version of the gambit: “If you give me 1 Galleon now, I’ll hand you 100 Galleons in one hour”, except that McGonagall has a big piece of evidence that the promise will be broken, namely that she doesn’t remember it being kept.
Vladmir and I agree with the applicability of UDT and have suggested time-travel-with-consistency is a good way to consider Newcomblike problems and the the decision theories that can handle them.
Precommit, give him the Galleon, then reach in her bag to get the 100 Galleons. (She must have been Obliviated; otherwise, she would remember.)
You can actually get around a lot of the problems with time travel by taking advantage of the difference between observation and reality. For instance, if you see one of your friends die, you can go back in time, save him, then plant a fake double so you still have the same observations.
You can never know consistency, can never rely on it, otherwise you are inconsistent (2nd incompleteness theorem).
Though Godel was interested in time travel loops, that’s not the type of consistency that his Second Incompleteness Theorem discussed (it’s limited to formal axiomatized systems that can describe arithmetic).
I suspect Vladmir is considering the system in question here in a way that meets that description.
It seems we can’t rely on setups, which include decision making inside time loop, because it is not clear who or what makes decisions (agent? consistency law? agent’s preferences?).
All of the above. Decision making is just physics.
As I wrote earlier I am not yet convinced, that this is a kind of physics we can effectively reason of.
Consider correcting your claim to:
If you say ‘we’ you invite contradiction as your stance implies magical thinking about decision making which not many people would want to admit to. Decisions are not a special case. If gravity works you can build a gravity powered mechanical device that makes a decision.
Either you treat decisions exactly as you usually would or nothing works at all.
No. It’s not a decision making that is special. It is closed time loops. They possibly can “magically” create information from nothing.
Can I be in the one where the ‘created information’ is a a freak quantum conversion of graphite into diamond and not the one where the created information is freak quantum effects making my neurons fire in a way that they normally wouldn’t?
You can be there, no problem. The problem is to setup everyting to get there. I’ve just considered the question of setting up, and found that I can’t say even what causes existence of time loop. Can you say what should I do to be sure that no matter what after 1.01 hour I will timeturn 1 hour back? Being the person that will do that is important, but it will not help if in 20 minutes someone will steal my timeturner.
Returning back to 6(grand)parent, I can say, that imposing any condition on a stable state of time loop (but initial conditions before time loop) seems unphysical. All in all, thought experiments with time loops are interesting, but their validity is highly questionable.
Eliezer can do that, because he is consistency law of Harry’s universe.
Go think about it some more from the perspective of an integrated physics that happens to include time travel of this kind and not as a special case. That seems to be confusing you.
Eliezer can have Harry become a Hari Krishna if he really wants. Or he could artificially select for extremely improbable quantum events either inside or outside of time loops. Neither of those would make for an especially good story in this instance.
Ok. Almost pure physics.
A trolley is running out of control down a track. In its path are 5 people who have been tied to the track by a mad physicist. Fortunately, if trolley ran down different track, it would activate timeturner that would send it 10 seconds back in time and then trolly would flip a switch, which will lead the trolley down a different track to timeturner. And also a bystander runs to flip a switch.
Possible stable states.
Bystander stops and wait for trolley to appear from nowhere. Trolley kills 5.
Bystander stops and wait for trolley to appear from nowhere. Trolley appears from nowhere and flips the switch, then original trolley runs to timeturner and disappears.
Trolley appears from nowhere kills bystander, which almost managed to reach the switch, and flips the switch, then original trolley runs to timeturner and disappears.
Bystander appears from nowhere and flips the switch, then original bystander runs to timeturner and disappears. Trolley run past deactivated timeturner.
Bystander appears from nowhere shouts “watch your step!” and fails to flip switch in time, original bystander looks on timetraveller, missteps and falls, then manages to activate timeturner and disappears. Trolley kills 5.
Bystander appears from nowhere shouts “careful!” and flips switch, original bystander looks on timetraveller, missteps, but manages to not fall, then activates timeturner and disappears. Trolley run past deactivated timeturner.
Bystander appears from nowhere looks on trolley, shouts “damn! too late” and fails to flip switch in time, original bystander hearing that tries to run faster, missteps and falls, then activates timeturner and disappears. Trolley kills 5.
Bystander appears from nowhere, shouts “Shout, what I shouting now, it is very important!” and flips switch, original bystander activates timeturner and disappears. Trolley runs past deactivated timeturner.
Even in those rigid conditions stable states can be numerous without any improbable events. But yes, maybe you are right, because amount of information-from-nowhere must be limited by communication channel bandwidth (spoken or written speach, nonverbal actions of future-agent, agent’s memory throughput), thus rendering stable states in principle analyzable.
In a time loop do things still fall down? Is there gravity? And if I implement a decision making mechanism using a gravity powered system of gears and pulleys where is the magic thing that makes reason no longer apply?
Information from future will affect any kind of decision making. This information is a consequence of consistency law, it even doesn’t need to have cause.
Only because you termed that event “real”, but the characters can’t know that it is.
Is information in other minds what gets stabilized?