Law wrote:

honestly quoted this just so people would have to look at it one more time as they scroll down.

I wrote up two posts on scifi.stackexchange.com related to the Novikov self-consistency principle in Interstellar and another movie (Predestination) which you guys might find interesting. The first one deals with Kip Thorne's own work analyzing the implications of self-consistency in thought-experiments where a billiard ball can travel backwards in time by going through a wormhole, and how Interstellar seems to fit this model of time travel too:

http://scifi.stackexchange.com/a/78787/22250

And the second one is inspired by a question about the movie Predestination, but it's a more philosophical discussion of self-consistent time loops in general, which tries to make them a little more intuitively palatable to people who find them paradoxical by imagining how we might simulate a universe with such causal loops on a computer:

http://scifi.stackexchange.com/a/78864/22250

People mentioned some really good films about time travel like Cronocrimenes or even Predestination, which is phylosophically interesting. I would, however, also recommend Primer and it might get you talking about time travel even more. It's one confusing film but quite brilliant in its theory.

I love me some time travel films, even when it's used just as a background scenario for the development of the plot like in BTTF or Terminator or action setpieces like in Looper.

JesseM wrote:I wrote up two posts on scifi.stackexchange.com related to the Novikov self-consistency principle in Interstellar and another movie (Predestination) which you guys might find interesting. The first one deals with Kip Thorne's own work analyzing the implications of self-consistency in thought-experiments where a billiard ball can travel backwards in time by going through a wormhole, and how Interstellar seems to fit this model of time travel too:

http://scifi.stackexchange.com/a/78787/22250

And the second one is inspired by a question about the movie Predestination, but it's a more philosophical discussion of self-consistent time loops in general, which tries to make them a little more intuitively palatable to people who find them paradoxical by imagining how we might simulate a universe with such causal loops on a computer:

http://scifi.stackexchange.com/a/78864/22250

Thanks for posting these dude. Way cool. I really need to watch Predestination.

Hi peoples,

So i saw Interstellar late last year at IMax in Sydney Australia. I loved the movie but at the time didn't know anything about Novikovs self consistency theory and the movie reeked of the bootstrap paradox. Even now that i know the basics of Novikovs' theory and have had some thorough discussions with people that say there is no paradox because the existence of 5d beings in the movie mean that time is essentially non-sequential, therefore humans in the 60's were always going to see the blackhole next to Saturn, Cooper was always going to see the gravity-books message, the tesseract was always going to exist, etc etc i still can't rectify the idea.

In my eyes Novikovs theory breaks down in relation to this movie simply because the beings who create the tesseract and place the black hole are reliant on ancestors who will assumingly die (therefore never creating the tesseract) from lack of food, if they don't receive the information of the blackhole.

I can only rectify this if there is a second timeline where the humans who face the food shortages somehow survive and evolve to eventually become the 5d beings (1st timeline). Therefore allowing them to place a blackhole in the past (unnecessarily creating a 2nd timeline) and save a human race that was always going to survive and even become space-time "lords".

If anyone has the time and patience to try and rectify this for me i'd greatly appreciate it. I have read JesseM links above but they obviously don't solve the issue for me. I've heard almost identical "explanations" before but they never tightly link what happens in the movie to the theory.

I look forward to your replies.

stevearico wrote:So i saw Interstellar late last year at IMax in Sydney Australia. I loved the movie but at the time didn't know anything about Novikovs self consistency theory and the movie reeked of the bootstrap paradox.

But the bootstrap paradox is not actually a "paradox" in terms of being logically inconsistent, only in terms of being counterintuitive. Kip Thorne suggests in his work that if time travel turns out to be possible, we might actually expect bootstrap-paradox type situations involving billiard balls as having some real physical likelihood in a scenario where we shoot a billiard ball towards a wormhole. Just consider the third scenario from the diagram I posted here, where the billiard ball's initial trajectory is such that if left undisturbed it won't travel into the wormhole at all, but then its future self comes out and deflects it at just the right angle so it can go into the wormhole and become that same future self.

stevearico wrote:Even now that i know the basics of Novikovs' theory and have had some thorough discussions with people that say there is no paradox because the existence of 5d beings in the movie mean that time is essentially non-sequential, therefore humans in the 60's were always going to see the blackhole next to Saturn, Cooper was always going to see the gravity-books message, the tesseract was always going to exist, etc etc i still can't rectify the idea.

Can you elaborate on what you mean by "time is essentially non-sequential", and what the 5D beings have to do with this? By "non-sequential" do you just mean that events at later dates can be the cause of events at earlier dates? If so, it seems like the existence of time travel (sending gravitational waves from the future back into the past) is what makes time "non-sequential" in this sense, not the 5D beings themselves. When the 5D beings are going about their "daily lives" they may not perceive time any differently than we do, they may just be different from us in having one extra spatial dimension, a bit like in that old 1800s piece of mathematical sci-fi, Flatland by Edwin Abbott--Thorne mentions in chapter 22 of The Science of Interstellar that "In my first meetings with Christopher Nolan, we were both delighted to find the other had read Abbott's novella and loved it." He also mentions in chapter 30 that he bases the notion of the extra spatial dimension on a real speculative physics idea, the Randall-Sundrum model, in which our 3D space (or 4D spacetime) is a brane sitting in a larger 4D space (or 5D spacetime) called "the bulk", and that "If this speculative extension is correct, then time behaves fundamentally the same in the bulk as in our brane. In particular, objects and signals in the bulk, like those in our brane, can only move in one direction through locally measured time (local bulk time): toward the future. They cannot move backward, locally." The same is imagined to be true in models of wormholes connecting different parts of our 4D spacetime--if you go through a wormhole you are always locally traveling forward in time, but the wormhole spits you out at an earlier time than you entered its other "mouth". From his description of the tesseract in this chapter, I think he's basically imagining it as a kind of kind of wormhole extending through the bulk but anchored to different points in our brane at different times.

A little later in the chapter he adds this comment about a line of dialogue that might have misled people into thinking that the 5D beings have a fundamentally different relation to time than we do:

How, in this interpretation, do I explain Amelia Brand's description of time as seen by beings in the bulk? "To Them time may be just another physical dimension. To Them the past might be a canyon They can climb into and the future a mountain They can climb up."

Einstein's laws, extended into the bulk, tell us that local bulk time can't behave this way. Nothing in the bulk can go backward in local time. However, when looking into our brane from the bulk, Cooper and bulk beings can and do see our brane's time (bedroom time) behave like Brand says. As seen from the bulk, "our brane's time can look just like another physical dimension," to paraphrase Brand. "Our brane's past looks like a canyon that Cooper can climb into [by traveling down the tesseract's diagonal channel], and our brane's future looks like a mountain that Cooper can climb up [by traveling up the tesseract's diagonal channel; Figure 29.14]."

This is my physicist's interpretation of Brand's words. And Chris interprets them similarly.

stevearico wrote:In my eyes Novikovs theory breaks down in relation to this movie simply because the beings who create the tesseract and place the black hole are reliant on ancestors who will assumingly die (therefore never creating the tesseract) from lack of food, if they don't receive the information of the blackhole.

When you say "Novikov's theory breaks down in relation to this movie" do you mean that you don't think the Novikov self-consistency principle would actually allow for bootstrap paradox type situations (if so I think that's wrong, see my comment about the billiard balls), or do you mean you think there is something wrong with Novikov's theory? If the second one, can you elaborate on why you think it's impossible the universe could work that way, where a given object/person/civilization only makes a trip back through time because of an interaction with their own future selves? Did you read my series of thought-experiments about the computer simulations here, and if so was there anything you didn't understand or didn't agree with there? It seems self-evident that if the computer simulations I imagine there could actually be carried out, then some of the possible rule-obeying self-consistent histories would involve such bootstrap paradox type loops, like the one I mentioned involving gliders in the game of life where a glider sent back in time by a simulated wormhole might then "interact with some other pattern of cells in a way that would lead to the creation of the same glider that would later enter the wormhole".

Some people's intuitive objection to this sort of thing is that they don't like to imagine the laws of nature (or God) selecting an entire spacetime "in one go", rather they take the "flow of time" to be fundamental, with the present continually moving forward and giving rise to new events, but with the future "not existing" until the present gets there (and perhaps in this picture the present would 'jump back' from a later date to an earlier one when someone took a trip in a time machine from the later date to the earlier date). Philosophically, the view that the future doesn't exist is known as either presentism (for those that assume the past doesn't exist either) or the growing block universe (for those that believe that the past and present exist but the future doesn't). The contrasting view that all times are equally real, and we simply aren't aware of future events because of the nature of our minds and memories, is known as eternalism. Is your objection to bootstrap paradoxes related to a rejection of the idea that the future events "already exist" in some sense even though we don't yet know their outcome, meaning you think events at later dates can't be determined until the present "reaches them" having already passed through all the earlier dates, or is it not related to this?

Hi JesseM,

Thanks a lot for that great post. I'm really busy but don't want to rush my reply. So i'm slowly attempting to assemble a reply that explains my position.

Cheers,
Steve.

Have you had a similar discussion with someone called Stevo1361 on google+ late last year? Because the way you write is familiar. If you have then that's me!

But the bootstrap paradox is not actually a "paradox" in terms of being logically inconsistent, only in terms of being counterintuitive. Kip Thorne suggests in his work that if time travel turns out to be possible, we might actually expect bootstrap-paradox type situations involving billiard balls as having some real physical likelihood in a scenario where we shoot a billiard ball towards a wormhole. Just consider the third scenario from the diagram I posted here, where the billiard ball's initial trajectory is such that if left undisturbed it won't travel into the wormhole at all, but then its future self comes out and deflects it at just the right angle so it can go into the wormhole and become that same future self.

Fair enough, i don't have an issue with the billiard ball scenario or thought experiments where the future influences the past in a cyclical loop. Where i have an issue with Interstellar and why i don’t think it fits the billiard ball theory is that the wormhole existing is reliant on beings who we are led to believe will die should they not be able to follow the sequence of events which we see unfold.

It is unique in that the creators of time travel will not exist should they not have the opportunity to go through the wormhole and the wormhole will never exist because the creators who put it there will have perished. There must be an instigator/initiator of the causality loop that is outside of the loop in order for the sequence we see to occur.

I’ve been trying to relate this back to the billiard ball thought experiment but am having trouble. It would be as though the billiard ball was set on a path in space that had two possible outcomes. The first is that if left unaffected it will fly into the sun and perish. The other is that if it reaches a point in space it would trigger the opening of a wormhole that at the other “end” would send it onto a collision corse with itself that would send it into the wormhole. So unless there is some force outside of this loop it will never be initiated. The billiard ball will simply continue on it’s path to destruction with the sun.

Much the same, unless there is a force outside of this causality loop in Interstellar the wormhole should never appear and humans should die from starvation because the tesseract doesn’t exist yet, and won’t exist because it’s creators should be dead.

stevearico wrote:Even now that i know the basics of Novikovs' theory and have had some thorough discussions with people that say there is no paradox because the existence of 5d beings in the movie mean that time is essentially non-sequential, therefore humans in the 60's were always going to see the blackhole next to Saturn, Cooper was always going to see the gravity-books message, the tesseract was always going to exist, etc etc i still can't rectify the idea.

Can you elaborate on what you mean by "time is essentially non-sequential", and what the 5D beings have to do with this? By "non-sequential" do you just mean that events at later dates can be the cause of events at earlier dates?

Yes and no. Specifically i mean that events at later dates should not occur because events at earlier dates should not physically allow them to happen. Taking the billiard ball example it would be as though the billiard ball would only enter into the wormhole at the right angle to be able to hit it’s past self at the right angle IF it gained information from it’s future self travelling along the right path. So as it will NOT travel along the right path it will not receive the information and therefore will not travel on the right path. This is equal to what happens in Interstellar.

If so, it seems like the existence of time travel (sending gravitational waves from the future back into the past) is what makes time "non-sequential" in this sense, not the 5D beings themselves.

Yes.

When the 5D beings are going about their "daily lives" they may not perceive time any differently than we do, they may just be different from us in having one extra spatial dimension, a bit like in that old 1800s piece of mathematical sci-fi, Flatland by Edwin Abbott--Thorne mentions in chapter 22 of The Science of Interstellar that "In my first meetings with Christopher Nolan, we were both delighted to find the other had read Abbott's novella and loved it." He also mentions in chapter 30 that he bases the notion of the extra spatial dimension on a real speculative physics idea, the Randall-Sundrum model, in which our 3D space (or 4D spacetime) is a brane sitting in a larger 4D space (or 5D spacetime) called "the bulk", and that "If this speculative extension is correct, then time behaves fundamentally the same in the bulk as in our brane. In particular, objects and signals in the bulk, like those in our brane, can only move in one direction through locally measured time (local bulk time): toward the future. They cannot move backward, locally." The same is imagined to be true in models of wormholes connecting different parts of our 4D spacetime--if you go through a wormhole you are always locally traveling forward in time, but the wormhole spits you out at an earlier time than you entered its other "mouth". From his description of the tesseract in this chapter, I think he's basically imagining it as a kind of kind of wormhole extending through the bulk but anchored to different points in our brane at different times.

Thats fine.

When you say "Novikov's theory breaks down in relation to this movie" do you mean that you don't think the Novikov self-consistency principle would actually allow for bootstrap paradox type situations (if so I think that's wrong, see my comment about the billiard balls), or do you mean you think there is something wrong with Novikov's theory? I don’t think Novikov’s theory can be applied to this movie-this movie doesn’t adhere to his theory in that it dictates that past events must not contradict or alter future events so they can't occur. I extend that to mean current events must not be reliant on future events which are reliant on past events that will never occur unless the future events occur Got it?

If the second one, can you elaborate on why you think it's impossible the universe could work that way, where a given object/person/civilization only makes a trip back through time because of an interaction with their own future selves? Because they should never have existed without information from the future.

Did you read my series of thought-experiments about the computer simulations here, and if so was there anything you didn't understand or didn't agree with there? I read some of them. But again, i don’t think this movie can be applied to those same thought experiments.

Is your objection to bootstrap paradoxes related to a rejection of the idea that the future events "already exist" in some sense even though we don't yet know their outcome, meaning you think events at later dates can't be determined until the present "reaches them" having already passed through all the earlier dates, or is it not related to this?

Not at all. I’m fine with time being “non-sequential”. Time is absolutely relative, i don’t think it defies any laws. What i have a problem with is what we see in this movie and the idea it occurs in a single timeline, that the 5d beings that have access to an “open” timeline despite the fact that their ancestors should have never been able to survive without information from the future.

I can’t think straight anymore! I don't think i've explained my position all that well. It's clear you know a hell of a lot about time travel scientifically and philosophically. Maybe i just can't comprehend it.

^Good post.

I feel like I've tried my hardest to understand the whole wormhole thing, but it's just barely beyond my grasp.

Personally I think they could've avoided the issue if they just left the origin of the wormhole as ambiguous.

rhonkt wrote:^Good post.

I feel like I've tried my hardest to understand the whole wormhole thing, but it's just barely beyond my grasp.

Personally I think they could've avoided the issue if they just left the origin of the wormhole as ambiguous.

I am so torn on this topic!! I too which they could have just taken out the 20 seconds where cooper suggests that 'its us.' and even after tars says humans couldn't he insists that eventually they did (did. not do.). But maybe people would have been really pissed after the movie "so just some wormhole showed up and there is no reason or explanation even though they say it's not a naturally occurring phenomenon?" The foreshadowing throughout the film to imply that it is humans makes me feel like it wasn't just some last ditch thought, but that they had this in mind throughout the writing process. But still, we keep trying to figure out how they hell they could have survived to made it.