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Can someone please help me understand the difference between Predestination and Bootstrap Paradox by pointing me in the direction of movies that deals with each of them?

For instance, Predestination the movie seems to deal with Predestination Paradox, hence the name.

Can someone point me in the direction of a movie that deals primarily with the Bootstrap Paradox?

I am NOT looking for a list of movies, just looking to understand through an example.

Gomes
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1 Answers1

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The two kinds of paradox are extremely closely related, so many times a movie which seems to deal with one actually deals with both. In fact, I've found quite a few places that consider them to be different names for the same thing.

Paradoxes

In a predestination paradox, an event in the past creates a chain of events that leads to some second event in the future, but that second event is ultimately the cause of the first event. This is equivalent to what theoretical physicists would call a "closed time-like loop" (something that is "allowed", though extremely unlikely to be real, according to relativity.) The key here is that the action in the future only happened because the action in the past happened, but the action in the past was explicitly caused by the action in the future.

In a bootstrap paradox, an object (which could be a physical object, or a piece of information) is sent to the past, and the receipt of that object triggers a series of cause/effect, which ultimately leads to a future event whereby the same object is sent back in time. The key here is that the object/information did not come from anywhere. It exists because it always existed. (This kind of paradox is not, as far as I understand, even theoretically possible under relativity, it violates several conservation laws.)

TV Shows

I know that you asked for movies, but really, TV shows are a much bigger pool of information on this stuff, if for no other reason than simple quantity. A good primer on both of these kinds of paradox is Doctor Who, since it involves quite a lot of time travel. An example of each (there are tons more):

  • The highly popular, acclaimed episode Blink contains a bootstrap paradox: The Doctor (stuck in the past) reads a transcript of a conversation into a camera, which he arranges to be embedded on a DVD. A girl in the future watches the DVD and transcribes the conversation, then later gives the transcript to The Doctor, who takes it into the past with him to read.

  • The mini-episodes Time/Space and Time Crash both feature The Doctor giving information to a future version of himself; it's much more explicit in Space.

  • The episode Fires of Pompeii contains a (sort-of) predestination paradox. The Doctor finds himself in Pompeii just before Vesuvius erupts, and spends much of the episode trying to escape. It is later learned that he caused the eruption, in order to prevent a much worse disaster that would have resulted in the destruction of the entire Earth. Had he not done so, at the very least his companion from present-day Earth would never have existed, so he would never had taken her back to Pompeii, etc.

Many other TV Shows that deal with time travel mix the two up; the entire third season of Fringe is a giant bootstrap/predestination paradox:

Peter sent the blueprints for The Machine back into the past, along with some of it's parts, by using the machine that was built from the blueprints he sent into the past.

Movies

As far as movies, it seems to be much harder to find recent examples of this; many time-travel movies these days explicitly avoid these two kinds of paradox by changing the future (Looper, Butterfly Effect, Days of Future Past, etc.) Both of these paradoxes involve a stable timeline -- nothing changes as a result of the time traveler. Most of the examples I found are from previous decades (or based on older books).

For the predestination paradox, other than Predestination, a good example would be:

  • The Time Traveler's Wife: the protagonist travels through time meeting his wife at various stages: She only falls in love with him because he time traveled to meet her as a child, but he only visited her because they were in love in the future, etc.

For the bootstrap paradox, a few that I came up with:

  • The Terminator series (specifically, 1 & 2): The original Terminator was sent back in time by Skynet to kill Sarah Conner; that Terminator is later found by Cyberdine, reverse-engineered, and used as the basis for Skynet. Thus, the technological information needed to build Skynet came from Skynet.

  • Bill and Ted's Excellent Adventure: a very small one, but they only know to call Rufus "Rufus" because they hear themselves call him that; he never actually gives his own name.

There's also a lot of implied bootstrap paradoxes in movies, but they require a bit of assumption. For example, in Star Trek IV, Scottie gives an engineer the formula for transparent aluminum. If we assume that engineer patented that formula, and the rest of the world learned it from him, that would count. However, that requires us to reject the possibility that someone else independently discovered that knowledge on their own, which is something that happens all the time in science and math.

KutuluMike
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  • But Predestination is also an example of a bootstrap paradox, since (spoilers!) the main character is a kind of "object" whose life forms a closed loop of sorts (or at least part of his body does--it would be analogous to an amoeba that went back in time, split in two, and then one became the younger version of the same amoeba that would later go back in time, while the other just aged and died). – Hypnosifl Mar 04 '15 at 14:54
  • Also, a clear example of a bootstrap paradox involving an actual physical object (rather than just information, as in your examples) can be found in the movie "Somewhere in Time", there's a watch in the movie that seems to have no origin--see the discussion here. Lastly, I disagree about the implied bootstrap in Interstellar--it would only be a bootstrap if Cooper sent the information back in time after being given it by humanity's descendants, but instead he and TARS actually discovered the information when falling through the black hole. – Hypnosifl Mar 04 '15 at 14:55
  • @Hypnosifl Yeah, that counts; there's also a predestination paradox in Terminator -- John Conner sends Kyle Reese back in time so John Conner can be conceived. As mentioned, lots of time travel movies contain examples of both. – KutuluMike Mar 04 '15 at 15:31
  • (I took out the interstellar bit since I never actually saw the movie, only read about the science/math in it so I'll take your word for it. :) ) – KutuluMike Mar 04 '15 at 15:34
  • One more point, I think your explanation here needs a little improvement: "In a bootstrap paradox, an object (which could be a physical object, or a piece of information) is sent to the past, and the receipt of that object triggers a series of cause/effect, which ultimately leads to a future event whereby the same object is sent back in time." This seems more like a description of a predestination paradox, which is not just any old causal loop, but a specific form of causal loop where a person's trip back ends up influencing their younger self to make that very trip. – Hypnosifl Mar 04 '15 at 17:25
  • Nothing in that quoted sentence necessarily implies that the object itself forms a closed loop in time--for example, if my future self gave me a watch, and later I spotted an identical-seeming watch in an antique shop, and so I bought it and that gave me the inspiration to go back in time and give the watch I bought in the shop to my younger self, that would fit your description but it wouldn't be a bootstrap paradox, since the watch in the antique shop was presumably manufactured in a conventional way. – Hypnosifl Mar 04 '15 at 17:27
  • @Hypnosifl that would not be the same object, merely a similar one. To be the same object, you would have to go back in time and give yourself the watch you went back in time and gave yourself. – KutuluMike Mar 04 '15 at 17:47
  • It would be the same object in my example, just at different points on its timeline. The watch that my future self gives me is an older version of the watch I see at the antique shop, which I then buy and take back in time to give to my younger self. After I buy the watch at the antique shop, I then own two nearly-identical versions of the same watch, which I could label "antique shop watch" and "gift watch" to distinguish them. If I were to go back in time and give "gift watch" to my younger self it would be a bootstrap paradox (and the similarity between the watches would be a coincidence), – Hypnosifl Mar 04 '15 at 17:53
  • (continued) but as long as I make sure to give "antique shop watch" to my younger self, taking the label off first, then he can later put the label "gift watch" on it, and there will be no bootstrap paradox here, yet this scenario will be consistent with the description you gave in the sentence I quoted (which is why I think it needs editing). – Hypnosifl Mar 04 '15 at 17:55
  • Thanks for the answer @MichaelEdenfield and comments Hypnosifl. Would I be correct in understanding that without a predestination paradox, there can not be a bootstrap paradox? – Gomes Mar 05 '15 at 05:57
  • @Hypnosifl I like the point you make about Predestination, think it's better tackled as a separate question. – Gomes Mar 05 '15 at 06:02
  • @Gomes - Do you mean the point I made about a bootstrap paradox in Predestination? It occurred to me that this may depend on one's definition of "same object" since technically the human body is constantly replacing its molecules. But there is at least a bootstrap paradox involving the information in his DNA (note that it would have been equally self-consistent if he wasn't a human at all genetically, but some other intelligent being like a Neanderthal or alien, though it would have been harder for him to blend in as an agent in that case). – Hypnosifl Mar 05 '15 at 14:16
  • @Hypnosifl, yes it was a very interesting thing you raised, hence I opened a new question for it - http://scifi.stackexchange.com/questions/83124/predestination-movie-predestination-or-bootstrap-paradox/ – Gomes Mar 09 '15 at 07:20