With the release of Looper, Bruce Willis joins a rare group of actors who have starred in three time travel movies, and he did it the hard way.  Several cast members of Back to the Future reprised their roles in Part II and either did so again or played related parts in Part III; Arnold Schwartzenneger appeared in three of the four (now four of the five) Terminator films (his appearance in the fourth was apparently done by CGI, using his face from a previous film).  Although there have been four StarTrek movies that used time travel (Star Trek IV:  The Voyage Home, Star Trek:  Generations, Star Trek:  First Contact, and 2009's Star Trek), various cast members appeared in various pairs of those films but never, as far as we can identify, in three, as no major character was played by the same actor in more than two of these.  There are quite a few who have been in two films--Sandra Bullock in both The Lake House and Premonition, Daveigh Chase reprising her Donnie Darko role as Samantha in the sequel S. Darko, much of the cast of Bill & Ted's Excellent Adventure reappearing in the sequel Bill & Ted's Bogus Journey.  However, the films in which Bruce appears, in addition to Looper, are 12 Monkeys and Disney's The Kid, which as far as we can see are not related to each other.  It is a distinction we feel we ought to mention, expressing our gratitude as time travel fans for someone willing to explore this aspect of science fiction/fantasy.  Of course, 12 Monkeys we have recognized as one of the best time travel films out there; it would be wrong to hold this to that standard.  This is a thoroughly enjoyable film, action packed and thought-provoking, certain to appeal to fans of the Die Hard franchise as much as to those who are of a time travel mind.

We should also recognize Rachel McAdams, who (although not in this film) at this point had already appeared as The Time Traveler's Wife in the film of that name, and as the time traveler's fiance in Midnight in Paris, and would again be married to the time traveler in a film yet to come, About Time.

It is also a clever premise.  Although it is set thirty years in our future, it posits a future beyond itself when time travel has been invented and as quickly outlawed, and as is often said about gun control, if time travel is outlawed, only outlaws will have time travel.  It is also a time in which disposal of bodies is nearly impossible, so hitmen are for practical purposes out of business.  Thus if someone is to be eliminated, he is sent to the past where a killer is waiting, shot at close range with a blunderbuss, and the body of someone who is either still alive or not yet born is easily disposed.  Payment in silver is strapped to the back of the victim, which can be exchanged at the local headquarters.  One man from the future, Abe, has been moved to the past, where he organizes and oversees the assassins, and also has his own squad of enforcers through whom he has taken over organized crime in his city.

The assassins are called "loopers", because they know that at some point they will be retired, and to prevent them from alerting the authorities to the time machines they are executed by the same method--only they are sent to be killed by themselves, and the payment strapped to them is gold, a retirement package.  They then know that they have about thirty years before a squad takes them to be their own victims.

Our main character is such a looper, named Joe.  His problem is that his older self manages to escape him and run, and since just a few days before his best friend Seth had that happen to him, he knows that torture awaits him, because Abe is persuaded that capturing and torturing the younger version of the looper will cripple the older version, and the older version will come to be killed to avoid having himself so totally disfigured that he cannot function.

We can put an approximate date on the events.  Some of the technology is on the cusp of what is available, and there is a conceit that a mutation has arisen which gives some people weak telekinetic abilities, so we are probably still in the twenty-first century.  Sara tells Jesse Cid is ten, but she is lying--he has all his baby teeth, so he is not older than six.  Given a birthdate of July 15th, 2039, that places our action in 2145, and the future end in 2175.

Some readers can already see flaws in the premise.  We will begin dissecting them next time.

There is a flaw in the basic concept.  We see it if we ask how a time traveler can be killed by his younger self before he ages to become his older self.  That is, Young Joe expects one day that Old Joe will appear, and Young Joe will kill him and take the gold; but until Young Joe has aged to become Old Joe, no one can send Old Joe to the past, and thus Old Joe will never appear.

This would work under a fixed time theory story, but it is clear that the actions of both Old Seth and Old Joe, as well as the reactions of others to them, are changing the past, so it is not fixed time.  Nor can we turn to parallel or divergent dimension theory, because it is equally clear that what happens to Young Joe and Young Seth become the history and memories of Old Joe and Old Seth.  Thus this must be some variant of replacement theory, in which the time traveler is altering his own history.  It is inherent in Old Joe's intentions, and in Young Joe's solution, that there is one history of the world, but it is mutable.

Once we understand this, we also begin to understand the flaw in the system overall.  Once it has been demonstrated that time travel works, Abe is the first person sent to the past.  He organizes his assassins and his protection squad, and he becomes the local crime boss; but no victims ever arrive from the future.

Why?

In the original history, Abe never came from the future, never organized his criminals, and never became the boss who ran crime in the city.  That means he changed history; he in fact changed organized crime.  He may even have formed the syndicates of the time from which he originated.  It is possible that he accidentally prevented himself from reaching the position that led to him being sent to the past, or that he became the force that put himself in that position; he may have impacted who the future bosses will be.  In short, we do not know whether he will make that trip and become that boss until all of the changes he causes have played through to the moment of his departure.  If somehow time then stabilizes (it will undoubtedly become a sawtooth snap and faces a very real danger of tying time into an infinity loop even if he makes the trip), then we can advance to the next minute, and the first victim can be put in a time machine and sent to the execution site.

But then, as it was for Abe, it is again for this victim:  a body, perhaps two hundred pounds of biochemicals, has been moved out of the future into the past, duplicating material already there; a quantity of silver has also made the trip, which is negotiable wealth that will have its own impact on the world.  The impact might be minor--but it might be significant, particularly if it keeps someone alive who would have died or kills someone who would have lived.  Whatever changes it might make, time must advance through the moment Abe is sent to the past to the moment the first victim is so sent, and stabilize to an N-jump, before the second victim can in turn be sent.  Thus for each victim all of history must be rewritten before the next victim is sent.

The first thing that means is that in history after history, the experience of the loopers will be that one day the victims stopped appearing and they never got their promised payoff, although they never had to complete their final contract either.  It also means that at some point Abe loses credibility when the payments stop coming, which alters his influence on the future shape of the syndicates.

Time has thus gotten very complicated, changing in unforeseeable ways each time another victim makes the trip.  The odds are against it remaining stable through all these separate anomalies.  The only consolation at this point is that if each version of Abe can hold everything together, with each iteration the problems become less pronounced as more victims appear, more silver is paid, and the problem is deferred long enough that people are more apt to wonder what is going to happen to their future employers than to believe they've been cheated.

One of our treasured correspondents alerted us in advance that Looper made the same mistake as Frequency.  Thus I was looking for the mistake in which information travels from the future to the past--but it is the other mistake, in which information travels from the past to the future, and by means that cannot be rationally justified.  We see it first when Old Seth runs and Young Seth is caught.

Old Seth is climbing a fence, when suddenly he sees a scar on his wrist which was not previously there.  It is an arrow pointing up his arm, so he pulls up his sleeve, and sees a message, an address to which he is to come so he can be killed.  Then, before he can do much more than notice this, one of his fingers vanishes, as if he lost it years before; then another, and another, and by the time he manages to flop to the door of the place where he will die he has lost more body parts than we can track.

There are only two ways this can work, and that is not either of them.

Let us assume that whatever injury is inflicted upon Young Seth immediately becomes an injury inflicted upon Old Seth thirty years before.  Thus when they carve the message into Young Seth's arm, Old Seth has the scar.  However, for the scar to be there today, it must have been there yesterday, and the day before, and every day for the past thirty years.  This version of Old Seth would not see a new scar, but a scar he has seen before.  As we noted with Evan Treborn's miracle in Butterfly Effect, scars cannot appear without having been there the day before.

Yet this tells us more, because if the scar was there every day since the wound was first inflicted, then when Young Seth loses a finger it doesn't just vanish from Old Seth--it becomes a handicap he has always had.  That means before Old Seth can lose that finger, all of history has to replay to reach that point.  Considering just the finger, Abe has Young Seth's finger removed, and Young Seth lives thirty years without that finger, and then as Old Seth makes the trip to the past without the finger, and runs without the finger; but he has always been without the finger.  Let us instead assume, though, that Abe keeps going, dismembering Young Seth to a quadriplegic.  The Old Seth climbing the fence is completely unaware of this--it is not his history.  The Young Seth ages as a deformed cripple and in thirty years is sent back to be executed, and without arms or legs he has no hope of running, and long before he can flop out of range Young Seth will have put him out of his misery.

That means that Young Seth will not be tortured, not be dismembered, because his old self did not--could not--run.  Abe was unwilling to kill Young Seth because it would cause a serious temporal problem; what he did instead has certainly caused an infinity loop.  The Seth that was never dismembered when young will run when old; the Seth from whom he runs will be dismembered and himself unable to run.  History is over; there is no saving it this time, no chance that the anomaly will rectify itself as with the problem with the premise.

The film uses a flashback technique to show us what Joe remembers--usually what Old Joe remembers, but sometimes what Young Joe remembers.  The first time it happens, though, it is a bit confusing because it is unexpected and unclear exactly what we are seeing.

We see Young Joe waiting for his victim, but the victim arrives late without a head sack, which confuses Young Joe long enough that the victim is able to get his gold-covered back toward the blunderbuss, absorbing the impact of the shot and giving the victim enough time to attack Young Joe and render him unconscious.  This obviously is Old Joe, and he takes the blunderbuss and the gold and leaves a note telling Young Joe to run for his life.

In an intervening scene we see Young Joe's apartment being ransacked; then we return to the same scene, Young Joe awaiting his victim, a victim arriving this time slightly earlier and hooded, the assassination being completed, and Young Joe taking the gold.  This is the history Old Joe remembers, and as it continues that Joe goes to France and eventually Shanghai, meets the unnamed beautiful woman who "saves his life" in the sense of getting him functional, and then one day is captured to be sent to the past.  We then see how he managed to overcome his attackers, but decided to escape to the past to change history--which, we ultimately learn, he does largely because when he was captured his captors killed his wife (wrong place wrong time--but no explanation of how they disposed of the body which would not have worked for other victims).  He then overcomes his younger self, replaying the first version we saw of his arrival but from the perspective of the intended older victim, and that brings us up to the present situation.

It is obvious that at this point he has already drastically altered his own past.  He clings to the memory of the girl, but can he, his younger self, even meet the girl given that his older self kept the gold, and the silver is even now being confiscated by raiders in his apartment?  He is already not going to France, and even if he thought leaving was the best idea, he knows that Abe knows he has been intending to go to France, so he can't go there.  If Old Joe's memories are dependent on Young Joe's future, the girl should already be forgotten.

Apparently, though, memories are tricky--again recalling Frequency, in which the hero in the future has two sets of memories that blur together.  Old Joe can remember events that now will never happen, and also some events that happen instead, and possibly some that might or might not happen.  Again, none of this makes any rational sense; Old Joe should remember the history he lived (as Marty McFly did), and once Young Joe becomes Old Joe, he will have different memories.

Old Joe's memories are spotty, though; he does not remember what Young Joe is going to do, and the only hint that something is happening here arises because Old Joe is struggling to keep his own memories when Young Joe's path turns elsewhere.

The more difficult question is whether the memories Old Joe has could have happened that way.  Ignoring the fact that there are perhaps a hundred anomalies, and probably more, from individual victims being sent back to perhaps a score of waiting assassins, we will begin with a consideration of Joe's "original" history.

It is a principle of replacement theory that there is always an "original" history in which no one leaves from the as yet non-existent future and so no one arrives in the past.  That concept of "original", though, only applies to the present anomaly--there may be previous arrivals in the past that are resolving, and these may interact with new trips.  Thus when we say that we are attempting to unravel Joe's "original" history, there are several earlier histories to be unraveled first.  In the history in which Abe never appeared, Joe was a small-time crook; we cannot unravel that fully.  It is obvious that he was not the first assassin recruited, and since victims were mysteriously not appearing Abe probably did not recruit too many assassins at first, and so there are several histories in which loopers exist but Joe is not one of them.  We then have a new history for every victim sent to the past, all the ones Joe killed plus all those killed by others, until the day suddenly victims ceased to come to the past.  That will happen in every history, but the one that matters is the last anomaly that matters to us:  it is the moment when Old Joe does not arrive, beginning the history from the point at which he will arrive.

There will be confusion and consternation, as some of the loopers have been "looped", that is, have killed their older selves and gotten their paychecks, and there were already rumors of a new "Rainmaker" boss who was terminating loopers.  When victims cease coming, the best guess will be that the bosses in the future have been compromised or arrested, that time travel is no longer possible.  There will be some ire because some of the loopers never got their golden payday; but there's nothing Abe can do about it other than give them other jobs.  Joe has a lot of silver, and will think he's rich, so he will go to France.

His money will not last as long as it does in the history we see because he does not have the gold.  (Abe might decide to give a bonus to all loopers to satisfy them, but it will be less than they were promised, so even with that Joe will run out of money sooner.  He is an addict, which will tap his money quickly.)  He probably will not meet the girl; his life will be different.

Now we hit another snag.  There is a predestination paradox in this film, and Joe is right in the middle of it.  In brief, Joe will not be sent to the past unless The Rainmaker comes to power, and The Rainmaker will not come to power unless Joe kills Sara.  That problem is addressed below; for the moment, though, it means that Old Joe will live a lot longer and not be sent back to be killed by Young Joe as soon, and that means that our anomalies change significantly--we will have more victims sent to the past, and Young Joe might be a lot older when Old Joe is finally terminated, who would also be significantly older.  It is in the interest of the organization to keep loopers as long as possible, for several reasons.  They keep their gold longer, and they make fewer golden payments because they don't have to replace loopers.  There is always the chance that a looper will die before it is necessary to kill him, and that also saves money and trouble.  The syndicates have more to fear from young retired loopers informing on the time travel than they do from old retired loopers doing so, because with enough information the time travel machines could be found before they are used.  So our critical anomaly won't happen yet.  In fact, probably neither will Seth's, or any of the other loopers whose "loops were closed".  The story we see cannot happen until Cid becomes The Rainmaker, and that won't happen in this history.

The crux of the film is a predestination paradox, that is, an uncaused cause, an event which causes itself and therefore does not happen unless it happens.  Because this is a replacement theory story (history changes), such a paradox must be unraveled by finding an original cause.  Such solutions are generally speculative, and there might be several possibilities.

To clarify the loop, The Rainmaker is "closing loops", having loopers killed.  He attempts to send Old Joe back to be killed by Young Joe, but Old Joe manages to avoid this and escape into the past; he has information with him that will lead him to The Rainmaker as the young boy Cid.  He arrives, fails to kill Cid, but kills Sara instead.  Cid matures with the knowledge that his mother was killed by a looper, and so uses his power to take over the syndicates, and starts terminating the loopers.  Thus Cid becomes The Rainmaker because Joe killed Sara because The Rainmaker's men killed Joe's wife when capturing Joe to send him to the past to be killed.  Thus Cid will not become the Rainmaker unless Joe kills Sara, and Joe will not kill Sara unless the Rainmaker's men kill his wife, and they won't do that unless Cid becomes the Rainmaker.  None of it will happen unless it all happens.

There was a similar loop in 12 Monkeys, but it was not as difficult to resolve as this one.  However, what we know about Cid here is that Sara intends to raise him to be able to control his power and use it wisely and beneficently--Cid is a good kid, and has the potential to grow up to be a good person, with the right support and guidance, which Sara is trying to give him.  If Sara is not killed, Cid will be a very different adult.  We might dare to believe he would be a very good person.

In fact, we might dare to believe that Cid would be the first of those superheroes which Joe in narration mentions the TKs weren't.  He might well go after the syndicates to destroy them, and that would present a completely different kind of problem for our future organized criminals.  They need to assassinate someone who can easily obliterate anyone who attempts to hurt him, and probably has harnessed and refined his powers to do a lot more than that.  So, taking a page from Terminator and its first two sequels, they send an assassin to the past to kill a child before he becomes a problem.  The assassin fails, but kills the mother, and the child grows up somehow knowing that his mother was killed by an assassin from the future.  He decides to destroy the syndicate and end their time travel abilities to save his mother, taking control, paying off the loopers, intending to bring an end to it; and in the process his people accidentally kill Joe's wife, Joe gets the information and goes after Cid when he is taken to the past, and instead of an assassin sent by the syndicate to kill him we have a looper doing so as a free agent.  This creates a close enough problem to the original--Sara dies, Cid escapes--that his actions are much the same, although this time he is closing the loops to eliminate the loopers, not to prevent the sending of the assassin.

We thus can get the loop we see, assuming that a good superhero Cid starts it and is replaced by the Cid who lost his mother.  Perhaps it falls in the category of "no good deed goes unpunished", but at least it is an anomaly that can be explained.

Old Joe brings quite a bloodbath to the past.  It begins when he kills a couple of Abe's men to save Young Joe from the ambush at his apartment.  He then kills a boy who is safely anonymous, and intends next to kill Suzie's boy.  That leads to the massive battle at Abe's headquarters, which only Old Joe and Kid Blue survive.

This raises the genetic issue we discussed in some detail in connection with Timeline; given thirty years, even the youngest victims would have had the potential to become parents, and the sheer number of those lying dead who would have lived another day means that there are changes to the future population of the world--not so much numbers as individuals, who would have been born but for this shift in who marries whom.  However, thirty years is barely long enough to reach the beginning of a second generation, and not long enough to impact any of the important players here unless by chance it prevents Joe from meeting the mystery woman.

More pressing is the impact it will have on Abe.  This massacre now becomes history; the syndicates are going to know that in this year, probably on this day, someone--and they might know who--entered Abe's headquarters and killed his entire army.  Abe thus will probably know this before he leaves for the past.  It seems like something he would try to remember.

It is, of course, a bit more complicated than that.  We have a history (many histories) in which Old Joe never comes to the past, and apparently at least one in which he is immediately executed.  Each of those will come to a moment when Abe, with knowledge of what happened, will make his trip to the past.  Then we will hit the problem, when Old Joe runs, is caught, and slaughters Abe's people.  Now history will advance to the moment when Abe is being tapped to make this trip to the past, only he knows what happened.  Will he agree to go to the past under those circumstances?  Will he decide not to recruit Young Joe as a looper?  Will he change how he handles precautions on that one particular day?

We might resolve this if we suppose there is an information problem.  If the future syndicates do not know who was responsible for the massacre, possibly they do not know exactly what happened or when.  They might be able to keep enough of the information secret that Abe is unaware of the trap into which he has been placed.

None of this seems particularly plausible.  Abe does not seem to be the sort of person who would agree to travel to the past without having studied as much as he could find about what happens in the past, and if the information in the future is at all reliable he will know that this is coming.  Either he will avoid it, perhaps even refusing to make the trip to the past himself, or he will prepare for it, perhaps rigging explosives in the antechamber to his inner sanctum.  Either way, it will not happen the same way twice, and we have created a sawtooth snap.

This also will make a difference to Abe's influence on the future shape of the syndicates.  As we noted, when he becomes powerful in the past he almost unavoidably alters who is powerful in the future.  When his power is snapped abruptly in the past, that will again alter his impact on the future.  Some of those future syndicate leaders are perhaps now lying dead in Abe's headquarters.  The future has changed.

And when the past is dependent on the future and the future changes, the past changes and so changes the future.

Of course, we don't necessarily expect a movie to explain everything, particularly when it involves as yet undiscovered future technology.  However, this point seems to be quite a puzzle once the question is asked:  how do the bosses in the future decide when a looper in the past should retire?

Our assassins have not signed up for so many years, nor for so many kills; they have no way of knowing that the next will be their last.  Also, it is unlikely that there is a pattern--if it were so many kills or so many years, the loopers (who know each other) would figure it out.  Thus it is fairly certain that there is no fixed date for a contract to cancel.  That leaves three possibilities.

The first is that the termination is entirely arbitrary, that someone in the future decides randomly to discontinue a particular looper's contract.  This is a silly idea, really; terminating good employees simply on a whim is poor strategy for the future.  While this is theoretically possible, it would be a terribly disorganized approach for organized crime.

It is more likely that there would be some sort of merit system, but here we hit a host of problems.  How are the evaluations done?  The killings are performed individually in lonely places, so unless someone loses a victim or gets caught with a body there's not really much of a way to evaluate them.  There's also the problem of communicating the evaluation to the future--leaving a written message that says Seth has not been doing as well, as of his thirty-second kill, arriving on June 4th 2045?  Those in the future will get whatever message is sent before they have sent their first victim.  Knowing before Seth's first victim is sent that Seth will have trouble with his tenth victim will undoubtedly change how Seth's victims are handled, and perhaps undo Seth's problem, and undo the changes to the handling.  Even if Abe could leave a message that says that Seth had trouble with the killing of Robert Walton, those in the future won't know when they will be killing Robert Walton, and the message itself tells them that there is someone they are going to kill for reasons they have not yet discovered.  Abe might be able to send a message suggesting that Seth should be retired after his thirtieth kill, but that will itself change how victims are handled, and might change the message Abe sends.

It thus seems most likely that Loopers are retired when there is reason to believe that their older selves are about to become trouble.  There's no particular reason to retire a young looper, as the syndicates always need hired killers and only have to pay when they use one.  It costs extra to end a looper contract, because the gold must be paid.  As long as an old looper is still capable of doing his job, there's no reason to kill him.

There's the rub.  There will come a point at which the old looper is no longer able to do his job, and the syndicate will want to retire him; but they won't want to retire him thirty years younger, but at that age.  So the old looper gets his penultimate kill, and then waits thirty years, at which time he is grabbed (and surprised, because he never received his golden payoff), and sent back to be his own last kill.  But it has already been decided that the younger version is losing his ability to do the job, so the risk is pretty high.

The alternative is awkward.  Let us suppose that Joe is killing people at twenty, at thirty, at forty, at fifty, at sixty; as he reaches seventy he's starting to become a bit mentally unstable, and he's recognized as a risk, so he is grabbed and sent back to be killed by himself.  But it is his forty-year-old self who pulls the trigger, takes the gold, and walks away, and anyone that this Joe killed after that he will not kill, because he retired.  That again changes events.

It is a completely unexplained aspect of the program, but no explanation seems to work.

We have already seen problems with the system in which Abe recruits loopers in the past and people in the future send victims until the assassin is is retired by people in the future; there is another we have to this point overlooked.  Each assassin has a place where his victim will appear, and is told when to expect him.  It has to be a relatively lonely place, a place where everyone can be certain only the assassin will be there when the victim arrives; it has to be easily accessible to the assassin, because no one can check to be certain he is there (he didn't have slotbike trouble) before sending the victim.  Further, because Abe has to start with a small number and increase it, the people in the future have to be told, somehow, when and where a new target site is created.  All the problems raised to this point are repeated, plus three more.

We don't know how the landing sites are selected, but obviously those in the future are involved if only in being informed of the sites.  There is an urban sprawl issue--that is, we know that Joe lives in a city and kills in a field surrounded by farms, which means he has to commute probably through suburbs into a rural area, but it is the nature of cities and suburbs to spread.  Farms are sold to create developments, and thirty years is long enough for towns that were entirely rural to become entirely suburban.  Of course, there is a resource for that:  the people in the future can in theory suggest what sites will remain isolated long enough to be useful--provided that they have some means of communicating that information to the people in the past.

That is not that difficult a problem to resolve.  We do have the two-way communication problem (which again we saw in Frequency), that a message received from the future creates a new history, in which thirty years must pass before the answer reaches the future, and another message creates another new history.  However, if those in the future name the site, those in the past can implement it, and we have a site that is isolated now and will remain so for many years.

There is also the possibility for sites to be compromised.  It does not seem that loopers are very careful about keeping their trades secret--they carry their weapons openly, brag about their silver, and spend money the source of which they cannot easily explain.  Abe might control the city, but if the state police or federal investigators get a lead, they could follow a looper, find his killing site, and arrest him when he kills his next victim.  If they have video of the looper shooting the man and they have the man's body, the fact that they can't identify the victim is not going to be a major obstacle to getting a conviction.  It also is going to lead to deals with assassins to get to Abe, and that can't be permitted--which means that the people in the future are going to have to close sites that are compromised.  Yet they won't be able to know this in advance.  That is, suppose Seth is arrested on June 4th when he kills his latest victim.  That becomes history.  To avoid this, the syndicate simply does not send that victim on that day, and in fact on the previous scheduled kill sends Old Seth to close Seth's loop so he won't return to be arrested.  Now Seth is not arrested, the victim is sent to someone else, and the syndicate's operation is safe--but in the process, they have erased the information that led to the decision to end Seth's loop, so they have no reason to do so.

The solution to this part is that Abe records the date that Seth's loop was closed.  Although we have already seen that this creates a problem, the people in the future will now know that on this date they have to close Seth's loop, for reasons they will never know.  So although it is complicated, it is soluable.

Of course, it all depends on Abe's records being preserved and reaching the syndicate in the future; but then, if at any point Abe's operation is destroyed, everything crashes and the entire project turns into an infinity loop, because the system cannot work unless Abe's messages reach the future, and they only do so by becoming recorded history.

To this point we have assumed the Loopers know when victims will arrive.  What is overlooked is how they know.  Joe has a watch, and his victims arrive at half past something--but the times change.  Although we see it only once, we learn that someone leaves a note with the time in his mailbox.  That logically comes from Abe.  For him to know, he must receive a message from the future, which must arrive significantly before the victim arrives.  This gives us several problems.

First, such messages become time travel events themselves:  information traveling from future to past altering the past, if only in changing where the assassin is.  As with all such trips, history must resolve to the departure point before the future can advance.  Thus, if they send a message then a victim, the message arrives but thirty years pass with no victim, then the victim is sent creating another history.  If, though, the victim is sent first, then the message, Abe will not know the victim is arriving, the victim will be free to do anything (including undermine the future of the syndicate) before the thirty years can resolve and the message be sent.  It is very risky; we will discuss the risk of a runner next.

The solution must be that the time travel device sends both the message and the victim simultaneously, from exactly the same moment of departure, targeting different arrival times.  Thus on April 3rd, 2075, the machine is activated, and sends a man to April 3rd, 2045, but a message to April 2nd, 2045.  The message is received, beginning the new history, and a day later the man arrives within that history.  It is more complicated (reminiscent of Donnie Darko and S. Darko, in which ghosts and objects share departure times and use the same anomaly to reach different arrival times), but not impossible.

This also allows the possibility that Abe knows who the victim will be, or at least whether it will be the looper.  However, two-way communication across time raises many more questions.

Much of the film is about assassins whose older selves avoid being executed by fleeing in the past.  Yet, apart from what Joe does to Abe's organization, is it such a big deal if a looper becomes a runner?

It is.  It is potentially very dangerous.

The damage Joe does to Abe's organization is extreme, improbable for anyone and impossible absent his level of ability.  Yet there are many ways in which an assassin even with limited skills and knowledge could damage the syndicate, once free in the past.  The execution of future syndicate leaders is just one obvious way of interfering with the future.  A runner could position himself to manipulate the future power of individuals or factions without much difficulty.  After all, he knows who the major players are alledged to be in the future; it should not be that difficult to locate them and tamper with their careers in the past.

It is also clear that loopers are not eunuchs, and a runner would impact the gene pool.  Although with only thirty years this impact would be minimal, we are not told for how long the program ran--and twenty to twenty-five years is a not at all unlikely intended duration, whatever its actual run.  Over half a century, the presence of one individual can impact a fair number of births in two generations, and these might matter to who is alive when the program ends.  Even if the runner does not kill the inventors of time travel, one of them might not be born.  Remember, with the genetic problem, it isn't only whether the time traveler marries someone, it is whether his presence prevents someone from marrying someone else, with a ripple effect as those who would have married one person instead marry another.

On top of this, the financial impact cannot be discounted.  Granted that it is inherent in the looper program that wealth in the past is significantly redistributed (payments in silver and gold are being made to assassins, increasing their available assets but possibly deflating the value of precious metals slightly as it floods the market), the runner has the advantages of knowing the future--he can make substantial investments in companies unknown in the twenty-forties which are household names in the twenty-seventies, and the wealth that flows to him does not, in turn, flow to its original beneficiaries.  Changes in the distribution of wealth can have significant impact in the short-term; it can change the outcome of political campaigns and thus of government policies, the assets of investors and thus the rise and fall of corporations, the contributions to charitable organizations and thus the aid to the needy, and more.  With the right knowledge, a runner could become very wealthy--and the looper knows well in advance that he is destined to be sent to the past, so it is worth the time to inform himself of the best investments before that happens.

All of this is true not only of loopers who run, but of any victim who manages to escape--and while escapes of those who are not loopers are less likely, they might be more difficult to correct.  Overall, running changes history considerably more than merely dying in the past.  Even a runner who is concerned about tampering with future history has the potential to impact events--and since the runner is unlikely to live another thirty years to the time he was sent, and loopers are not selected for their altruism, he almost certainly does not care what happens to time after he dies.

Old Joe, caught by Kid Blue, kills Abe and every one of his soldiers (except Kid Blue, killed by Young Joe).  This destroys the Looper program, because Abe must tell the loopers when victims will arrive.

It seems certain that those in the future would try to prevent this, but now everything hinges on Abe's records.  Either they are preserved and reach the handlers in the future, or they are destroyed.

We have already seen the importance of the records:  if they do not reach the future, the program collapses before it starts.  Old Joe thus will not be sent to the past, and will not kill anyone.  However, if the records are preserved, the handlers will know that Joe is going to run and will kill Abe, so they won't send him.  Either way, Old Joe will not arrive in the past and will not kill anyone.

This creates an infinity loop; but the film treats its time travel changes differently, in a way that is ultimately inconsistent.  It wants us to believe that future history remains unchanged until the moment of its occurrence arrives in the present timeline, but is not entirely consistent in this treatment.

Most of the time the creators of the film want us to believe that future history remains unchanged until the moment of its occurrence arrives in the present timeline.  We see this with Joe's memories.  He says his memories of what is now future but was his past are "cloudy because the future is in flux."  He does not know what Young Joe is going to do, nor what Young Joe is thinking or planning, but as soon as Young Joe does anything, Old Joe remembers it.

Old Joe's ability to remember his wife is justified by the suggestion that this part of his history has become not impossible, just increasingly improbable.  The fact that when Old Joe was young he had all his silver and gold and the blessings of the syndicates on his retirement, while this Young Joe is bankrupt, fleeing for his life, and trying to fix everything by killing his older self, does not absolutely prevent all futures in which he meets and marries the girl.

It is more difficult with Seth.  At the moment Young Seth loses his leg, Old Seth loses his, and remembers having lost it thirty years before.  We observed the problems with this, in that once he has lost the leg he has lost the ability to be where he is; yet he is where he is, finding himself now crippled but in the place he got before he was crippled in the condition that would make it impossible for him to have gotten there.  That is to some degree consistent with the memory idea; Seth changes, and his memories change, but he remains where he was.

At some point, Sara asks Young Joe what will happen if Old Joe kills Cid.  Young Joe says that he thinks that Old Joe believes that as soon as that happens he will be back in the future with his wife, never having been sent to the past by the Rainmaker who now will never have existed.  Were that true, it would also mean having killed Cid Joe never comes to the past and so never kills Cid--we have a grandfather paradox, in which an event prevents itself, happening only if it does not happen, not happening if it happens.  The same act of killing Cid that restores Joe to the future saves Cid and removes Joe from the future, and we have an infinity loop.

Yet at the critical moment, time does not work that way or the other way.  That is, in the climactic moment, Young Joe, having had a "flashforward" in which he understands all the events on the path ahead in Cid's life, solves the problem by killing himself.  The moment he does, Old Joe vanishes.

That is entirely inconsistent.  We saw what happened to Seth, and if the film is to be consistent, when Young Joe pulls the trigger, Old Joe should remember the pain in his chest and should die and perhaps decay thirty years' worth, but should be there, still, a corpse in the field.

The fact that he vanishes suggests he was never there; but that in turn creates too many more problems.  Why is the truck there?  Why is the silver there?  He brought these to the farm; they could not be there without him.  What happened to his gun--the gun he brought from Abe's enclave?  And why is Young Joe's body here, if not because he knew Old Joe was coming to kill Cid?

If he was never there, of course, it is because Young Joe did not survive to become Old Joe; if Young Joe did not become Old Joe, then Old Joe was not sent to the past, did not run getting Young Joe in trouble, did not kill Abe's people, did not threaten Sara, and did not inspire Young Joe to shoot himself.  If none of that happened, then it will all happen.  We once again have fallen into an infinity loop.

It is an exciting film and a challenging film, but ultimately it is one that does not work temporally, which time and again runs headlong into the kinds of problems that are fatal to time travel stories.

It is interesting to consider what things change instantly in the future when things change in the past; but it is even more interesting to contrast these against what things do not change instantly in the future.

The easiest way to illustrate this is probably to consider Seth.  When Old Seth runs, Young Seth is grabbed by Abe, and then two things happen to Young Seth, probably simultaneously, one of which also happens to Old Seth, but apparently not the other.

One thing that happens to Young Seth is that Abe's surgeon carves a message in Young Seth's arm; it immediately produces a wound which will scar.  It is obvious that this also happens to Old Seth, because Old Seth then sees the scar.

The other thing that happens at that same instant is that Young Seth decides that running is a very bad idea.  We can be quite certain that even if Abe were to stop at this point, Young Seth would never run; he recognizes the folly of such an act.  Yet this does not happen to Old Seth.  We know that it does not because he continues, for the moment, trying to scale the fence into the rail yard, until he realizes that his fingers are vanishing.

Thus physical damage to a person is instantly part of the body of the person in the future, but psychological damage is not part of the person's mind.

The film is consistent in this, and it is a necessary rule for the ending to work.  After all, Old Joe is set on killing Cid.  As he pursues his objective, Young Joe shifts from trying to kill Old Joe so as to save himself to trying to protect Sara and Cid, because he cares about them and believes that Sara might be able to raise Cid to use his power wisely and well.  Should Young Joe live, it is likely that he will never meet the mystery woman who saves him and becomes his wife; Sara has already saved him, whether or not she survives, and he has no chance of living that other life or ever developing that relationship to that woman.  Sure, in a sense it has not yet "unhappened"; but at this point Sara and Cid matter to Young Joe in a way that says they should also now matter to Old Joe.

So again the film disappoints with its inconsistencies:  physical change moves through history in a way that does not make sense, but psychological change fails to move through history in the same way even though that would make more sense.  It is as if a looper's older body is connected to his younger body, but his older mind is not really connected to his younger mind, that he never was that person and the changes to that person don't affect him, only the changes to that body.

We have looked at the experience of those in the past, as history is repeatedly rewritten, and they wonder why the victims stopped arriving.  There is a similar problem from the perspective of those in the future which is also confusing.

In the original history, there is no record of Abe being in 2040.  Yet our time travel senders might assume this is because they have not yet sent him.  Once they send him, he appears in the histories--but not abruptly.  At the moment he leaves 2070, that history ceases ever to have existed, and is replaced by a history in which Abe was always there.  Thus the senders know that Abe arrived in the past before they send him--but they also know that no one else ever did.

We might think they think that makes sense, since they have not yet sent anyone else; but since they knew Abe arrived before they sent him, the reasonable conclusion is they are never going to send anyone else.

For some reason, they choose to do so anyway, and again at that moment history ends and replays from the victim's arrival point.  Now before they send Abe, they know that both Abe and one--only one--victim arrived in the past.

With each iteration, each new victim, the list gets longer--that is, they will know that five, ten, thirty, fifty victims arrived, but it will always seem that at some moment in the future the departures abruptly stopped, without closing all the loops.  And since they do not know the erased histories, they do not know that they are making the list longer.

They also may have identities of all the victims up to that moment, if they included this in the messages they sent to Abe.  (They must do so when they close loops, so it is likely that they always do.)  Thus they have a list of who they are going to kill, and when, and a date beyond which they kill no more, but no explanation of why.

This will impact the syndicates in many ways.  As the date approaches, they will wonder, even fear, what might happen, which will impact their conduct and so change history.  Further, they will treat those on the list differently from how they did when they were not listed, which may impact the decision to kill them, or to kill someone not listed whose position changed because the list changed.

And so the changing list becomes one more hazard, one more way in which time can crash into an infinity loop.  Time is highly unstable in this film, as the past and the future change in inconsistent and unpredictable ways.  It is an exciting film, and thought provoking, but its temporal concepts prove poorly considered.