A temporal paradox is a paradoxical situation that occurs as a result of time travel in the opposite direction, when, as a result of some actions in the past, such travel cannot be undertaken.

A typical example is the grandfather paradox, when the hero, traveling into the past, kills his grandfather before he can conceive his father. This is a paradox, because by killing the grandfather, the hero prevents his own birth and thus prevents the time travel that prevents his birth.

Different philosophical schools differently consider the question of how the grandfather paradox will be solved if the time machine is nevertheless invented.

Time sequence protection hypothesis

The essence of this hypothesis is that a time traveler simply cannot create a paradox, because the natural flow of time will not allow him to. For example, he will appear in the wrong place and will not be able to do anything at all, or various twists of fate will interfere with him, or even he, without noticing it, will restore the course of events in the form in which he remembers them. This, by the way, creates another paradox - the paradox of predestination, which is also a time loop, when a time traveler is predestined to go on a journey through time and there to perform some actions that have already occurred. Usually these actions predetermine the need for travel in the future, an example is a phone call to oneself.

A similar theory holds that time travel is responsible for how the world is today, that is, the actions of travelers in the past influence the present. On the other hand, in such a case, travelers will try to interact with the past as little as possible for fear of the consequences.

In Fallout 2, the Chosen One can enter Vault 13 using a time portal and accidentally break a water chip, causing his ancestor, the Vault Dweller, to leave the Vault, only to be expelled and found a village in which the Chosen One will be born. By the way, the hero may not go to this portal and even never see him in the whole game, but the events have already happened, which makes fans wonder about the true cause of the breakdown.

Such a course of history can be quite easily imagined. Imagine that time is a book. The time machine allows you to flip through several pages, but the text in them will not change from this, neither written about others, nor written about you.

Time sequence corruption hypothesis

This hypothesis assumes that any actions of a time traveler have a strong influence on the future and cause the so-called "butterfly effect", that is, even a slight change in the past leads to a complete change in the whole history in the future, as, for example, in the movie "The Butterfly Effect" or in Ray Bradbury's story "Thunder Came" when, during a Jurassic safari, one of the participants steps on a butterfly and the wrong president is elected in the United States.

A very popular illustration of this example is the movie "Back to the Future", where schoolboy Marty McFly travels in a time machine created by Doc Brown, and tries to first save Doc from death, and then restore the "natural" course of history in order to get back to the familiar world.

In addition, this hypothesis underlies many works with the so-called "alternative history". For example, in the Command & Conquer: Red Alert series of games, the action takes place in a world in which, after the Second World War, Einstein created a time machine, went back in time and killed Adolf Hitler. As a result, in the 50s, the USSR, under the leadership of Stalin, invades Europe and unleashes a world war.

In World of Warcraft, the Bronze Dragons, the lords of time, sometimes ask the player to restore the natural course of history, claiming that if this is not done, the consequences will be much worse. Thus, players are able to take part in the events that took place in the past of Azeroth, which they saw in previous games from Blizzard: the opening of the Dark Portal between the worlds by the mage Medivh, the battle for Mount Hyjal, the escape of Thrall, the Cleansing of Stratholme by Prince Arthas Menethil.

The hypothesis of multiple universes

The essence of this hypothesis is that there are an infinite number of universes, one for each possibility of choice. Thus, if the time traveler killed the grandfather, then there would be a universe with a living grandfather and a dead grandfather.

Another hypothesis is that the grandfather's murder creates a new universe in which the murder occurred, but neither the killer nor his original universe is affected.

For example, in one of the comics, Superman tries to prevent many historical events, such as the assassination of Lincoln. However, upon returning to his own time, he does not find any differences, but later discovers a neighboring universe with an alternate history resulting from his actions.

The confluence hypothesis

In contrast to the multiple universe hypothesis, this hypothesis suggests that any action taken while traveling through time rewrites the past. Thus, if the time traveler meets his double from the past, he will simply merge with him, becoming part of the time in which the action takes place. The same is true for events: two events will merge into one that does not generate a paradox.

That is, the grandfather's death in one universe and his life in another will merge so that the hero's past allows him to continue to exist, or, if this is not possible, to destroy all traces of him from the future.

Hypothesis about the choice of time sequence

The idea is that history changes as soon as a time traveler thinks about time travel. Thus, he can send messages from the past to the future and obtain the tools or materials he needs at the moment with another trip to the earlier past. This was described by Harry Harrison in the Steel Rat books and in the movie Bill & Ted's Excellent Adventure.

“This cannot be, because it can never be!”

This hypothesis states that the time traveler is the past in relation to the future self. If a time machine is created one day in the future, then it will probably be replicated someday, and someday a potential time traveler in the future will get to it and send it to his past. But, since this does not happen, time machines have not been invented and cannot be invented.

There is also a point of view that a time machine would possibly self-destruct if sent back in time before the date of its invention.

Motive Loss Hypothesis

The bottom line is that if a traveler builds a time machine with the goal of fixing something in particular and achieves that goal by time travel, then the reason for building the time machine will be removed and thus the machine will not be created, but another paradox will be created, essentially similar to the grandfather paradox.

On the other hand, this paradox can be circumvented if no amount of time manipulation can change the event that the time traveler needs to change. Then the time machine will still be built, no matter what the traveler does while traveling into the past.

Harmonious Universe

Everything is quite simple here: the universe strives for harmony and therefore will correct itself back, even if a certain person, event or idea threatens to destroy this harmony. An example of this in Soviet literature is the work of the Strugatsky Brothers "A billion years before the end of the world" with the concept of "homeostatic universe".

empty time

The theory of time travel, roughly described by Stephen King in The Langoliers and in more detail by Clifford Simak in the story What could be simpler than time. Once in the future or past, the traveler will find that it is empty. There are no people, matches and gasoline do not burn, food and drinks are tasteless, there is no electricity, weather and time of day are either static or change anyhow (in other words, there are only those objects that are deeply rooted in time and almost eternal - for example, our planet under your feet; all other objects exist only in the form of their shadows or ghosts).

The past disappears after some time, there is no distant future, and when the hero hits the nearest one, all that remains is to wait for the present to overtake him (or, alternatively, there really is no future, and anyone who gets there will face a complete emptiness in which there is no even air). At this moment, people around will suddenly appear for the hero (and he will appear suddenly for those around him, which can be fraught with nothing at best, a slightly less better collision, and at worst it depends on the author’s imagination), matches will burn when struck on the boxes, etc. d.

Memory replacement hypothesis

The essence of this hypothesis is that a person, by changing the past, changes himself, which means he will not remember anything. For example, if a certain person goes back in time and kills Stalin, then Hitler will win the war and conquer the world. But in this case, it turns out that this certain person was born in a fascist society, lived, speaking German and observing the swastika wherever possible and wherever it was impossible.

So, when he returns to the future, it will seem to him that nothing has changed (after all, he changed the past and never lived in our society), although in reality everything has changed, because Hitler did win the war. A similar example can be observed in the film "The Butterfly Effect", with the difference that the main character of the film is aware and remembers all the "alternative branches of development" of time.

The paradoxes of time travel regularly occupy the minds of not only scientists who comprehend the possible consequences of such a movement (albeit hypothetical), but also people who are completely far from science. Surely you have argued with your friends more than once about what will happen if you see yourself in the past - like many science fiction authors, writers and directors. Today, the film with Ethan Hawke in the lead role, Time Patrol, based on the story of one of the best science fiction writers of all time, Robert Heinlein, was just released. This year has already been a success of several films relating to the theme of time like "Interstellar" or "Edge of Tomorrow". We decided to speculate what potential dangers might await the heroes of temporary sci-fi, from killing their predecessors to splitting reality.

Text: Ivan Sorokin

Paradox of the dead grandfather

The most common, and at the same time the most understandable of the paradoxes that overtake the time traveler. The answer to the question “what will happen if you kill your own grandfather (father, mother, etc.) in the past?” may sound different - the most popular outcome is the occurrence of a parallel time sequence, erasing the culprit from history. In any case, for the temponaut himself (this word, by analogy with "astronaut" and "astronaut", sometimes refers to the pilot of the time machine), this does not bode well at all.

Movie example: The whole story about teenager Marty McFly, who accidentally travels to 1955, is built on preventing an analogue of this paradox. Having accidentally conquered his own mother, Marty begins to literally disappear - first from photographs, and then from tangible reality. There are many reasons why the first film in the Back to the Future trilogy can be considered an absolute classic, but one of them is how neatly the script sidesteps the idea of ​​potential incest. Of course, in terms of the scale of the idea, this example can hardly be compared with the well-known plot from Futurama, as a result of which Fry still becomes his own grandfather, accidentally destroying the one who was supposed to become this grandfather; in the end, this event had consequences that literally affected the entire universe of the animated series.

Pulling yourself by your hair

The second most common time travel plot in cinema: going to a glorious past from a terrible future and trying to change it, the hero ends up causing his own (or everyone's) troubles. Something similar can happen in a positive context: the fairy-tale assistant who directs the plot turns out to be the hero himself, who came from the future and ensures the correct course of events. This logic of the development of what is happening can hardly be called a paradox: the so-called time loop is closed here and everything happens exactly as it should, but in the context of the interaction of cause and effect, the human brain still cannot but perceive this situation as paradoxical. This technique is named, as you might guess, in honor of Baron Munchausen, who pulls himself out of the swamp.

Movie example: In the space epic Interstellar (spoiler alert) there are a huge number of plot twists of varying degrees of predictability, but the emergence of a "closed loop" is almost the main twist: Christopher Nolan's humanistic message that love is stronger than gravity takes its final form only in at the very end of the film, when it turns out that the spirit of the bookshelf, protecting the astrophysicist performed by Jessica Chastain, was the hero Matthew McConaughey, sending messages to the past from the bowels of a black hole.

The Bill Murray Paradox

Plots about looped time loops have already become a separate subgenre of sci-fi about temponauts for some time - both in literature and in cinema. It is not surprising that almost any such work is automatically compared to Groundhog Day, which over the years has come to be seen not only as a parable of existential despair and the desire to appreciate life, but also as an amusing exploration of the possibilities of behavior and self-development in extremely limited conditions. The main paradox here lies not in the presence of a loop itself (the nature of this process is not always touched upon in such plots), but in the temponaut’s incredible memory (it is she who is able to provide any movement of the plot) and the equally incredible inertness of those around him to all the evidence. that the protagonist's position is truly unique.

Movie example: Detractors have dubbed "Edge of Tomorrow" something like "Groundhog Day with aliens," but in fact the script for one of the best science fiction films of the year (which, by the way, was super-successful for this genre) handles its loops much more delicately. The paradox of perfect memory is bypassed here as a result of the fact that the protagonist writes down and thinks through his moves, interacting with other characters, and the problem of empathy is solved by the fact that there is another character in the film who at some point had similar skills. By the way, the occurrence of a loop is also explained here.

Deceived expectations

The problem of not meeting expectations is always present in our lives - but in the case of time travel, it can hurt especially badly. Usually this plot device is used as an embodiment of the proverb "Be careful what you wish for" and works according to Murphy's laws: if events can develop in the worst possible way, then everything will happen. Since it is difficult to assume that a time traveler is able to predict in advance what the tree of possible outcomes of his or her actions will look like, the viewer rarely doubts the plausibility of such plots.

Movie example: One of the saddest scenes in the recent rom-com "Future Boyfriend" looks like this: Domhnall Gleason's temponaut tries to go back in time to the time before the birth of his child and ends up coming home to a complete stranger. This is corrected, but as a result of such a collision, the hero realizes that more restrictions are imposed on his movements along the temporary arrow than he thought before.

Aristotle with smartphone

This paradox is a special case of the popular sci-fi trope "advanced technology in a backward world" - only the "world" here is not another planet, but our own past. It is not difficult to guess what the introduction of a conditional pistol into the world of conditional batons is fraught with: the deification of aliens from the future, destructive violence, a change in the way of life in a particular community, and the like.

Movie example: Of course, the Terminator franchise should serve as the most striking example of the destructive influence of such an invasion: it is the appearance of androids in the United States in the 1980s that ultimately leads to the emergence of artificial intelligence Skynet, which literally destroys humanity. Moreover, the main reason for the creation of Skynet is given by the protagonists Kyle Reese and Sarah Connor, due to the actions of which the main Terminator chip falls into the hands of Cyberdyne, from the depths of which Skynet eventually emerges.

The hard part of remembering

What happens to the temponaut's memory when, as a result of his own actions, the temporary arrow itself changes? The gigantic stress that must inevitably arise in such a case is often ignored by science fiction authors, but the ambiguity of the hero's position cannot be ignored. Well, there are a lot of questions here (and all of them do not have an unambiguous answer - to adequately check the answers to them, you need to literally get a time machine in your hands): does the temponaut remember all events or only part of them? Do two parallel universes coexist in the temponaut's memory? Does he perceive his changed friends and relatives as different people? What happens if you tell people from the new timeline in detail about their counterparts in the previous timeline?

Movie example: There is at least one example of such a state in almost every time travel movie; from a recent one, Wolverine from the last series of X-Men immediately comes to mind. The idea that as a result of the success of the operation, Hugh Jackman's character will be the only one who can remember the original (extremely gloomy) course of events, is voiced several times in the film; in the end, Wolverine is so happy to see all his friends again that memories that can hurt even a person with an adamantium skeleton fade into the background.

scary you #2

Neuroscientists are quite actively studying how people perceive their appearance; an important aspect of this is the reaction to twins and twins. Typically, such meetings are characterized by an increased level of anxiety, which is not surprising: the brain ceases to adequately perceive the position in space and begins to confuse external and internal signals. Now imagine how a person must feel, seeing himself - but of a different age.

Movie example: The interaction of the protagonist with himself is perfectly played out in Rian Johnson's film Looper, where the young Joseph Simmons is played by Joseph Gordon-Levitt in cunning makeup, and the elderly, who arrived from the near future, is played by Bruce Willis. Cognitive discomfort and the inability to establish normal contact is one of the important themes of the picture.

Unfulfilled predictions

Your opinion about whether such events are paradoxical depends directly on whether you personally adhere to a deterministic model of the universe. If there is no free will as such, then a skilled temponaut can safely bet huge amounts of money on various sports competitions, predict the results of elections and award ceremonies, invest in shares of the right companies, solve crimes, and so on. If, as is usually the case in films about time travel, the actions of the temponaut are still able to change the future, then the function and role of predictions based on a kind of insight from a stranger from the future are as ambiguous as in the case of those predictions that are based solely on on logic and past experience (that is, similar to those that are used now).

Movie example: Despite the fact that only "mental" time travel appears in "Minority Report", the plot of this film serves as a vivid illustration for both models of the universe: both deterministic and free will. The plot revolves around the prediction of yet uncommitted crimes with the help of "clairvoyants" who are able to visualize the intentions of potential killers (a situation of extreme determinism). Toward the end of the film, it turns out that visions are still able to change in time - accordingly, a person to some extent determines his own fate.

I was yesterday into tomorrow

In most of the world's major languages, there are multiple tenses for events in the past, present, and future. But what about the temponaut, who yesterday could observe the death of the Sun, and today he is already in the company of dinosaurs? What tenses to use in speech and writing? In Russian, English, Japanese and many other languages, such functionality is simply absent - and you have to get out in such a way that something comical inevitably happens.

Movie example: Doctor Who, of course, belongs to the field of television, not cinema (although several television films can be found in the list of works related to the franchise), but the series cannot be left out here. The Doctor's confusing use of different times became a cause for bullying back in pre-Internet times, and after the revival of the series in the mid-2000s, the authors decided to deliberately emphasize this detail: now the on-screen Doctor is able to connect his non-linear perception of time with the peculiarities of the language (and at the same time laugh at the resulting phrases) .

multiverse

The most fundamental paradox of time travel is not for nothing that it is directly related to a serious conceptual discussion in quantum mechanics, based on the acceptance or rejection of the concept of a “multiverse” (that is, a collection of multiple universes). What actually needs to happen the moment you "change the future"? Do you remain yourself - or do you become a copy of yourself in a different timeline (and, accordingly, in a different universe)? Do all the timelines co-exist in parallel so that you just jump from one to the other? If the number of decisions that change the course of events is infinite, then is the number of parallel universes infinite? Does this mean that the multiverse is infinite in size?

Movie example: The idea of ​​multiple parallel timelines is usually not adequately portrayed in films for one simple reason: writers and directors become afraid that no one will understand them. But Shane Carratt, the author of The Detonator, is not like that: to understand the plot of this film, where one non-linearity is superimposed on another, and to fully explain the movements of the characters in time, it is necessary to draw a diagram of the multiverse with intersecting timelines, it is possible only after considerable effort.

Time travel is one of the strongest desires of all people. On the one hand, this is an incredible opportunity to live in almost every era, on the other hand, we can face temporary paradoxes that can change the world. There is nothing in Einstein's theory of relativity to rule out such travel, although travel into the past itself violates one of the fundamental constants of physics, causality.

There are two groups of scientists who argue about the very structure of time: some believe that by returning to the past and changing at least something, you can change the future, and in the most unpredictable way. Others believe that time is a vicious cycle that constantly repeats, and some events do not affect others, as they exist in different time planes. According to these theories, there were, which we will tell you about.

1. The paradox of predestination

This paradox occurs when a time traveler becomes a part of past events and their actions eventually lead to the event they are trying to influence or prevent. It creates a temporal cycle of causality, in which Event 1 in the past affects Event 2 in the future (meaning time travel to the past), which caused Event 1. A cycle of cycles is created that ensures that history does not change, so that any time travel and attempts to change the past will lead to the very cause, not the correction of these actions. This paradox assumes that everything will happen as it should anyway, and nothing will change this.

In other words, a person's journey and actions become the very reason why certain events happened. Let's say your dog gets hit by a car and you decide to go back in time to fix it. You know the time and place and are ready to save the dog. Here you see how he starts to run across the road, and you rush to prevent him from doing this. At this moment, a car is taxiing out from around the corner, which is about to knock you down. In order not to run into a person, the driver turns the steering wheel and accidentally runs into a dog. That is, your appearance in the past was the reason that the dog died.

2. Ontological paradox

This paradox states that any object, person, or piece of information that is sent back in time will result in an endless loop in which that object has no apparent origin, or was not even created. Otherwise, this one is based on the example of a young man who went back to the past and there he seduced a lady, with whom he then slept. After 3 months, he returned to his own time, not knowing that this woman was pregnant. Her child grows up and becomes, guess what, yes, a time traveler who goes back and meets a woman, and so on in an endless circle.

This paradox implies that the past, future, and present are undetermined, leaving scientists unable to figure out how to determine the origin of anything that might not exist at all. Einstein's field equation allows for the possibility of such cycles, so nothing is impossible.

3. The grandfather paradox

And he's damn interesting! This paradox suggests a "self-consistent solution" because if you go back in time and kill your grandfather, you will never be born and you won't be able to go back in time. Paradox! Suppose you decide to kill your grandfather because he created a dynasty that destroyed the world and turned it into a burning ashes. The decision is made to kill him before he meets his grandmother, so that in this way your entire family line will disappear, including you. This approach generates 2 hypotheses.

Hypothesis about the protection of the time line: you return to the past, come to your grandfather and put a revolver to his head, pull the trigger, but nothing happens. You press again and again, and all you hear is “clack”, “clack”, “clack”! Perhaps the bullets are defective, or the trigger is not working properly. But point the gun at any other point, and you will hear a shot. On the grandfather - again nothing. The same will happen with the knife: you will leave only scars that it will boast in the future; try to poison - anyone will drink the poison, but not the grandfather. You will make many attempts that will never lead to a result.

Multiple Universe Hypothesis: You went back in time and shot your grandfather, so it's done. But in the "present" you are confronted with the fact that you never existed here. All memories, the fact of life - erased. By killing your grandfather, you create a timeline where you never existed. Scientists believe that in this way it is possible to create an alternative timeline or a parallel universe.

4. The paradox of Hitler's assassination

Like the paradox of a grandfather who can prevent his own birth, Hitler's paradox erases the very reason for going back in time and killing. In addition, killing a grandfather has a limited "butterfly effect", and killing an evil German will result in consequences that will reverberate around the world. The paradox itself arises primarily due to the fact that it is unlikely that someone so successful, having a time machine at his disposal, would travel to destroy Hitler, because today he is on horseback, why change something. On the other hand, if you had killed the Fuhrer, he would not have committed a single action that would have caused a desire to do so.

5. Polchinsky's paradox

American theoretical physicist Joseph Polchinski proposed a time paradox scenario in which a billiard ball enters a wormhole and appears in the past just at that moment to collide with a younger version of itself and stop the entry. Polchinskiy's paradox is taken very seriously by physicists thanks to Einstein's theory of relativity, which suggests the possibility of time travel.

When Joseph suggested , he put into it the Novikov principle, which confirms the possibility of time travel, but prohibits time paradoxes. Thanks to this, solutions were formed that will help to avoid temporal paradoxes, and hence changes in the past. Take our billiard ball: the ball that emerges from the wormhole will hit the target version and change its direction, but not enough to prevent it from entering the wormhole.

This means that intervention in the past can occur, but it will only change the timeline of history, adding some event, but it will not be possible to change history itself. This also explains the grandfather's paradox, in which attempts to kill him will end in failure.

The idea that you can get into the past or the future gave rise to a whole genre of chrono-fiction, and it seems that all possible paradoxes and pitfalls have long been known to us. Now we read and watch such works not for the sake of looking at other eras, but for the confusion that inevitably arises when trying to disrupt the flow of time. What tricks over time underlie all chrono-operas and what plots can be assembled from these building blocks? Let's figure it out.

Wake up when the future comes

The easiest task for a time traveler is to get into the future. In such stories, you don’t even have to think about exactly how the time stream works: since the future does not affect our time, the plot will hardly differ from a flight to another planet or to a fairy-tale world. In a sense, we are all already traveling through time - at a rate of one second per second. The only question is how to increase the speed.

In the XVIII-XIX centuries, dreams were considered one of the fantastic phenomena. A lethargic dream was adapted for traveling into the future: Rip van Winkle (the hero of the story of the same name by Washington Irving) slept for twenty years and found himself in a world where all his loved ones had already died, and he himself had been forgotten. Such a plot is akin to the Irish myths about the people of the hills, who also knew how to manipulate time: the one who spent one night under the hill returned after a hundred years.

This "hit" method never gets old

With the help of dreams, the writers of that time explained any fantastic assumptions. If the narrator himself admits that he has dreamed of outlandish worlds, what is the demand from him? Louis-Sebastien de Mercier resorted to such a trick when describing a "dream" about a utopian society ("Year 2440") - and this is already a full-fledged time travel!

However, if the journey to the future needs to be plausibly justified, it is also not difficult to do this without contradicting science. The cryo-freezing method famed by Futurama could, in theory, work - which is why many transhumanists now try to preserve their bodies after death in the hope that future medical technologies will allow them to be revived. True, in fact, this is just Van Winkle’s dream adapted to modern times, so it’s hard to say whether this is considered a “real” journey.

faster than light

For those who want to seriously play with time and delve into the wilds of physics, travel at the speed of light is better suited.

Einstein's theory of relativity makes it possible to compress and stretch time at near-light speeds, which is used in science fiction with pleasure. The famous “twin paradox” says that if you rush through space at near-light speed for a long time, a couple of centuries will pass on Earth in a year or two of such flights.

Moreover, the mathematician Gödel proposed a solution for Einstein's equations in which time loops can appear in the universe - something like portals between different times. It was this model that was used in the film "", first showing the difference in the flow of time near the horizon of a black hole, and then throwing a bridge into the past with the help of a "wormhole".

Einstein and Gödel already had all the plot twists that the authors of chrono-operas are now thinking up (filmed on iPhone 5)

Is it possible to get into the past in this way? Scientists strongly doubt this, but their doubts do not interfere with science fiction writers. Suffice it to say that only mere mortals are forbidden to exceed the speed of light. And Superman can make a couple of revolutions around the Earth and go back in time to prevent the death of Lois Lane. Why is there the speed of light - even sleep can work in the opposite direction! And at Mark Twain, the Yankees received a crowbar on the head and at the court of King Arthur.

Of course, flying into the past is more interesting - just because it is inextricably linked with the present. If the author introduces a time machine into a story, he usually wants to at least confuse the reader with time paradoxes. But most often the main theme in such stories is the struggle with predestination. Is it possible to change one's own destiny if it is already known?

Cause or effect?

The answer to the question of predestination - like the very concept of time travel - depends on how time works in a particular fantasy world.

The laws of physics are not a decree for terminators

In reality, the main problem with traveling into the past is not the speed of light. Sending anything, even a message, back in time would violate a fundamental law of nature: the principle of causality. Even the most seedy prophecy is already, in a sense, time travel! All scientific principles known to us are based on the fact that first an event occurs, and then it has consequences. If the effect is ahead of the cause, it breaks the laws of physics.

To “fix” the laws, we need to figure out how the world reacts to such an anomaly. This is where science fiction writers give free rein to the imagination.

If the genre of the film is a comedy, then there is usually no risk of “breaking” time: all the actions of the characters are too insignificant to affect the future, and the main task is to get out of their own problems

It can be said that time is a single and indivisible stream: between the past and the future, a thread is stretched, as it were, along which you can move.

It is in this picture of the world that the most famous loops and paradoxes arise: for example, if you kill your grandfather in the past, you can disappear from the universe. There are paradoxes due to the fact that this concept (philosophers call it "B-theory") states that the past, present and future are as real and unchanging as the three dimensions we are used to. The future is still unknown - but sooner or later we will see the only version of events that must happen.

Such fatalism gives rise to the most ironic stories about time travelers. When an alien from the future tries to fix the events of the past, he suddenly discovers that he himself caused them - moreover, it has always been so. Time in such worlds is not rewritten - a causal loop simply appears in it, and any attempts to change something only reinforce the original version. This paradox was one of the first to be described in detail in the short story "On His Own Footsteps" (1941), where it turns out that the hero was carrying out a task received from himself.

The heroes of the gloomy series "Darkness" from Netflix go back in time to investigate a crime, but involuntarily they are forced to do the things that lead to this crime.

It happens even worse: in more “flexible” worlds, a careless act of a traveler can lead to a “butterfly effect”. Intervention in the past rewrites the entire time stream at once - and the world not only changes, but completely forgets that it has changed. Usually only the traveler himself remembers that everything was different before. In the trilogy "", even Doc Brown could not follow Marty's jumps - but he at least relied on the words of a friend when he described the changes, and usually no one believes such stories.

In general, single-threaded time is a confusing and hopeless thing. Many authors decide not to limit themselves and resort to the help of parallel worlds.

The plot, in which the hero finds himself in a world where someone canceled his birth, came from the Christmas film It's a Wonderful Life (1946)

The bifurcation of time

This concept not only allows you to get rid of contradictions, but also captures the imagination. In such a world, everything is possible: every second it is divided into an infinite number of reflections similar to each other, differing in a couple of little things. The time traveler does not really change anything, but only jumps between different facets of the multiverse. Such a plot is very popular in TV shows: in almost any show there is a series where the characters find themselves in an alternative future and try to return everything to normal. On an endless field, you can frolic endlessly - and there are no paradoxes!

Now in chrono-fiction, the model with parallel worlds is most often used (frame from Star Trek)

But the most interesting thing begins when the authors abandon the "B-theory" and decide that there is no fixed future. Maybe uncertainty and uncertainty is the normal state of time? In such a picture of the world, specific events occur only on those segments on which there are observers, and the rest of the moments are just a probability.

An excellent example of such "quantum time" was shown by Stephen King in "". When the Gunslinger unwittingly created a time paradox, he almost went insane because he remembered two lines of events at the same time: in one he traveled alone, in the other with a companion. If the hero came across evidence reminiscent of past events, the memories of these points formed into one consistent version, but the gaps were like in a fog.

The quantum approach has recently become popular, partly due to the development of quantum physics, and partly because it allows us to show even more intricate and dramatic paradoxes.

Marty McFly almost erased himself from reality by preventing his parents from meeting. I had to fix it right now!

Take, for example, the film Loop of Time (2012): as soon as the young incarnation of the hero performed some actions, an alien from the future immediately remembered them - and before that, fog reigned in his memory. Therefore, he tried not to interfere once again in his past - for example, he did not show his young self a photograph of his future wife, so as not to disrupt their first unexpected meeting.

The "quantum" approach is also visible in "": since the Doctor warns satellites about special "fixed points" - events that cannot be changed or bypassed - it means that the rest of the fabric of time is mobile and plastic.

However, even the probabilistic future pales in comparison with worlds where Time has its own will - or it is guarded by creatures that lie in wait for travelers. In such a universe, laws can work in any way - and it's good if you can negotiate with the guards! The most striking example is the langoliers, who, after every midnight, eat yesterday along with everyone who was unfortunate enough to be there.

How the time machine works

Against the background of such a variety of universes, the technique of time travel itself is a secondary issue. Since the time of the time machine, they have not changed: you can come up with a new principle of operation, but this is unlikely to affect the plot, and from the outside, the journey will look about the same.

Wells' time machine in the 1960 film adaptation. That's where the steampunk is!

Most often, the principle of operation is not explained at all: a person climbs into a booth, admires the buzz and special effects, and then gets out at a different time. This method can be called an instant jump: the fabric of time seems to be pierced at one point. Often, for such a jump, you first need to accelerate - pick up speed in ordinary space, and the technique will already translate this impulse into a jump in time. So did the heroine of the anime "The Girl Who Leapt Through Time", and Doc Brown on the famous DeLorean from the "Back to the Future" trilogy. Apparently, the fabric of time is one of those obstacles that storm with a running start!

DeLorean DMC-12 is a rare time machine that deserves to be called a machine (JMortonPhoto.com & OtoGodfrey.com)

But sometimes the opposite happens: if we consider time as the fourth dimension, in the three ordinary dimensions the traveler must remain in place. The time machine will rush him along the time axis, and in the past or future he will appear at exactly the same point. The main thing is that they do not have time to build anything there - the consequences can be very unpleasant! True, such a model does not take into account the rotation of the Earth - in fact, there are no fixed points - but in the extreme case, everything can be attributed to magic. This is how it worked: each revolution of the magic clock corresponded to one hour, but the travelers did not move from their place.

The most severe of all such “static” travels was done in the film “Detonator” (2004): there the time machine squandered exactly one minute for a minute. To get to yesterday, you had to sit in an iron box for 24 hours!

Sometimes a model with more than three dimensions is interpreted even more cunningly. Let us recall Gödel's theory, according to which loops and tunnels can be laid between different times. If it is correct, you can try to get through additional dimensions to another time - which the hero "" took advantage of.

In earlier fiction, a "time vortex" worked on a similar principle: a kind of subspace where you can get into it on purpose (on Doctor Who's TARDIS) or by accident, as happened with the crew of the destroyer in the movie The Philadelphia Experiment (1984). Flying through the funnel is usually accompanied by dizzying special effects, and leaving the ship is not recommended, so as not to get lost in time forever. But in fact, this is still the same ordinary time machine, delivering passengers from one year to another.

For some reason, lightning always strikes inside temporary funnels and sometimes credits fly

If the authors do not want to delve into the jungle of theories, the anomaly of time can exist on its own, without any adaptations. It is enough to enter the wrong door, and now the hero is already in the distant past. Is it a tunnel, a pinhole or magic - who will take it apart? The main question is how to get back!

What can't be done

However, usually science fiction still works according to the rules, albeit fictional, - therefore, restrictions are often invented for time travel. For example, one can say, following modern physicists, that it is still impossible to move bodies faster than the speed of light (that is, into the past). But in some theories there is a particle called "tachyon", which is not affected by this limitation, because it has no mass ... Maybe consciousness or information can still be sent into the past?

When Makoto Shinkai takes on time travel, he still comes up with a touching story of friendship and love ("Your Name")

In reality, most likely, it will not work to cheat like that - all because of the same principle of causality, which does not care about the type of particles. But in science fiction, the "informational" approach seems more plausible - and even more original. It allows the hero, for example, to be in his own young body or go on a journey through other people's minds, as happened with the hero of the Quantum Leap series. And in the Steins;Gate anime, at first they only knew how to send SMS to the past - try to change the course of history with such restrictions! But plots only benefit from limitations: the more difficult the task, the more interesting it is to watch how it is solved.

A hybrid phone with a microwave to connect with the past (Steins;Gate)

Sometimes additional conditions are imposed on ordinary, physical time travel. For example, often a time machine cannot send anyone back in time before the moment when it was invented. And in the anime The Melancholy of Haruhi Suzumiya, time travelers forgot how to go into the past beyond a certain date, because on that day a catastrophe occurred that damaged the fabric of time.

And here the most interesting begins. Plain jumps into the past and even time paradoxes are just the tip of the chrono-fiction iceberg. If time can be changed or even corrupted, what else can be done with it?

Paradox upon paradox

We love time travel for its confusion. Even a simple leap into the past generates twists like the butterfly effect and the grandpa paradox, depending on how time works. But using this technique, you can build much more complex combinations: for example, jump into the past not once, but several times in a row. This creates a stable time loop, or Groundhog Day.

Do you have deja vu?
"Haven't you already asked me about this?"

You can loop for one day or several - the main thing is that everything ends with a “reset” of all changes and a journey back to the past. If we are dealing with linear and unchanging time, such loops themselves arise from causal paradoxes: the hero receives a note, goes to the past, writes this note, sends it to himself ... If time is rewritten every time or creates parallel worlds, it turns out to be an ideal trap : a person experiences the same events over and over again, but any changes still end up resetting to the original position.

Most often, such plots are devoted to attempts to unravel the cause of the time loop and break out of it. Sometimes the loops are tied to the emotions or tragic fates of the characters - this element is especially loved in anime ("Magical Girl Madoka", "The Melancholy of Haruhi Suzumiya", "When Cicadas Cry").

But "groundhog days" have a definite plus: they allow, due to endless attempts, sooner or later to succeed in any endeavor. No wonder Doctor Who, having fallen into such a trap, recalled the legend of a bird that for many thousands of years grinded away a stone rock crumbly, and his colleague managed to bring an extraterrestrial demon to white heat with his “negotiations”! In this case, you can destroy the loop not with a heroic deed or insight, but with ordinary perseverance - and along the way, learn a couple of useful skills, as happened with the hero of Groundhog Day.

In "Edge of Tomorrow" aliens use time loops as a weapon - to calculate the perfect battle tactics

Another way to build a more complex structure from ordinary jumps is to synchronize two segments of time. In the movie "X-Men: Days of Future Past" and in "Time Scout", the time portal could only be opened at a fixed distance. Roughly speaking, at noon on Sunday, you can move to noon on Saturday, and an hour later - already at one in the afternoon. With such a restriction, an element appears in the story about a journey into the past, which, it would seem, cannot be there - time pressure! Yes, you can go back and try to fix something, but in the future, time goes on as usual - and the hero, for example, may be late to return.

To complicate the traveler's life, you can make time jumps random - take away control over what is happening from him. In the TV series Lost, such a disaster happened to Desmond, who interacted too closely with a temporary anomaly. But back in the 1980s, the series Quantum Leap was built on the same idea. The hero constantly found himself in different bodies and eras, but did not know how long he would last in this time - and even more so he could not return "home".

We twist the time

The heroine of the game Life is Strange faces a difficult choice: to undo all the changes that she made to the fabric of time in order to save her friend, or to destroy the whole city

The second technique with which to diversify time travel is to change the speed. If you can skip a couple of years to find yourself in the past or the future, why not, for example, put time on pause?

As Wells showed in the story "The Newest Accelerator", even slowing down time for everyone except yourself is a very powerful tool, and even if you stop it completely, you can secretly penetrate somewhere or win a duel - and completely unnoticed by the enemy. And in the web series "Worm" one superhero was able to "freeze" objects in time. With the help of this simple technique, it was possible, for example, to derail a train by placing an ordinary sheet of paper in its path - after all, an object frozen in time cannot change or move!

Enemies frozen in time are very convenient. In the Quantum Break shooter, you can see this for yourself

The speed can also be changed to a negative one, and then you get the counterwinds familiar to readers of the Strugatskys - people living "in the opposite direction." This is possible only in worlds where the "B-theory" works: the entire time axis is already predetermined, the only question is in what order we perceive it. To further confuse the plot, you can launch two time travelers in different directions. This is what happened to the Doctor and River Song in the Doctor Who series: they jumped back and forth through the eras, but the first (for the Doctor) their meeting for River was the last, the second - the penultimate one, and so on. To avoid paradoxes, the heroine had to be careful not to accidentally spoil his future to the Doctor. Then, however, the order of their meetings turned into a complete leapfrog, but the heroes of Doctor Who are no strangers to this!

Worlds with "static" time give rise not only to counter-motors: creatures often appear in science fiction who simultaneously see all points of their life path. Thanks to this, the Trafalmadorians from Slaughterhouse Five treat any misadventures with philosophical humility: for them, even death is just one of the many details of the overall picture. Doctor Manhattan from "" because of such an inhuman perception of time, moved away from people and fell into fatalism. Abraxas from The Endless Journey regularly messed up grammar, trying to figure out which event had already happened and which would happen tomorrow. And the aliens from Ted Chan's story "The Story of Your Life" had a special language: everyone who learned it also began to see the past, present and future at the same time.

The movie "Arrival", based on "The Story of Your Life", begins with flashbacks ... Or not?

However, if countermeasures or Trafalmadorians really travel in time, then with the abilities of Quicksilver or the Flash, everything is not so obvious. After all, in fact, it is they who are accelerating relative to everyone else - how can we assume that the whole world around is actually slowing down?

Physicists will notice that the theory of relativity is called that way for a reason. It is possible to speed up the world and slow down the observer - this is the same thing, the only question is what to take as a starting point. And biologists will say that there is no fantasy here, because time is a subjective concept. An ordinary fly also sees the world "in slow-mo" - so quickly its brain processes signals. But you can not limit yourself to the fly or the Flash, because in some chrono-operas there are parallel worlds. Who prevents them from letting time pass at different speeds - or even in different directions?

A well-known example of such a technique is the Chronicles of Narnia, where there is no formal time travel. But time in Narnia flows much faster than on Earth, so the same heroes fall into different eras - and observe the history of a fairy-tale country from its creation to its fall. But in Homestuck, which is perhaps the most confusing story about time travel and parallel worlds, two worlds were launched in different directions - and the contacts between these universes had the same confusion that the Doctor had with River Song.

If clock faces haven't been invented yet, the hourglass will do too (Prince of Persia)

kill time

Any of these devices can be used to write a story that would make even Wells' head crack. But modern authors are happy to use the entire palette at once, tying time loops and parallel worlds into a ball. Paradoxes with this approach accumulate in batches. Even with one jump into the past, a traveler can inadvertently kill his grandfather and disappear from reality - or even become his own father. Perhaps, he mocked the “paradox of causality” best of all in the story “All you zombies”, where the hero turns out to be both his own father and mother.

Based on the story "All You Zombies", the film "Time Patrol" (2014) was made. Almost all of his characters are the same person.

Of course, paradoxes must be somehow resolved - therefore, in worlds with linear time, it is often restored by itself, by the will of fate. For example, almost all first-time travelers decide to kill Hitler first. In worlds where time can be rewritten, he will die (but according to the law of meanness, the resulting world will be even worse). Asprin's attempt in "Time Scouts" will fail: either the gun will jam, or something else will happen.

And in worlds where fatalism is not respected, you have to monitor the safety of the past on your own: for such cases, they create a special “time police” that catches travelers before they do trouble. In the film Loop of Time, the role of such police was taken over by the mafia: the past for them is too valuable a resource to allow someone to spoil it.

If there is no fate, no chronopolice, travelers run the risk of simply breaking time. At best, it will turn out like in Jasper Fforde’s “Thursday Nonetoth” cycle, where the time police played to the point that they accidentally canceled the very invention of time travel. At worst, the fabric of reality will collapse.

As Doctor Who has repeatedly shown, time is a fragile thing: a single explosion can cause cracks in the universe across all eras, and an attempt to rewrite a “fixed point” can collapse both the past and the future. In Homestuck, after such an incident, the world had to be recreated, and in all eras they mixed together, which is why the events of the books can no longer be combined into a consistent chronology ... Well, in the manga Tsubasa: Reservoir Chronicle, the son of his own clone, erased from reality, had to replace himself with a new person, so that in the events that have already happened there was at least some character.

Some heroes of the Tsubasa multiverse exist in at least three incarnations and come from other works of the same studio

Fans' favorite pastime is to draw for the most intricate pieces of chronology

Sound crazy? But for such madness, we love time travel - they push the boundaries of logic. Sometime, it must be, even a simple leap into the past could drive an unaccustomed reader crazy. Now, chrono-fiction truly shines at long distances, when the authors have room to turn around, and time loops and paradoxes are layered on top of each other, giving rise to the most unimaginable combinations.

Alas, it often happens that the construction develops under its own weight: either there are too many jumps in time to make sense to follow them, or the authors change the rules of the universe on the go. How many times has Skynet rewritten the past? And who can say now how time works in Doctor Who?

On the other hand, if chrono-fiction, with all its paradoxes, turns out to be harmonious and internally consistent, it is remembered for a long time. This is what bribes BioShock Infinite, Tsubasa: Reservoir Chronicle or Homestuck. The more complex and intricate the plot, the stronger the impression left on those who got to the end and managed to look at the whole canvas at once.

* * *

Time travel, parallel worlds and the rewriting of reality are inextricably linked, which is why almost no science fiction work can do without them now - whether it's fantasy like "Game of Thrones" or science fiction exploration of the latest theories of physics, like in "Interstellar". Few plots give the same scope for imagination - after all, in a story where any event can be canceled or repeated several times, everything is possible. At the same time, the elements that make up all these stories are quite simple.

It seems that over the past hundred years, the authors have done everything possible with time: they let them go forward, backward, in a circle, in one stream and in several ... Therefore, the best of these stories, as in all genres, are based on characters: on the one who came again from ancient Greek tragedies to the theme of the struggle with fate, on attempts to correct one's own mistakes and on the difficult choice between different branches of events. But no matter how the chronology jumps, history will still develop in only one direction - in the one that is most interesting to viewers and readers.