Who goes on a journey through time. Six time travel theories that might work
In the spring of 2003, unknown Andrew Karlsin made $350 million on the stock exchange with $800, making 126 trades in two weeks. The US Securities Market Commission suspected Karlsin of obtaining insider information from company owners, and the man was detained by the FBI. After interrogation, he admitted that ... he arrived from 2256 in a time machine to earn money on historical information. This was written by the weekly tabloid Weekly World News, posting a photo of 44-year-old Karlsin. Later, unidentified persons posted a bail of $1 million for the man, and no one saw him again. This fantasy story would have been more like the plot of the movie "Back to the Future 2", if not for a number of statements by scientists in recent months.
At the end of March 2017, Popular Mechanics published an article about the possibility of time travel due to the principles of quantum mechanics. Three methods of teleportation are known today. The first one has been repeatedly described by science fiction writers - the body moves through the "rabbit hole" of time. The second method involves the biotechnological disassembly of a person or objects into molecules that are easier to teleport separately, and then collection at the point of arrival. And the third method - it seems to scientists the most probable, although it sounds absolutely fantastic. A person is scanned at the atomic level, then the information is sent to the point of arrival and there a new body is created from the available materials with information attachment to the molecules of the transmitted information. This method is reminiscent of scientists trying to put the human brain on the World Wide Web by creating human-based artificial intelligence.
Note that teleportation itself - moving at a distance, has already taken place in 2012 and 2014 in London by the efforts of physicists. And already in the fall of 2016, these experiments were successfully repeated in Canada and China. Canadian scientists moved photons - particles of light - 6 km, and the Chinese twice as far - 12.5 kilometers. So far only teleportation of photons and atoms is possible. Thanks to such a property as "quantum entanglement" in quantum mechanics, a change in a particle can be instantly transferred to another particle that has an information connection. As a result, one particle can influence another, as well as transfer properties to it. This phenomenon can be called the quantum Internet, which will become cosmically fast. That is, we are talking about the first stage of teleportation.
Photo: Zuma/GlobalLook
Foreign scientists believe that human teleportation is possible by 2050-2080. Today's failure is due to the lack of the necessary technologies, since it is necessary to form the architecture of the human body at the mathematical and biotechnological level. That is, take on the role of God, the Architect. The lack of technology can be compared to the desire to introduce wireless cellular communication, cordless phones in the 1930s. You can know how to do it theoretically, but the lack of compact transistors - microchips, will make you wait for the development of technology.
True, there was one video recording of 1938, where a girl walks through the territory of the industrial giant Dupont, talking on a compact mobile phone. Conspiracy theorists hurried to record the girl as a time traveler, but in 2013 the grandson of the "girl" - Gertrude Jones, was found, who discovered the secret. Dupont was researching mobile radio communications and the girl was given the device to test, and she spoke to a man who was walking not far from her with the same tube.
There are hundreds of stories of people who have seen "time travelers", but the most popular are authentic photos and videos. One of the most popular and still unsolved is a 1940 photo of the opening of the South Fork bridge over a river in the Canadian province of British Columbia. On the picture appearance the guy was radically different from the style of the 1940s and 1950s. He is wearing trendy sunglasses, a printed T-shirt and a cardigan - a knitted jacket jacket, hair in the style of the 1990s. But even if you believe in his fashionable predictions, there is no way to explain a compact camera that was ahead of its time by several decades. The experts who studied the picture are sure that there is no computer manipulation. The person is present in different pictures from different angles taken by different photographers.
Photo: virtualmuseum.ca
It is difficult to say whether the guy ended up in the past by accident or on purpose. There is a high probability that people can be divided into travelers and "passengers" natural area movement in time. One of the most popular travelers from the future was the American John Titor in early 2000. He appeared on the Internet on forums, blogs and claimed to have come from 2036. The only reason why he was not mistaken for a schizophrenic, but continued to listen and discuss, is the knowledge of complex software algorithms, with the help of which time travel occurs. He also predicted the war in Iraq, the conflict in the US presidential elections in 2004 and 2008. According to him, in 2015 the Third World War, which will kill about three billion people. Then there will be a global computer failure, destroying the usual infrastructure.
USA will start Civil War, which will split America into five factions with the capital in Omaha. A computer virus will force mankind to return to agriculture for survival, but the global network will partially work. Titor himself is allegedly a soldier sent in 1975 to collect information about the IBM-5100 computer, as his grandfather worked on the creation of a computer. The old model should help defeat the virus, however, he did not explain how. And in 2000, he got to meet his three-year-old self. On March 24, 2001, Titor gave his final piece of advice: "Take a can of gasoline with you when you leave your car on the side of the road." Then he logged out and went back. Since then, no one has heard from him again.
Like Karlsin, Titor is perhaps a conscious traveller. Nobody saw him, but Karlsin was photographed, but still not identified. Moreover, Wall Street traders are sure that all 126 transactions for $350 million could not be calculated, even with classified information. Some stocks rose in price for completely unexpected reasons, including political and military, and natural phenomena. It's impossible to collect classified information on 100 companies and pull it off in two weeks and use $800 to get $350 million. It is suspicious that the Weekly World News site has completely removed all information about Karlsin, despite the fact that it does not shun fried stories. Deleted all messages from his journalists about the investigation of the traveler and the Yahoo News portal.
If the stories of "tourists in time" are rare, then there are no less random "passengers" than UFO evidence. True, witnesses do not always manage to take pictures. So in 1932, the reporter for the German newspaper Hutton and the photographer Brandt involuntarily found themselves in a different time. The journalists went to a shipyard in Hamburg to make a report. Upon their return, they stated that they had miraculously survived the bombing by unknown aircraft. Brandt took photographs of the city blazing from hundreds of bombs, but the film was empty. The editor-in-chief advised not to abuse alcohol, and 11 years later, when Hamburg was completely destroyed by aircraft during the Gomorrah operation, he remembered the story. 600 bombs were dropped on the city, a firestorm killed 40,000 people.
All "passengers" can be attributed to the victims of the phenomenon " Bermuda Triangle". Over the second half of the twentieth century, this small point on the map of the Earth gained fame as a natural time machine. According to unverified reports, the Pentagon classified the incident with the submarine in the 1990s, when the boat passed Bermuda. In one second, it disappeared from the radar, and after In an instant, she made contact from the Indian Ocean, while the entire crew had aged 20 years.
But the Earth is full of places where a person falls, as if into a well, at another time, and after a couple of hours he ends up at home. A similar incident occurred in 1992 with the Italian Bruno Leone, who disappeared right in front of his wife during their joint walk. Bruno returned two days later, looking very tired and confused. And no wonder, because the disappeared suddenly moved into the future five centuries ahead. He turned out to be a curiosity among identically dressed descendants. When he managed to explain that he was from Italy, it caused great astonishment. According to them, such a country ceased to exist in the 21st century. The city of the future seemed to Bruno uncomfortable and hostile, there was not a single old building familiar to him, trees and even bushes did not grow. Food in the future did not differ in variety, it was replaced by some colorless jellyfish-like jelly - tasteless, but very satisfying. The descendants decided to show him the safest places where he could survive the coming in the XXI century. cataclysms. When they began to show him Mongolia, Siberia, he suddenly moved back to his own time.
If humanity manages to survive the twenty-first century. without global upheavals, and in the second half of the century we will be able to teleport, then such travel, in the first place, will allow states to take crime under control. Looking a little ahead, it will be possible to prevent murders and robberies at the stage of the idea. This will lead to a total reduction in thoughtful, organized crimes and the prevention of everyday crimes. At the same time, businesses will be able to organize "oceanariums", parks with animals and plants from time 20-50 thousand years later, simply by moving people in a safe capsule. Partial entry into the past will allow teachers to show students Gladiator fights in reality, attend the meetings of Alexander the Great and Napoleon.
At the same time, if humanity wants to take control of time into its own hands, then it is ready either to oppose itself to God, or to take an atheistic position. Since time is a tool for the destruction of matter, it is intended to demonstrate to a person the frailty and momentary nature of material goods, in contrast to eternal spiritual values. Time will tell how far humanity will be allowed to go in its aspirations.
It doesn't take much to travel through time. Each of us moves about 24 hours ahead each day. Another thing is that this movement remains as unintentional as it is inevitable. Unlike space, we cannot own will get up and move so many "steps" into the past or future ... or can we?
The idea of the flow of time as something unchanging, constant, eternal and uniform sits somewhere very deep in our psyche. We measure it in seconds, hours, years, but the duration of these intervals can vary. Just as a river flow, which is indeed often compared to the flow of time, can either speed up on sharp drops, or slow down, spreading widely, time itself is subject to change. This discovery was perhaps the key to that scientific revolution, which in 1905-1915. did the work of Albert Einstein.
The impermanence of time originates in its complex relationship with space. Three spatial dimensions and one temporal dimension form a single, inseparable continuum - the stage on which everything that happens in our world unfolds. The complex weaves and interactions of these four dimensions with each other give us hope that travel to the past and future is still possible. To gain power over time, you just need to tame space. How is this possible?
Only forward
For simplicity, let's imagine that the continuum of our universe includes not four, but only two dimensions: one spatial and one temporal. Every object, from a photon to Donald Trump, moves along this continuum at a constant speed. Whatever it does, whether it is crossing the galaxy or answering questions from journalists while sitting on a chair, its overall speed remains the same - simplifying, we can say that the sum of the speeds at which an object moves is always equal to the speed of light. If the president does not move in space, then all the energy of his movement goes into moving along the time axis. If a photon moves through space at the speed of light, then it has no energy left for a while, and for these particles time does not move at all.
It can be said that movement in space “steals” movement from time. If Donald Trump speeds up - gets on a plane and crosses the Atlantic at a speed of about 900 km / h - he will slow down his movement in time and find himself somewhere 10 nanoseconds in the "future", in the time that his "internal clock" hasn't arrived yet. The current space record holder, Gennady Padalka, has moved several tens of milliseconds into the future for 820 days on the ISS, during which he moved at a speed of about 27.6 thousand km / h. Upon reaching the speed of 99.999% of light per year, you can move into the future by 223 "ordinary" Earth years.
This overflow of motion from space to time and back should be extended to gravity. In the description of the General Theory of Relativity, gravity is a deformation of the space-time continuum, and in the vicinity of a black hole (and any other gravitating object) all four dimensions are “curved”, and the stronger the attraction. Time at the surface of the Earth flows more slowly than in orbit, and the ultra-precise clocks of satellites run off by about 1/3 billionth of a second per day. This movement into the future is much more noticeable for bodies located near more massive objects.
The supermassive black hole at the center of our Galaxy weighs about 4 million Suns, and if we start to cut circles near it, then after some time - when on our spaceship in just a few days, we may be in the universe a few years older than us. Again, in the future. As we have seen, Einstein's formulas easily allow for such movements, although in practice they are as difficult as it is difficult to gain speed close to light, or to survive in the vicinity of a supermassive black hole. But what about the past?
Back and up
By and large, traveling back in time is even easier than going forward: just look at the starry sky. The diameter of the Milky Way is about 100 thousand light years, and the light of more distant stars and galaxies can travel to us for millions and billions of years. Looking around the night sky, we see flashes of the past. The moon as it was about a second ago, Mars about 20 minutes ago, Alpha Centauri almost four years ago, the nearby Andromeda galaxy 2.5 million years ago.
The farthest limit available for this kind of "movement" in time is more than 10 billion years: a picture of that incredibly distant era can be seen in the microwave range, like traces of the cosmic microwave background radiation. But, of course, we cannot be satisfied with such journeys; they seem to have something "fake" in comparison with how such movements look in science fiction. You select the desired era on the screen, press the button - and ...
Interestingly, Einstein's equations do not impose restrictions on such purposeful travel into the past. Therefore, some theorists, arguing about this, suggest that when moving at a speed greater than the speed of light, time in this frame of reference will flow in the opposite direction relative to the rest of the Universe. On the other hand, Einstein's theories still forbid such a movement: when the mass reaches the speed of light, it will become infinite, and in order to accelerate an infinite mass at least a little faster, infinite energy will be needed. But, most importantly, the introduction of such time machines can violate an equally fundamental cause-and-effect principle.
Imagine that you are a fierce supporter of Hillary Clinton and decide to go back in time to beat the petty Donald Trump and keep him away from politics forever. If it worked, and Donald decided in the 1950s to focus entirely on business or playing chess after such a "teaching", then how would you even know about his existence, let alone inflame dislike for this politician? .. These paradoxes are well revealed by the cult series of films “Back to the Future”, and many scientists believe that they make travel to the past fundamentally impossible. On the other hand, we can always reason and fantasize. Let's try?
through the ring
Approaching some sufficiently large black hole leads to time dilation. Falling inside is hardly an option: it's too dangerous to keep both you and your time travel machine safe. However, there is a variant in which a black hole may be a very suitable "portal" to the past. It was pointed to by calculations carried out back in the 1960s by the famous (and then very young) New Zealand physicist Roy Kerr, who studied the gravitational field of rotating black holes.
Indeed, if an ordinary spherical body is compressed to a critical radius and forms a black hole singularity, then the mass of the rotating body is affected by centrifugal forces. This angular momentum does not allow the formation of the usual "point" singularity, and instead of it, a very unusual singularity appears - in the form of a ring of zero thickness, but non-zero diameter. And if the singularity of an ordinary black hole cannot be avoided by anyone who dares to approach it too close, then an observer approaching the annular singularity may well “skip” it - and end up on the other side.
Some scientists suggest that these properties can make "Kerr" black holes a kind of antipodes of ordinary ones - somewhere, in a different space-time, they do not absorb, but, on the contrary, throw out everything that got into them in ours. The lucky one who avoided complete disintegration in the ring singularity will find himself somewhere in a completely different place and time. Where? Alas, even here no management is provided yet: how lucky. So far, we are not even sure of the existence of a singularity of such a suitable form, not to mention how to control their occurrence and exactly which sections of the space-time continuum they connect. Does this remind you of something?
Burrows and strings
If we remember our simplified two-dimensional continuum, which contains only one time dimension and one space dimension, then it will be easy for us to imagine how its fabric not only deforms and bends, but also tears - as in the vicinity of massive bodies and in the singularity of a black hole . But where do such gaps lead? Apparently, again, - to a different part of the continuum - as if we took a flat two-dimensional sheet and folded it in half, punching "holes" from one surface to another. No theory forbids the existence of such holes in our four-dimensional space-time - objects commonly known as wormholes.
In practice, physicists have never observed them anywhere, but there are a number of models describing such wormholes, and their authors include very authoritative figures, including the American Kip Thorne and the British Stephen Hawking. The latter believes that wormholes exist only on the Planck scale, in the "quantum foam" of virtual particles that are continuously born and annihilated in the vacuum of space-time. Together with them, countless tunnels of wormholes are born and crumble, which for a tiny fraction of a second - randomly - connect completely different regions of space-time, and disappear again.
To use such burrows for any good, they will have to learn how to stabilize and increase in size. Alas, calculations show that this will require colossal amounts of energy, unimaginable either for the American president or for all of humanity in any more or less foreseeable future. Therefore, another semi-fantastic concept, developed in the second half of the 20th century, gives somewhat greater hope for free movement in time. Thomas Kibble, Yakov Zel'dovich and Richard Gott - we are talking about cosmic strings.
They should not be confused with superstrings from another well-known theory: cosmic strings in Gott's view are very dense one-dimensional folds of space-time that arose even at the dawn of the existence of the Universe. To put it simply, the "fabric" of space-time in that era had not yet "smoothed out", and some of the then folds have survived to this day. They have stretched to tens of parsecs, but are still unusually thin (of the order of 10-∧31 m) and carry enormous energy (density of the order of 10∧22 g per cm of length).
Thinner than an atom, cosmic strings pierce the space-time continuum, exhibiting the most powerful, albeit locally limited, gravity. But if we learn how to manipulate them, bring them together, twist and intertwine, we can “tune” the space-time around as we please. Such superpowers promise already quite full-fledged movements into the past and future at will, according to need or mood. Unless there are fundamental prohibitions against it. Remember Back to the Future?
Paradoxes and their resolution
Violation of cause-and-effect relationships when traveling into the past can confuse not only philosophers, but also any reasonable physical and mathematical calculations. The most famous example of this is the "murdered grandfather paradox", first described in science fiction back in the 1940s. The book by the French writer René Barjavel tells how a careless time traveler killed his own grandfather, so that later he could not be born, fly into the past and kill his grandfather ... Any logic starts to fail here: a broken chain of cause and effect arises, which neither science nor our everyday experience accepts.
One solution to this paradox could be the "post-selection" of events in the universe itself. In other words, once in the past, the traveler will not be able to do anything that would disrupt the correct course of causes and effects. The gun will not work, or he will not find his grandfather, or a thousand other accidents, oddities, embarrassments will happen, but the course of things will not allow the Universe to be knocked off its measured course. But in general it is difficult to imagine any action in the past that did not have far-reaching consequences. Recall another term that came from science fiction - the “butterfly effect”, which indicates the property of some systems to amplify an insignificant influence to large and unpredictable consequences. Perhaps a post-selective solution to the paradoxes of time will still prevent us from traveling through it.
However, there is another approach, much more promising. According to the hypothesis of the Multiverse popular today, any possible (and impossible) option can be realized in the universe, they just all “diverge” in different ways. parallel universes. You can move to the past and shoot grandfather, and he really will not give birth to your father, and he will not give birth to you, but in another, parallel world. Just like somewhere out there, Donald Trump can lose the election, or not be born at all, or be a famous cyclist. Just as somewhere there are worlds inhabited by green thinking jellyfish or generally subject to other laws of physics.
Thus, time travel paradoxically leads us to the problems of the fundamental structure of the space-time continuum. Problems that can only be finally solved by the first experience of a real movement into the past - it is a pity that in our world this incredible event will have to wait for an indefinite time.
He argued that it is enough to accelerate to to get into both the past and the future. Although many have the audacity to disagree with the light and offer their own theories. However, they are all questionable, because they have not been tested; there is no documentary evidence of their success, and the scientists themselves are not sure. Everyone knows that this is possible, but they have not decided how.
Anyway, the idea to move in time is a very strange thing. How many temporary collapses are waiting for us, plus the emergence of alternative universes in which we will be confused like mental patients in straitjackets. And is it worth going to the past if 6,000 Earth years pass after returning to Earth, while the journey took no more than a day? Deal with the present before ruining the past. In the end, if it were not for Hitler and the Second World War, then most of our grandparents would hardly have married each other. There were all sorts of situations, novels at the front and evacuations. Yes, and there was not much choice. Well, God bless him, it's not about that. It's about something that's not written in the Bible.
1. Punch the future with your forehead
Here is the most primitive of all theories: you need to run as fast as you can until you reach and pierce the future with your forehead. And what is most strange: in fact, this statement is absolutely true. The faster you walk, the further you fly.
This has been the subject of many experiments. For example, in 1971 an experiment was conducted. In order not to delve into the technical component, let's say briefly: the research team flew around the Earth until time travel occurred. No, for real. They loaded the atomic clock onto the plane and flew east until they returned to where they started. When the researchers landed, clocks on Earth were 60 nanoseconds ahead of aircraft clocks. In other words, the clock on the plane was effectively pushed 60 nanoseconds into the future. The explorers then flew off in a different direction. This time, the aviation clock was 270 nanoseconds ahead of the earth clock.
This is explained by the fact that the clock on Earth was not stationary, because it was on the rotating surface of the planet. The clocks on the plane flying west ran slower, so everything on Earth slowed down by comparison. It turns out that the famous scene where Superman flies around the Earth and turns back time is just the fruit of the screenwriter's sick brain.
By the way, consider this type of time travel in our pocket. Your phone is connected to GPS satellites, which have to be corrected for slowing down (satellites have their own time course). If this is not done, the navigation system will take you to the crack den of the neighboring area instead of the nearest KFC.
Let's assume that a car has already been invented that actually allows you to travel in this way. We reach speed and jump not by 60 nanoseconds, but by 60 years. A few minutes or a few hours around the planet, and then - boom! - bright future!
Only now, can you live in this future, where everyone has forgotten you, and if they remember you, then only as an asshole who spins around the Earth endlessly?
2. Dense holey objects of comic proportions
If you have seen Interstellar, then the essence of the theory should be clear. The closer you are to a large, dense object, the slower time passes. For you.
Massive time travel is already happening. Scientists fired a huge laser 10,000 kilometers up. Sometimes science is left with no other choice but to shoot from a mega-gun into space. But the experiment confirmed that time really moves with different speed depending on the distance to gravity.
And what did this shot give? Nothing, once again confirmed the theory that time flows much more slowly near a supermassive object. Closer to the Earth, the passage of time is not as fast as in the layers of the stratosphere. So, if someone suddenly decides to use the mass of Jupiter for travel, then good luck. It is enough to compress the mass of the planet to the size of a tin can, and then travel will become 2 times faster. And you don’t have to fly to, which is not only supermassive, but also a real galactic time machine: time flows around it very slowly.
The strangest part of this theory is that a similar journey is already happening to you right now. In fact, it happens everywhere, not just in the magical horizons of some mysterious black hole on the other side of the galaxy. The core of the Earth moves in time more slowly than people standing at a bus stop in Makhachkala. When you stand, your butt ages more slowly than your face (although it would be better the other way around). We don't need a car to travel through time. We just need something huge nearby, like the ego of Milonov or the carcass of Stas Baretsky. Although, even if such a machine using a monstrous mass is created, then a crowd of protesters will instantly appear, fearing a cosmic collapse and the fact that the Earth's axis will shift, and Snoop Dogg will become president.
3. Wormholes and Krasnikov's pipes
You cannot travel through space and time faster than the speed of light, but with Krasnikov's pipes this problem is instantly solved. You just cut a tunnel through space and time and go back and forth like one of those green pipes in Super Mario. Here, too, there is an entrance, an exit, and most importantly - the journey goes very quickly, regardless of the distance, so it is unlikely to get bored.
Such "wormholes" are not a physical object, but a distortion of space and time. Schematically, it looks like this: two layers of space bend in a certain place until they touch each other, like underpants stuck in the ass.
The main advantages of pipes are that they can be created artificially, and the biggest plus is that the traveler returns there exactly at the same time from which he began the journey. But remember: cutting a window to new stars located at a distance of 3000 light years, you risk getting into an intergalactic war.
In 1993, University of Wellington professor Matt Visser noted that two wormhole entrances with an induced time difference could not be combined without a quantum field and gravitational effects causing the wormholes to collapse or repel each other. Simply put, the mass will increase, which will only destroy the unfortunate pipes. In addition, this method of movement does not, in fact, violate the so-called universal speed limit - the speed limit of light - because the ship itself does not move faster than light. The wormhole shortens the path not only in space, but also in time.
4. Mexican bubbles
Traveling faster than light is as real as milking a female unicorn and giving that milk to a malevolent leprechaun. So stop thinking about it - it's stupid and unrealistic.
So everyone thought until, in the 90s, the Mexican scientist Miguel Alcubierre thought about a bubble that compresses the space in front of it and expands it behind it. All that is needed for this is tons of negative energy (we are not talking about envy, murder, apathy, speeches by Vladimir Solovyov). The idea was purely theoretical and even fantastic. Given the existence of negative energy, moving a bubble 200 meters in diameter would require energy equivalent to the mass of Jupiter. Here you can’t get by with the Solovyovs - you will have to connect Kurginyan.
However, in the last few years, modifications of his idea have been proposed, in which the "bubble" was replaced by a torus, and the negative energy turned out to be completely unnecessary. In this case, calculations show the need for energy contained in just hundreds of kilograms of mass. Even an experiment was carried out that proved that space is perfectly curved without negative energy. But there is one problem: the bubble is sensitive, like a virgin in the first experience with a woman, and too many extraneous facts can confuse him.
5. A cylinder in some galaxy
What is a Tipler Cylinder? Somewhere in space, approximately to the left of Betlgeuse, there is a rotating cylinder. You take a ship and happily go there. When you get close enough to the surface of the cylinder (the space around it will be mostly deformed), you will need to go around it several times and return to Earth. Reminiscent of the Buryat shamanic rite, but with the cosmos, everything is not always simple. But you will arrive in the past. How far depends on how many times you go around the cylinder in orbit. Even if your own time seems to be moving forward as usual, as you circle the cylinder, outside of the distorted space, you will inevitably move into the past. It's like running up an escalator going down.
It remains only to find this cylinder. Apparently, this is something very big and long, like ... films by Nikita Mikhalkov. But so far no one has seen them. Not in a telescope, not in any other instruments. The astronauts were asked - they also did not see. The cylinder is a hypothetical thing, verified from Einstein's equations, and therefore no one knows how this journey will turn out.
Ever dreamed of going somewhere else? No, not at the usual speed with which we "boringly" go forward - second by second. Or:
- faster, so that you can climb far into the future, remaining at the same age;
- slower so that you can do much more than others in the same amount of time;
- V reverse direction so that you can return to the era of the past and change it, perhaps changing the future or even the present?
It may sound downright sci-fi, but not everything on this list will be purely "fantastic": traveling through time is a scientifically possible process that is always with you. The only question is how you can manipulate it for your own purposes and control the movement in time.
When, in 1905, Einstein put forward special theory relativity, the realization that every massive object in the universe must travel through time was just one of its startling consequences. We also learned that photons - or other massless particles - cannot experience time in their frame of reference at all: from the moment one of them is emitted to the moment it is absorbed, only massive observers (like us) can see the passage of time. From the position of a photon, everything is compressed into one point, and absorption and emission occur simultaneously in time, instantly.
But we have a lot. And anything that has mass is limited to always traveling at less than the speed of light in a vacuum. And not only that, but no matter how fast you are moving relative to something - whether you're accelerating or not, it doesn't matter - for you, light will always travel at the same constant speed: c, the speed of light in a vacuum. This powerful observation and awareness comes with a surprising consequence: if you are watching a person moving relative to you, their clock will run slower for you.
Imagine a “light clock,” or a clock that works on the principle of bouncing light back and forth in an up and down direction between two mirrors. The faster the person moves relative to you, the greater will be the speed of light in the transverse (along) direction, and not in the direction up and down, which means that the clock will go slower.
Similarly, your clock will move slower relative to them; they will see time flowing more slowly for you. When you get back together, one of you will be older and the other younger.
Such is the nature of Einstein's "twin paradox". Short answer: assuming you started in one frame of reference (e.g., at rest on Earth), and end up in the same frame later, the traveler will age less, because time will go "slower" for him, and the one who stayed at home, will face the "normal" passage of time.
Therefore, if you want to accelerate in time, you have to accelerate to near-light speed, move at that pace for a while, and then return to your original position. You have to turn around a bit. Do this and you can travel days, months, decades, epochs, or billions of years into the future (depending on your gear, of course).
You could witness the evolution and destruction of mankind; the end of the earth and the sun; the dissociation of our galaxy; the heat death of the universe itself. As long as you have enough power in your spaceship, you can see as far into the future as you like.
But going back is another story. Simple special relativity, or the relationship between space and time on basic level was enough to take us to the future. But if we want to go back in time, back in time, we need general relativity, or the relationship between space-time and matter and energy. In this case, we regard space and time as an inseparable fabric, and matter and energy as something that distorts this fabric, causes changes in the fabric itself.
For our Universe as we know it, space-time is rather boring: it is almost perfectly flat, almost not curved, and in no way obsessed with itself.
But in some simulated universes - in some solutions to Einstein's general theory of relativity - it is possible to create a closed loop. If space loops on itself, you can move in one direction for a long, long time to get back to where you started.
Well, there are solutions not only with closed spacelike curves, but also with closed timelike curves. A closed time-like curve means that you can literally travel through time, live in certain conditions and return to the same point from which you left.
But this is a mathematical solution. Does this math describe our physical universe? It seems not quite. The curvatures and/or discontinuities we need for such a universe are wildly inconsistent with what we observe even in the vicinity of neutron stars and black holes: the most extreme examples of curvature in our universe.
Our universe may rotate on a global scale, but the observed limits of rotation are 100,000,000 times tighter than those that allow for the closed time-like curves we need. If you want to go forward in time, you need a relativistic DeLorean.
But back? It might be better if you can't travel back in time to prevent your father from marrying your mother.
In general, summing up, we can conclude that traveling back in time will always fascinate people at the level of the idea, but, most likely, will remain in the unattainable future (paradoxically). It's not mathematically impossible, but the universe is built on physics, which is a special subset of mathematical solutions. Based on what we have observed, our dreams of righting our wrongs by going back in time are likely to remain only in our fantasies.
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 most simple task for a time traveler - 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 theoretically 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 black hole, and then throwing a bridge to 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 - precisely 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 main topic in such stories - 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 known to us scientific principles 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, went from the Christmas movie "This 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 faces 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 last resort 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 were treated 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 science fiction, a “time funnel” worked according to a similar principle: a kind of subspace where you can get on purpose (on TARDIS Doctors Who) or by chance, as happened to 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 restriction, because it has no mass ... Maybe consciousness or information can still be sent to 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 ... Parallel Worlds, it turns out 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 emotions or tragic fates 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, 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 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 reverse side". 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-winders: 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 yourself: for such cases, they create a special “time police” that catches travelers before they do trouble. In the film Looper, the role of such police was taken over by the mafia: the past for them is too valuable a resource to be allowed 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 fantasy work can do without them now - whether it be fantasy like "Game of Thrones" or sci-fi research latest theories 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 that is possible over 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.
