How to travel to the future. Is time travel possible? Programmer from the future
It doesn't take much intelligence to travel through time. Each of us moves about 24 hours ahead every day. Another thing is that this movement remains as unintentional as it is inevitable. Unlike space, we cannot of our own free will stand 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 in fact is often compared to the flow of time, can either accelerate at sudden changes or slow down, spreading widely, time itself is subject to change. This discovery was perhaps the key in the scientific revolution that took place in 1905-1915. performed the work of Albert Einstein.
The impermanence of time originates in its complex relationship with space. Three spatial dimensions and one time form a single, inseparable continuum - the stage on which everything that happens in our world unfolds. The complex interweaving and interaction of these four dimensions with each other gives us hope that travel into 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. No matter what he does, whether he is crossing the Galaxy or answering questions from journalists while sitting on a chair, the overall speed of his movement remains the same - to simplify, 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.
We can say that movement in space “steals” movement from time. If Donald Trump accelerates - 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 end up somewhere 10 nanoseconds in the “future”, in the time that for his “internal clock” It hasn't arrived yet. The current record holder for being in space, Gennady Padalka, during 820 days on the ISS, during which he moved at a speed of about 27.6 thousand km/h, moved into the future by several tens of milliseconds. By reaching 99.999% of the speed of light in a year, you can travel 223 “normal” Earth years into the future.
This flow of motion from space into 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 “bent”, and the stronger the attraction, the more strongly. Time passes slower near the Earth's surface than in orbit, and satellites' ultra-precise clocks slip by about 1/3 of a 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 circling around it, then after some time - when only a few days have passed on our spacecraft - we could find ourselves in a Universe several years older than us. Again, in the future. As we understand, Einstein’s formula easily allows for such movements, although in practice they are as complex as it is difficult to reach a 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 to arrange than traveling 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 take millions or billions of years to reach us. 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 neighboring galaxy the Andromeda Nebula - 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 of the Universe. But, of course, such travels will not satisfy us; there seems to be something “unreal” about them compared to 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 targeted trips into the past. Therefore, some theorists, discussing this, assume that when moving at a speed greater than the speed of light, time in this reference frame will flow in the opposite direction relative to the rest of the Universe. On the other hand, Einstein’s theories still prohibit such movement: upon reaching the speed of light, the mass will become infinite, and in order to accelerate the infinite mass even 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 rabid Hillary Clinton supporter and decide to go back in time to beat up petty Donald Trump and drive him away from politics forever. If it worked, and Donald, after such a “teaching” back in the 1950s, decided to completely focus on business or playing chess, then how would you even know about his existence, let alone become disliked by this politician? .. These paradoxes are well revealed by the cult film series “Back to the Future,” and many scientists believe that they make travel into the past fundamentally impossible. On the other hand, we can always reason and fantasize. Let's try?
Through the ring
Approaching a sufficiently large black hole causes time to slow down. Falling inside is hardly an option: this activity is too dangerous and will not keep both you and your time travel machine safe. However, there is an option in which a black hole may turn out to be a completely suitable “portal” to the past. It was pointed out 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.
In fact, 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 influenced by centrifugal forces. This angular momentum does not allow the formation of an ordinary “point” singularity, and instead 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 is not avoided by anyone who dares to get too close to it, then an observer approaching a ring-shaped singularity may well “overshoot” it - and end up on the other side.
Some scientists suggest that these properties can make “Kerr” black holes a kind of antipodes to ordinary ones - somewhere, in another space-time, they do not absorb, but, on the contrary, throw out everything that got into them in ours. The lucky one who avoids complete disintegration in the ring-shaped singularity will end up somewhere completely different in place and time. Where? Alas, no control is provided for here yet: it depends. So far, we are not even sure of the existence of a singularity of such a suitable form, not to mention the ability to control their occurrence and exactly which parts of the space-time continuum they connect. Does this remind you of anything?
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 breaks - 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 the other. No theory prohibits the existence of such holes in our four-dimensional space-time - objects commonly known as wormholes.
Practically, physicists have never observed them anywhere, but there are a number of models that describe 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 Planck scales, in the “quantum foam” of virtual particles that are continuously born and annihilated in the vacuum of space-time. Together with them, countless wormhole tunnels are born and crumble, which for a tiny fraction of a second - randomly - connect completely different areas of space-time, and disappear again.
In order to use such burrows for any benefit, they will have to be learned 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 Zeldovich 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 at the dawn of the existence of the Universe. To put it simply, the “fabric” of space-time in that era had not yet been “smoothed out,” and some of the folds that were then preserved to this day. They stretched to tens of parsecs, but are still unusually thin (on the order of 10-∧31 m) and carry enormous energy (density on the order of 10-∧22 g per cm of length).
Thinner than an atom, cosmic strings penetrate the space-time continuum, exhibiting powerful, albeit locally limited, gravity. But if we learn to manipulate them, bring them together, twist and weave them, we can “tune” the space-time around us in any way we want. Such superpowers promise full-fledged movements into the past and future at will, need or mood. Unless there are fundamental prohibitions on this. 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 Rene Barjavel tells how a careless time traveler killed his own grandfather, so that subsequently he could not be born, fly into the past and kill his grandfather... Here any logic begins to fail: a broken chain of causes and effects arises, which Neither science nor our everyday experience accepts this.
One solution to this paradox may be “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 won’t work, or he won’t find his grandfather, or a thousand other accidents, oddities, embarrassments will happen, but the flow of things will not allow the Universe to be thrown off its measured course. But in general it is difficult to imagine any action in the past that would not have far-reaching consequences. Let us recall another term that comes from science fiction - the “butterfly effect”, which indicates the property of some systems to amplify a minor influence to large and unpredictable consequences. Perhaps the post-selective solution to the paradoxes of time will not allow us to travel through it anyway.
However, there is another approach, much more promising. According to the popular Multiverse hypothesis today, any possible (and impossible) option can be realized in the universe, they just all “diverge” into different parallel universes. You can go back in time and shoot your grandfather, and he really won’t give birth to your father, and he won’t give birth to you, but in another, parallel world. Just like somewhere out there Donald Trump may lose the election, or not be born at all, or turn out to 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. For problems that can only be finally resolved by the first experience of truly moving into the past, it is a pity that in our world this incredible event will have to wait for an indefinite period of time.
This may sound completely 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 movement in time.
When Einstein proposed his theory of special relativity in 1905, the realization that every massive object in the universe must travel through time was just one of its astonishing consequences. We also learned that photons - or other massless particles - cannot experience time in their frame of reference at all: from the moment one is emitted to the moment it is absorbed, only massive observers (like us) can see the passage of time. From the position of the photon, everything is compressed into one point, and absorption and emission occur simultaneously in time, instantly.
But we have plenty. And anything that has mass is limited to always traveling less than the speed of light in a vacuum. Not only that, but no matter how fast you are moving relative to anything - whether you are accelerating or not, it doesn't matter - to you, light will always move at one constant speed: c, the speed of light in a vacuum. This powerful observation and awareness comes with a surprising consequence: if you watch a person moving relative to you, their clock will run slower for you.
Imagine a “light clock,” or a clock that works by reflecting light back and forth in an up and down direction between two mirrors. The faster a person moves relative to you, the greater the speed of light will be in the transverse (along) direction, and not in the up and down direction, which means the slower the clock will go.
Likewise, your watch will move slower relative to it; they will see time passing more slowly for you. When you get back together, one of you will be older and the other younger.
This is the nature of Einstein's "twin paradox". Short answer: Assuming you started out in one frame of reference (for example, at rest on Earth), and end up in the same frame of reference later, the traveler will age less because time will pass "slower" for him, and the one who stayed at home, will face the “normal” passage of time.
Therefore, if you want to accelerate through time, you will have to accelerate to near the speed of light, move at this pace for some time, and then return to your original position. We'll have to turn around a little. Do this and you can travel days, months, decades, epochs or billions of years into the future (depending on your equipment, of course).
You could witness the evolution and destruction of humanity; the end of the Earth and the Sun; dissociation of our galaxy; the heat death of the Universe itself. As long as you have enough power on your spaceship, you can see as far into the future as you want.
But getting back is a different story. Simple special relativity, or the relationship between space and time at a basic level, was enough to take us into the future. But if we want to go back in time, back in time, we need general relativity, or the relationship between spacetime 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, causing changes in the fabric itself.
For our Universe as we know it, spacetime is pretty boring: it's almost perfectly flat, practically uncurved, and doesn't loop back on itself in any way.
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 back on itself, you can move in one direction for a long, long time only to end up back where you started.
Well, there are solutions not only with closed spacelike curves, but also with closed timelike curves. A closed timelike curve implies 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 mathematics 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 near neutron stars and black holes: the most extreme examples of curvature in our Universe.
Our Universe may be rotating on a global scale, but the observed rotation limits are 100,000,000 times tighter than those allowed by the closed timelike curves we need. If you want to travel forward in time, you'll need a relativistic DeLorean.
But back? It might be better if you couldn't travel back in time to prevent your father from marrying your mother.
In general, to summarize, we can conclude that traveling back in time will always fascinate people at the level of idea, but most likely will remain in an 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 correcting our mistakes by going back in time will likely remain only in our fantasies.
Time travel is a favorite plot among science fiction writers and the subject of dreams of their fans. However, there are also those who claim that they actually arrived from the future - some fleeing from the special services, some in an attempt to warn humanity about the impending disaster. told the stories of the most odious guests from the future.
Soldier from 2036
In 2000, the minds of Americans were captured by the story of John Titor, who allegedly arrived from 2036. He registered on one of the resources and talked about his experience, demonstrating his time machine in between.
Titor admitted that he was a soldier who was sent back in time to deliver an IBM 5100 computer to scientists. Future programmers must fix bugs in it that will cause problems in 2038. However, Titor decided to temporarily stop in 2000 to communicate with his family, collect photographs lost in a future war and prevent the coming catastrophe - World War III.
Titor suggested learning basic firearms skills and keeping everything at the ready to “leave the house in ten minutes and never return.” He even gathered a team of volunteers ready to go with him to 2036. “I don’t set myself the goal of being believed,” Titor explained. - I’ll tell you a little secret: in the future no one will love you. We consider you a generation of lazy, self-centered and incredibly ignorant sheep. I think this should worry you more than me.”
Titor scheduled a global catastrophe for 2015. It was supposed to begin with a Russian nuclear strike on the United States, which collapsed during the 2005 civil war. The cause of the war was the conflict between Arabs and Jews. As a result, almost the entire world would have to lie in ruins: Russia and Europe would disappear from the face of the planet, and only a few military bases would remain from the United States.
Titor finally disappeared from the Internet in 2005, when one after another his predictions turned out to be false. In 2008, private investigators determined that neither John Titor nor his family existed. The only person to confirm Titor's existence was his lawyer, Larry Haber. Some fans still believe in the reality of Titor, and explain the unfulfilled predictions as a temporary paradox: since he spoke about them, they did not happen. The Habers were simply friends of the guest’s family from the future, with whom he was staying, and therefore, from their computer he accessed the Internet.
Nuclear attack on the Bitcoin rich
In 2003, the entertainment resource Weekly World News published a story about the arrest of an unusually successful economist. Andrew Carlssin allegedly made $350 million in two weeks on risky investments, investing just $800. Such an exceptional case could not fail to attract the attention of the police, who arrested the newly rich man. During interrogation, he did not reveal the fraudulent schemes, but admitted that he arrived from 2256. A source in the Securities and Exchange Commission told reporters about this.
During interrogation, Karlsin admitted that he got too carried away: he planned to invest in both successful and unsuccessful business projects, but “it was too difficult to resist the temptation,” so all of his 126 investments brought him instant profits. According to journalists, they could not find information about him until December 2002, as if Karlsin really did not exist before that.
For his release, he promised the government to tell the government where bin Laden was and to reveal the secret of the cure for AIDS, but he flatly refused to admit where the time machine was located and explain its structure, since he was very afraid that the unit would fall “into the wrong hands.” They refused to release him from prison until an unknown well-wisher paid his $1 million bail. Karlsin was released and was due to appear in court in April 2013, but disappeared on his way to the hearing.
The story was picked up by many world media: publications about Karlsin appeared in The New Yorker and The Scotsman. But most of all, the mysterious story of Andrew Carlsin surprised not newspaper readers, but employees of the FBI and the Securities and Exchange Commission. Journalists literally tortured them with requests to comment on the “time traveler.” The refusal of the intelligence services to comment on Karlsin’s case only emboldened conspiracy theorists, who were confident that the authorities were simply hiding the truth.
The entertainment resource also found its own prophet. In August 2013, a user under the nickname Luka_Magnotta wrote an appeal to Americans asking them to abandon Bitcoin. According to him, the use of cryptocurrency could lead to nuclear war, and he came from 2026 to warn humanity about this and force them to stop in time.
Luke said that in his time, the dollars familiar to people had already disappeared. After the value of Bitcoin reached a million dollars, humanity became disillusioned with other currencies and abandoned them: “Now all wealth exists only in two forms: bitcoins and land.” The population, according to him, is suffering from hunger, since all the money is concentrated in the Citadels - completely robotic fortified cities where the cryptocurrency rich live. But having money does not guarantee a comfortable life: at least every fourth Bitcoin owner is tortured to find out his password.
Politics is also not all right: most governments were destroyed, as people preferred to hide their income and stopped paying taxes. Russian hackers stole 60 percent of Africa's wealth in two days, after which a civil war began, which only the two richest countries could stop: Saudi Arabia and North Korea.
Luke claimed that he was planning a nuclear apocalypse to end the dominance of the Bitcoin rich. With the help of 20 nuclear submarines, he plans to cut all underwater Internet cables and launch missiles into densely populated areas. He concluded his story with a request to nip Bitcoin in the bud, because “he knows how it will all end.”
Magnotta’s prediction was remembered in November 2017, when Bitcoin reached the ten thousand dollar mark, as predicted by the “guest from the future.”
The future is unclear
The latest fad among self-proclaimed time travelers is the display of photographs from the future. Guests from another time prefer to do this on YouTube- ApexTV channel dedicated to paranormal phenomena. Just since the beginning of 2018, three time travelers have already shown their photographs: from the year 6000, 10,000 and 2118. All the photographs are similar in one thing: for some reason they are not clear.
An alien from the year 6000 explains the blurriness of the photo by saying that when traveling through time, they are distorted. He was lucky that the same thing did not happen to his insides: according to him, scientists have observed this too. He stated that he was born in the 20th century and participated in experiments in the 1990s, when researchers sent several people into the future, to different periods. He is forced to hide his name and face and change his voice to avoid being caught by the mysterious "they".
Frame: ApexTV / YouTube
According to the testimony of the “guest from the future,” this is how the world will be in a hundred years.
In 40 centuries, he said, everyone will be able to teleport and move through time. But there is no need to worry about time paradoxes: the travelers will be invisible and will not be able to interfere with the course of history (he does not explain how he was able to appear in the video). The world will be ruled by artificial intelligence, devoid of emotions, which will also reduce people in size so that they take up minimal space and consume fewer resources.
A man who visited the year 10,000 explained the blurriness of the image by “changes in the electromagnetic properties of the Earth,” due to which cameras began to work differently. According to him, while studying in America in 2008, he met a professor who invited him to fly to the future. Having doubted a little, he made up his mind. According to him, in the future, grass grows everywhere, and skyscrapers are so tall that their tops cannot be seen behind the clouds. All the cars fly in the sky, and aliens walk on the earth. People also learned to fly, and the time traveler suggested that nanotechnology helps them with this. There were soft robots and holograms everywhere. He really wanted to fly into the future again, but when he came to the professor the next day, he was not at home, and the time machine had disappeared without a trace.
Having moved from 1981 to 2118, and then to 2018, Alexander Smith, that the original photo from the future was confiscated from him by the government, and he was left with only a poor quality copy. According to him, he is wanted, so he lives in hiding and hides his real name. As for the future, the robots told him that “smart aliens will come to Earth in the middle of the 21st century.” Smith called global warming the most terrible danger to humans and asked residents of 2018 to think about the environment “at least for the sake of their children and grandchildren.”
The same channel has already published several interviews with a guest from 2030 under the pseudonym Noah. He even took a lie detector test, and he passed the test with honor: when asked directly whether he was a guest from the future, he answered “yes,” and the polygraph showed that it was true.
Noah looks about 20 years old, but claims that he is twice as old and has retained the appearance of a young man thanks to a “secret medicine.” According to him, scientists learned to travel in time 15 years ago, but they hide it from the public. And only in 2028 will the government allow anyone to travel to the past or future. Then humanity will go to Mars.
Frame: ApexTV / YouTube
According to him, by 2030, humanity will learn to treat many forms of cancer, robots will run the house, and almost everyone will have some kind of Google glasses with the same power as today's computers. Bitcoins will finally come into circulation, but traditional money will not disappear either. Due to global warming, the climate will become hotter in the United States and colder in Europe. He also said that the US President would be re-elected for a second term, but refused to provide evidence so as “not to cause a time paradox.”
There is probably no other topic in the world as exciting as time travel. For centuries, humanity has not only been interested in its meaning, etc., but also dreamed of a time machine. As a result, many famous science fiction writers have created incredibly interesting novels and time travel stories that have become real bestsellers.
But will we ever be able to create a time machine and travel to the future or the past? Is this possible in principle, or is all this a figment of our imagination and the dreams of scientists and science fiction writers? You won't believe it, but today we know how to build a time machine. So now it’s a matter of time - when we finally create a real time machine and go to the distant future.
In September 2015, cosmonaut Gennady Padalka returned to Earth from his last, sixth flight into space. On this day, he broke the world record for the time a person spent outside the earth's atmosphere. This astronaut was in space for a total of 879 days. That's 2.5 years in orbit! During this time, spent in Earth's orbit at enormous speed, cosmonaut Gennady Padalka became a real time traveler, once again testing Einstein's theory of general relativity in action.
When Padalka returned to Earth for the last time, he essentially found himself in the future. True, he ended up in the future for only 1/44 of a second. This is exactly how much faster time passed for him during all 879 days spent in Earth’s orbit, compared to time for all of us who were on Earth all this time. That is, literally, cosmonaut Gennady Padalka traveled through time during all his flights... into the future.
As a result, our Russian cosmonaut turned out to be a fraction of a second younger than all those who remained on Earth all this time. As you can see, such time travel turned out to be very simple and did not involve the use of charged plutonium on the DeLorean car, which became famous after the release of the Back to the Future film trilogy.
The secret of Gennady's time travel is high speed in Earth's orbit, where time flows faster. In fact, if our astronaut had the opportunity to move in space for all 879 days at the speed of light, when he landed on Earth, he would literally find himself in the future, since many years would have passed on Earth during this period.
That is, according to Einstein's theory of relativity, the higher your speed, the slower time flows for you. Accordingly, if you move at near-light speed, not only time will slow down for you, but also all physical processes in the body. And when you return to Earth, you will find that in your absence, time on Earth has moved forward much further, and your peers have noticeably aged.
As a result, since the discovery of Einstein, who determined that time in our Universe is relative (that is, time flows differently for each of us), humanity, in fact, has learned the main “ingredient” of traveling to the future. It's about speed. So if you want to literally travel to the future today, all you have to do is figure out how to get to near-light speed.
How can you travel through time scientifically?
Until the 20th century, it was believed that time is unchangeable and that for each of us it flows the same way, that is, that it is absolutely throughout the entire Universe. Accordingly, it was generally accepted that time travel was impossible. In the 1680s, Isaac Newton began to think about the nature of time, establishing that time flows regardless of external forces or your location. As a result, for many years the scientific community took as a basis all of Newton’s teachings about the movement of bodies and the passage of time.
But two centuries later, the scientific world expected a revolution in knowledge.
In 1905, the young scientist Albert Einstein developed the special theory of relativity, using his theory of general relativity as a basis. Einstein defined many new concepts related to time.
He established that time in the Universe is elastic and depends on speed, deceleration or acceleration depending on how fast an object or person is moving.
In 1971, an experiment was conducted that confirmed that time flows slower for us on Earth than for those moving above it at a faster speed. Moreover, the higher above the Earth we move at higher speeds, the faster time flows for us.
During this experiment, scientists sent four atomic clock instruments (cesium atomic clocks) into flight. This watch flew around the Earth. Next, the clock readings were compared with the same clocks that were on Earth at that moment. The experiment confirmed Einstein's theory that time flows faster for objects or people flying at speed above the Earth. Thus, as a result of comparing the clock readings, it turned out that the clocks that flew around the Earth went nanoseconds ahead compared to the clocks on Earth during the experiment.
By the way, your smartphones have one interesting technology that also confirms Einstein’s theory.
"WITHOUT EINSTEIN'S GENERAL THEORY OF RELATIVITY
OUR GPS/GLONASS SYSTEM WILL NOT WORK" .
We are talking about a satellite navigator (GPS, or GLONASS system) built into our phones, which, with the help of satellites in Earth orbit, receives a signal about the location of our smartphone.
After all, due to the fact that satellites in orbit move at high speed and are far from the Earth, it turns out that time moves faster for them than for our smartphone located on Earth. As a result, it is periodically necessary to synchronize the time of navigation equipment on Earth and the electronics used on the satellites. Otherwise, the satellites would incorrectly determine our location.
By the way, in addition to the fact that time is relative for each of us, Einstein calculated the exact speed of light, which is 300,000,000 meters per second. Einstein also established that this is the speed limit in the Universe. That is, according to Einstein's theory, nothing in the world can move faster than the speed of light.
The last idea of the great scientific thinker was that gravity also slows down time. Einstein discovered that time runs faster where gravity is weaker. For example, time moves slower on Earth, the Sun, and Jupiter than in outer space because these planets have a greater force of gravity (gravity), which affects the passage of time. Accordingly, the passage of time, as you see, is influenced not only by the speed of an object in space, but also by the force of gravity.
For example, time at the top of Everest passes faster than time at its base. If you take an atomic clock, one of which you place at the top of a mountain, and the other one you leave lying at the foot, then exactly 24 hours later, the clock at the top will advance by nanoseconds. That is, in essence, the watch on Mount Everest will travel to the future. True, for a negligibly short time. This is possible due to the fact that the force of gravity at the top of the mountain will be weaker than at the foot.
Time machine of the subatomic world - Already a reality
But why did the Russian cosmonaut end up in the future just 1/44 of a second? The thing is that it moved in Earth orbit for 879 days at a speed of 27,000 km/h. As you can see, compared to the speed of light, at which time stops, the speed in low-Earth orbit is negligibly small to literally send an astronaut hundreds of years into the future. In fact, the astronaut made a leap into the future for an insignificantly short time.
Now let's see what would happen if we created a spacecraft that could fly faster than the geostationary objects that orbit the Earth today. No, as you can see, we are not talking about a commercial airliner capable of flying at a speed of 1000 km/h, or a rocket flying to the ISS at a speed of 40,000 km/h. Let's think about an object that could accelerate to almost the speed of light, which is almost 300,000 km per second.
Do you think this is impossible in our nature? It turns out not. Of course, it is still very, very early to talk about any large object that can be accelerated to near-light speed. But we have learned to accelerate subatomic particles to the speed of light, literally sending them into the distant future. We are talking about the most high-tech project of scientists from many countries of the world in the entire history of mankind - the Large Hadron Collider, which can accelerate subatomic particles to almost the speed of light.
Believe it or not, this particle accelerator is capable of accelerating protons to 99.999999% of the speed of light. At this speed, relative time moves approximately 6,900 times slower compared to their stationary observers.
“THE LARGE HADRON COLLIDER...REGULARLY SENDS
SUBATOMIC PARTICLES INTO THE FUTURE.”
So, yes, we have learned to send atoms into the future. Moreover, scientists have been doing this quite successfully over the past decade. But sending a person into the future is another matter.
But the most interesting thing is that given the fact that scientists have learned to regularly move particles at the speed of light, it is conceptually possible to send a person to travel into the future. The fact is that human travel into the future is really possible and is not prohibited by any law of physics.
In fact, in order, for example, to send a person to 3018, today it is enough to put him in a spacecraft and accelerate the shuttle to 99.995 percent of the speed of light.
Let's assume that such a ship has been created. So, imagine boarding a supership like this that is sent to a planet 500 light-years away (such as the recently discovered Earth-like planet Kepler 186f, which is 500 light-years away). For those who do not know or do not remember, let us remind you that 500 light years is the distance that light will travel in 500 years of its journey. Knowing the speed of light, you can calculate the incredible distance at which the Kepler space telescope managed to discover a planet with characteristics similar to Earth.
So now let's imagine that you board a spacecraft that is flying to the planet Kepler 186f. Next, your ship accelerates to the speed of light and flies for 500 years, moving almost at the speed of light. Having approached the planet, your ship turns around and flies back to Earth for another 500 years at the same near-light speed.
As a result, the entire journey will take you 1000 years. When the ship returns to Earth, it will be already 3018.
But wait, how can you survive in this spaceship for 1000 years? Surely people can't live that long?
This is where Einstein's theory of relativity comes to the rescue. The thing is that when you move 500 years (by earthly standards) towards the distant relative of the Earth at the speed of light, time will flow slower for you than for all the inhabitants of the planet.
So, when moving at near-light speed, your clock on the ship and all your processes in the body will slow down. For example, your clock on a spaceship will tick at 1/100th the speed of a clock on Earth. That is, having traveled a distance of 500 light years and the same amount back, you will age only 10 years, whereas on Earth 1000 years will pass during your journey.
But this is just a theory and our fantasies. Yes, as you can see, time travel is theoretically possible. It's real. Unfortunately, there is always a huge gap between theory and reality. After all, today we cannot build a spaceship that could accelerate almost to the speed of light. So how do we overcome the challenges of creating a time machine?
Will humanity soon be able to build a ship that can travel at the speed of light?
As you can see, in order to travel to the future, we need a spaceship that can accelerate to near-light speed. True, this is very difficult to implement. After all, there are huge engineering obstacles. Firstly, today humanity is still far from being able to build such a spaceship capable of traveling at the speed of light.
The fact is that today the fastest spacecraft ever created by mankind is solar probe "Parker", which will soon be launched into space. This space probe will be able to accelerate to a maximum speed of 450,000 miles per hour (724,204.8 km/h). Yes, it will be the fastest object created by man throughout its history. But compared to the speed of light, this speed is negligible. For example, at this speed you could get from Philadelphia to Washington in just 1 second. But during this time the light will cover the same distance 8 times.
Now imagine how much energy is needed to accelerate a spaceship to the speed of light. What fuel, then, is best used to generate incredible energy that could accelerate the ship to near-light speed?
Some scientists and astrophysicists propose using highly efficient antimatter fuel (fuel based on antimatter) for such a spacecraft. By the way, many scientists around the world believe that such fuel could indeed be potentially invaluable in interstellar travel.
But beyond fuel, there is an even bigger problem for interstellar travel. We are talking about the safety of people who will travel at the speed of light. After all, such a spaceship will have to carry a sufficient amount of supplies for the crew members embarking on an interstellar journey (food, water, medicine, etc.). But to ensure long-term travel in space, the ship must be large enough. As a result, the larger the ship, the more energy it will need to accelerate to the speed of light.
In particular, when accelerating to the speed of light, it must be taken into account that the acceleration must be smooth, since otherwise the people on the spacecraft will receive too much overload during acceleration, which is life-threatening.
But then it would take too much time to accelerate the ship to near-light speed. After all, in fact, the ship can be slowly accelerated, adding a little speed so that the overload experienced by the ship’s crew for a long time does not exceed 1g (usually, when we are on Earth, we experience this overload).
Thus, it may take too long to reach the speed of light, which will significantly increase travel time. And this ultimately minimizes the possible travel time into the future.
For example, using our example of traveling a distance of 500 light years with smooth acceleration, as a result of which the g-force will not exceed 1g, our flight will take the clock on a spaceship not 10 years, but already 24 years. But nevertheless, if you move at near-light speed to a distance of 500 light years and back, you can still get to the year 3018.
Unfortunately, to create such an incredible space vehicle with such specifications, humanity will still need a lot of time, resources and, of course, a lot, a lot of money. But the same can be said about other large-scale, ambitious projects that seemed impossible just a few decades ago. We're talking about the gravitational wave detection project and the Hader Large Collider. Today these projects are already a reality and do not surprise anyone.
So who knows what awaits us in the coming decades. After all, it is quite possible that the next scientific megaproject will be the creation of a time machine (a spaceship capable of accelerating to the speed of light).
Is it possible to travel back in time?
But in the time machine we described, which may someday become a reality, travel to the future takes place in real time. That is, if you get into a spaceship today and accelerate to the speed of light, the time of your clock and the clocks of people on Earth will tick in reality. The only difference is that your clock will slow down while traveling.
As a result, the spaceship, which is a time machine, essentially throws you into the future in real time, but not back. That is, on such a spaceship you will not be able to go back in time. But is it even theoretically possible to time travel to the past?
Some scientists believe (not all, for example, Hawking proved that traveling into the past is impossible) that traveling into the past is also possible. But to do this, you need to find a place where you can bypass the laws of physics.
The most interesting thing is that there can be such places in the Universe.
For example, purely theoretically, traveling into the past is possible through a wormhole (wormhole in space-time), through which one can get into the past.
The problem is different - to find a similar place in space where there is a wormhole connecting a rift in space-time. Unfortunately, in most cases, such burrows disappear within nanoseconds after their appearance.
Meanwhile, according to Einstein's theory of relativity, such wormholes are real. The fact is that such wormholes can form as tunnels crossing through curved space-time. Theoretically, through such holes it is possible to send a beam of light to a certain point in space. Accordingly, theoretically, a beam of light can be sent into the past.
Fantastic? Not at all. Look at the sky at night and you will see the light of thousands of stars that reached your eyes only today, despite the fact that many stars ceased to exist billions of years ago. The thing is that these stars are located at a great distance from us, and also, given that our Universe is constantly expanding, it turns out that the light of many stars came to us from the past.
Thus, as you can see, theoretically sending someone into the future is much more realistic than sending someone into the past. Therefore, in the future, most likely, scientists will be willing to send someone into the future first, rather than into the past. Unfortunately, this will not happen in the near future. After all, for this, humanity will still need to come up with a superfuel capable of accelerating the ship to near-light speed.
However, as you can see, traveling to the future is real and possible. But this requires huge funding. According to many scientists, if today many states united and financed a project to create a spaceship capable of moving at the speed of light, then within 20 years such a ship would become a reality.
Well, for now, to enjoy the effect of a time machine, we can only review famous films about time travel, as well as re-read various popular science fiction books.
Moreover, many films actually show what space travel through time might look like. For example, watch the old original Planet of the Apes movie, where the astronauts thought they were on another planet similar to Earth, which was ruled by apes instead of people.
But in fact, the astronauts arrived on the same planet Earth in the future, where for some reason monkeys seized power on the planet. Essentially, in this film, the astronauts arrived in the future of planet Earth as their journey through space was accomplished at the speed of light. This movie accurately depicts Einstein's theory of special relativity and shows how man can travel into the future.
The idea that you can go into the past or the future has given 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 sake of the confusion that inevitably arises when trying to disrupt the flow of time. What tricks eventually form the basis of all chrono-operas and what plots can be assembled from these building blocks? Let's figure it out.
Wake me up when the future comes
The simplest task for a time traveler is to travel to the future. In such stories, you don’t even have to think about how exactly the time flow works: since the future does not affect our time, the plot will be almost no different from a flight to another planet or to a fairy-tale world. In a sense, we all already travel through time - at a speed of one second per second. The only question is how to increase the speed.
In the 18th-19th centuries, dreams were considered one of the fantastic phenomena. Lethargic sleep 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. This 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, writers of that time explained any fantastic assumptions. If the narrator himself admits that he has imagined strange worlds, what is the demand from him? Louis-Sébastien 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 travel to the future needs to be plausibly justified, doing this without contradicting science is also not difficult. The cryogenic freezing method made famous by Futurama could, in theory, work - which is why many transhumanists are now trying to preserve their bodies after death in the hope that future medical technologies will allow them to be revived. True, in essence this is just Van Winkle’s dream adapted to modern times, so it’s difficult 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 jungle of physics, traveling at the speed of light is better suited.
Einstein's theory of relativity allows time to be compressed and stretched at near-light speeds, which is used with pleasure in science fiction. The famous “twin paradox” says that if you rush through space for a long time at near-light speed, in a year or two of such flights a couple of centuries will pass on Earth.
Moreover: the mathematician Gödel proposed a solution for Einstein’s equations in which time loops can arise 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 using a “wormhole” to create a bridge into the past.
All the plot twists that the authors of chronoopers are now coming up with were already in Einstein and Gödel (filmed on an iPhone 5)
Is it possible to go back in time this way? Scientists strongly doubt this, but science fiction writers are not bothered by their doubts. Suffice it to say that only mere mortals are prohibited from exceeding 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. What about the speed of light - even sleep can work in the opposite direction! And Mark Twain got the Yankees on the head with a crowbar at the court of King Arthur.
Of course, it’s more interesting to fly into the past, precisely because it is inextricably linked with the present. If an 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 fight against predestination. Is it possible to change your own destiny if it is already known?
Cause or effect?
The answer to the question of predestination - like the concept of time travel itself - depends on the principle by which time is organized 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, 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 their imagination.
If the film genre 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 stated that time is a single and indivisible flow: between the past and the future there is, as it were, a thread along which one 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. Paradoxes arise because this concept (philosophers call it “B-theory”) states that the past, present and future are as real and unchangeable as the three dimensions we are familiar with. The future is still unknown - but sooner or later we will see the only version of events that must happen.
This fatalism gives rise to the most ironic stories about time travelers. When an alien from the future tries to correct 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 cause-and-effect loop simply arises 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 “In My Own Footsteps” (1941), where it turns out that the hero was carrying out a task received from himself.
The heroes of the dark series "Dark" from Netflix go back in time to investigate a crime, but are forced to commit actions that lead to this crime.
It can be worse: in more “flexible” worlds, a careless act by a traveler can lead to the “butterfly effect.” Intervention in the past rewrites the entire time flow 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 couldn't keep track of Marty's jumps - but he at least relied on the words of his comrade 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).
Split time
This concept not only removes controversy, but also captures the imagination. In such a world, everything is possible: every second it is divided into an infinite number of similar reflections, differing in a couple of little things. A time traveler doesn't actually change anything, but only jumps between different facets of the multiverse. This kind of plot is very popular in TV series: in almost any show there is an episode where the heroes 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!
Nowadays, in chrono-fiction, the model with parallel worlds is most often used (a still from Star Trek).
But the fun begins when the authors abandon the B-theory and decide that there is no fixed future. Maybe the unknown and uncertainty are the normal state of time? In such a picture of the world, specific events occur only in those segments where there are observers, and the remaining moments are just probability.
An excellent example of such “quantum time” was shown by Stephen King in “”. When Strelok unwittingly created a time paradox, he almost went crazy 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 that reminded him of past events, the memories of these points formed into one consistent version, but the gaps were as if in a fog.
The quantum approach has become popular recently, 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 each other. I had to fix everything urgently!
Take, for example, the film “Time Loop” (2012): as soon as the young incarnation of the hero performed some actions, the alien from the future immediately remembered them - and before that, fog reigned in his memory. Therefore, he tried not to interfere once again with his past - for example, he did not show his younger 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 companions 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 a probabilistic future pales in comparison to worlds where Time has its own will - or its guard is guarded by creatures that lie in wait for travelers. In such a universe, the laws can work as they please - and it’s good if you can come to an agreement with the guards! The most striking example is the langoliers, who after every midnight eat yesterday along with everyone who is unlucky enough to be there.
How does a time machine work?
Against the background of such a diversity of universes, the technology of time travel itself is a secondary issue. Time machines have not changed since the time of time: you can come up with a new operating principle, but this is unlikely to affect the plot, and from the outside the journey will look approximately the same.
Welles's time machine in the 1960 film adaptation. That's where steampunk is!
Most often, the principle of operation is not explained at all: a person climbs into a booth, admires the buzzing and special effects, and then gets out at a different time. This method can be called an instantaneous leap: the fabric of time seems to be pierced at one point. Often, for such a jump, you first need to accelerate - gain speed in ordinary space, and the technology will already translate this impulse into a jump in time. This is what the heroine of the anime “The Girl Who Leapt Through Time” and Doc Brown did in the famous DeLorean from the “Back to the Future” trilogy. Apparently, the fabric of time is one of those obstacles that can be attacked with a running start!
DeLorean DMC-12 is a rare time machine that deserves to be called a car (JMortonPhoto.com & OtoGodfrey.com)
But sometimes it happens the other way around: if we consider time to be 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 don’t 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 extreme cases, everything can be attributed to magic. This is exactly how it worked: each revolution of the magic clock corresponded to one hour, but the travelers did not move.
Such “static” travel was dealt with most harshly in the film “Detonator” (2004): there the time machine rewinded exactly one minute at a time. 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's remember 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 is what the hero “” took advantage of.
In earlier science fiction, a “time funnel” worked on a similar principle: a kind of subspace that can be entered on purpose (on Doctor Who’s TARDIS) or by accident, as happened to the destroyer crew in the film “The Philadelphia Experiment” (1984). Flight through the funnel is usually accompanied by dizzying special effects, and leaving the ship is not recommended, so as not to be lost in time forever. But in essence, this is still the same ordinary time machine, delivering passengers from one year to another.
For some reason, lightning always strikes inside temporary craters and sometimes credits fly
If the authors do not want to delve into the jungle of theories, the time anomaly can exist on its own, without any devices. It is enough to enter the wrong door, and now the hero is already in the distant past. Is it a tunnel, a puncture or magic - who can figure it out? The main question is how to get back!
What can't be done
However, usually science fiction still works according to rules, albeit fictitious ones, which is why restrictions are often invented for time travel. For example, one can follow modern physicists in declaring 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 a “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 manages to create a touching story about friendship and love (“Your Name”)
In reality, most likely, you won’t be able to cheat like that - all because of the same principle of causality, which doesn’t care about the type of particles. But in science fiction, the “informational” approach seems more plausible - and even original. It allows the hero, for example, to find himself in his own young body or to travel through other people’s minds, as happened with the hero of the series “Quantum Leap.” And in the anime Steins;Gate, at first they could only send SMS to the past - try changing the course of history with such restrictions! But plots only benefit from restrictions: the more complex the problem, the more interesting it is to watch how it is solved.
Microwave-phone hybrid 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 this is where the fun begins. Simple leaps into the past and even time paradoxes are just the tip of the iceberg of chrono-fiction. If time can be changed or even damaged, what else can be done with it?
Paradox on paradox
We love time travel for its confusion. Even a simple leap into the past gives rise to such twists as the “butterfly effect” and the “grandfather paradox,” depending on how time works. But this technique can be used to build much more complex combinations: for example, jump into the past not just once, but several times in a row. This creates a stable time loop, or “Groundhog Day.”
Do you experience deja vu?
“Didn’t you already ask me about this?”
You can cycle 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 cause-and-effect paradoxes: the hero receives a note, goes into the past, writes this note, sends it to himself... If time is rewritten each time or creates parallel worlds, the result is an ideal trap : a person experiences the same events over and over again, but any changes still end with a reset to the original position.
Most often, such stories 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 an undoubted advantage: they allow you, through endless attempts, to sooner or later achieve success in any endeavor. It’s not for nothing that Doctor Who, having fallen into such a trap, recalled the legend about a bird that, over many thousands of years, chipped away a stone rock, and his colleague managed with his “negotiations” to drive an extraterrestrial demon into a white heat! In this case, you can break the loop not with a heroic act or insight, but with ordinary perseverance, and along the way you can learn a couple of useful skills, as happened with the hero of Groundhog Day.
In Edge of Tomorrow, aliens use time loops as weapons to calculate the ideal battle tactics
Another way to build a more complex structure from ordinary jumps is to synchronize two periods of time. In the film "X-Men: Days of Future Past" and in "Time Scout", the time portal could only be opened to a fixed distance. Roughly speaking, at noon on Sunday you can move to noon on Saturday, and an hour later - only at one o'clock in the afternoon. With such a limitation, an element appears in a story about traveling into the past that, 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 misfortune happened to Desmond, who interacted too closely with a time anomaly. But back in the 1980s, the TV 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 certainly could not return “home.”
Spin time
The heroine of the game Life is Strange faces a difficult choice: undo all the changes she made to the fabric of time to save her friend, or destroy an entire city.
The second technique used to diversify time travel is changing speed. If you can skip a couple of years to find yourself in the past or future, why not, for example, put time on pause?
As Wells also showed in the story “The Newest Accelerator,” even slowing down time for everyone except yourself is a very powerful tool, and if you completely stop it, you can secretly sneak somewhere or win a duel - and completely unnoticed by the enemy. And in the web series “Worm,” one superhero could “freeze” objects in time. Using 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. You can see this for yourself in the shooter Quantum Break
The speed can also be changed to negative, and then you will get the countermotors 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 happened with the Doctor and River Song in the Doctor Who series: they jumped back and forth through eras, but their first (for the Doctor) meeting was River’s last, the second was the penultimate, and so on. To avoid paradoxes, the heroine had to be careful not to accidentally spoil the Doctor's future. Then, however, the order of their meetings turned into complete leapfrog, but the heroes of Doctor Who are not used to this!
Worlds with “static” time give rise not only to contrarians: often in science fiction there appear creatures 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 "" due to such an inhuman perception of time, moved away from people and fell into fatalism. Abraxas from The Endless Journey regularly got confused with his grammar, trying to understand which event has already happened and which will happen tomorrow. And the aliens from Ted Chan’s story “The Story of Your Life” developed a special language: everyone who learned it also began to simultaneously see the past, present and future.
The film "Arrival", based on "The Story of Your Life", begins with flashbacks... Or does it?
However, if the countermoths or Trafalmadorians really travel in time, then with the abilities of Quicksilver or Flash everything is not so obvious. After all, in fact, they are the ones accelerating relative to everyone else - can we really 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. You can speed up the world and slow down the observer - this is the same thing, the only question is what to take as the starting point. And biologists will say that there is no science fiction here, because time is a subjective concept. An ordinary fly also sees the world “in slow-mo” - that’s how quickly its brain processes signals. But you don’t have to limit yourself to the fly or the Flash, because in some chronoopers there are parallel worlds. Who's stopping you from letting time pass through them at different speeds - or even in different directions?
A well-known example of such a technique is “The Chronicles of Narnia,” where formally there is no time travel. But time in Narnia flows much faster than on Earth, so the same heroes find themselves in different eras - and observe the history of a fairy-tale country from its creation to its fall. But in the comic Homestuck, which, perhaps, can be called the most confusing story about time travel and parallel worlds, two worlds were launched in different directions - and when contacts between these universes arose the same confusion that the Doctor had with River Song.
If dials haven't been invented yet, hourglasses will do too (Prince of Persia)
Kill time
Based on any of these techniques, you can write a story that would make even Wells's 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 leap into the past, a traveler can inadvertently kill his grandfather and disappear from reality - or even become his own father. Perhaps the best mockery of the “paradox of causation” was in the story “All of You Zombies,” where the hero turns out to be both his own mother and father.
The story “All You Zombies” was adapted into the film Time Patrol (2014). Almost all of his characters are the same person
Of course, paradoxes must be resolved somehow, which is why in worlds with linear time it often restores itself, according to the will of fate. For example, almost all novice travelers first decide to kill Hitler. 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 assassination attempt in "Time Scouts" will fail: either the gun will jam, or something else will happen.
And in worlds where fatalism is not held in high esteem, you have to monitor the preservation of the past on your own: for such cases, they create a special “time police” that catches travelers before they do anything bad. In the film "Looper" the mafia took on the role of such police: the past for them is too valuable a resource to allow someone to spoil it.
If there is neither fate nor chronopolice, travelers risk simply breaking time. At best, it will turn out like in Jasper Fforde’s “Thursday Nonetot” series, where the time police went so far as to accidentally cancel the very invention of time travel. At worst, the fabric of reality will collapse.
As Doctor Who has shown more than once, time is a fragile thing: one explosion can cause cracks in the universe across all eras, and an attempt to rewrite a “fixed point” can cause both the past and the future to collapse. In Homestuck, after a similar incident, the world had to be recreated anew, and all eras were mixed together, which is why the events of the books are now impossible to combine 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 kind of 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 drawing for the most confusing works of chronology
Sounds crazy? But this kind of madness is why we love time travel - it pushes the boundaries of logic. Once upon a time, an ordinary leap into the past must have driven an unaccustomed reader crazy. Nowadays, chrono-fiction truly shines at long distances, when authors have room to expand, 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 structure collapses under its own weight: either there are too many time jumps for it to make sense to keep track of them, or the authors change the rules of the universe on the fly. How many times has Skynet rewritten the past? And who can now say by what rules time works in Doctor Who?
But 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 captivates BioShock Infinite, Tsubasa: Reservoir Chronicle or Homestuck. The more complex and intricate the plot, the stronger the impression left on those who reached the end and managed to look at the entire canvas at once.
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Time travel, parallel worlds and the rewriting of reality are inextricably linked, so now almost no work of science fiction can do without them - be it a fantasy like Game of Thrones or a sci-fi exploration of the latest theories of physics, as in Interstellar. Few plots give the same scope for imagination - after all, in a story where any event can be undone or repeated several times, everything is possible. However, 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 such stories, as in all genres, rest on the characters: on the one who has yet to come from ancient Greek tragedies on the theme of 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, the story will still develop only in one direction - in the one that is most interesting to viewers and readers.
