Time travel fascinates the imagination of many. We see time travel in many films, such as the Terminator and Back to the Future franchises. There are even those of us who consider certain people to be time travelers.
From today there is no proof that there are time travelers among us. All the travelers we know come from the screen. What we have today are theories about how time travel is possible and how it would work.
10 Einstein's General Theory of Relativity
The first theory on this list is Einstein's General Theory of Relativity.  This theory helped physicists to theorize how time travel might exist. The General Theory of Relativity discusses how objects in space create a distortion of the space-time continuum that we know as gravitation. Well, gravity does not lead to time travel, but it has produced phenomena (both known and theorized) that can lead to time travel.
Physicists have used this theory to explain wormholes and black holes. We will continue to discuss these two phenomena in this list. These two "holes" are considered as journeys to time travel. Without Einstein's theory of general relativity, physicists would not have been able to connect wormholes and black holes with possible time travels.
The second theory we will consider is one of many but no real proof. Wormholes have not been detected. No wormhole was ever found in space, but scientists still think they might be there. Although no wormholes have ever been identified, physicists believe they could exist when they consider Einstein's theory of relativity.  If wormholes do exist, they can be the answer to travel through time.
It is theorized that wormholes are abbreviations of space and time. This could mean that someone who has entered a wormhole could travel to another part of the universe or through time. Another problem with this theory is that if wormholes were present they would be so small that a person could not even fit in them, then that would make it impossible for a spacecraft to fly in one. Although there is no evidence that wormholes exist, this theory is one of the reasons why time travel might someday be possible.
8 Black Holes
Black holes are areas of the Universe with such heavy gravity that not even light escapes. This could have been caused by a supernova or possibly the collision of stars. Physicists believe that everything that goes into a black hole would never escape. Their gravity is so strong that even time is slowed down.  For time travel working with a black hole, you would have to orbit and not be sucked into the event horizon.
Since the Gravity of the Black The hole is so large that the time it takes for a spaceship to circle it would be very different from time on Earth. Years would fly home. This means that you are considerably younger than someone as old as you when you returned to Earth. Obviously, this has never been tried, but in the future, it could be a time journey for someone.
7 Cosmic Strings
Cosmic strings are narrow tubes of energy that pass through the universe. They are considered remnants of the early cosmos and are believed to contain a huge amount of mass. Therefore, they could deform space-time around them. Scientists also believe that these strings can be found either in loops or in straight, infinite lines.  If these strings are actually in lines around the universe, they might be able to generate time travel.
Scientists believe that if two cosmic strands ran parallel to each other and were close enough together, they could bend space-time. As this would be such a big turn, time travel could be possible. This theory would work much like the black hole theory of time travel.
6 Time Machines
We have seen time machines in countless films, and as children, some of us have even imagined that one day we could go into a time machine and travel all over the past or the future. Although time machines do not yet exist, theories about how a time machine travels through time are fascinating.
Scientists believe that negative energy density matter is needed to run a time machine. Such a thing would do strange things like moving in the opposite direction of regular matter when it's pushed. The problem is that if there were this matter, there would not be enough of it for a time machine.  There are more theories about how a time machine might work, but this one is the most prominent.  Travel faster than the speed of light
This theory comes from Superman himself, somehow. In Superman (1978) Superman turns back time by flying so fast that the Earth's rotation reverses. Of course this is ridiculous, and so some have published the explanation that Superman actually went back in time by traveling faster than the speed of light. How would that work? The speed of light is, as far as we know, the fastest that is possible. If moving slightly faster than the speed of light, the time the object reaches its target would be negative. Thus, theoretically, it would travel back in time. 
The big mistake in this theory is that nothing can go faster than the speed of light. In addition, scientists who have explored this concept have found that a number of factors must be met for this to work. Traveling faster than the speed of light would not fulfill all the factors necessary for time travel.
4 Tipler cylinder
This theory would be almost impossible to try, but it gives a very interesting idea of how much mass we would need for time travel. For this theory, we would have to find a piece of matter that is ten times the mass of the sun. It would then have to be rolled into a very dense, long and thin cylinder. In our universe we can find objects that are ten times the mass of the Sun, but it would be quite difficult to roll one into a long cylinder.
As if this first part were not hard enough, the cylinder would have to rotate at a few billion revolutions per minute. If all of these factors are correct, a spaceship following a perfectly precise spiral route around the cylinder could go through a closed time curve. This would then allow the spaceship to travel through time. 
The film Interstellar showed time travel in a variety of ways. The characters traveled through a wormhole and circled a black hole. This film also showed how higher time dimensions can to some extent cause time travel. This would be possible with a Tesseract, the four-dimensional analogue to a cube.  Tesseracts can be projected into two- and three-dimensional shapes.
For a journey through time to work, a mosaic stone would have to have more than three dimensions. When a ship enters the Tesseract, it would represent time as a dimension of space. This would create different time levels to which the ship can then travel, as seen in Interstellar . That's a completely invented theory, but we never know what the future might bring.
2 Grandfather Paradox
This theory is less about time travel than about removing oneself from existence. If someone could travel back in time, it could hurt their future very much. Take, for example, the grandfather paradox. Suppose you invent and build a time machine. Then you travel back in time and meet your grandfather before he has children. Then you kill him for unspecified reasons. Well, you would never have been born, and the time machine that brought you back to the good old days was never built. 
In many shows and films, we have seen that evil travels back in time to kill someone before he could do good in the future. This happens in the movie The Terminator . As fascinating as time travel is, it would have many effects if it were possible.
1 Have we seen time travelers yet?
There are many theories about people who can be time travelers. There are many bizarre stories that have convinced some people that others have already mastered the art of time travel, and they live among us. One of the most famous cases of this was in one of Charlie Chaplin's films The Circus . People have claimed that you can see a passerby speaking on a cell phone. This movie came out in 1928 before cell phones were invented. The movie is in black and white, and the picture is a bit blurry, but it's easy to see why people think it's actually a cell phone. 
Another recent conspiracy theory is that the creator of The Simpsons is a time traveler. There were many episodes in which the future was accurately predicted. The Simpsons have successfully predicted events as Donald Trump becomes president and the year the Chicago Cubs would win the World Series. Predictions such as these have given some viewers the suspicion that there may be time travel.
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