Time travel
Time is referred to as a movement in the time, which is different from the ordinary time and a directed movement through time. By means of the theory of relativity scenarios can be described, in which take place through the effect of time dilation "travel" into the future. Whether, however, also travel into the past, as they are described in many science fiction stories, even in principle, physically, logically or metaphysically would be possible, it is often doubted and there is no empirical evidence for it.
Physical possibility of time travel
The theory of relativity, Albert Einstein offers various possibilities for time travel:
Traveling into the future
When leaving a nearly the speed of light spaceship ( it rich may also relativistic speeds by 10% the speed of light ) the earth and returns after a period back, so on earth, a longer period elapsed as on board the spaceship. The reason for this is the time dilation that occurs after the special theory of relativity by Albert Einstein at such high speeds. The exact sequence of such a journey is described in twin paradox.
For sufficiently large travel speed and acceleration an arbitrarily distant future on Earth would this in principle in arbitrarily short duration achievable. For a man reasonable acceleration, however, a time lag of years requires a travel time from the perspective of the spaceship crew of over one year ( approximately 347 days each for acceleration and deceleration of 9.81 m / s ²).
According to the general theory of relativity, the passage of time is also dependent on the gravitational and acceleration conditions to which a system is subject. Thus, the time on a high mountain passes slightly faster than at sea level. This phenomenon could be described as time travel into the future, interpret, whereby not only faster, but also a braked travel is possible.
In a neutron star the gravitational time dilation can be substantial. So could a hypothetical residents of a neutron star do a time-consuming task in an orbit around the star, in order to keep an appointment at the stellar surface more easily.
Travel into the past
According to the current state of the science time travel is in principle not possible in the past. Existing theories, according to which such travel is possible, are speculative and controversial. Undeniably, in any case, that the practical implementation of such theories is impossible in the foreseeable future.
1949 Kurt Gödel discovered that a solution of general relativity, in which the universe rotates, the return of an object in its own past allows. Such a universe is called the Gödel universe (R- universe ).
Even if it can be proven that our universe is not rotating, shows the R- Universe, that the Einstein field equations admit a universe with closed time-like curves. Consequently, the uniform passage of time is not one of the necessary a priori properties of a universe that satisfies the equations.
According to the general theory of relativity, it is conceivable that two different regions of space-time could be connected to each other via so-called wormholes. If the two outputs of such a wormhole would combine two areas of different time, a time travel would be possible in the past. However, calculations show that wormholes are not normally stable and collapse so quickly that a passage is not possible. Had a hypothetical matter with negative energy density, the so-called exotic matter, one could thus stabilize a wormhole. The required amount of exotic matter is but according to current knowledge in the entire universe is not available.
Possibly a journey into his past would be possible on a specific trajectory in the vicinity of a sufficiently rapidly rotating black hole. However, it is believed that there is no such a rapidly rotating black hole.
A time travel into the past would be possible also in the vicinity of two cosmic strings that sufficiently quickly fly past each other. The existence of such strings is controversial.
After a very controversial interpretation of a time-reversal was achieved by Superluminares tunnels for particles or photons, that is, from the experimental arrangement - the "tunnel " - the particles seemed to come out before they were blasted into it. However, in these experiments a very controversial definition of the signal time point was used.
Should be able to travel into the past, then the question would arise how the paradoxes are avoided, which may arise in this connection from the breach of causality, such as the grandfather paradox. As a possible answer would especially Everettsche Much worlds theory in question. After that would be the past, in which one travels, settled in a parallel world. The original course of events and by an intervention in the past modified sequence would play both. In particular, it would be impossible for the traveler to return to his original version of the present, but in a parallel world that would be almost identical to this one.
Occasionally, when by traveling into the past is mentioned, hypothetical faster than light particles, called tachyons, brought into play. Could move to B, a particle with superluminal velocity of A, as always, an observer could find for would take place, the movement from B to A. Since the observers judge the temporal order of events A and B are different, moving for all involved the tachyon from the past to the future. From a hypothetical superluminal motion derive the possibility of a trip to the past, is not possible.
Time travel in literature and film
Time travel is an old dream of mankind and are therefore often discussed in science fiction literature and science-fiction film. Mostly there occurs a journey through a time machine (as in Back to the Future ), rarely by other methods, for example in the Highland Saga by Diana Gabaldon by passage through a stone circle or else by magic, as in the series Charmed - Magical Witches. However, in contrast with the series back to the past, where Dr. Samuel "Sam" Beckett (played by Scott Bakula ), a Nobel Prize-winning quantum physicist and inventor of the " quantum accelerator ", as a result of a failed self- test uncontrollably within his own lifetime by the time travels while temporarily assumes the identity of different people this time and exchanged the body with them. In the science fiction television series Star Trek time travel is a recurring, popular and both methodological and narrative varied topic.
In particular, the problems associated with the causality in time travel into the past are making a popular subject of science fiction literature, as in the novels of Dean Koontz or guardian angel story by Stephen Fry.
Here, the butterfly effect of chaos theory is often discussed. This means that even the smallest changes in the past can have extreme effects on the further development ( see, eg, butterfly effect, or Back to the Future ), which terminate in certain circumstances with the non-existence of time travelers. This problem is solved often with the surprising point that the journey from the beginning was to part of the known past and by the time travel a circle is closed. This acceptance is again denied, change through time travel "time line " or even destroy.
Another recurring idea is the time loop in which the protagonist is stuck. This is, for example, in the movies 12:01, Retro Active or And Groundhog Day and in Supernatural Season 3 Episode 11 (" Groundhog day ...") the case.
Erdoğan Ercivan claims in his books that the Egyptian underworld Imydwat book contains an exact itinerary of the deceased pharaoh to the double star Sirius, which is 8.6 light years away from Earth. Among other things, the gods of the Egyptians shall have a wormhole used southwest of Orion, which they called Wamemti.
Michael Crichton used in his book timeline the proposition that different times are just different worlds in the many-worlds interpretation. Therefore, a time travel takes place through the journey into a parallel world.
A similar interpretation can be found in the novels The last day of the Creation and the Cusanus game by Wolfgang Jeschke, where people travel to the past, thus creating parallel, divergent futures that make traveling all other people in the past.
The problem of grammatical tense formation for time travelers is discussed The Restaurant at the End of the Universe by Douglas Adams in his novel.
The description of a journey into the future gives the author the opportunity to undesirable developments and social criticism pointed represent. Of these collaborations include HG Wells in 1895 in his book The Time Machine use.
Closely related is the theme of parallel worlds, such as in the film the life Is not it beautiful? or in the series Sliders.
In the novel by Audrey Niffenegger The Time Traveler's Wife ends must be the main character (Henry) travel through time because of a genetic defect.
In the novel, The Jesus Video by Andreas Eschbach travels an involuntary time traveler to the scene of the last weeks of life of Jesus Christ and also ensures involuntarily by a handed down to the present day video for dramas whether the actual events and reports in the Bible about the life of Jesus.
In the series the way to Atlantis, according to Joan of Koczian and Ota Hofman, a journey through time with tasks is compared with the dreams.
In the Stargate franchise (SG -1, SGA & SGU) is often given in conjunction with the Stargate wormholes that lead by just taking place at this time solar flares as a means for time travel. It travels in both directions, into the future and into the past possible.
In the gem trilogy 's heart is through all time by Kerstin Gier is about a girl who jumps erratically through the ages.
In Fabian Lenk's children's book series The travel time detectives, three teenagers and a magic cat using a Tempus on through time and resolve cases in history.
In the film Star Trek (2009) traveling Romulan Nero and the old Spock using a wormhole 154 years into the past.
In the first season of the series Youth Hotel 13 travel three best friends in a ball of metal into the year 1927. The smallest change in the past can have great consequences in the present. Also in the movie series for Hotel 13 - Rock'n'Roll High School meet the three friends on a girl from the past. You must bring the girl back back in her presence, the 1950s, or the three friends would never get to know. In the second season, the three friends have an adventure in the future.