Time travel is the concept of moving forward and backward to different points in time, much as we do through space. It also includes traveling sideways in time between parallel realities or universes. Wikiquote has a collection of quotations related to: Space Attempting to understand the nature of space has always been a prime occupation for philosophers and scientists. ... A multiverse (or meta-universe) is the hypothetical set of multiple possible universes, including the observable universe, which comprise the whole of physical reality. ...

Unsolved problems in physics: Is time travel theoretically and practically possible? Will such travel invoke paradoxes, such as often used in fiction?

Humans are in fact always travelling in time — in a linear fashion, from the present to the immediate future, inexorably, until death. Some theories, most notably special and general relativity, suggest that suitable geometries of spacetime, or certain types of motion in space, may allow time travel into the past and future if these geometries or motions are possible. It has been confirmed that the effects of relativistic and gravitational time dilation can cause a traveller who starts at and returns to a point of origin that remains stationary, to arrive at a time farther in the future in that reference frame than their subjective elapsed time would indicate (a constrained form of time travel into the future). Image File history File links Question_dropshade. ... This is an incomplete list of some of the unsolved problems in physics. ... Listen to this article · (info) This audio file was created from the revision dated 2005-07-07, and does not reflect subsequent edits to the article. ... This article needs to be cleaned up to conform to a higher standard of quality. ... A simple introduction to this subject is provided in Special relativity for beginners Special relativity (SR) or the special theory of relativity is the physical theory published in 1905 by Albert Einstein in his article On the Electrodynamics of Moving Bodies. SR theory is based on the previous works of... General relativity (GR) is the geometrical theory of gravitation published by Albert Einstein in 1915. ... World line of the orbit of the Earth depicted in two spatial dimensions X and Y (the plane of the Earth orbit) and a time dimension, usually put as the vertical axis. ... Wikiquote has a collection of quotations related to: Space Attempting to understand the nature of space has always been a prime occupation for philosophers and scientists. ... This article is in need of attention from an expert on the subject. ...

In physics, the concept of time travel has been often used to examine the consequences of physical theories such as special relativity, general relativity and quantum mechanics. There is no experimental evidence of time travel, and it is not even well understood whether (let alone how) the current physical theories permit any kind of time travel. However, theories do exist about the possibility of folding time to hop from one point to another. In the fictional movie Event Horizon, Dr Weir (played by Sam Neill) explained to his crew members that time travel is accomplished by 'bending' space such that two different points in space of the same time match together. Once done, they would fly their spaceship through it and then 'straighten' the space again. In this case, time travel in zero distance travelled in an instant is achieved. Since antiquity, people have tried to understand the behavior of matter: why unsupported objects drop to the ground, why different materials have different properties, and so forth. ... A simple introduction to this subject is provided in Special relativity for beginners Special relativity (SR) or the special theory of relativity is the physical theory published in 1905 by Albert Einstein in his article On the Electrodynamics of Moving Bodies. SR theory is based on the previous works of... General relativity (GR) is the geometrical theory of gravitation published by Albert Einstein in 1915. ... Fig. ... Video Release: December 15, 1998 This article is on the film Event Horizon. ... Sam Neill Sam Neill OBE (born September 14, 1947) is a New Zealand film and television actor, and owner of the Two Paddocks winery in Central Otago. ...

In science fiction, a popular recurring plot device is to set a character in a particular time not their own, and explore the character's interaction with the people and technology of that time—as a kind of culture shock (as in Mark Twain's A Connecticut Yankee In King Arthur's Court). Another common theme is the effects on the present or future of changing events in the past (as in A Sound Of Thunder), which forms a genre known as alternate histories. Science fiction is a form of speculative fiction principally dealing with the impact of imagined science and technology, or both, upon society and persons as individuals. ... A plot device is a person or an object introduced to a story to affect or advance the plot. ... A watch Attempting to understand Time has long been a prime occupation for philosophers, scientists and artists. ... Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), better known by his pen name Mark Twain, was a famous and popular American humorist, novelist, writer and lecturer. ... A Sound of Thunder is a science fiction short story by Ray Bradbury, first published in Colliers magazine in 1952. ... Alternative history or alternate history can be: A history told from an alternative viewpoint, rather than from the view of imperialist, conqueror, or explorer. ...

Physics

Albert Einstein's special theory of relativity (and, by extension, the general theory) very explicitly permits a kind of time dilation that would ordinarily be called time travel. The theory holds that, relative to a stationary observer, time appears to pass more slowly for faster-moving bodies: for example, a moving clock will appear to run slow; as a clock approaches the speed of light its hands will appear to nearly stop moving. The effects of this sort of time dilation are discussed in the popular "twin paradox" which asks the question, "If two twins are moving relative to each other, they will each appear to the other to have aged more slowly. But when they reunite, how can each twin be younger than the other?" Albert Einstein photographed by Oren J. Turner in 1947. ... A simple introduction to this subject is provided in Special relativity for beginners Special relativity (SR) or the special theory of relativity is the physical theory published in 1905 by Albert Einstein in his article On the Electrodynamics of Moving Bodies. SR theory is based on the previous works of... General relativity (GR) is the geometrical theory of gravitation published by Albert Einstein in 1915. ... This article is in need of attention from an expert on the subject. ... The twin paradox, sometimes called the clock paradox, stems from Paul Langevins 1911 thought experiment in special relativity: one of two twin brothers, undertakes a long space journey with a high-speed rocket at almost the speed of light, while the other twin remains on Earth. ...

A second, similar type of time travel is permitted by general relativity, where a distant observer sees time passing more slowly for a clock at the bottom of a deep gravity well, and a clock of an object lowered into a deep gravity well and pulled back up will indicate that less time has passed than the distant observer's clock. However, these effects allow "time travel" only toward the future: never backward. This is not typical of the "time travel" featured in science fiction, and there is little doubt surrounding its existence. "Time travel" will hereafter refer to travel with some degree of freedom into the past or future. General relativity (GR) is the geometrical theory of gravitation published by Albert Einstein in 1915. ... A gravity well is the scientific/science fictional term for the distortion in space-time caused by a massive body such as a planet. ...

Many in the scientific community believe that time travel is highly unlikely. This belief is largely due to Occam's Razor. Any theory which would allow time travel would require that issues of causality be resolved. What happens if you try to go back in time and kill your grandfather?—see grandfather paradox. Also, in the absence of any experimental evidence that time travel exists, it is theoretically simpler to assume that it does not happen. Indeed, Stephen Hawking once suggested that the absence of tourists from the future constitutes a strong argument against the existence of time travel—a variant of the Fermi paradox, with time travellers instead of alien visitors. However, assuming that time travel cannot happen is also interesting to physicists because it opens up the question of why and what physical laws exist to prevent time travel from occurring. Occams Razor (also spelled Ockhams Razor), is a principle attributed to the 14th-century English logician and Franciscan friar, William of Ockham. ... The philosophical concept of causality or causation refers to the set of all particular causal or cause-and-effect relations. ... The grandfather paradox is a paradox of time travel, supposedly first conceived by the science fiction writer René Barjavel in his book Future times three (Le voyageur imprudent, 1943). ... Stephen Hawking in 2005 Professor Stephen William Hawking, D.Phil. ... A graphical representation of the Arecibo message, Humanitys first attempt to communicate our existence to alien civilizations The Fermi Paradox is a physical paradox that was brought to light by a simple question posed by the physicist Enrico Fermi when speculating about the existence of technologically advanced civilizations within...

The equivalence of time travel and faster-than-light travel

If one were able to move information or matter from one point to another faster than light, then according to special relativity, there would be an observer who sees this transfer as allowing information or matter to travel into the past. Further, faster than light travel along suitable paths would correspond to travel backward in time as seen by all observers. This results simply from the geometry of spacetime and the role of the speed of light in that geometry.

Special spacetime geometries

The general theory of relativity extends the special theory to cover gravity, describing it in terms of curvature in spacetime caused by mass-energy and the flow of momentum. General relativity describes the universe under a system of "field equations," and there exist solutions to these equations that permit what are called "closed time-like curves," and hence time travel into the past. The first and most famous of these was proposed by Kurt Gödel, but all known current examples require the universe to have physical characteristics that it does not appear to have. Whether general relativity forbids closed time-like curves for all realistic conditions is unknown. Most physicists believe that it does, largely because assuming some principle against time travel prevents paradoxical situations from occurring. General relativity (GR) or general relativity theory (GRT) is the theory of gravitation published by Albert Einstein in 1915. ... A simple introduction to this subject is provided in Special relativity for beginners Special relativity (SR) or the special theory of relativity is the physical theory published in 1905 by Albert Einstein in his article On the Electrodynamics of Moving Bodies. SR theory is based on the previous works of... From the point of view of general relativity, a closed timelike curve (CTC) is a closed worldline. ... Kurt Gödel Kurt Gödel [kurt gøːdl], (April 28, 1906 – January 14, 1978) was a logician, mathematician, and philosopher of mathematics. ...

Using wormholes

A proposed time-travel machine using a wormhole would (hypothetically) work something like this: A wormhole is created somehow. One end of the wormhole is accelerated to nearly the speed of light, perhaps with an advanced spaceship, and then brought back to the point of origin. Due to time dilation, the accelerated end of the wormhole has now experienced less subjective passage of time than the stationary end. An object that goes into the stationary end would come out of the other end in the past relative to the time when it enters. One significant limitation of such a time machine is that it is only possible to go as far back in time as the initial creation of the machine; in essence, it is more of a path through time than it is a device that itself moves through time, and it would not allow the technology itself to be moved backwards in time. This could provide an alternative explanation for Hawking's observation: a time machine will be built someday, but has not yet been built, so the tourists from the future cannot reach this far back in time. 2D analogy to a wormhole. ... This article is in need of attention from an expert on the subject. ...

Creating a wormhole of a size useful for macroscopic spacecraft, keeping it stable, and moving one end of it around would require significant energy, many orders of magnitude more than the Sun can produce in its lifetime. Construction of a wormhole would also require the existence of a substance known as "exotic matter", which, while not known to be impossible, is also not known to exist in forms useful for wormhole construction (but see for example the Casimir effect). Therefore it is unlikely such a device will ever be constructed, even with highly advanced technology. On the other hand, microscopic wormholes could still be useful for sending information back in time. The Sun (or Sol) is the star at the center of our Solar system. ... Exotic matter is a hypothetical concept of particle physics. ... In 1948 Dutch physicist Hendrik B. G. Casimir of Philips Research Labs predicted that two uncharged parallel metal plates will be subject to a force pressing them together. ...

Matt Visser argued in 1993 that the two mouths of a wormhole with such an induced clock difference could not be brought together without inducing quantum field and gravitational effects that would either make the wormhole collapse or the two mouths repel each other. [1] Because of this, the two mouths could not be brought close enough for causality violation to take place. However, in a 1997 paper, Visser hypothesised that a complex "Roman ring" (named after Tom Roman) configuration of an N number of wormholes arranged in a symmetric polygon could still act as a time machine, although he concludes that this is more likely than not a flaw in classical quantum gravity theory rather than proof that causality violation is possible. [2] 1993 (MCMXCIII) is a common year starting on Friday of the Gregorian calendar and marked the Beginning of the International Decade to Combat Racism and Racial Discrimination (1993-2003). ... The philosophical concept of causality or causation refers to the set of all particular causal or cause-and-effect relations. ... 1997 (MCMXCVII) is a common year starting on Wednesday of the Gregorian calendar. ... A Roman ring, in theoretical physics, is a type of wormhole where the time difference across its mouths is such that it may not allow a closed timelike curve (CTC), or closed-time loop. If these wormholes and their mouths are arranged in a suitable configuration, a closed time loop...

Another approach — attributed to Frank Tipler, but invented independently by Willem Jacob van Stockum [3] in 1936 and Kornel Lanczos [4] in 1924 — involves a spinning cylinder. If a cylinder is long, and dense, and spins fast enough about its long axis, then a spaceship flying around the cylinder on a spiral path could travel back in time (or forward, depending on the direction of its spiral). However, the density and speed required is so great that ordinary matter is not strong enough to construct it. A similar device might be built from a cosmic string, but none are known to exist, and it does not seem to be possible to create a new cosmic string. Frank J. Tipler is a professor of mathematical physics at Tulane University, New Orleans, physicist, theologian and cornucopian philosopher. ... Willem Jacob van Stockum (November 20, 1910-June 10, 1944) was a physicist who made an important contribution to the early development of general relativity. ... 1936 (MCMXXXVI) was a leap year starting on Wednesday (link will take you to calendar). ... 1924 (MCMXXIV) was a leap year starting on Tuesday (link will take you to calendar). ... This article is in need of attention from an expert on the subject. ... A cosmic string is a hypothetical 1-dimensional topological defect in the fabric of spacetime. ...

Physicist Robert Forward noted that a naïve application of general relativity to quantum mechanics suggests another way to build a time machine. A heavy atomic nucleus in a strong magnetic field would elongate into a cylinder, whose density and "spin" are enough to build a time machine. Gamma rays projected at it might allow information (not matter) to be sent back in time. However, he pointed out that until we have a single theory combining relativity and quantum mechanics, we will have no idea whether such speculations are nonsense. Robert Lull Forward commonly known as Robert L. Forward (August 15, 1932 - September 21, 2002) was a United States physicist and science fiction writer. ... Current flowing through a wire produces a magnetic field (M) around the wire. ...

Using Quantum Entanglement

Quantum-mechanical phenomena such as quantum teleportation, the EPR paradox, or quantum entanglement might appear to create a mechanism that allows for faster-than-light (FTL) communication or time travel, and in fact some interpretations of quantum mechanics such as the Bohm interpretation presumes that some information is being exchanged between particles instantaneously in order to maintain correlations between particles. This effect was referred to as "spooky action at a distance" by Einstein. This article might not be written in the formal tone expected of an encyclopedia entry. ... In quantum mechanics, the EPR paradox is a thought experiment that demonstrates that the result of a measurement performed on one part of a quantum system can have an instantaneous effect on the result of a measurement performed on another part, regardless of the distance separating the two parts. ... Quantum entanglement is a quantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be spatially separated. ... The Bohm interpretation of quantum mechanics, sometimes called the Causal interpretation, or Ontological interpretation, is an interpretation postulated by David Bohm in which the existence of a non-local universal wavefunction (Schrödinger equation) allows distant particles to interact instantaneously. ... In physics, action at a distance is the instantaneous interaction of two objects which are separated in space; the term was coined as spooky action at a distance by Albert Einstein. ...

Nevertheless, the rules of quantum mechanics curiously appear to prevent an outsider from using these methods to actually transmit useful information, and therefore do not appear to allow for time travel or FTL communication. This misunderstanding seems to be widespread in popular press coverage of quantum teleportation experiments. The assumption that time travel or superluminal communications is impossible allows one to derive interesting results such as the no cloning theorem, and how the rules of quantum mechanics work to preserve causality is an active area of research. Information theory is the mathematical theory of data communication and storage, generally considered to have been founded in 1948 by Claude E. Shannon. ... Superluminal communication is the term used to describe the hypothetical process by which one might send information at faster-than-light (FTL) speeds. ... The no cloning theorem is a result of quantum mechanics which forbids the creation of identical copies of an arbitrary unknown quantum state. ...

The possibility of paradoxes

The Novikov self-consistency principle and recent calculations by Kip S. Thorne indicate that simple masses passing through time travel wormholes could never engender paradoxes—there are no initial conditions that lead to paradox once time travel is introduced. If his results can be generalised they would suggest, curiously, that none of the supposed paradoxes formulated in time travel stories can actually be formulated at a precise physical level: that is, that any situation you can set up in a time travel story turns out to permit many consistent solutions. The circumstances might, however, turn out to be almost unbelievably strange. The Novikov self-consistency principle, also known as the Novikov self-consistency conjecture, is a principle developed by Dr. Igor D. Novikov in the mid-1980s to solve the problem of paradoxes in time travel. ... Kip Stephen Thorne (born June 1, 1940) is an American theoretical physicist, known for his prolific contributions in the field of gravitation physics and astrophysics. ...

Parallel universes might provide a way out of paradoxes. Everett's many-worlds interpretation of quantum mechanics suggests that all possible quantum events can occur in mutually exclusive histories. These alternate, or parallel histories would form a branching tree symbolizing all possible outcomes of any interaction. The many-worlds interpretation (or MWI) is an interpretation of quantum mechanics that proposes the existence of multiple parallel universes, all of which have the same physical laws and constants, but occupy different states. ...

Another possibility is that a Time Paradox may cause such a powerful conflict in the time lines that the entire universe may annihilate itself.

Since all possibilities exist, any paradoxes can be explained by having the paradoxical events happening in a different universe. This concept is most often used in science-fiction. However, in actuality, physicists believe that such interaction or interference between these histories is not possible (see Chronology protection conjecture). The chronology protection conjecture is a conjecture by the physicist Professor Stephen Hawking that the laws of physics are such as to prevent time travel (closed timelike curves) on all but sub-microscopic scales. ...

A further suggestion related to paradoxes suggests that time travel will never exist, even if theoretically possible. The reasoning is that as long as time travel exists, history will change, and will only become static when a timeline is reached in which no time travel exists and thus no further changes can be made. Assuming there is only a single dimension of time, the timeline we perceive must be the one that exists after all changes (if any) are made, and thus we will never perceive the invention of time travel, since it has already destabilised itself out of the timeline by the time we reach it.

If time travel was practical, and affordable, then masses of people would want to be spectators at great events of history, leading to the Cumulative Audience Paradox; our history tells of significantly less than multitudes watching at great events (but then perhaps audiences would remain hidden).

“History would become an experimental science.” says Carl Sagan.

Time travel and the direction of time

The notion of time travel (either towards the future or towards the past) tacitly assumes that there exists a direction of time, the direction from the past to the future. On the other hand, the direction of time (or the arrow of time) is not a fundamental intrinsic property of time, but an emergent property that can be traced back to the fact that we live in a universe in which the entropy increases with time. In this sense, as the direction of time is not fundamental, the notion of time travel is also not fundamental. Without a fundamental notion of time travel there can be no fundamental problems with time travel. Without a direction of time, time can be viewed as a "static" coordinate similar to other spacetime coordinates. From this point of view, the Novikov self-consistency principle is a tautology, a demand that hardly needs to be questioned, which automatically prevents causal paradoxes. Physical processes at the microscopic level are either entirely or mostly (see below) time symmetric, meaning that the theoretical statements that describe them remain true if the direction of time is reversed; yet when we describe things at the macroscopic level this is not the case: there is an obvious... A watch Attempting to understand Time has long been a prime occupation for philosophers, scientists and artists. ... For other senses of the term, see entropy (disambiguation). ... World line of the orbit of the Earth depicted in two spatial dimensions X and Y (the plane of the Earth orbit) and a time dimension, usually put as the vertical axis. ... The Novikov self-consistency principle, also known as the Novikov self-consistency conjecture, is a principle developed by Dr. Igor D. Novikov in the mid-1980s to solve the problem of paradoxes in time travel. ... In logic, a tautology is a statement which is true by its own definition. ...

Time travel and the anthropic principle

It has been suggested by physicists such as Max Tegmark that the absence of time travel and the existence of causality may be due to the anthropic principle. The argument is that a universe which allows for time travel and closed time-like loops is one in which intelligence could not evolve because it would be impossible for a being to sort events into a past and future or to make predictions or comprehend the world around them. Max Tegmark Max Tegmark born 1967 in Sweden to Karin Tegmark and Harold S Shapiro, is a cosmologist formerly at the University of Pennsylvania and now at the Massachusetts Institute of Technology as an Associate Professor. ... The philosophical concept of causality or causation refers to the set of all particular causal or cause-and-effect relations. ... In cosmology, the anthropic principle in its most basic form states the truism that any valid theory of the universe must be consistent with our existence as carbon-based human beings at this particular time and place in the universe. ...

Note that this imposes no restriction on supernatural agents (i.e. gods) which are not confined by the bounds of space-time. See the next section for details.

Time travel and religion

Prophecy and theology

It is interesting to note that any religion which postulates the existence of fulfilled prophecy requires, at the very least, an agent which can move information from the future into the past. Prophecy, in a broad sense, is the prediction of future events. ...

In Christian theology, for example, God is assumed to exist unbound by space or time. Doctrinally, God is held to be omniscient, omnipresent, and omnipotent. Statements in the Bible such as Jesus's claim "before Abraham was born, I am" (John 8:58) and Peter's claim "[Jesus] was chosen before the creation of the world" (1 Peter 1:20) (assuming the creation of the world began at t = 0) imply that God does not occupy the same timeline that we do. This is further supported by the assertion "I the LORD do not change" (Malachi 3:6), since change requires movement along, and constrained by, a temporal continuum. As a noun, Christian is an appellation and moniker deriving from the appellation Christ, which many people associate exclusively with Jesus of Nazareth. ... Theology is reasoned discourse concerning God (Greek θεος, theos, God, + λογος, logos, word or reason). It can also refer to the study of other religious topics. ... This article discusses the term God in the context of monotheism and derived henotheistic forms. ... The Bible (sometimes The Book, Good Book, Word of God, The Word, or Scripture), from Greek (τα) βιβλια, (ta) biblia, (the) books, is the classical name for the Hebrew Bible of Judaism or the combination of the Old Testament and New Testament of Christianity (The Bible actually refers to at least two... Abraham (אַבְרָהָם Father/Leader of many, (circa 1700 BCE) Standard Hebrew Avraham, Tiberian Hebrew ; Arabic ابراهيم ; Geez አብርሃም ) is regarded as a patriarch of Israelite religion, recognized by Judaism and later Christianity, and a very important prophet in Islam. ... John is a common given name for males. ... Peter is a popular male given name. ... Malachi or Malachi (מַלְאָכִי My messenger/angel, Standard Hebrew Malʾaḫi, Tiberian Hebrew Malʾāḵî) was a prophet in the Bible Old Testament and Jewish Tanakh. ...

Two popular interpretations of these statements are that God either exists outside the space-time continuum; or exists at every point in space-time simultaneously. In either case, God can transfer information from one point in space-time to any other point without restriction because of his great overwhelming power.

Transcending time through ancient wisdom

The Yoga Sutras of Patanjali have been considered by some, such as physicist Fred Alan Wolf in his book, The Yoga of Time Travel, to describe an inner process by which we can access knowledge of the past and future in the present. This form of time travel can be acquired by transcending the five earthly anchors of the ego mind which otherwise leave us locked into the illusory self. This is an article about the Yoga Sutras of Patanjali. ... Fred Alan Wolf (December 3, 1934– ) is a theoretical physicist (Ph. ... PASTa building located at Zielna 37 street - Built in 1904-10. ... For the meaning in finance, see futures contract. ... The present is the time that is perceived directly, not as a recollection or a speculation. ... eGO is a company that builds electric motor scooters which are becoming popular for urban transportation and vacation use. ...

Time travel in fiction

Main article: Time travel in fiction

This article needs to be cleaned up to conform to a higher standard of quality. ...

Types of time travel

Time travel themes in science fiction and the media can generally be grouped into two types (based on effect—methods are extremely varied and numerous), each of which is further subdivided. These type classifications do not address the issue of time travel itself, i.e. how to travel through time, but instead call to attention differing rules of the time line. Science fiction is a form of speculative fiction principally dealing with the impact of imagined science and technology, or both, upon society and persons as individuals. ...

1. The time line is consistent and can never be changed.

1.1 One does not have full control of the time travel. One example of this is The Morphail Effect.

1.2 The Novikov self-consistency principle applies (named after Dr. Igor Dmitrievich Novikov, Professor of Astrophysics at Copenhagen University). The principle states that if you travel in time, you cannot act in such a way so as to create a paradox.

1.3 Any event that appears to have changed a time line has instead created a new one.

1.3.1 Such an event can be the life line existence of a human (or other intelligence) such that manipulation of history ends up with there being more than one of the same individual, sometimes called time clones.

1.3.2 The new time line may be a copy of the old one with changes caused by the time traveler. For example there is the Accumulative Audience Paradox where multitudes of time traveler tourists wish to attend some event in the life of Jesus or some other historical figure, where history tells us there were no such multitudes. Each tourist arrives in a reality that is a copy of the original with the added people, and no way for the tourist to travel back to the original time line.

2. The time line is flexible and is subject to change.

2.1 The time line is extremely change resistant and requires great effort to change it. Small changes will only alter the immediate future and events will conspire to maintain constant events in the far future; only large changes will alter events in the distant future.

2.2 The time line is easily changed (example: Doctor Who, where the time line is fluid and changes often naturally).

There are also numerous science fiction stories allegedly about time travel that are not internally consistent, where the traveler makes all kinds of changes to some historical time, but we do not get to see any consequences of this in our present day. For example in SPI's time travel wargame a player's traveler machine gunned a Roman legion has no effect on same traveler's subsequent feudal era adventures. The Morphail Effect refers to the imminent Dr. Brannart Morphail, from Michael Moorcocks classic science fiction novel, Dancers at the End of Time. ... The Novikov self-consistency principle, also known as the Novikov self-consistency conjecture, is a principle developed by Dr. Igor D. Novikov in the mid-1980s to solve the problem of paradoxes in time travel. ... Igor Dmitrievich Novikov (И́горь Дми́триевич Но́виков) (born November 10, 1935) is a Russian theoretical astrophysicist and cosmologist. ... University of Copenhagen The University of Copenhagen (Danish: Københavns Universitet) is the oldest and largest university and research institution in Copenhagen, Denmark. ... Jesus, also known as Jesus of Nazareth or Jesus the Nazarene, is the central figure of Christianity, in which context he is known as Jesus Christ (from Greek Ιησούς Χριστός) with Christ being a title meaning Anointed One. He is also considered a very important prophet in Islam and a manifestation of... Main article: History of Doctor Who Doctor Who first appeared on BBC television at 5:15 p. ...

Immutable timelines

Time travel in a type 1 universe does not allow any paradoxes, although in 1.3, events can appear to be paradoxical. Listen to this article · (info) This audio file was created from the revision dated 2005-07-07, and does not reflect subsequent edits to the article. ...

In 1.1, time travel is constrained to prevent paradox. If one attempts to make a paradox, one undergoes involuntary or uncontrolled time travel. Michael Moorcock uses a form of this principle and calls it The Morphail Effect. In the time-travel stories of Connie Willis, time travelers encounter "slippage" which prevents them from either reaching the intended time or translates them a sufficient distance from their destination at the intended time, as to prevent any paradox from occurring. Michael John Moorcock (born December 18, 1939) is a prolific British writer of both science fiction and science fantasy. ... Connie Willis at Worldcon 2005 in Glasgow Constance Elaine Trimmer Willis (born December 31, 1945) is an American science fiction writer. ...

Example: In the Legacy of Kain series, Kain, as a vampire, receives the mystical Soul Reaver from the time traveler Moebius. He then takes the soul-sucking weapon and uses it to kill the Sarafan prince William. He then travels to a tomb containing the Sarafan bodies of Raziel and his brothers. Kain raises the brothers and turns them into vampires. Kain is insulted because Raziel grows wings (while he has none) and throws him into the abyss. Raziel is resurrected as a soul-sucking fiend. Raziel travels through time to kill Kain and in doing so, confronts his former (human) self and brothers. He then kills his brothers (and himself) with the spectral vesion of the Soul Reaver. These bodies become the same bodies that Kain, 500 years later, resurrects as vampires.

In 1.2, the Novikov self-consistency principle asserts that the existence of a method of time travel constrains events to remain self-consistent (i.e. no paradoxes). This will cause any attempt to violate such consistency to fail, even if extremely improbable events are required. Legacy of Kain is a series of video games developed by Crystal Dynamics and published by Eidos Interactive. ... This article is about the weapon. ... Time travel is a concept that has long fascinated humanity—whether it is Merlin experiencing time backwards, or religious traditions like Mohammeds trip to Jerusalem and ascent to heaven, returning before a glass knocked over had spilt its contents. ... A Sarafan warrior. ... Raziel in his wraith form. ...

Example #1: You have a device that can send a single bit of information back to itself at a precise moment in time. You receive a bit at 10:00:00 PM, then no bits for thirty seconds after that. If you send a bit back to 10:00:00 PM, everything works fine. However, if you try to send a bit to 10:00:15 PM (a time at which no bit was received), your transmitter will mysteriously fail. Or your dog will distract you for fifteen seconds. Or your transmitter will appear to work, but as it turns out your receiver failed at exactly 10:00:15 PM. Etc, etc. Two excellent examples of this kind of universe is found in Timemaster, a novel by Dr. Robert Forward, and the 1980 Jeannot Szwarc film Somewhere In Time (based on Richard Matheson's novel Bid Time Return).

Example #2: In the case of Somewhere In Time, the film deals with events that have already or are about to happen which the lead character Richard Collier (played by Christopher Reeve) could not control. Here, Collier is given a watch by a lady he has not yet known (but who already knew him in the past). Sometime later, Collier is fascinated by a picture taken in 1912 of a young actress. Eventually he learns that the woman in the picture is the old lady who gave him the watch, and that he was actually there in 1912 to meet her. Collier chooses to willfully go back in time 68 years in the past to fulfill what was written in the history books. He meets her and falls in love with her, but one day finds a penny in his pocket that he had brought back in time accidentally; the minting date on it is 68 years in the future. Holding tangible proof that he does not "belong" in the past hurls him back to the present day, and so everything that will be/was written in history has happened and Collier could not do anything to change that history. Had he remained in 1912, history would have been altered, and everything that happened at the beginning of the film would not have come true. Interesting, the watch causes a "time paradox", it has no start in the timeline. The present-day Richard is given the watch by the older Elsie, Richard then travels back in time, leaving the watch in the care of the younger Elsie when he is thrust back into the future, Elsie then holds the watch till she meets the present-day Richard, causing the paradox.

An example which could conceivably fall into either 1.1 or 1.2 can be seen in book and film versions of Harry Potter and the Prisoner of Azkaban. Harry and Hermione go back in time to change history. As they do so it becomes apparent that they are simply performing actions that were previously seen in the story, although neither the characters nor the reader were aware of the causes of those actions at the time. This is another example of the predestination paradox. It is arguable, however, that the mechanics of time travel actually prevented any paradoxes, firstly, by preventing them from realising a priori that time travel was occurring and secondly, by enabling them to recall the precise action to take at the precise time and keep history consistent. Jeannot Szwarc (born 21 November 1939) is a French film director. ... Somewhere in Time is a 1980 time-travel romance film starring Christopher Reeve, Jane Seymour and Christopher Plummer. ... Richard Matheson Richard Matheson (born February 20, 1926) is an American author and screenwriter, typically of fantasy, horror or science fiction. ... Christopher Reeve (September 25, 1952 – October 10, 2004) was an American actor, director, producer and writer renowned for his film portrayal of Superman/Kal-El/Clark Kent in four films from 1978-1987. ... 1912 (MCMXII) was a leap year starting on Monday. ... Cover of the UK Childrens edition by Bloomsbury Harry Potter and the Prisoner of Azkaban is the third book in the Harry Potter series of childrens books by J. K. Rowling. ... Harry James Potter (born 31 July 1980 in Godrics Hollow, UK)[2] is a fictional character and the protagonist of J. K. Rowlings Harry Potter series. ... Hermione Jane Granger (born 19 September 1979) is a fictional character in the Harry Potter series of books. ... A predestination paradox, also called a causal loop or causality loop, is a paradox of time travel that is often used as a convention in science fiction. ...

In a universe that allows retrograde time travel but no paradoxes, any present moment is the past for a future observer, thus all history/events are fixed. History can be thought of as a filmstrip where everything is already fixed. See block time for a detailed examination of this way of considering the nature of time. Block time is one way of approaching the problem of the nature of time. ...

In 1.3, any event that appears to have caused a paradox has instead created a new time line. The old time line remains unchanged, with the time traveller or information sent simply having vanished, never to return. A difficulty with this explanation, however, is that conservation of mass-energy would be violated for the origin timeline and the destination timeline. A possible solution to this is to have the mechanics of time travel require that mass-energy be exchanged in precise balance between past and future at the moment of travel, or to simply expand the scope of the conservation law to encompass all timelines. Some examples of this kind of time travel can be found in David Gerrold's book The Man Who Folded Himself, the Robert Zemeckis film Back to the Future Part II (1989), and the (1994) film Star Trek: Generations. David Gerrold, born Jerrold David Friedman (January 24, 1944), is a science fiction author who started his career in 1966 as a college student by submitting an unsolicited story outline for the television series Star Trek. ... The Man Who Folded Himself is a 1973 science fiction novel by David Gerrold. ... Director Robert Zemeckis Robert Zemeckis (born May 14, 1952) is an American movie director, producer and writer. ... Back to the Future Part II is a 1989 film and is the second part of a trilogy, coming after Back to the Future and followed by Back to the Future Part III. It was directed by Robert Zemeckis and written by Zemeckis and Bob Gale. ... 1989 (MCMLXXXIX) is a common year starting on Sunday of the Gregorian calendar. ... 1994 (MCMXCIV) was a common year starting on Saturday of the Gregorian calendar, and was designated the International year of the Family. ... Star Trek: Generations (Paramount Pictures, 1994, see also 1994 in film) is the seventh feature film based on the popular Star Trek science fiction television series. ...

Example: In Back to the Future Part II, Marty McFly and Doc Brown decide (after Doc returns from the 21st century to 1985) to travel to 2015 to save McFly's future son. While there, McFly buys an almanac of sporting events from 1950-2000, and decides to use it for financial gain via time travel. Doc Brown forbids him to take the book, and inadvertently leaves it lying around for the aged Biff Tannen to take. That night, without McFly and Doc Brown knowing it, Tannen takes the time-traveling DeLorean with the book and goes back in time to change history (using the sports almanac for his own financial success). From the movie audience's point of view, Tannen soon after returns to 2015. McFly and Doc Brown again use the Delorian in an attempt to go back to 1985. But the two soon discover what Tannen had done: Tannen went back to a certain point in the past, met up with his younger self, and gave the younger Tannen the almanac for him to use for personal and financial gain. The alternate 1985 that McFly and Brown returned to was the future of a tangent that started in 1955, where Hill Valley is now corrupt and its citizens' lives changed because of Tannen. McFly and Brown could not just go back to the alternate 2015 to nab Tannen because whatever they would have done there would have been the future of the original timeline. In other words, once you go back in time to change history in this particular instance, whatever happens next will be the future of that particular tangent you just altered (so, for example, if you went back in time to prevent the assassination of President Kennedy in 1963, which in the Twilight Zone episode Profile in Silver saved Kennedy but simultaneously led to Khrushchev assassinated instead, and nuclear war in Europe, or, in the case of Star Trek: Generations, change the fate of a planet and thus saving the crew of the Starship Enterprise, the future after that will be the future based on whatever you altered). Back to the Future Part II is inconsistent in allowing Tannen himself to return to his own original 2015. (However, in scenes deleted from the film, an older Biff Tannen dies once arriving in the future, having been erased from existence in that time period. Marty's mother, Lorraine, shot Biff before 2015; therefore he would not exist in that time period.) An example to explain this, though rare, is that since very little, less than a minute or two's worth, of time is spent in 2015 after Biff returns, and little is seen, so the timeline may have perhaps altered around Marty and Doc, and we cannot see any change or alteration because of the limited camera angles before the group returns to an altered 1985.

Back to the Future Part II is a 1989 film and is the second part of a trilogy, coming after Back to the Future and followed by Back to the Future Part III. It was directed by Robert Zemeckis and written by Zemeckis and Bob Gale. ... An almanac (also spelled almanack, especially in Commonwealth English) is an annual publication containing tabular information in a particular field or fields often arranged according to the calendar. ... John Fitzgerald Kennedy (May 29, 1917 – November 22, 1963), often referred to as John F. Kennedy, JFK, or Jack Kennedy, was the 35th President of the United States. ... In the Star Trek fictional universe, the USS Enterprise (NCC-1701-D) is the Galaxy class starship that is the principal setting of the television series Star Trek: The Next Generation (TNG). ...

Mutable timelines

Time travel in a Type 2 universe is much more difficult to explain. The biggest problem is how to explain changes in the past. One method of explanation is that once the past changes, so too do the memories of all observers. This would mean that no observer would ever observe the changing of the past (because they will not remember changing the past). This would make it hard to tell whether you are in a Type 1 universe or a Type 2 universe. You could, however, infer such information by knowing if a) communication with the past were possible or b) it appeared that the time line had never been changed as a result of an action someone remembers taking, although evidence exists that other people are changing their time lines fairly often. An example of this kind of universe is presented in Thrice Upon a Time, a novel by James P. Hogan. At the 63rd World Science Fiction Convention in Glasgow, August 2005 James Patrick Hogan (born June 27, 1941, London, U.K.) is a science fiction author. ...

Larry Niven suggests that in a type 2.1 universe, the most efficient way for the universe to "correct" a change is for time travel to never be discovered, and that in a type 2.2 universe, the very large (or infinite) number of time travellers from the endless future will cause the timeline to change wildly until it reaches a history in which time travel is never discovered. However, many other "stable" situations may also exist in which time travel occurs but no paradoxes are created; if the changeable-timeline universe finds itself in such a state no further changes will occur, and to the inhabitants of the universe it will appear identical to the type 1.2 scenario. This is sometimes referred to as the "Time Dillution Effect." Larry Niven Laurence van Cott Niven (born April 30, 1938) is a US science fiction author. ...

Gradual and instantaneous

In literature, there are two (commonly used) methods of time travel:

1. The most commonly used method of time travel in science fiction is the instantaneous movement from one point in time to another, like the hand of a boy lifting a toy train from the rails with the wheels still turning, and putting it back at a different place. There is not even the beginning of a scientific explanation for this kind of time travel; its popularity is probably due to the fact that it is more spectacular and makes time travel easier.

2. In The Time Machine H.G. Wells explains that we are moving through time with a constant speed. Time travel then is, in Wells' words, "stopping or accelerating one's drift along the time-dimension, or even turning about and travelling the other way." This method of gradual time travel fits best in quantum physics, but is not popular in modern science fiction. Perhaps the oldest example of this method of time travel is in Lewis Carroll's Through the Looking-Glass (1871): the White Queen is living backwards, hence her memory is working both ways. Her kind of time travel is uncontrolled: she moves through time with a constant speed of –1 and she cannot change it. This would make Lewis Carroll the inventor of time travel. T.H. White, in the first part of his Arthurian novel The Once and Future King, The Sword in the Stone (1938) used the same idea: the wizard Merlyn lives back in time, because he was born "at the wrong end of time" and has to live backwards from in front. "Some people call it having second sight". The Time Machine is a novel by H. G. Wells, first published in 1895, later made into two films of the same title. ... H. G. Wells at the door of his house at Sandgate Herbert George Wells (September 21, 1866 - August 13, 1946) was an English writer best known for his science fiction novels such as The War of the Worlds and The Time Machine. ... Photograph of Lewis Carroll taken by himself, with assistance Charles Lutwidge Dodgson (January 27, 1832 – January 14, 1898), better known by the pen name Lewis Carroll, was a British author, mathematician, logician, Anglican clergyman and photographer. ... Through the Looking-Glass, and What Alice Found There (1871) is a work of childrens literature by Lewis Carroll (Charles Lutwidge Dodgson) It is the sequel to Alices Adventures in Wonderland, (although it makes no reference to its events). ... Terence Hanbury White (May 29, 1906 - January 17, 1964) was a writer. ... The Once and Future King The Once and Future King is an Arthurian fantasy novel written by T.H. Whiteses. ... Wikibooks has more about this subject: The Sword in the Stone The Sword in the Stone is a novel by T. H. White, published in 1938, initially a stand-alone work but now the first part of a tetralogy The Once and Future King. ...

Time travel, or space-time travel?

The classic problem with the concept of "time travel ships" in science fiction is that it invariably treats Earth as the frame of reference in space. The idea that a traveller can go into a machine that sends you to "A.D. 1865" and leave through a door into the same spot in Poughkeepsie ignores the issue that Earth is moving through space around the Sun, which is moving in the galaxy, etc. So, given space-time as four dimensions, and "time travel" referring to just "moving" along one of them, a traveller could not stay in the same place with respect to the surface of Earth, because Earth is an accelerating platform with a highly complicated trajectory! A vessel that moves "ahead" 5 seconds might materialise in the air, or inside solid rock, depending on where Earth was "before" and "after." (As seen in the 2000AD Comic, in which Mutant Bounty Hunter Johnny Alpha uses "Time Bombs" to propel an enemy several seconds into the future, during which time the planets passage through space causes the unfortunate victim to re-materialise in vacuum) If you moved "behind" a year, you'd end up in cold outer space, where Earth was a year earlier—in the same part of the Sun's orbit, yes, but where has the sun gone over that year? So, to really do what filmmakers make look so easy in films such as the Back to the Future series and The Time Machine, a time machine might have to be a very powerful spacecraft that could move you large distances and that kept track of Earth's motion through space as part of the solar system, galaxy, etc. Frame of reference - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... 1865 is a common year starting on Sunday. ...

But how can you decouple the ship from momentum? If you try to move forward in time, is your ship automatically going to be propelled by the momentum gained by riding Earth? Or does it decouple? But does not that bring back the idea of an absolute reference frame? Again, even to move one millisecond forward or backward in time, the ship would have to be far beyond anything humans can build, not to mention that the acceleration and deceleration in space-time would challenge the structural integrity not only of the vessel but also of the passengers' bodies. A theorist might even use this to argue in the style of Zeno's paradoxes, for the impossibility of time machines. Zenos paradoxes are a set of paradoxes devised by Zeno of Elea to support Parmenides doctrine that all is one and that contrary to the evidence of our senses, the belief in plurality and change is mistaken, and in particular that motion is nothing but an illusion. ...

A possible rebuttal to this criticism, of course, is the fact that cars and airplanes built by humans manage to move around the surface of the Earth with it, despite the surface itself moving with an astronomical speed. It is reasonable to assume that a time traveller experiences a combination of spatial temporal inertia that makes him move along with the Earth.

In 1980 Robert Heinlein published a novel The Number of the Beast about a ship that lets you dial in the six (not four!) co-ordinates of space and time and it instantly moves you there—without explaining how such a device might work. The television series Seven Days also dealt with this problem; when the chrononaut would be 'rewinding', he would also, be propelling himself backwards along the earth's orbit, with the intention of landing in the same place (in space) that he originated. 1980 (MCMLXXX) was a leap year starting on Tuesday. ... Book cover The Number of the Beast is a science fiction novel by Robert A. Heinlein published in 1980 (ISBN 0-44-913070-3). ... For the American Civil War battle, see Seven Days Battles. ... In science fiction, the term chrononaut refers to an individual who travels through time, either into the past or the future. ...

"Distance" of time travel

According to special relativity, the physical laws are invariant over Lorentz transformations. This mixes time and space dimensions as distance can be equated to time multiplied by the speed of light (D = T x D/T, where D/T = c). So, the second is comparable to a unit of distance equal to 299,792.458 kilometres. Conversely, the distance of 1 metre is comparable to about 3.34 nanoseconds. A "year" can also be considered comparable to a "light-year". In the Lorentz transformations however, the square of a distance has the opposite sign to the square of a time, so time and space are not actually identical. A simple introduction to this subject is provided in Special relativity for beginners Special relativity (SR) or the special theory of relativity is the physical theory published in 1905 by Albert Einstein in his article On the Electrodynamics of Moving Bodies. SR theory is based on the previous works of... Invariant may have meanings invariant (computer science), such as a combination of variables not altered in a loop invariant (mathematics), something unaltered by a transformation invariant (music) invariant (physics) conserved by system symmetry This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the... The Lorentz transformations (LT), were discovered and published by Joseph Larmor in 1897. ... A kilometre (American spelling: kilometer), symbol: km is a unit of length in the metric system equal to 1000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). ... The metre (Commonwealth English) or meter (American English) (symbol: m) is the SI base unit of length. ... To help compare orders of magnitude of different times this page lists times between 10−9 seconds and 10−8 seconds (1 nanosecond and 10 nanoseconds) See also times of other orders of magnitude. ... A light year (or light-year), abbreviated ly, is the distance light travels in one year: about 9. ...

The correspondence between distances in space and time allows analogies to be drawn between time travel and travel through space. Moving in time for just one second, forward or backward, is analogous to flying three quarters of the way to the moon. Moving for a few years would be like flying to some of the nearest stars. Visiting dinosaurs involves a distance analogous to visiting galaxies half way across the Virgo Supercluster. If the difficulty of travelling a given distance in time is assumed to be comparable to that of travelling a given distance in space, time travel any substantial distance into the past or future becomes impractical to the point of near-impossibility. It is important to note that this assumption is an arbitrary one, as mechanisms proposed for time travel typically do not directly tie together energy expenditure and travel distance, and the "difficulty" of traversing a given distance in space is very sensitive to assumptions made about the desired duration, mechanism of travel, and other parameters of the trip. Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... Orders Saurischia    Sauropodomorpha    Theropoda Ornithischia Dinosaurs are giant reptiles that dominated the terrestrial ecosystem for most of their 165-million year existence. ... NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 56,000 light years in diameter and approximately 60 million light years distant. ... The Virgo Supercluster or Local Supercluster is the supercluster of galaxies that contains the Local Group and with it our galaxy, the Milky Way. ...

Fundamental problems with time "travel"

Perhaps there is a more fundamental problem with time travel. That is, the concept of "travel" through time may be inherently flawed. "Travel" through space is a time dependent event. For example, you drive 50 miles in 1 hour. Your rate of travel is 50 miles through space per hour of time. To make the analogy between space travel and time travel then becomes problematic. What if I travel 50 years into the future? What then is my rate of travel? 50 years per what? In other words, travel through time would require another dimension that would assume the role that the time dimension plays in normal "space travel".

Another issue with time travel arises from our definition of the passage of time. It is often said that we all travel at a constant rate through time. This statement, however, may be flawed because of the reason described above about "travel" through time. The passage of time then could instead be rationalized as the way our consciousness observes the four dimensional world, rather than our travel through it. We see our four dimensional universe as a series of three dimensional cross-sections in succession. Einstein referred to a "world line" as the path a point traces out through time. This "point" is not "moving" through time but instead it is just a cross-section of the "world line". This applies to planets, rocks, and people. What we see in the present is just a cross-section of a higher dimensional world. Any type of "movement" in space is just how we observe objects of four dimensions that have shapes that deviate from a straight "world line". Bends in the world line, for example, would be perceived as movement. Such a description of the universe would probably not allow for time travel.

Another problem with time travel is the absence of guests from the future in our time — who should be here when we develop the ability to timetravel anytime in the future. The reason of the lack of guests from the future may be that Time Travel backwards is not possible, but forward (faster than usual) in time may be still feasible. The chance that Time Travel backwards is possible but that no one notices it today is very low, unless "time tourists" research the historical period they travel to prior to their trip, in order to blend in. Alternatively, people who do experience or witness time travel may be afraid to speak out for fear of being stigmatized, or branded as insane or lying.

It is also possible to state that time travel into the future, then returning to the past, is impossible as well. If one were able to see themselves in the future, they would have the option to change that destiny, thus it is no longer their future. This paradox is discussed in the popular cult film Donnie Darko. To avoid this type of paradox, one would have to stay in the future, or assume that "the" future is actually "a" future that is no longer accessible, or assume that one's "destiny" is impossible to change via time travel interactions. Donnie Darko is a 2001 cult film, the first by writer and director Richard Kelly. ...

Open future models

There are two primary theories for open future universes, growing universe and branching universe. In the growing universe model there exists a single four-dimensional trunk that contains all of the temporal locations in the objective past, and at the very ‘edge’ of that trunk is the objective present which peers into nothingness, since no future temporal locations are ontologically real (Miller 2005). Basically, this means that in our timeline, only past events can actually be viewed because they have already occurred. Future events have not occurred, so they are not considered to be real yet. In the case of the growing universe model there exists another four-dimensional trunk where, the objective present lies at the end of that trunk peering into an array of non-actual but ontologically real future branches. On this model then, not only must the past be closed, but the future must be open: each of the non-actual future branches represents one possible way that things could be, given the way they are in the objective present. This model then, entails that there is both an objective present and an open future (Miller 2005). Each branch of the future is real, but yet has not happened and as a single branch is chosen, the other branches now represent what didn’t happen. New branches are then formed that allow for new choices of future events. World line of the orbit of the Earth depicted in two spatial dimensions X and Y (the plane of the Earth orbit) and a time dimension, usually put as the vertical axis. ... For alternate uses of time, see Time (disambiguation) or see TIME (magazine). ... This article is about the philosophical meaning of ontology. ...

Example: Richard Kelly's Donnie Darko uses time traveling as a plot for the movie. The story has the main character time travel through the point of access through a dimension, or worm hole in order to save his friends. The Fourth Dimension in this movie is water, time and the Tangent Universe which leads Donnie to flood his school. The airplane engine goes through the Tangent Universe and lands in his room. The main character uses the device in order to change the past by destroying himself and saving his parents who travel on a plane and are supposed to die due to incidents he created. This outlines the belief that two of the same objects can coexist in the same time. It also implies that the character has god-like powers and can change the past. Richard Kelly - Wikipedia /**/ @import /skins-1. ... Donnie Darko is a 2001 cult film, the first by writer and director Richard Kelly. ... A wormhole, also known as an Einstein-Rosen bridge, is a hypothetical topological feature of spacetime that is essentially a shortcut from one point in the universe to another point in the universe, allowing travel between them that is faster than it would take light to make the journey through...

It is to be noted that theoretically, a split in a timeline could result in either a move to another dimension, though not truly parallel, due to the fact there is now a significant difference, or even possibly the creation of an entirely new dimension all together. This would effectively surpass the grandfather clause.

References

Film & Television

• Back to the Future trilogy
• Bill & Ted's Excellent Adventure and Bill & Ted's Bogus Journey
• Dexter's Laboratory
• Doctor Who
• Donnie Darko
• Frankenstein Unbound
• Futurama
• Jimmy Neutron
• Millennium
• Phil of the Future
• Quantum Leap
• Seven Days
• Sliders
• Star Trek
• The Terminator Series
• Timecop
• Twelve Monkeys

Doc Brown (Christopher Lloyd) and Marty McFly (Michael J. Fox) watching the first test of the time machine. ... Bill & Teds Excellent Adventure Bill & Teds Excellent Adventure (1989) is a comedy/science fiction film based on the idea of time travel. ... DVD cover Bill & Teds Bogus Journey is a 1991 American comedy science fiction film, the sequel to Bill & Teds Excellent Adventure. ... Dexters Laboratory (Dexters Lab for short) is an American animated series created by Genndy Tartakovsky. ... Main article: History of Doctor Who Doctor Who first appeared on BBC television at 5:15 p. ... Donnie Darko is a 2001 cult film, the first by writer and director Richard Kelly. ... Frankenstein Unbound is a 1990 horror movie based on Brian Aldiss novel of the same name. ... Futurama is an animated American cartoon series created by Matt Groening (creator of The Simpsons) and David X. Cohen (also a writer for The Simpsons). ... Jimmy Neutron may refer to: the 2001 animated film Jimmy Neutron: Boy Genius. ... The film Millennium came out in 1989, and starred Kris Kristofferson, Cheryl Ladd (formerly of the 1970s action show, Charlies Angels), Robert Joy, Al Waxman, and Daniel J. Travanti as Dr. Arnold Mayer. ... Phil of the Future is a comedy television series that debuted on June 18, 2004 on the Disney Channel. ... Quantum Leap was a science fiction television program which ran from 1989 to 1993 on NBC. It followed the adventures of Dr. Sam Beckett (played by Scott Bakula), a brilliant theoretical scientist who finds himself abruptly and uncontrollably jumping in time, temporarily switching places with diverse people at various times... For the American Civil War battle, see Seven Days Battles. ... This article is about the Sci-Fi television show. ... http://www. ... The Terminator is a 1984 science fiction-action film which became the break-through role for former body-builder Arnold Schwarzenegger. ... Timecop (1994) is a science fiction thriller film directed by Peter Hyams (2010: The Year We Make Contact, The Relic). ... Twelve Monkeys is a 1995 time travel movie co-written by David Webb Peoples and directed by Terry Gilliam. ...

Scientific references

• Paul Davies, About Time ISBN 0684818221

  How to Build a Time Machine ISBN 0142001864

• J. Richard Gott, Time Travel in Einstein's Universe: The Physical Possibilities of Travel Through Time ISBN 0618257357
• Gribbin, In Search of Schrodinger's Cat
• Paul J. Nahin, Time Machines: Time Travel in Physics, Metaphysics, and Science Fiction ISBN 0387985719
• Pagels, Perfect Symmetry, the Search for the Beginning of Time
• Clifford A. Pickover, Time: A Traveler's Guide ISBN 0195130960
• Kornel Lanczos, On a Stationary Cosmology in the Sense of Einsteins Theory of Gravitation, 1924, republished in 1997 by Springer Science+Business Media B.V.
• Willem Jacob van Stockum, The Gravitational Field of a Distribution of Particles Rotating about an Axis of Symmetry, 1936, Proceedings of the Royal Society of Edinburgh.
• Frank J. Tipler, Rotating Cylinders and the Possibility of Global Causality Violation, Physical Review D 9 (1974), 2203
• H. Nikolic, Causal paradoxes: a conflict between relativity and the arrow of time
• Miller, Kristie. “Time travel and the open future.” Disputatio Vol 1. Issue 19 (2005): 223-232.

Paul Charles William Davies (born April 22, 1946) is a British-born, internationally acclaimed physicist, writer and broadcaster, who holds the position of Professor of Natural Philosophy in the Australian Centre for Astrobiology at Macquarie University, Sydney. ... Clifford A. Pickover is a writer in the fields of science, mathematics, and science fiction. ... Willem Jacob van Stockum (November 20, 1910-June 10, 1944) was a physicist who made an important contribution to the early development of general relativity. ... 1936 (MCMXXXVI) was a leap year starting on Wednesday (link will take you to calendar). ... Frank J. Tipler is a professor of mathematical physics at Tulane University, New Orleans, physicist, theologian and cornucopian philosopher. ...

Literary references

Main article: Time travel in fiction

• A Christmas Carol by Charles Dickens
• A Connecticut Yankee in King Arthur's Court by Mark Twain
• All the Myriad Ways by Larry Niven
• "All You Zombies", By His Bootstraps, The Cat Who Walks Through Walls, Farnham's Freehold, and Time Enough For Love by Robert A. Heinlein
• Richard Mgrdechian's 3000 Years[5]
• The Time Machine by H. G. Wells
• The Time Ships, an authorized sequel to Wells' novel, by Stephen Baxter
• Timelike Infinity, also by Stephen Baxter
• A Bridge of Years and The Chronoliths by Robert Charles Wilson
• Bones of the Earth by Michael Swanwick
• Cascade Point by Timothy Zahn
• Harry Potter and the Prisoner of Azkaban and Harry Potter and the Order of the Phoenix by J.K. Rowling
• "The Hounds of Tindalos" by Frank Belknap Long
• Mastadonia by Cliford Simak
• October the First is Too Late by Hoyle
• Paratime series by H. B. Piper
• Rotating Cylinders and the Possibility of Global Causality Violation by Larry Niven
• Scape Scope by Stith
• The Coming of the Quantum Cats by Frederik Pohl
• The End of Eternity by Isaac Asimov
• "The Hitchhiker's Guide to the Galaxy" series by Douglas Adams
• The Other Side of Time by Keith Laumer
• The Time Traveler's Wife by Audrey Niffenegger
• Thrice Upon a Time by James Hogan
• Time Wars series by S. Hawke
• Twice Upon a Time by Allen Appel
• Doomsday Book (ISBN: 0553562738) and To Say Nothing of the Dog by Connie Willis
• Lost in a Good Book by Jasper Fforde
• The House on the Strand by Daphne du Maurier
• Household Gods (1999) by Judith Tarr and Harry Turtledove
• "Thus We Frustrate Charlemagne" by R. A. Lafferty published in Galaxy in 1966 and also appeared in Alpha 1 (edited by Robert Silverberg) and World's Best SF 1968 (edited by Donald A. Wollheim and Terry Carr).
• Up the Line by Silverberg
• Wrinkle in Time by L'Engle, with several sequels
• Night Watch by Terry Pratchett
• Timeline by Michael Crichton

This article needs to be cleaned up to conform to a higher standard of quality. ... A Christmas Carol frontpiece, first edition 1843. ... Dickens was a prolific writer who was almost always working on a new installment for a story and rarely missed a deadline. ... Connecticut Yankee in King Arthurs Court book cover A Connecticut Yankee in King Arthurs Court is a novel by American humorist and writer Mark Twain, first published in 1889. ... Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), better known by his pen name Mark Twain, was a famous and popular American humorist, novelist, writer and lecturer. ... All the Myriad Ways is a collection of short stories and essays by science fiction author Larry Niven, originally published in 1971. ... Larry Niven Laurence van Cott Niven (born April 30, 1938) is a US science fiction author. ... All You Zombies is a song by The Hooters on their second album Nervous Night released in 1985. ... By His Bootstraps is a science fiction short story by Robert A. Heinlein that plays with some of the inherent paradoxes that would be caused by time travel. ... Book cover The Cat Who Walks Through Walls is a science fiction novel by Robert A. Heinlein published in 1985. ... Farnhams Freehold is a science fiction tale set in the near future by Robert Heinlein. ... Time Enough for Love is a science fiction novel by Robert A. Heinlein published in 1973. ... Heinlein autographing at the 1976 Worldcon Robert Anson Heinlein (July 7, 1907 – May 8, 1988) was one of the most influential and controversial authors in science fiction. ... The Time Machine is a novel by H. G. Wells, first published in 1895, later made into two films of the same title. ... H. G. Wells at the door of his house at Sandgate Herbert George Wells (September 21, 1866 – August 13, 1946) was a British writer best known for his science fiction novels such as The War of the Worlds, The Invisible Man, The Island of Dr. Moreau and The Time Machine. ... The Time Ships is a 1995 science fiction novel by Stephen Baxter. ... Stephen Baxter at 63rd World Science Fiction Convention in Glasgow, August 2005 Stephen Baxter (born in Liverpool, November 13, 1957) is a British hard science fiction author. ... Timelike Infinity is a 1993 science fiction book by Stephen Baxter. ... Stephen Baxter at 63rd World Science Fiction Convention in Glasgow, August 2005 Stephen Baxter (born in Liverpool, November 13, 1957) is a British hard science fiction author. ... The Chronoliths is a 2001 science fiction novel by Robert Charles Wilson. ... Robert Charles Wilson (born 1953) is a science fiction author. ... At the 63rd World Science Fiction Convention in Glasgow, August 2005 Michael Swanwick (born November 18, 1950) is a science fiction author based in Philadelphia who began publishing in the early 1980s. ... Timothy Zahn (born September 1, 1951) is a science fiction novelist. ... Cover of the UK Childrens edition by Bloomsbury Harry Potter and the Prisoner of Azkaban is the third book in the Harry Potter series of childrens books by J. K. Rowling. ... Cover of the UK Childrens Edition, Bloomsbury Harry Potter and the Order of the Phoenix is the fifth book in the Harry Potter series of childrens books by J. K. Rowling. ... Joanne Rowling OBE (born July 31, 1965 in Chipping Sodbury, South Gloucestershire), commonly known as J.K. Rowling (pronunciation: roll-ing; her former students used to joke with her name calling her the Rolling Stone), is a British fiction writer. ... Hounds of Tindalos - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... Frank Belknap Long (April 27, 1903 - January 3, 1994) was a prolific American writer of horror fiction, fantasy, science fiction, poetry, gothic romance, comic books, and non-fiction. ... Larry Niven Laurence van Cott Niven (born April 30, 1938) is a US science fiction author. ... The Coming of the Quantum Cats is a 1986 science fiction novel by American writer Frederick Pohl. ... Frederik Pohl (November 26, 1919—) is an American science fiction writer and editor who received the Grand Master Nebula in 1993. ... The End of Eternity by Isaac Asimov is a science fiction novel, with mystery and thriller elements, on the subjects of time travel and social engineering. ... Isaac Asimov (courtesy of Jay Kay Klein) Dr. Isaac Asimov (c. ... The cover of the first novel in the Hitchhikers series, from a late 1990s printing. ... Douglas Noël Adams in an undated publicity photograph by Jill Furmanovsky. ... John Keith Laumer (June 9, 1925 – January 23, 1993) was an American science fiction author. ... The Time Travelers Wife (ISBN 015602943X) is a novel by Audrey Niffenegger. ... Audrey Niffenegger is a writer and artist. ... The Time War is an event referred to on several occasions in the 2005 series of the long running British science fiction television series Doctor Who. ... Allen Appel, born January 6, 1945, in Bethlehem, Pennsylvania, is a novelist best known for his series about time traveler Alex Balfour. ... Doomsday Book is a novel by Connie Willis. ... Connie Williss 1997 science-fiction comedy novel To Say Nothing of the Dog returns to the same universe of time-traveling historians she explored in her Doomsday Book. ... Connie Willis at Worldcon 2005 in Glasgow Constance Elaine Trimmer Willis (born December 31, 1945) is an American science fiction writer. ... Jasper Fforde Jasper Fforde (born in London on January 11, 1961) is a novelist and aviator living in Wales, United Kingdom. ... Dame Daphne du Maurier DBE (May 13, 1907 – April 19, 1989) was one of the most successful Cornish novelists of all time. ... Household Gods is a science fiction/time-travel novel written by Harry Turtledove and Judith Tarr. ... Judith Tarr, (1955 - ) has a B.A. in Latin and English from Mount Holyoke College, an M.A. in Classics from Cambridge University, and an M.A. and Ph. ... Harry Turtledove at Worldcon 2005 in Glasgow Harry Norman Turtledove (born June 14, 1949), is a historian and prolific novelist who has written historical fiction, fantasy, and science fiction works. ... Raphael Aloysius Lafferty (November 7, 1914 - March 18, 2002) was a noted science fiction and fantasy writer. ... At the 63rd World Science Fiction Convention in Glasgow, August 2005 Robert Silverberg (born January 15, 1935 in Brooklyn, NY) is a prolific author best known for writing science fiction, a multiple winner of both the Hugo and Nebula Awards. ... Donald Allen Wollheim (October 1, 1914 - November 2, 1990) was a science fiction writer (under pseudonyms, including David Grinnell), editor and publisher. ... Terry Carr (February 19, 1937 - April 7, 1987) was a science fiction author and editor. ... A Wrinkle in Time is a childrens fantasy novel by Madeleine LEngle, written in 1962. ... Night Watch is the 27th novel in Terry Pratchetts Discworld series, published in 2002. ... Terence David John Pratchett OBE is an English fantasy author (born April 28, 1948, in Beaconsfield, Buckinghamshire, England), best known for his Discworld series. ... Alternative meanings: Timeline is a 1999 science fiction novel by Michael Crichton Timeline is a 2003 film based on the novel. ... Michael Crichton Dr. John Michael Crichton (born October 23, 1942, pronounced cry-ton ) is an author, film producer and television producer. ...

Philosophical references

• Richard M Gale, The Philosophy of Time
• Fred Alan Wolf, The Yoga of Time Travel (2004) ISBN 083560828X

Fred Alan Wolf (December 3, 1934– ) is a theoretical physicist (Ph. ...

See also

• Tipler Cylinder
• Anachronism
• The mysterious "Chronovisor" device
• Grandfather paradox
• Predestination paradox
• Ronald Mallett
• Temporal mechanics
• Thiotimoline

Main article: Time travel in fiction

• John Titor
• UFO Phil
• Montauk Project
• Time Traveler Convention

This article is in need of attention from an expert on the subject. ... An anachronism (from Greek ana, back, and chronos, time) is something that is out of its natural time or appears to be. ... The Chronovisor was supposedly a machine for viewing past and future events. ... The grandfather paradox is a paradox of time travel, supposedly first conceived by the science fiction writer René Barjavel in his book Future times three (Le voyageur imprudent, 1943). ... A predestination paradox, also called a causal loop or causality loop, is a paradox of time travel that is often used as a convention in science fiction. ... Ronald Mallett with a model of a fictional time machine, unrelated to the one he has plans for. ... Temporal mechanics is an entirely theoretical area of quantum physics devoted to thought experiments regarding time and causality, and the effects of time travel on them. ... Thiotimoline is a fictitious chemical compound conceived by science fiction author Isaac Asimov and described in a spoof scientific paper entitled The Endochronic Properties of Resublimated Thiotimoline in 1948. ... This article needs to be cleaned up to conform to a higher standard of quality. ... John Titors military insignia. ... Phil Hill, better known as UFO Phil has gained moderate fame and a cult-following as a novelty songwriter, appearing frequently on the nationally syndicated Dr. Demento radio show as well as on Coast to Coast AM with George Noory as a guest and contributor. ... The Montauk Project was purportedly a series of secret United States government projects conducted at Camp Hero and/or Montauk Air Force Station on Montauk, Long Island. ... A convention to be (or already, depending on your point of reference) held at the East Campus Courtyard of MIT on May 7, 2005 at 10:00pm EDT (May 8, 2005 02:00 UTC). ...

External links

• Time Travel's message forum
• The logic of time travel, by Dr Paul Shackley
• Time Travel and Poul Anderson, by Dr Paul Shackley
• Time, Time Travel & Traversable Wormholes and other time travel related science & technology topics
• SF Chronophysics, a discussion of Time Travel as it relates to science fiction
• On the Net: Time Travel by James Patrick Kelly in Asimov's Science Fiction
• Howstuffworks' article on "How Time Travel Will Work"
• Time Travel in Flatland?
• NOVA Online: Time Travel
• Time Traveler Convention, at MIT - "Technically, you would only need one..."
• Stanford Encyclopedia of Philosophy:
  • Time Machines
  • Time Travel and Modern Physics
• UFO Phil in a short documentary film about time travel called "The Machine"
• Time Travel from the Internet Encyclopedia of Philosophy
• Theoretical Space Science Alternative science site.