Time travel: Grandfather paradox, Tachyon, Wormhole, Novikov self-consistency principle, Causality, Bootstrap paradox, Predestination paradox, Temporal paradox, John Titor, Time travel urban legends, Ronald Mallett, Closed timelike curve

Source: Wikipedia. Pages: 62. Chapters: Grandfather paradox, Tachyon, Wormhole, Novikov self-consistency principle, Causality, Bootstrap paradox, Predestination paradox, Temporal paradox, John Titor, Time travel urban legends, Ronald Mallett, Closed timelike curve, Quantum mechanics of time travel, Sergei Avdeyev, Chronology protection conjecture, Roman ring. Excerpt: Time travel is the concept of moving between different points in time in a manner analogous to moving between different points in space, either sending objects (or in some cases just information) backwards in time to some moment before the present, or sending objects forward from the present to the future without the need to experience the intervening period (at least not at the normal rate). Although time travel has been a common plot device in fiction since the 19th century, and one-way travel into the future is arguably possible, given the phenomenon of time dilation based on velocity in the theory of special relativity (exemplified by the twin paradox), as well as gravitational time dilation in the theory of general relativity, it is currently unknown whether the laws of physics would allow backwards time travel. Any technological device, whether fictional or hypothetical, that is used to achieve time travel is commonly known as a time machine. Some interpretations of time travel also suggest that an attempt to travel backwards in time might take one to a parallel universe whose history would begin to diverge from the traveler's original history after the moment the traveler arrived in the past. There is no widespread agreement as to which written work should be recognized as the earliest example of a time travel story, since a number of early works feature elements ambiguously suggestive of time travel. Ancient folk tales and myths sometimes involved something akin to travelling forward in time; for example, in Hindu mythology, the Mahabharata mentions the story of the King Revaita, who travels to heaven to meet the creator Brahma and is shocked to learn that many ages have passed when he returns to Earth. Another one of the earliest known stories to involve traveling forwards in time to a distant future was the Japanese tale of "Urashima Taro", first described in the Nihongi (720). It was about a young fisherman named Urashima Taro who visits an undersea palac