Time TravelMain article: Time travel See also: Time travel in fiction, Wormhole, and Twin paradox
Time travel is the concept of moving backwards and/or forwards to different points in time, in a manner analogous to moving through space, and different from the normal "flow" of time to an earthbound observer. In this view, all points in time (including future times) "persist" in some way. Time travel has been a plot device in fiction since the 19th century. Traveling backwards in time has never been verified, presents many theoretic problems, and may be an impossibility. Any technological device, whether fictional or hypothetical, that is used to achieve time travel is known as a time machine.
A central problem with time travel to the past is the violation of causality; should an effect precede its cause, it would give rise to the possibility of a temporal paradox. Some interpretations of time travel resolve this by accepting the possibility of travel between branch points, parallel realities, or universes.
Another solution to the problem of causality-based temporal paradoxes is that such paradoxes cannot arise simply because they have not arisen. As illustrated in numerous works of fiction, free will either ceases to exist in the past or the outcomes of such decisions are predetermined. As such, it would not be possible to enact the grandfather paradox because it is a historical fact that your grandfather was not killed before his child (your parent) was conceived. This view doesn't simply hold that history is an unchangeable constant, but that any change made by a hypothetical future time traveler would already have happened in his or her past, resulting in the reality that the traveler moves from. More elaboration on this view can be found in the Novikov self-consistency principle.
Read more about this topic: Time
Other articles related to "time travel, time":
... an oncoming truck but saved his own life by traveling in time to before he left his home ... I made the decision instantly to turn back time," says the anonymous Scientologist, who then found himself "standing by the door I'd left not 10 seconds before - completely ...
... Time travel is a recurrent theme in science fiction television programs ... In some television series, time travel creates the premise and direction for the plot and/or setting of the show ... Two model examples of television shows that utilize time travel in this way are Doctor Who and Quantum Leap ...
... Single-player and multi-player free-form time travel ... Players can play at different points in time simultaneously and can stop, slow, and fast forward through the flow of time ... Players can also send units through time ...
... that is sometimes raised against the concept of time machines in science fiction is that they ignore the motion of the Earth between the date the time machine departs and the date it returns ... so on, so that advocates of this argument imagine that "realistically" the time machine should actually reappear in space far away from the Earth's position at that date ... However, the theory of relativity rejects the idea of absolute time and space in relativity there can be no universal truth about the spatial distance between ...
... players "overwhelm" their opponent Doctor Who Battles in Time, designer uncredited in 2006 for G E Fabbri Collectible card game and magazine Time Travel Baseball, designed by Stanley ... rummy-like" play, special deck, play direction changes Time Gradient, designed by Stephen Tavener in 2003 self-published uses two decks of standard Playing cards, players compete to alter time favorable to their ...
Famous quotes containing the words travel and/or time:
“Some people swallow the universe like a pill; they travel on through the world, like smiling images pushed from behind.”
—Robert Louis Stevenson (18501894)
“The little toy dog is covered with dust,
But sturdy and stanch he stands;
And the little toy soldier is red with rust,
And the musket moulds in his hands.
Time was when the little toy dog was new,
And the soldier was passing fair;
And that was the time when our Little Boy Blue
Kissed them and put them there.”
—Eugene Field (18501895)