Time travel in fiction

Time travel is a common theme in fiction, mainly since the late 19th century, and has been depicted in a variety of media, such as literature, television, film, and advertisements. The concept of time travel by mechanical means was popularized in H. G. Wells' 1895 story, The Time Machine. In general, time travel stories focus on the consequences of traveling into the past or the future. The central premise for these stories often involves changing history, either intentionally or by accident, and the ways by which altering the past changes the future and creates an altered present or future for the time traveler upon their return home. In other instances, the premise is that the past cannot be changed or that the future is predetermined, and the protagonist's actions turn out to be either inconsequential or intrinsic to events as they originally unfolded. Some stories focus solely on the paradoxes and alternate timelines that come with time travel, rather than time traveling itself. They often provide some sort of social commentary, as time travel provides a "necessary distancing effect" that allows science fiction to address contemporary issues in metaphorical ways. Time travel in modern fiction is sometimes achieved by space and time warps, stemming from the scientific theory of general relativity. Stories from antiquity often featured time travel into the future through a time slip brought on by traveling or sleeping, or in other cases, time travel into the past through supernatural means, for example brought on by angels or spirits. Time slip A time slip is a plot device in fantasy and science fiction in which a person, or group of people, seem to travel through time by unknown means. The idea of a time slip has been used in 19th century fantasy, an early example being Washington Irving's 1819 Rip Van Winkle, where the mechanism of time travel is an extraordinarily long sleep. Mark Twain's 1889 A Connecticut Yankee in King Arthur's Court had considerable influence on later writers.