Tipler cylinder

A Tipler cylinder is a cylinder of dense matter of infinite length, rotating about its longitudinal axis. This hypothetical object is theorized to allow time travel and is also called a Tipler time machine. While references to infinite length cylinders can be found in literature back to 1936, it was Frank Tipler in 1974 who recognized it would allow closed timelike curves and thus allow time travel. Tipler's solution was for a cylinder of infinite length. He suggested that a finite cylinder might produce closed timelike curves if the rotation rate were fast enough but he did not prove this. Stephen Hawking in his 1992 paper on the chronology protection conjecture posited that closed timelike curves cannot be created, and thus cannot be used for time travel.

Tipler cylinders in fiction
* John DeChancie's Starrigger series uses vertically-aligned Tipler cylinders (officially called Kerr-Tipler objects) to create spacetime gateways along an intergalactic highway.* Larry Niven wrote a short story, Rotating Cylinders and the Possibility of Global Causality Violation that borrowed its title from Tipler's paper. * Poul Anderson in The Avatar novel. * Vernor Vinge in the novel Marooned in Realtime, p. 174 (although the object is described as being a naked black hole).* Kris Straub's Starslip comic includes a Tipler cylinder created as a work of art (comic 569). *Ian Douglas in "Star Carrier Singularity" has a Tipler cylinder created by aliens of unknown origin

Time Warps
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===Time warps are generally gateways to other times. What is unique about time warps is that the time traveler can still be directly linked to his "home" time. Sometimes they resemble nothing more than a hole in the air, and on the other side is the exact same location in space but in a different time. Upon entering a time warp, the traveler is instantly transfered to the time on the other side.===

Wormholes
===Wormholes are gateways linking one black hole to another. It is thought that if one is able to go into a black hole without being stretched into a string of atoms, he will be able to go through a wormhole to another black hole, therfore transporting him to another place and time in the universe.The danger with wormholes is that there are so many black holes in this universe, that the odds of finding a black hole that would transport back to your present time and space would be a million to one. ===

Tipler Cylinders
===It is not known if Tipler Cylinders actually exist, as it is only a theory developed by US astronomer Frank Tipler. A Tipler Cylinder is a piece of material 10 times the mass of the sun, squeezed into a near infinitely long, incredibly dense cylinder, and made to spin a few billion revolutions per minute. A carefully plotted course could take you possibly billions of years from the starting point and maybe even several galaxies away.There are no known dangers of Tipler Cylinders. ===

Cosmic Strings
===A cosmic string is a purely theoretical, variation of the Tipler Cylinder. A cosmic string would be an infinitely long thin line. If two cosmic strings or possibly just one string and a black hole are maneuvered close together, it is theorized to create a "whole array of closed, timelike curves". To travel by means of cosmic strings, one should fire two infinitely long cosmic strings past each other, then fly his ship around them in a carefully calculated figure eight.There are no known dangers of Cosmic Strings. === {| border="10" height="1434" style="font-family:'CenturyGothic';" width="100%"
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There are no known dangers of Tipler Cylinders, aside from the obvious.

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should fire two infinitely long cosmic strings past each other, then fly his ship around them in a carefully calculated figure eight.

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There are no known dangers of Cosmic Strings.
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Cylinders
===It is not known if Tipler Cylinders actually exist, as it is only a theory developed by US astronomer Frank Tipler. A Tipler Cylinder is a piece of material 10 times the mass of the sun, squeezed into a near infinitely long, incredibly dense cylinder, and made to spin a few billion revolutions per minute. A carefully plotted course could take you possibly billions of years from the starting point and maybe even several galaxies away.===
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