Time Travel

Chronos Shrugged: The World of Time Travel
A brief tour of the world of time travel - from the myths and psychology to the science (including relativity). Also includes a bibliography and links.
http://www.umich.edu/~engtt415/menu.html

Everything You Always Wanted to Know About Time Travel
A collection of brief articles by the renowned non-fiction author John Gribbin. Includes "How to build a time machine", articles about wormholes and time travel, and a discourse on the question whether the laws of physics forbid travel into the past.
http://www.lifesci.sussex.ac.uk/home/John_Gribbin/Time_Travel.html

How Time Travel Will Work
Article about time travel from "How Stuff Works"; by Kevin Bonsor. Includes background information about relativity and black holes, and possible time travel scenarios involving wormholes and cosmic strings.
http://www.howstuffworks.com/time-travel.htm

NOVA Online: Time Travel
Companion site to the NOVA program "Time Travel" (1999); includes a description of the connection with Einstein's theories of relativity, an interview with Carl Sagan, a teacher's guide, and a transcript of the show.
http://www.pbs.org/wgbh/nova/time/

The Relativistic Asynchronous Machine
Design of a hypothetic machine for travel into the future by Tilmann Schneider.
http://www.tilmannschneider.de/dok_en.html

Space-Time Physics and the Future of Time Travel
Elementary exposition of Euclidean geometry, Newton vs. Einstein, and the possibility to travel into the future, and see into the past, in relativity. By Alex MacLellan.
http://themaclellans.com/timetravel.html

Taking the Cosmic Shortcut
Article on the site of the Australian Broadcasting Corporation about the physics of time travel, from special relativity and time travel into the future to general relativity, Ron Mallet's time machine, and wormholes. By Elizabeth Warnes.
http://www.abc.net.au/science/slab/wormholes/default.htm

Time Loops
An interview on Edge with the author and physicist Paul Davies about time travel and the ensuing paradoxes, physical time-travel scenarios from Gödel's universe to wormholes, and the interplay between physics and science-fiction. Includes both a transcript and a video version.
http://www.edge.org/3rd_culture/davies/davies_index.html

Time Travel
Brief text by Neil Johnson (Oxford University) about the connection between gravity, black holes, singularities, the multiple worlds of quantum theory, and time travel. From BBC Science and Nature.
http://www.bbc.co.uk/science/space/exploration/timetravel/index.shtml

Time Travel - Fact or Fiction?
Brief overview of physics issues related to time travel, including the question of conversation laws, general relativity, possible paradoxes, and the notion of tachyons. From the Physics FAQ; original by Jon J. Thaler.
http://math.ucr.edu/home/baez/physics/Relativity/GR/time_travel.html

Time Travel and Modern Physics
Article from the Stanford Encyclopedia of Philosophy about the basis of time travel scenarios in modern physics, including a discussion of mechanisms such as wormholes, and the question of paradoxes.
http://setis.library.usyd.edu.au/stanford/archives/fall2001/entries/time-travel-phys/

Time Travel in Flatland?
Superb pages by Patricia Schwarz, explaining special relativity, general relativity, and the basics of relativistic time travel in a hypothetical world with just two dimensions ("flatland").
http://www.theory.caltech.edu/people/patricia/lctoc.html

Why Faster-Than-Light Implies Time Travel
Account of a hypothetical dual with pistols firing faster-than-light bullets showing how, in special relativity, the ability to travel faster than the speed of light implies the ability to travel into the past. By Wayne Throop.
http://sheol.org/throopw/tachyon-pistols.html

How to Build a Time Machine
Article in Scientific American, written by Paul Davies. Covers time travel into the future in special and general relativity and a variety of hypothetical mechanisms for time travel into the past, such as cosmic strings and wormholes, including caveats such as the chronology protection conjecture. Images not available in the free version. <small>(September, 2002)</small>
http://www.sciam.com/article.cfm?articleID=0004226A-F77D-1D4A-90FB809EC5880000

Getting in a Twist over Time
Article on Space Daily about Ron Mallet's attempts to design a time machine using a loop of laser light. By Michael Brooks; also includes a brief history of time travel in relativity, including remarks on wormholes and the chronology protection conjecture. <small>(May 19, 2001)</small>
http://www.spacedaily.com/news/timetravel-01a.html

Quantum Time Travel
Brief description of the work by Yakir Aharonov's group on a "quantum time machine", including parallels with published science-fiction stories. From John G. Cramer's column "The Alternate View", published in Analog Science Fiction and Fact Magazine. <small>(September 30, 1990)</small>
http://www.npl.washington.edu/AV/altvw45.html