Warped Space Time:

Wormholes and Time Travel Time Travel Basics of Spacetime General Euclidean Geometry Light Cone Lorentz Contraction and Time Dilation Twin Paradox Lorentzian Wormholes Einstein - Rosen Bridges Creating a Wormhole Classical Quantum Maintaining a Wormhole Curvature Exotic Matter Negative Energy Density Squeezed States Casimir Effect Feynman Closed Loops In general Euclidean geometry you can calculate the velocity of Observer 2 by using Observer 1s time reading and measurement of distance.

This does not hold true when considering relativity.

Simultaneity is no longer arbitrary. B & C are timelike to A

F is lightlike to A

E & D are spacelike to A The length of Obs2's meter stick as determined by Obs1 is less than one meter or Obs2's clock runs slower.

The meter stick didn't shrink.

The observers disagree about simultaneity. B should be occuring at a single time distant from A's time.

O2 and O2 did not take the same time to reach B.

O1 and O2 were twins, O1 could reach B several years younger than O2. An antiparticle is just a particle moving backwards in time http://www.lefthandedtoons.com/154/ http://commons.wikimedia.org/wiki/File:Light_cone.png Thorne, Black Holes and Time Warps. 1994 What is a Wormhole? A topological shortcut through spacetime. Hawking, A Briefer History of Time. 2005. Also known as Schwarzschild Wormholes and Einstein Rosen Bridges Thorne, 1994. Quantum Foam: At small distances comparable to the planck length, there is subatomic spacetime turbulence. At these small scales of spacetime, the uncertainty principle allows for energy and particles to come into existence and then annihilate, without violating the conservation laws. Keeps the wormhole open gravitationally

Defocuses light beams

Must have -ve energy density when measured by an observer travelling through the wormhole at the speed of light. It can have +ve energy density with respect to a stationary observer Thorne, 1994. http://science.howstuffworks.com/dictionary/astronomy-terms/space-shape2.htm Heisenberg's uncertainty principle says that the energy density of any electric, magnetic, or other fields fluctuates randomly. A quantum vacuum can never be empty. It has virtual particles.

Zero energy density: Vacuum with all these functions. Ford and Roman, 2000. 2 uncharged metal plates alter vacuum fluctuations in away that they attract each other. Energy density between the plates is -ve. Plates reduces the fluctuations in the gap between them. -ve energy and pressure pulls the plates together http://en.wikipedia.org/wiki/Casimir_effect Theories Consistent Histories hypothesis: You can only go back in time if it is prerecorded in history that you did go back in time. And if you do go back in time, you cannot change anything, only follow history.

Alternative Histories hypothesis: "Back to the Future"-there is every possible history, and the probabilities of each being dominant can be changed. Chronology Protection Conjecture Laws of physics conspire to disallow macroscopic bodies from transporting from the present to the past (Hawking, 2005).

If spacetime is warped enough to make time travel (to the past) possible then the particle/antiparticle pairs moving around and around on the feynman closed loops will create large enough positive energy densities that will counteract the negative energy density warpage, thereby disallowing the time travel. http://www.centauri-dreams.org/?p=1883 Thank you! http://en.wikipedia.org/wiki/File:Worm3.jpg References Ford, Lawrence H., and Thomas A. Roman. "Wormholes and Warp Drive." Scientific American, January 2000.

Hawking, Stephen. A Briefer History of Time. Bantam, 2005.

Holman, Richard F., William A. Hiscock, and Matt Visser. "What exactly are wormholes? Have wormholes been proven to exist or are they still theoretical?" Scientific American, Septermber 15, 1997.

Khalili, Jim Al. Blackholes, Wormholes & Time Machines. New York: Taylor and Francis Group, 1999.

Thorne, Kip S. Blackholes and Time Warps. New York: W W Norton & Company, 1994.

Wald, Robert M. Space, Time, and Gravity: The Theory of the Big Bang and Black Holes. Chicago: University of Chicago Press, 1977.

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# Wormholes and Time Travel

a presentation discussing modern theories on wormholes and their possible use for time travel.