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MG11 Berlin July 23-29, 2006


Parallel Session GT5

 Wormholes, Energy Conditions and Time Machines

Chairperson Dr Mark Hadley

This is the web page for the Parlalel Session, GT,5 of the 11th Marcel Grossmann Meeting. A link to the meeting home page is on the right. I will be pleased to add content from any contributor or similarly informed researcher.

The last surprise of General Relativity?

Shortly after its formulation General Relativity made two ridiculous predictions: The existence of black holes and the expansion (or contraction) of the Universe. Einstein tried to show that the first was not correct and tried to change the theory to avoid the second! In many ways Einstein's theory was better than its inventor.

General relativity also allows time travel. This is another ridiculous prediction. Will it too turn out to be true? It has been suggested by Hawking that there is some chronology protection mechanism to prevent time travel - but such a mechanism has never been found. Solutions of the equations of general relativity with closed timelike curves (loops of time) do exist. They are very easy to write down mathematically. By cutting and pasting Minkowskii spacetime it is simple to construct flat time machines. The most common candidates for realistic time machinse are traversable wormholes, but all known wormhole solutions seem to require some form of negative energy to allow time travel. Much work has been done to  construct solutions using the most plausible sources of negative energy - or to be more precise they look for the least implausible sources of negative energy.

Speakers, Papers and links

I would like to add links to author's papers and home pages. We can add the papers afterwards if you want to maintain an element of surprise! However given the short duration of the talks, you might find it more effective to allow questions from an informed audience. Please email content to me.


Revised Schedule (22 July)

We have had one withdrawl. I have moved one talk forward and we have a schedule with a little bit of space. I intend to use this to allow extra questions if a talk attracts particular interest - it is not an invitation to squezze in an extra slide!


Mark Hadley Time machines and quantum theory (Slides 1.1 MB ppt)   Abstract  Slides 1.1MB  
Krasnikov, Serguei Withdrawn -    
Lobo, Francisco Traversable wormholes supported by cosmic accelerated expanding equations of state.  Abstract    
Gonzalez-Diaz, Pedro F. Wormholes in the accelerating Universe. Abstract Slides 1.3MB  
Adamiak, Jaroslaw  Static and Dynamic Traversable Wormholes.   (Full thesis 1.6MB pdf) Abstract Slides 110kB pdf  
de Felice, Fernando Naked singularities, time machines and impulsive events. Abstract    
Tea break

16:30 to 17:00

Mitskievich, Nikolai V. Nariai--Bertotti--Robinson spacetimes as a building material for one-way wormholes with horizons, but without singularity.  Abstract  Slides 300kB pdf  
Darabi, Farhad Classical and quantum wormholes in a $\Lambda$-decaying cosmology. Abstract  Slides 220kB  
Zannias, Thomas On Wormholes solutions of Einstein-Masless K-Theory.  Abstract    
Garattini, Remo Self sustained traversable wormholes? Abstract Slides 1.5MB  
Zaslavskii, Oleg N-spheres: regular black holes without apparent horizons, static wormholes with event horizons and gravastars with a tube-like core. Link to papers  Abstract Slides 240kB  
Osterbrink, Lutz  Averaged Energy Inequalities for Non-Minimally Coupled Classical Scalar Fields   Abstract    
Berrocal Arellano, Aaron Vicente Dynamic Wormhole spacetimes coupled to nonlinear electrodynamics. Abstract Slides 1MB