[ninty]

[quote:52ead]Instead of contracting the space around it, as ordinary matter does, antigravity—or negative energy, as it is sometimes called—pushes it apart. In theory, antigravity would be placed inside a wormhole's throat, opening it wide enough for an astronaut, or possibly even a spaceship, to pass through. Antigravity does the trick; the problem is finding it. Einstein first postulated the existence of antigravity on cosmic scales in 1915, a conjecture proven correct eight decades later. But Einstein's antigravity is wispy and dilute, a spoonful of sugar dissolved in the Pacific Ocean. Opening a wormhole requires a regular torrent of antigravity.
[/quote:52ead]

http://www.popsci.com/popsci/science/ar ... -2,00.html

Try this article too:

http://abcnews.go.com/sections/scitech/ ... 20306.html