Maggie McKee in New Scientist:
Would-be wormhole travellers may have to choose between danger and unpredictability for their journeys through space-time, a new study suggests. The research may spell doom for time machines, but it suggests the universe will survive to a ripe old age instead of being ripped apart by a particularly repulsive form of dark energy.
As fans of science fiction know, wormholes provide short-cuts through space and time, sucking in objects at one end and spitting them out at the other. The distance from one point to the other would be much shorter than conventional travel across the universe.
A useful analogy in helping to visualise the wormhole phenomenon is to imagine a sheet of paper – which represents the universe – which is then folded neatly in half. Next, near the edge furthest from the fold, a pin is pushed through the paper. This creates a “wormhole” connecting two distant points in the universe…
More here.