Generally, scientists prefer to avoid the concept of perpetual motion. The idea of a machine that could produce movement that goes on forever, and using that movement to generate an endless stream of energy, is usually considered more science fiction than science. But recently, physicist Pavel Ivanov has investigated previous speculation that an exotic fluid with unusual properties could cause energy to flow continuously between different regions of space, resulting in a runaway transfer of energy. If an advanced civilization were able to construct a device to capture this energy, it might finally possess its own “perpetuum mobile” — or perpetual motion.
Or, you know, create a convenient wormhole:
The problem of how to keep the mouth of a wormhole open has been hideously difficult to resolve in mathematical detail, but is quite easily stated in physical terms: Gravity sucks! Any kind of normal matter or energy will tend to collapse under its own gravitational attraction unless something else stops it. Similarly, the mouth of a wormhole will pinch off in nothing flat under normal circumstances.
So, the trick is to get rid of the normal circumstances. In recent years, the Caltech physicist Kip Thorne, among others, has argued that the only way to keep wormholes open is to thread them with “exotic material.” By this is meant material that will be measured, at least by certain observers, to have “negative” energy. As you might expect (although naive expectations are notoriously suspect in general relativity), such material would tend to “blow” not “suck,” as far as gravity is concerned.
(from The Physics of Star Trek, of course)