Sunday, February 20, 2005
Leaky Universe
The speeding up of the universe may be caused by gravitational leaks, says Georgi Dvali, physicist at New York University. Dvali believes that gravity leaks out into extra space dimensions like water from a strainer. The depleted gravity then exerts less pull on stars and galaxies and allows them fly apart from each other. "The cosmic acceleration of the universe indicates that the laws of General Relativity get modified not only at very short but also at very large distances," Dvali says. "It is this modification, and not dark energy, that is responsible for the accelerated expansion of the universe." Dark energy is the mysterious force currently considered the most likely culprit behind the speeding up of the universe.
The stuff that's leaking out are gravitons. They are theoretical messenger particles of the gravitational force predicted by the string theory. That's a unified theory of the universe, which says that nature is made of one-dimensional filaments called strings. The string theory also postulates that space has more than three dimensions. "Virtual gravitons exploit every possible route between the objects, and the leakage opens up a huge number of multidimensional detours, which bring about a change in the law of gravity," he says.
One problem with gravitons: so far, no one has been able to find one.
The stuff that's leaking out are gravitons. They are theoretical messenger particles of the gravitational force predicted by the string theory. That's a unified theory of the universe, which says that nature is made of one-dimensional filaments called strings. The string theory also postulates that space has more than three dimensions. "Virtual gravitons exploit every possible route between the objects, and the leakage opens up a huge number of multidimensional detours, which bring about a change in the law of gravity," he says.
One problem with gravitons: so far, no one has been able to find one.
