11 March 2005
Black Holes May Be "Hiding" The Ancient Universe
by Kate Melville

Researchers believe that black holes and their associated large gravity wells may be hindering our ability to ever locate the center of the universe. Multiple black holes and other massive objects can make the light beams bend in unexpected and unpredictable ways, say the researchers. "Any attempt to discover what was happening a long time ago at the beginning of our universe must take into account what gravitationally assisted negative refraction does to the radiation being viewed," says Akhlesh Lakhtakia, at Penn State University.

Both radio and visual astronomy rely on electromagnetic radiation which is affected by the material through which it travels. Materials with a negative index of refraction transmit light or other wave energy differently than those with a positive index of refraction. Natural materials have a positive index of refraction. When radiation - light, radar, microwaves - passes through water, glass or some other natural material, it displaces the beam in the same direction. A material with a negative index of refraction displaces the radiation in the opposite direction.

The researchers previously showed that no material is needed for negative refraction in outer space. Instead, when a beam passes through the gravitational field of a massive object such as a rotating black hole, negative refraction is theoretically possible. The influence of gravity caused by rotating black holes or other massive objects depends on where the observer is located. A local observer can only see a very small piece of the universal picture of how large gravitational forces influence electromagnetic radiation. To the local observer, gravity is uniform and does not cause negative refraction.

The paper, appearing in Physics Letters A, indicates that not only do the effects of the minute stuff of the universe have to be considered when mapping the universe, but the existence of large gravity wells must also be considered. "When we are tracking light, we must take into account gravitational forces," says Lakhtakia. "Although the effect is only significant very close to rotating black holes."

"We should not be disappointed if we cannot discover the origin of the universe," says Lakhtakia. "The gravitational effect probably makes it so that we do not really know where we are looking." On a more optimistic note, Lakhtakia and his collaborators at the University of Edinburgh believe science will eventually overcome many of the obstacles created by negative refraction that hinder our efforts to map the universe.