Scientists predict how to detect a fourth dimension of space

From:
http://www.eurekalert.org/pub_releases/2006-05/du-sph052506.php

DURHAM, N.C. -- Scientists at Duke and Rutgers
universities have developed a mathematical framework they
say will enable astronomers to test a new five-dimensional
theory of gravity that competes with Einstein's General
Theory of Relativity.

Charles R. Keeton of Rutgers and Arlie O. Petters of Duke
base their work on a recent theory called the type II
Randall-Sundrum braneworld gravity model. The theory holds
that the visible universe is a membrane (hence
"braneworld") embedded within a larger universe, much like
a strand of filmy seaweed floating in the ocean. The
"braneworld universe" has five dimensions -- four spatial
dimensions plus time -- compared with the four dimensions
-- three spatial, plus time -- laid out in the General
Theory of Relativity.

The framework Keeton and Petters developed predicts
certain cosmological effects that, if observed, should
help scientists validate the braneworld theory. The
observations, they said, should be possible with
satellites scheduled to launch in the next few years.

If the braneworld theory proves to be true, "this would
upset the applecart," Petters said. "It would confirm that
there is a fourth dimension to space, which would create a
philosophical shift in our understanding of the natural
world."

The scientists' findings appeared May 24, 2006, in the
online edition of the journal Physical Review D. Keeton is
an astronomy and physics professor at Rutgers, and Petters
is a mathematics and physics professor at Duke. Their
research is funded by the National Science Foundation.

The Randall-Sundrum braneworld model -- named for its
originators, physicists Lisa Randall of Harvard University
and Raman Sundrum of Johns Hopkins University -- provides
a mathematical description of how gravity shapes the
universe that differs from the description offered by the
General Theory of Relativity.

Keeton and Petters focused on one particular gravitational
consequence of the braneworld theory that distinguishes it
from Einstein's theory.

The braneworld theory predicts that relatively small
"black holes" created in the early universe have survived
to the present. The black holes, with mass similar to a
tiny asteroid, would be part of the "dark matter" in the
universe. As the name suggests, dark matter does not emit
or reflect light, but does exert a gravitational force.

The General Theory of Relativity, on the other hand,
predicts that such primordial black holes no longer exist,
as they would have evaporated by now.