'Dark energy' expands, contracts universe: researchersMysterious "dark energy" works simultaneously to expand the universe and shrink objects inside it, astronomers in the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. said Tuesday. By studying how gravity competes with the expansion of galaxy clusters This page lists some of the more interesting galaxy clusters and groups. Defining the limits of galaxy clusters is imprecise as many clusters are still forming. In particular, clusters close to the Milky Way tend to be classified as galaxy clusters even when they are much smaller , scientists have found "a crucial independent test of dark energy," said the research compiled by scientists using NASA's Chandra X-ray Observatory Chandra X-ray Observatory U.S. X-ray space telescope. It was named after astrophysicist Subrahmanyan Chandrasekhar and was launched into orbit in 1999. Its mirror, with an aperture of 1.2 m (4 ft) and a focal length of 10 m (33 ft), produces unprecedented resolution. . "This result could be described as 'arrested development of the universe,'" said lead researcher Alexey Vikhlinin of the Smithsonian Astrophysical Observatory The Smithsonian Astrophysical Observatory (SAO) is a "research institute" of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). in the northeastern state of Massachusetts. "Whatever is forcing the expansion of the universe to speed up is also forcing its development to slow down." Dark energy makes up about 70 percent of the universe, said the research to be published in the February 10 issue of Astrophysical Journal. After years of research, scientists now believe that dark energy is "a form of repulsive gravity that dominates the universe, although they have no clear picture of what it actually is," the research report said. "What this means for the future of this universe is that accelerated expansion will proceed forever but will probably not result in a Big Rip," said Vikhlinin. "That is, nearby galaxies will eventually disappear from our sight, but the structures already formed by clusters of galaxies and our own galaxy will not be torn apart, not in the near future anyway." The research differed from previous studies on supernovas, which are the explosive deaths of massive stars, and provided the "strongest evidence yet that dark energy is the cosmological constant," he said, similar to the energy of empty space. "Or in other words Adv. 1. in other words - otherwise stated; "in other words, we are broke" put differently , that 'nothing weighs something,'" said Vikhlinin. The discovery of dark energy in 1998 sparked renewed interest in Albert Einstein's theory of cosmological constants, a modification of his theory of relativity theory of relativity Einstein’s contribution to the space-time relationship. [Science: NCE, 843–844] See : Turning Point which suggests a possible repulsive force in the universe. Einstein hypothesized that a repulsive force in space could explain the universe's equilibrium with the force of gravity. Without such a contrary force, gravity would cause the universe to implode To link component pieces to a major assembly. It may also refer to compressing data using a particular technique. Contrast with explode. , Einstein suggested. 
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