Mysterious energy: We may not know what it is, but dark energy is busy expanding and contracting our universe, researchers say.
Credit: NASA/CXC/SAO/A.Vikhlinin et al.
WASHINGTON: Mysterious dark energy works simultaneously to expand the universe and shrink objects inside it, astronomers have found.
"This result could be described as 'arrested development of the universe'... Whatever is forcing the expansion of the universe to speed up is also forcing its development to slow down," said Alexey Vikhlinin of the Smithsonian Astrophysical Observatory in Massachusetts.
Vikhlinin was the lead researcher of the study, to be published next year in the Astrophysical Journal.
A galaxy torn apart?
By studying how gravity competes with the expansion of galaxy clusters, using NASA's Chandra X-ray Observatory, "a crucial independent test of dark energy" has been found, said the researchers.
After years of research, scientists now believe that dark energy makes up about 70 per cent of the universe, and is "a form of repulsive gravity that dominates the universe," the researchers wrote, "although [we] have no clear picture of what it actually is."
The discovery of dark energy's dual effects of expansion and contraction sheds light on changes in the universe to come: "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."
"Nothing weighs something"
The new research provides the "strongest evidence yet that dark energy is the cosmologicalconstant," Vikhlinin said, being similar to the energy of empty space. "Or in other words, that 'nothing weighs something."
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 which suggests a possible repulsive force in the universe.
Einstein hypothesised 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, Einstein suggested.
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