Article Posted on : - Mar 29, 2010

The galaxy cluster Abell 85. This galaxy cluster is one of 86 observed by Chandra X-ray Observatory to trace how dark energy has stifled the growth of these massive structures over the last 7 billion years. NASA photo

HYDERABAD (PTI): Astronomers have confirmed the mysterious dark energy as the most comprehensive evidence yet for the accelerated expansion of the universe, based on a study of nearly half a million galaxies using the Hubble Space Telescope (HST).

They mapped the matter distribution and the expansion history of the universe to conclude that the universe was indeed expanding faster and faster with time, a B M Birla Science Centre release said here on Sunday.

"Our results confirmed that there is an unknown source of energy in universe which is causing the cosmic expansion to speed up," leading astronomer Ludovic Van Waerbeke of Leiden University in the Netherlands is quoted having said in the press note.

Till 1997, the accepted model of the universe was that assisted by some unknown substance called dark matter, the universe is actually slowing down as it expands. It was believed that ultimately the universe would halt and possibly collapse.

The identity of dark matter itself was anybody's guess.

It could have been black holes or exotic particles or unseen stars called brown dwarfs. This was called the Standard Bib Bang Model, the release said.

The breakthrough published in the American Science magazine recently has been supported by two observational surveys called the Wilkinson Microwave Anisotropy and Sloan Digital Sky Survey.
But early that year, Dr B G Sidharth, Director of the B M Birla Science Centre proposed an opposite theory -- that pushed by a mysterious force called dark energy, the universe was accelerating.

Early last century Einstein proposed a force called cosmic repulsion so that the universe would not collapse, but soon dismissed it as his greatest blunder when it was discovered shortly thereafter that the universe was expanding, the release said.

The latest finding from the HST is the most comprehensive to date confirming this paradigm shift in science, it said.