Evidence of universe expansion found

This image provided by Nasa shows the results from the Wilkinson Microwave Anisotropy Probe (WMAP). According to scientists WMAP has produced a new, more detailed picture of the infant universe. PHOTO: AP

The discovery which involves an analysis of variations in the brightness of microwave radiation is the first direct evidence to support the two-decade-old theory that the universe went through what is called inflation.

It also helps explain how matter eventually clumped together into planets, stars and galaxies in a universe that began as a remarkably smooth, superhot soup.

"It's giving us our first clues about how inflation took place," said Michael Turner, assistant director for mathematics and physical sciences at the National Science Foundation. "This is absolutely amazing."

Brian Greene, a Columbia University physicist, said: "The observations are spectacular and the conclusions are stunning."

Researchers found the evidence for inflation by looking at a faint glow that permeates the universe. That glow, known as the cosmic microwave background, was produced when the universe was about 300,000 years old long after inflation had done its work.

But just as a fossil tells a palaeontologist about long-extinct life, the pattern of light in the cosmic microwave background offers clues about what came before it. Of specific interest to physicists are subtle brightness variations that give images of the microwave background a lumpy appearance.

Physicists presented new measurements of those variations during a news conference at Princeton University. The measurements were made by a spaceborne instrument called the Wilkinson Microwave Anistropy Probe, or WMAP, launched by Nasa in 2001.

Earlier studies of WMAP data have determined that the universe is 13.7 billion years old, give or take a few hundred thousand years. WMAP also measured variations in the cosmic microwave background so huge that they stretch across the entire sky.