By Xinhua
Washington : NASA, the U.S. space agency, released on Friday five years of data collected by the Wilkinson Microwave Anisotropy Probe (WMAP), which include three major findings about the universe.
The probe got the new evidence that a sea of cosmic neutrinos permeates the early universe. According to the scientists’ analysis, universe is awash in “a sea of cosmic neutrinos”. Neutrinos made up a much larger part of the early universe than they do today.
Microwave light seen by WMAP from when the universe was only 380,000 years old shows that, at the time, neutrinos made up 10 percent of the universe, atoms 12 percent, dark matter 63 percent, photons 15 percent, and dark energy was negligible. In contrast, estimates from WMAP data show the current universe consists of 4.6percent atoms, 23 percent dark matter, 72 percent dark energy and less than 1 percent neutrinos.
Another breakthrough derived from WMAP data is clear evidence the first stars took more than a half-billion years to create a cosmic fog. The data provide crucial new insights into the end of the “dark ages,” when the first generation of stars began to shine. The glow from these stars created a thin fog of electrons in the surrounding gas that scatters microwaves, in much the same way fog scatters the beams from a car’s headlights.
“We now have evidence that the creation of this fog was a drawn-out process, starting when the universe was about 400 million years old and lasting for half a billion years,” said WMAP team member Joanna Dunkley of the University of Oxford in Britain.
A third major finding arising from the new WMAP data places tight constraints on the astonishing burst of growth in the first trillionth of a second of the universe, called “inflation”, when ripples in the very fabric of space may have been created. Some versions of the inflation theory now are eliminated. Others have picked up new support.
Prior to the release of the new five-year data, WMAP already had made a pair of landmark finds. In 2003, the probe’s determination that there is a large percentage of dark energy in the universe erased remaining doubts about dark energy’s very existence. That same year, WMAP also pinpointed the 13.7 billion year age of the universe.
Launched on June 30, 2001, WMAP is a NASA Explorer mission named in honor of David Wilkinson of Princeton University, a world-renown cosmologist and WMAP team member who died in September 2002.