March 16, 2006
NASA Probe Peers Back to an Instant after Big Bang
By Deborah Zabarenko
WASHINGTON -- A NASA space probe has peered back in time to a bare instant -- less than a trillionth of a trillionth of a second -- after the Big Bang, astronomers reported on Thursday.
The robotic probe looked at the afterglow from the Big Bang, the energetic event scientists believe gave birth to the universe some 13.7 billion years ago, and managed to discern unprecedented detail about the earliest moments of the cosmos.
"We report today the most precise measurements of our infant universe," said Charles Bennett, principle investigator for NASA's WMAP spacecraft.
"We have new evidence that the universe suddenly grew from sub-microscopic to astronomical size in less than the blink of an eye," Bennett said at a telephone news conference. "This tremendous inflation of the universe happened in much less than a trillionth of a second."
The WMAP mission -- short for Wilkinson Microwave Anisotropy Probe -- detected light created in the early universe that has been traveling across the universe for more than 13 billion years, he said.
Seen in the form of faint microwaves, this early light helped astronomers perceive tiny variations in what Bennett called "an otherwise astonishingly empty sea of nothingness" that was the baby universe.
Back then, there were no planets, no stars, no galaxies, nothing but infinitesimal differences in temperature.
COSMIC GROWTH SPURT
It may have seemed empty, but these tiny temperature differences formed patterns that eventually clumped into all the physical features we know as matter, including Earth and everything on it.
WMAP's current picture of the neonatal universe looks like a flat oval with cool spots shown in blue and green and hot spots in red and yellow. White lines show polarization -- the direction of the oldest light.
The probe's observations show, in the most basic terms, the contents of the universe. Only about 4 percent of it is ordinary matter, with 22 percent composed of so-called dark matter -- which is not made of atoms, doesn't emit or absorb light and is only detected by its gravity -- and 74 percent made up of a mysterious dark energy, which scientists believe is making the universe expand now.
"Dark energy is causing yet another current growth spurt," Bennett said. "Fortunately, it is more gentle than the one 13.7 billion years ago."
Three years ago, WMAP scientists reported the age of the universe at 13.7 billion years and said the stars first began to shine about 200 million years after the Big Bang. The latest observations confirm the universe's age but change the estimate of when the first stars shone -- astronomers currently believe this happened 400 million years after the Big Bang.
The WMAP probe, an ungainly looking craft about the size of a minivan, was launched in 2001 from Cape Canaveral. Now about 1 million miles away from Earth, the probe's mission is expected to continue through September 2009.
Images and more information are available online at http://wmap.gsfc.nasa.gov/results.