'Baby pic' shows cosmos 13 billion years ago
WASHINGTON (CNN) -- Our universe is about 13.7 billion years old, flat, composed almost entirely of matter and energy that scientists still don't completely understand -- and will continue to expand forever, according to a new "baby picture" of the early universe captured by a NASA satellite.
Scientists from NASA and Princeton University Tuesday unveiled the first results from the Wilkinson Microwave Anisotropy Probe, of WMAP, terming them a revolutionary "turning point" in understanding how the universe formed and evolved.
"Every astronomer will remember when they first heard the results from WMAP," said Dr. John Bahcall of Princeton's Institute for Advanced Study. "The announcement ... represents a rite of passage for cosmology from speculation to precision science."
In June 2001, NASA launched the WMAP satellite, a joint project of the space agency and Princeton. The $145 million observatory has been orbiting about 1 million miles above Earth, measuring microwave radiation that has traveled 13 billion light years and was generated just 380,000 years after the Big Bang that scientists theorize started the universe.
By measuring temperature variations in the microwaves, down to a millionth of a degree, scientists on the WMAP team were able to create a picture of the early universe, before galaxies and stars were even formed.
With those findings, scientists were able to make the most precise calculations yet about the age and make-up of the universe, including:
-- The universe formed about 13.7 billion years ago, give or take about 200 million years.
-- Only about 4 percent of the universe is composed of atoms -- the "ordinary matter" making up the physical universe we know. About 23 percent is "cold, dark matter," about which scientists know little, and 73 percent is "exotic dark energy," about which they know even less.
-- The first stars were "turned on" within about 200 million years of the "big bang" -- much earlier than scientists had previously believed.
-- The geometry of the universe is flat, and WMAP's measurements support an "inflation" model, which holds that the universe formed with the "big bang" and expanded rapidly over a short period of time, before slowing to the rate of expansion seen today.
That expansion will continue, said Dr. Charles Bennett of NASA's Goddard Space Flight Center.
"The universe will expand forever. It will not turn back on itself and collapse in a great crunch," he said.
The data from WMAP fits with conclusions drawn from other investigations of the early universe, including observations by the Hubble telescope and the Cosmic Background Explorer, which was sent up a decade ago to study the universe's origins.
The "baby picture" of the universe was made possible by discoveries in the 1960s of faint, uniform radiation emanating from deep space and reaching Earth nearly 14 billion years after it was generated by the Big Bang. The radiation can be more accurately measured with satellites in distant space than it can on Earth.
By measuring the temperature patterns of the radiation, scientists can map these "anisotropic" differences and compare them to what they would expect to find with various theories about the origins of the universe, a process NASA scientists compared to fingerprint analysis.
Bahcall's analogy of the process: If the current universe is a 50-year-old man, what WMAP scientists have been able to do is accurately measure his weight when he was just 12 hours old.
NASA officials announced Tuesday that they had named the satellite for David Wilkinson, a Princeton cosmologist who worked on WMAP and died in September.