ARLINGTON, Va., May 23 (UPI) -- New findings lend even more evidence that the universe as we know it began not only with a Big Bang, but also a superbrief but superpowerful outward push by a mysterious phenomenon called inflation, scientists reported Friday.
Data collected by the Cosmic Background Imager observatory of tiny variations in the universe's background radiation represent the finest detail yet seen of what CBI astronomers call "the seeds of the first galaxies." The data seem to confirm what cosmological theories have been predicting for years -- exquisitely small inconsistencies in the expanding fireball of the early universe resulted in all the stars, galaxies, galaxy clusters and superclusters that exist today.
"It is the earliest visible signal we can see from the Big Bang," said Anthony Readhead, professor of astronomy at the California Institute of Technology in Pasadena and head of the CBI project. CBI is a collaboration among several universities and agencies in the United States, Canada and Chile. It is funded jointly by Caltech and the National Science Foundation.
"For the first time, we are seeing the seeds of galaxy clusters, and this for the first time places theories for the formation of galaxies on a firm observational footing," Readhead said. "There were very, very small fluctuations in the density of matter, and those tiny fluctuations ... are what have caused the formation of all structure in the universe -- clusters of galaxies, galaxies, stars and planets."
The variations emerged because of a fundamental property called quantum fluctuation. At the subatomic scale, the laws of physics become strange and unpredictable, so much so that no aggregation of matter or energy -- such as the background radiation -- can develop in a uniform way.
"Those fluctuations in (matter) density are mirrored in the cosmic microwave background by fluctuations in temperature," Readhead explained.
CBI, actually a bunch of 13 small radio telescope dishes, is located in the Chilean Andes. At an elevation of 16,700 feet, it is the highest observatory in the world -- so high that the dishes must be completely enclosed in a dome to protect scientists and staff from the harsh surrounding environment. Anyone working with the instrument or doing "careful thought" is required to breathe bottled oxygen, Readhead explained.
The high altitude is necessary, Readhead told reporters at a news conference, because water vapor from the lower atmosphere corrupts the radiation signals CBI collects.
The signals provide temperature readings of the faint background radiation that represents the dying embers of the Big Bang, the primordial fireball from which, theory describes, the universe sprung into existence some 14 billion years ago. Cosmic background radiation originated about 300,000 years after that event, at a time when the temperature of the fireball had cooled to about 4,000 degrees Fahrenheit -- cool enough to produce the first photons carrying microwave energy.
Ten years ago, a spacecraft called the Cosmic Background Explorer or COBE first detected slight temperature variations in the background radiation. CBI -- a ground-based instrument much larger than COBE -- has a resolution capability 10 times greater. Each night, it scans a patch of sky about the size of the Moon and breaks up that area into about 100 separate images.
"It's this very high resolution which has enabled us to make these new studies," Readhead said. The resolution is so great that CBI can pick up radiation temperature variations on the order of only a few 10-millionths of a degree.
Yet the temperature variations are completely consistent with equally tiny variations in the early universe's matter density, he explained. The hotter temperature regions coincide with denser matter regions, which over billions of years went on to form clusters of galaxies.
CBI's improved resolution is important, Readhead continued, because scientists can use it to "determine a number of fundamental properties in the universe," such as its geometry, size and age, matter content, and evidence for the mysterious and as-yet-unobserved "dark matter" and "dark energy," which scientists now believe comprise up to 95 percent of the universe.
Using CBI's data, Readhead said, "we can also address interesting questions like 'are the observations consistent with the theory of inflation?'"
John Mather, of NASA's Goddard Space Flight Center in Greenbelt, Md., said analysis of the data collected by CBI "agreed so extraordinarily precisely" with theoretical predictions "that people were astonished. Almost everyone had a gut feeling it couldn't be that perfect."
Mather, who headed the COBE project for NASA, said until the spacecraft presented images showing variations in the background radiation, there were no observations linking the Big Bang to the structure of the present-day universe. "The interpretation at the time was these (variations) had to exist but we had never found them," he said, "so we did have some doubts about the Big Bang."
Alan Guth, professor of physics at the Massachusetts Institute of Technology, said the fluctuations detected by CBI are "an important tool for testing theories of cosmology. In particular, I am very excited about the current experiment because of the ability it has to test the predictions of inflation." So far, he said, "and ... wonderfully, those tests seem to turn out positive."
Guth was one of the originators of inflation theory, which suggests spacetime itself underwent an extremely rapid expansion at the dawn of the universe for an incredibly small fraction of a second. That expansion occurred faster than the speed of light and was powerful enough to draw out the universe to its present size of tens of billions of light-years across. It also allowed all visible matter, plus dark matter and dark energy, to pour in.
"Basically, you should think of inflation as an add-on to the Big Bang theory," Guth explained. "It only changes the first tiny fraction of a second in the scenario and all the rest of the conventional Big Bang theory is left intact. But nonetheless, this first tiny fraction of a second is very important."
