Sound waves in the embryonic Universe are revealed for the first time in this image captured by the BOOMERANG balloon-borne telescope during its maiden voyage around the Antarctic. The patterns visible in the image are consistent with those that would result from sound waves racing through the early universe, creating the structures that by now have evolved into giant clusters and super-clusters of galaxies. The image records the intense heat that filled the universe just after the Big Bang, which is still present today as a faint glow of microwave radiation that fills the sky. Photo: UCSB

An international team of cosmologists has released the first detailed images of the universe in its infancy. The images reveal the structure that existed in the universe when it was a tiny fraction of its current age and 1,000 times smaller and hotter than it is today. Detailed analysis of the images is already shedding light on some of cosmology's outstanding mysteries -- the nature of the matter and energy that dominate intergalactic space and whether space is "curved" or "flat."

The project, dubbed BOOMERANG (Balloon Observations of Millimetric Extragalactic Radiation and Geophysics), obtained the images using an extremely sensitive telescope suspended from a balloon that circumnavigated the Antarctic in late 1998. The balloon carried the telescope at an altitude of almost 120,000 feet (37 kilometers) for 10 1/2 days. The results will be published in the April 27 issue of Nature.

Today, the universe is filled with galaxies and clusters of galaxies. But 12 to 15 billion years ago, following the Big Bang, the universe was very smooth, incredibly hot and dense. The intense heat that filled the embryonic universe is still detectable today as a faint glow of microwave radiation visible in all directions. This radiation is known as the cosmic microwave background (CMB). Since the CMB was first discovered by a ground-based radio telescope in 1965, scientists have eagerly sought to obtain high-resolution images of this radiation. NASA's Cosmic Background Explorer satellite discovered the first evidence for structures, or spatial variations, in the microwave background in 1991.

The image records the intense heat that filled the universe just after the Big Bang, which is still present today as a faint glow of microwave radiation that fills the sky. The first evidence of structure in this Cosmic Microwave Background (CMB) was found in 1991 by NASA's Cosmic Background Explorer (COBE) satellite, which mapped the entire sky with high sensitivity but coarse angular resolution (upper left). The BOOMERANG image covers approximately 2.5 percent of the sky with angular resolution 35 times that of COBE, revealing hundreds of complex structures that are visible as tiny variations -- typically only 100 millionths of a degree (0.0001 C) -- in the temperature of the CMB. Detailed analysis of this image will determine the geometry of the universe to high precision, and will shed light on the nature of the matter and energy that fill the Universe. Photo: UCSB

The BOOMERANG images are the first to bring the cosmic microwave background into sharp focus. The images reveal hundreds of complex regions visible as tiny variations -- typically only 100-millionths of a degree Celsius (0.0001 C) -- in the temperature of the CMB. The complex patterns visible in the images confirm predictions of the patterns that would result from sound waves racing through the early universe, creating the structures that by now have evolved into giant clusters and super-clusters of galaxies.

"The structures in these images predate the first star or galaxy in the universe," said U.S. team leader Andrew Lange of the California Institute of Technology, Pasadena. "It is an incredible triumph of modern cosmology to have predicted their basic form so accurately."

Italian team leader Paolo deBernardis of the University of Rome La Sapienza added: "It is really exciting to be able to see some of the fundamental structures of the universe in their embryonic state. The light we have detected from them has traveled across the entire universe before reaching us, and we are perfectly able to distinguish it from the light generated in our own galaxy."

The BOOMERANG images cover about 3 percent of the sky. The team's analysis of the size of the structures in the cosmic microwave background has produced the most precise measurements to date of the geometry of space-time, which strongly indicate that the geometry of the universe is flat, not curved. This result is in agreement with a fundamental prediction of the "inflationary" theory of the universe. This theory hypothesizes that the entire universe grew from a tiny subatomic region during a period of violent expansion occurring a split second after the Big Bang. The enormous expansion would have stretched the geometry of space until it was flat.

The BOOMERANG telescope being readied for launch. With Mt. Erebus as a backdrop, NASA/NSBF personnel inflate the 28 million cubic foot balloon which will carry the BOOMERANG telescope on its 10 day trip around the Antarctic continent. Photo: UCSB

NASA's National Scientific Balloon Facility was instrumental in flying the giant helium balloon that carried the instruments above the earth's atmosphere. The National Science Foundation (NSF), which provides logistic support for all U.S. scientific operations in Antarctica, facilitated the launch near McMurdo Station and recovery of the payload after the flight. The constant sunshine and prevailing winds at high altitudes in Antarctica were essential to maintaining a stable long-duration balloon flight for the BOOMERANG project. The balloon, with a volume of 28 million cubic feet (800,000 cubic meters), carried the two-ton telescope 5,000 miles (8,000 km) and landed within 31 miles (50 km) of its launch site.

The 36 team members are from 16 universities and organizations in Canada, Italy, the United Kingdom and the United States. Primary support for the BOOMERANG project comes from NSF and NASA in the United States; the Italian Space Agency, Italian Antarctic Research Programme and the University of Rome La Sapienza in Italy; and the Particle Physics and Astronomy Research Council in the United Kingdom. The Department of Energy's National Energy Research Scientific Computing Center provided supercomputing support in the United States.