In the largest galaxy survey ever, the Sloan Digital Sky Survey (SDSS) confirmed the role of gravity in growing structures in the universe, using the result to precisely measure the geometry of the universe, eurekalert.com said.
The SDSS researchers from the University of Arizona, New York University, the University of Portsmouth (UK), the University of Pittsburgh and the Massachusetts Institute of Technology, detected ripples in the galaxy distribution made by sound waves generated soon after the Big Bang.
"These sound waves left their imprint in the Cosmic Microwave Background, remnant radiation from the Big Bang seen when the universe was 400,000 years old," lead investigator Daniel Eisenstein of the University of Arizona said.
Ripples as yardsticks the early universe was smooth and homogenous, quite a contrast from the clumpy array of galaxies and clusters of galaxies observed today.
The galaxies we see today consist of ordinary matter, made up of the atoms of our familiar world. However, astronomers have long known that there is roughly five times more 'dark matter' than ordinary or 'baryonic' matter. Understanding how gravity causes the clumps that will become galaxies and clusters of galaxies to grow as the universe expands requires studying the interaction between ordinary and dark matter.
"In the early Universe, the interaction between gravity and pressure caused a region of space with more ordinary matter than average to oscillate, sending out waves very much like the ripples in a pond when you throw in a peeble," explains SDSS scientist and co-author Bob Nichol, an astrophysicist at the Institute of Cosmology & Gravitation at the University of Portsmouth (UK), the most recent institution to join the SDSS collaboration.

A study of more than 1 million South Koreans suggests diabetes can raise the risk of developing and dying from several types of cancer, including digestive-tract tumors, ABC News said.
This is not the first study to suggest such a link, but it sheds more light on exactly how diabetes might contribute to cancer.
Diabetes is often linked to obesity, and obesity is known to increase the risk of cancer. Yet few of the study participants were overweight, so the researchers think high blood sugar levels another hallmark of diabetes might also be involved.
The highest risks for developing cancer and dying from it were found in people with the highest blood sugar levels, the South Korean researchers found.
Researchers analyzed data on 1.29 million South Korean men and women ages 30 to 95 who received health insurance from a group that covers government employees, teachers and their families. Participants were followed for up to 10 years starting in 1992.
About 5 percent of the participants had diabetes. A total of 26,473 participants died of cancer during the follow-up.
Participants with diabetes were roughly 30 percent more likely than those without to develop and die from cancer. The highest risks were for cancer of the pancreas, the organ that produces blood sugar-regulating insulin. Diabetes involves inadequate production or use of insulin.
Increased risks also were seen for cancers of the liver, esophagus and colon.
Data suggest in South Korea that an estimated 3.9 percent of cancer deaths in men and 0.8 percent of cancer deaths in women are attributable to diabetes a modest portion partly attributable to the low prevalence of diabetes in South Korea.

Symptoms of anxiety may speed the progression of certain physical disabilities in older women, new research suggests.
According to Reuters, the study of 1,000 women with physical limitations such as trouble walking or performing other daily routines found that those who reported at least two anxiety symptoms at the outset were at greater risk of their disability worsening over the next 3 years.
Frequent anxiety symptoms -- such as feeling nervous, tense, "shaky" or fearful -- were linked to a 41 percent higher risk of deterioration in what researchers refer to as activities of daily living. These include the basic routines of getting out of bed, bathing, dressing and eating.
Women with two or more anxiety symptoms were also more likely to develop problems doing light housework, according to findings published in the Journal of the American Geriatrics Society.
Dr. Gretchen A. Brenes of Wake Forest University School of Medicine in Winston-Salem, North Carolina, led the study.
Brenes and her colleagues followed 1,002 women age 65 or older who started the study with limitations such as difficulty walking more than a short distance, limited mobility in their arms, and problems with bathing and other everyday routines.
The women completed standard measures of anxiety and depression symptoms at the study's start. Nineteen percent said they had frequently had two or more anxiety symptoms over the previous week, and were considered to be suffering from anxiety.
Overall, Brenes and her colleagues found, these women were more likely than their less anxious peers to have worsening problems with daily activities and light housework over the next three years.
This link was independent of depression, which has been implicated in disability, and of any use of medications called benzodiazepines--sedatives that can have adverse health effects, including raising the risk of falls and bone fractures.