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LOS ANGELES, July 22 (Xinhua) -- Two teams of astronomers have discovered the largest and farthest reservoir of water ever detected in the universe, NASA's Jet Propulsion Laboratory (JPL) said on Friday.The water, equivalent to 140 trillion times all the water in the world's ocean, surrounds a huge, feeding black hole, called a quasar, more than 12 billion light-years away, according to JPL in Pasadena, California."The environment around this quasar is very unique in that it's producing this huge mass of water," said Matt Bradford, a scientist at JPL. "It's another demonstration that water is pervasive throughout the universe, even at the very earliest times. "This artist's concept illustrates a quasar, or feeding black hole, similar to APM 08279+5255, where astronomers discovered huge amounts of water vapor. Gas and dust likely form a torus around the central black hole, with clouds of charged gas above and below. X-rays emerge from the very central region, while thermal infrared radiation is emitted by dust throughout most of the torus. While this figure shows the quasar's torus approximately edge-on, the torus around APM 08279+5255 is likely positioned face-on from our point of view.A quasar is powered by an enormous black hole that steadily consumes a surrounding disk of gas and dust. As it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.Astronomers expected water vapor to be present even in the early, distant universe, but had not detected it this far away before. There's water vapor in the Milky Way, although the total amount is 4,000 times less than in the quasar, because most of the Milky Way's water is frozen in ice. Water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light-years in size (a light-year is about six trillion miles).Its presence indicates that the quasar is bathing the gas in X- rays and infrared radiation, and that the gas is unusually warm and dense by astronomical standards, JPL said.Although the gas is at a chilly minus 63 degrees Fahrenheit ( minus 53 degrees Celsius) and is 300 trillion times less dense than Earth's atmosphere, it's still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way, said JPL.Measurements of the water vapor and of other molecules, such as carbon monoxide, suggest there is enough gas to feed the black hole until it grows to about six times its size, JPL said.Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or might be ejected from the quasar.Bradford's team made their observations starting in 2008, using an instrument called "Z-Spec" at the California Institute of Technology's (Caltech's) Submillimeter Observatory, a 33-foot (10- meter) telescope near the summit of Mauna Kea in Hawaii. Follow-up observations were made with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes in the Inyo Mountains of Southern California.The second group, led by Dariusz Lis, senior research associate in physics at Caltech and deputy director of the Caltech Submillimeter Observatory, used the Plateau de Bure Interferometer in the French Alps to find water. In 2010, Lis's team serendipitously detected water in APM 8279+5255, observing one spectral signature.Bradford's team was able to get more information about the water, including its enormous mass, because they detected several spectral signatures of the water, according to JPL.

BEIJING, July 26 (Xinhuanet) -- Hong Kong scientists announced that they had determined the idea of time travel is impossible by proving nothing can travel faster than the speed of light.The finding is contained in a study done by a research team from Hong Kong University of Science and Technology. The study was published Monday in a scientific journal "Physical Review Letters" in the United States."The study, which showed that single photons also obey the speed limit c, confirms Einstein's causality, that is, an effect cannot occur before its cause," the university said on its website."By showing that single photons cannot travel faster than the speed of light, our results bring a closure to the debate on the true speed of information carried by a single photon." said Professor Du Shengwang, who led the study.The possibility of time travel was raised 10 years ago when scientists discovered the optical pulses in some specific medium might propagate information in a faster-than-light speed."Our findings will also likely have potential applications by giving scientists a better picture on the transmission of quantum information." Du said.

BEIJING, Aug. 22 (Xinhuanet) -- U.S. presidential candidate Rick Perry's controversial stem-cell treatment may inspire desperate patients to follow his lead while causing medical and legal concerns, according to media reports Monday.The Texas governor underwent a procedure on July 1 where stem cells, made from fat taken from his body, were put into his bloodstream to see if they might find their way to fix a bad back.The treatment carries potential risks ranging from blood clots to infection to cancer and may even run afoul of federal rules, doctors say. File photo of U.S. Republican presidential candidate Texas Governor Rick Perry."As a highly influential person of power, Perry’s actions have the unfortunate potential to push desperate patients into the clinic of quacks,” Harvard’s stem cell expert George Daley told the Associated Press.Worries about the safety and wisdom of this treatment are widespread among stem cell researchers as such a treatment has not been thoroughly vetted by researchers or approved by the FDA.

PARIS, Aug. 19 (Xinhua) -- Marine scientists and representatives from the private sector and military establishments would meet at UNESCO at the end of this month to measure noise's impact on marine life, the Paris-based UN scientific branch UNESCO said Friday.The main agenda of the meeting, which is due from Aug. 30 to Sep. 1, was to discuss the program of the International Quiet Ocean Experiment (IQOE)."This decade-long project aims to fill the considerable knowledge gaps in this area, so that management of ocean noise can be more informed and effective," UNESCO said in a statement.The Quiet Ocean Experiments was initiated against the background that human activities on the high seas have increased significantly in recent decades, and resulted in impact upon many marine species relying mainly on sound to communicate.However, some sounds are suspected to alter the behavior of marine animals. For example, several whale species have raised the volume of the squeaks, clicks and moans by which they communicate with each other.The experiment is organized by the Scientific Committee on Oceanic Research (SCOR) and the Partnership for Observation of the Global Oceans (POGO), of which UNESCO's Intergovernmental Oceanographic Commission (IOC) is a member.

SAN FRANCISCO, Aug. 2 (Xinhua) -- Social networking giant Facebook on Tuesday announced that it has bought Push Pop Press, a digital publishing company that develops the technology to help make interactive books optimized for iPad and other Apple devices."We're thrilled to confirm that we've acquired Push Pop Press, a startup whose groundbreaking software changes the way people publish and consume digital content," Facebook said in a statement.Push Pop Press was co-founded by Mike Matas and Kimon Tsinteris, both former Apple employees, and was known for teaming up with former U.S. vice president Al Gore to create a digital version of his book "Our Choice"."Although Facebook isn't planning to start publishing digital books, the ideas and technology behind Push Pop Press will be integrated with Facebook, giving people even richer ways to share their stories," Push Pop Press said in a statement posted on its website."With millions of people publishing to Facebook each day, we think it's going to be a great home for Push Pop Press," the statement added.Financial terms of the deal were not disclosed by the two companies.

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