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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, Sept. 27 (Xinhuanet) -- Last-minute preparations for the launch of the Tiangong-1 spacecraft began at the Jiuquan Satellite Launch Center on Monday, meaning the vehicle can soon embark on a mission that will eventually have it dock with a spaceship, according to the center.That feat, if carried out successfully, will mark the completion of China's first rendezvous and docking mission.At the launch site on Monday afternoon, crews were putting in place pipes and cables that will be used to inject fuel into the rocket that will carry Tiangong-1 into outer space.Without complications from the weather or other causes, the Long March II-F rocket will lift off from the launch center on Thursday or Friday, taking the Tiangong-1 with it, according to the Xinhua News Agency.Despite the preparations, space experts said carrying out the plan still comes with many risks. They explained that the spacecraft and much of the other equipment being used is new and has not been tried on an actual mission."Tiangong-1 is a brand new spacecraft designed by China and is bigger and heavier than the Shenzhou spaceships China had developed as a means of transporting astronauts from the Earth to space," said Yang Hong, chief designer of Tiangong-1.In a vertical position, the Tiangong-1 looks like a cigar standing 10.4 meter tall, a height equal to that of a three-story building. It weighs 8.5 tons and has a maximum diameter of 3.35 meters, a dimension shared by its launch vehicle, he said.In comparison, the Shenzhou spaceship stands shorter, at nearly 9 meters, is slimmer, having a diameter of less than 3 meters, and weighs less.In another difference, the Tiangong-1 is composed of two modules rather than the three that had made up the Shenzhou spaceship. Of the Tiangong-1's two primary components, one is an experimental module that contains a place that astronauts can live and work in on future missions. It is also equipped with a docking port.The other chief component, a resource module, will provide the craft with power.Astronauts on Tiangong-1 will have 15 cubic meters of space to move in, "much more than they had in the Shenzhou spaceship", Yang said.Inside the spacecraft are two sleeping sections with adjustable lighting systems, exercise equipment, entertainment systems and visual communication devices, he said.Hou Xiangyang, who helped design Tiangong-1, said: "The sleeping section is big enough for a 1.8-meter-tall man to sleep in. An astronaut can adjust the light as he likes."In space, Tiangong-1 will fly in a horizontal position. A paint scheme inside will help the astronauts aboard maintain their sense of direction; the module's inner walls will be in two colors, one commonly associated with the sky and one with the ground."This will help astronauts avoid feeling as if they are standing upside down in the microgravity environment," he said.Yang said the Tiangong-1 spacecraft is expected to stay in orbit for two years and rendezvous and dock with three different spaceships. Beyond the Shenzhou VIII, ships named Shenzhou IX and Shenzhou X will embark on similar missions; at least one of the two is to be manned.Before astronauts climb on board Tiangong-1, the conditions inside its experimental module will be adjusted to ensure they can live in an environment that contains enough oxygen, moisture and heat to be safe.Tiangong-1 was originally scheduled to be launched into a low orbit around the Earth between Sept 27 and 30. The earlier days were removed as possible launch dates, though, after forecasters predicted a cold air mass would move into the area containing the Jiuquan Satellite Launch Center.To ensure the spacecraft and Long March II-F carrier rocket are ready for launch, a full ground simulation was conducted on Sunday afternoon.

SAN FRANCISCO, June 20 (Xinhua) -- Google and the British Library announced Monday that the Internet search giant will digitize 250,000 out-of-copyright books from the library's collections, making up to 40 million pages from 1700 to 1870 available to the public online.In a joint statement, the British Library and Google said they will work in partnership over the coming years to deliver the content free through Google Books and the library's website, and full text search, download and reading will be available. Google will cover all digitization costs.The project is going to cover a huge range of printed books, pamphlets and periodicals dated 1700 to 1870, a period of political and technological turmoil, from the Industrial Revolution to the French Revolution, from the introduction of the income tax in Britain and the invention of the telegraph and railway.It will include material in a variety of major European languages and will focus on books that are not yet freely available in digital form online, said the statement.Since December 2004, Google has announced partnership with some 40 high-profile university and public libraries, planning to digitize and make available some 15 million volumes within a decade through Google Books service.The project has triggered controversy as publisher and author associations oppose the plan to put copyrighted titles online in a class action lawsuit.

BEIJING, Aug. 22 (Xinhuanet) -- Researchers have discovered how a human egg captures an incoming sperm for fertilization, paving the way to help couples suffering from infertility, according to media reports on Monday.An international team of researchers found that a sugar chain known as the sialyl-lewis-x sequence (SLeX) makes the outer coat of the egg “sticky,” which has proven to be helpful in binding the egg and the sperm.As a result, this observation has filled in a huge gap in the understanding of fertility and provides hope for ultimately helping couples who currently cannot conceive.Scientists and doctors know that a sperm identifies an egg when proteins on the head of the sperm match and bind to a series of specific sugars in the egg’s outer coating. With a successful match of proteins, the outside surfaces of the sperm and egg then bind together before merging, which is then followed by delivery of sperm’s DNA into egg.To identify this molecules, the researchers used ultra-sensitive mass-spectrometric imaging technology to observe and identify which molecules are most likely to be key in the binding process.They experimented with a range of synthesised sugars in the laboratory and found that it is SLeX that specifically binds sperm to an egg.According to the World Health Organisation, infertility affects about 15 percent of reproductive-aged couples around the world and almost one in every seven couples in Britain has problems conceiving a child for various reasons.