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A boost to the search for extraterrestrial life
THIS UNIVERSE Trends |
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A boost to the search for extraterrestrial life The
wide dishes, 20 feet across and raised high on their pedestals, creaked and groaned as the winds from an approaching snowstorm pushed into Hat Creek, a highland valley. Forty-two in all, the radio telescopes laid out in view of some of California’s tallest mountains look otherworldly, and now their sounds conjured up visions of deep-space denizens as well.
The instruments, the initial phase of the planned 350-dish Allen Telescope Array, are designed to systematically scan the skies for radio signals sent by advanced civilizations from distant star systems and planets. Fifty years after it began — and 18 years since Congress voted to strip taxpayer money from the effort — the nation’s search for extraterrestrial intelligence is alive and growing. “I think there’s been a real sea change in how the public views life in the universe and the search for intelligent life,” said Jill Tarter, a founder of the non-profit SETI Institute and the person on whom Carl Sagan’s book “Contact,” and the movie that followed, were loosely based. “We’re finding new extra-solar planets every week,” she said. “We now know microbes can live in extreme environments on Earth thought to be impossible for life not very long ago, and so many more things seem possible in terms of life beyond Earth.” The Hat Creek array, which began operation two years ago, is a joint project of the SETI Institute and the nearby radio astronomy laboratory of the University of California at Berkeley. Made possible by an almost $25 million donation from Microsoft co-founder Paul Allen, the array is unique and on the cutting edge of radio astronomy. SETI and Berkeley share both the facility, 290 miles northeast of San Francisco, and all the data it collects. The dishes also represent a coming-of-age for SETI Institute enthusiasts and its sometimes hailed, sometimes ridiculed mission. While their effort was long associated with UFOs, over-excited researchers and little green men, it is now broadly embraced as important and rigorous science, and astronomers and astrobiologists in an increasing number of nations have become involved in parallel efforts. “This is legitimate science, and there’s a great deal of public interest in it,” said Alan Stern, a former assistant administrator at NASA who, in 2007, decided that proposals for extraterrestrial search programs should not be banned from the agency, as they had been since the early 1990s. The National Science Foundation had come to a similar decision a few years before. Search activity by the institute and others is often criticized for its lack of results. It has been 50 years since astronomer Frank Drake first used a radio antenna at the Green Bank National Radio Astronomy Observatory in West Virginia to listen for extraterrestrial signals, and so far no messages have been detected and confirmed. UCLA physicist and astronomer Ben Zuckerman often lectures on what he considers the overly optimistic predictions of search advocates, and he argues that if the Milky Way were home to technologically advanced civilizations we would know it by now. “I think very strong arguments can be brought to bear that the number of technological civilizations in the galaxy is one — us,” he said. Although disappointing to scientists searching for intelligent life beyond Earth, the absence of contact is something they consider far from surprising. As Tarter described the effort, the number of star systems studied so far for possible communications is minuscule compared with the number of stars in the sky — on the same scale as if a person searched for a fish in the Earth’s combined oceans by drawing out a single cup of water. “The chances of finding a fish in that one cup are obviously very small,” she said. As she and others often point out, astronomers think the universe contains something on the order of 1,000,000,000,000,000,000,000,000 stars and, given the discovery so far of more than 400 extra-solar planets, it is generally assumed that billions or trillions more are orbiting in distant systems. What’s more, it remains far from certain that listening for radio signals is the right approach. Radio is a relatively primitive form of communication, and advanced civilizations could be sending signals in many different ways. Given that possibility, astronomers have begun using optical telescopes to search for nanosecond laser blips and beeps that might be coming our way. A Harvard-Princeton University collaboration has resulted in some of the most sophisticated optical searches, and the effort now has worldwide appeal. In November, for instance, a group of 30 optical and radio observatories and amateur astronomers dedicated two nights to simultaneously viewing one particular star system in search of radio signals or laser pulses. The effort, led by Shin-ya Narusawa of the Nishi-Harima Observatory in southern Japan, targeted a system described in 1993 by Sagan and Paul Horowitz (leader of the optical search team at Harvard) as potentially habitable. Narusawa said he hoped to cooperate with the SETI Institute in the future, as well as with more fledgling SETI programs in South Korea and Australia. —By arrangement with
LA-Times-Washington Post |
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THIS UNIVERSE We are taught that virtual images are formed when the light rays are assumed to go behind a mirror and meet at a point. These images cannot be obtained on a screen. But actually the light rays cannot go past the mirror. Then what is the actual happening when virtual images are formed? What your eyes discern is the direction from which the light is coming. If most of the rays come from directions such that they would meet when projected backwards at a point, that point would be called virtual image-virtual because the rays seem to come from the back of the mirror. Why do we wear white clothing and use a red cricket ball in test cricket and wear coloured clothing and use a white cricket ball in day-night one-day matches. Just convention and fashion, besides the fact that it is sensible to use a white ball at night because of the contrast it provides. Why is the earth revolving in the anti-clockwise direction when we see from the top? I think you have provided the answer in your question. There is no way to call a direction up, unless you say that by definition the up is that direction from where the direction of motion of the earth around the sun appears to be anticlockwise! Take a moment to think about what I have just said. Readers wanting to ask Prof Yash Pal a question can e-mail him at palyash.pal@gmail.com
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Exotic life in ocean depths OSLO: The permanent darkness of the ocean depths is home to a far greater range of animals, from luminous jellyfish to tubeworms that live off oil seeping from the seabed, than previously thought, scientists said on Sunday. A total of 17,650 species of animals, also including shrimps, corals, starfish or crabs, have been identified in the frigid, sunless waters down to about 5 km deep.
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