Universe is a jungle with every civilization a hidden hunter: Those who are exposed will be eliminated
“WE are lucky to be in a special era, with the next generation of giant telescopes on the way. There may be some exciting discoveries in the following 10 to 20 years,” says Mao Shude, director of the Center for Astrophysics of the Beijing-based Tsinghua University.
FAST now under construction deep in the mountains of southwest China’s Guizhou Province, will become the world’s largest radio telescope once completed this month, which has spurred several of China’s leading astronomers to comment publicly about the potential as well as the unknown dangers to humanity of the search for advanced extraterrestrial civilizations.
According to mainstream scientific opinion, it is possible that extraterrestrial life exists, as the Earth is not unique in the universe.
“I think primitive life is likely to be abundant, but intelligent life might be rarer,” says Mao, also director of the Galaxy and Cosmology Division of the National Astronomical Observatories of China (NAOC), Chinese Academy of Sciences.
The next generation of giant telescopes might help astronomers resolve some long-standing issues, such as analyzing the spectrum of distant planets, making it possible to detect biomarkers of life.
Biomarkers are certain elements that might indicate the existence of life. An important biomarker, oxygen molecules, without supporting life, can only last for a short time compared with the 13.7 billion-year history of the universe.
Oxygen easily reacts with other elements, and Mars appears red as a result of oxidation. “If we find a lot of oxygen molecules in the atmosphere of an extraterrestrial planet, they are probably produced by life activities,” Mao explains.
The most common method of searching for extraterrestrial life is to search first for planets similar to Earth, with plenty of sunshine, liquid water and a protective atmosphere. However, that method is constantly questioned as some speculate that life elsewhere in the universe might be quite different from that on Earth.
A few dozen are Earth-like planets, which are likely composed of silicate rocks or metals and may have water on them. “Astronomers first pick sample planets suitable for life, and then think about further study and analysis, or even communication with them,” Mao says.
For more effective observation, astronomers are also striving for breakthroughs in another critical technology -- adaptive optics.
Adaptive optics is a technology that aims to correct the distortions induced by atmospheric turbulence. The system is mainly composed by three parts: a wavefront sensor, a deformable mirror and a real time controller.
The next generation of ground-based telescopes, including the Thirty Meter Telescope, the Giant Magellan Telescope (GMT) and the European Extremely Large Telescope (E-ELT), will have better adaptive optics systems, so they will be central to future observations, says Feng Lu, an associate researcher with the NAOC.
Compared with space telescopes, ground-based telescopes can be larger and connected to more instruments, and can work longer and look deeper into space. The adaptive optics technology will improve their resolution close to or even above space telescopes, making them capable of observation tasks previously impossible on the ground, such as tracking extra-solar planet candidates, Feng says.
For example, with the assistance of adaptive optics, TMT will have a resolving power and sensitivity much greater than the Hubble Space Telescope when it goes into use around mid-2020s. One of its major tasks will be to analyze the spectrum of extra-solar planets.
But the next generation of space telescopes will also revolutionize astronomy. The Transiting Exoplanet Survey Satellite (TESS), to be launched by the US National Aeronautics and Space Administration (NASA) in 2017, is one of them.
Kepler, TESS’ predecessor launched by NASA in 2009, is the world’s first space observatory dedicated to the search for planets outside our solar system. So far, Kepler has confirmed 2,325 extra-solar planets, more than 70 percent of the total. Twenty-one of them are Earth-like, staying in habitable zone and within twice the size of Earth.
While both can monitor planetary transits, TESS is capable of carrying out all-sky surveys, while Kepler can only observe a small part of our region of the Milky Way.
“More importantly, TESS will look for extra-solar planets in orbit around the brightest stars, which will help analyze the physical nature of these planets. Kepler’s planets are often around dim stars, which makes it difficult to carry out follow-up studies,” Mao says. “The number of planets that TESS will detect is not necessarily much more (than Kepler), but the quality will be more advanced.”
As well as searching for Earth-like planets, scientists also scan the skies for extraterrestrial signals via radio telescopes, as some believe other civilizations will inevitably produce and release radio waves, as we do, during their evolution.
So far, about nine million volunteers in 226 countries have analyzed a total of 15 years of data from the Arecibo telescope, according to Dan Werthimer, co-founder and chief scientist of the SETI@home project.
“We have identified about 100 very short radio bursts, about one millionth of a second long, that we don’t fully understand,” Werthimer said in an e-mail interview, Radio communications from Earth still haven’t been ruled out as the source of these signals.
So far, no signals have been confirmed as from extraterrestrial civilizations. “We’ve only had radio for 100 years and lasers for 60 years,” Werthimer said. “We are just getting in the game and just beginning to explore the potential different frequencies and signal types that another civilization might use. There’s a long way to go before we can do a thorough search.
“The good news is that the capabilities of earthlings are growing. The computing power is developing quickly and the FAST telescope will be very powerful,” he added. With a dish the size of 30 football grounds, FAST is 500 meters in diameter and made of 4,450 panels. Scientists have depicted it as a super-sensitive “ear”, capable of spotting very weak messages -- if there are any -- from “cousins” of human beings.
It will be 10 times more sensitive than the telescopes in the Breakthrough Listen project, a 100 million-US-dollar initiative by Russian tycoon Yuri Milner to search for extraterrestrial civilizations, says Li Di, chief scientist with the radio astronomy department of the NAOC.
Werthimer is seeking cooperation with Chinese astronomers to develop a SETI@home project for FAST. “We hope to work with China to do SETI at the same time while the telescope carries out sky surveys to search for pulsars, fast radio bursts and to map the galaxy as planned.”
Though unsure of how such cooperation would work, Li Di is interested in working with the SETI@home project. “With their experience and advanced technologies, they will help us improve the telescope’s scientific capabilities and operating conditions. It’s like standing on the shoulders of a giant,” Li says.
Chinese scientists have also actively participated in the preparations for the Square Kilometer Array (SKA), a large multi-radio telescope project to be built in Australia and South Africa.
Regardless of the theoretical debate, scientists have never wavered in the search. “I think we shall call out. As a matter of fact, we have been yelling for years, and our radios and televisions are broadcasting in space all the time,” Mao says, “Aren’t you curious what our counterparts would look like?
“If they are inferior or equal to us in terms of civilization, we won’t be easily destroyed. If they are much more intelligent than us, they wouldn’t be so narrow-minded as to compete with us. Some worry they will come to rob us of our natural resources, but they likely have the power to transform the entire globe already. What’s the point of eliminating a much lower civilization?”
Mao believes the result will be significant however it turns out. “If we find other life, it will undoubtedly be the most important scientific discovery in our history; if not, it shows that life on Earth is unique and we should respect life and cherish each other.
“No matter the outcome, we shall never stop searching, and I hope to hear more voices and contributions from Chinese scientists.”