"I really hope that one day I will establish contact with aliens, and I hope that this day will really come sooner rather than later." In the live broadcast of the Chinese Academy of Sciences' 2022 New Year's Eve speech, Academician Wu Xiangping said he believed aliens existed because Australian scientists received a signal on Proxima Centauri two months ago, which was ruled out by human interference.
"The signals received by FAST (China's Large Radio Telescope) are also likely to be signals of extraterrestrial civilizations, but we don't have time to identify them yet." Peng Bo, director of the FAST Key Laboratory of the Chinese Academy of Sciences and researcher at the National Astronomical Observatories, also said.
To search for signals from alien civilizations, radio telescopes are very important tools, which can take images of the universe billions or even tens of billions of years ago, help humans understand the origin of the universe, detect gravitational waves, and so on. In December 2020, after the complete collapse of the Arecibo Radio Telescope in the United States, the "China Sky Eye" FAST in Pingtang County, Qiannan Province, Guizhou Province, has become the world's largest single-antenna radio telescope.
A few days ago, as a witness who has lasted for more than 20 years, Peng Bo published the book "Sky Eye Project: Fast Dream Pursuit of large radio telescopes", which recorded the birth process of "China's Sky Eye".
The "Heavenly Pot" is 30 football fields large
For thousands of years, humans have observed the universe mainly through the visible light band, and in fact, radiation from cosmic celestial bodies has covered the entire electromagnetic spectrum. Among them, the discovery of radio waves, which is only 90 years old, is an important way for humans to "listen" to the universe. In 1932, Carl Jansky of Bell Labs in the United States accidentally discovered radio radiation from the center of the Milky Way, marking the birth of radio astronomy.
Peng Bo said that by looking at two photos of the M81 galaxy group located in the direction of Ursa Major, 12 million light-years from Earth, the advantages of radio telescopes can be clearly found. In the photos taken by the optical telescope, these galaxy groups are three isolated galaxies, while the photos taken by the radio telescope show that there is a relationship between the three, "that is, the radio observation can 'see' the faint connections between the optically invisible galaxies, providing a 'holographic photo' of the cosmic celestial body." ”
In 1993, at the International Joint Conference of Radio Scientists in Kyoto, Japan, astronomers, including China, jointly proposed to see the original appearance of the universe before the Earth's radio wave environment was completely destroyed, so it was decided to build a new generation of large radio telescope array LT (Large Telescope). Before that, the world's largest single-aperture telescope was the famous Arecibo Radio Telescope in the United States. Built in 1965 and built with a diameter of 305 meters and later expanded to 350 meters, its figure has appeared in films such as "007's GoldenEye", and it is one of the "top ten projects of the 20th century" of mankind, ranking even before the Apollo moon landing program.
In 1994, under the leadership of scientists Nan Rendong and Peng Bo, the plan to build a Chinese radio telescope was also on the agenda. After a long period of repeated outdoor investigations, scientists found that the Guizhou Karst Depression is very suitable for the construction of spherical reflective surface-shaped telescope arrays, and finally the site was finalized in Pingtang County, Qiannan Buyi and Miao Autonomous Prefecture. In September 2016, FAST was finally inaugurated, an area equivalent to 30 football fields, "assuming it is a cauldron that can hold wine, and each person on the earth can get 4 bottles of Guizhou Maotai."
"When I first participated in the project, I estimated that it would take 10 years or more, because the big scientific projects of big cooperation are long-term, such as the Hubble telescope, the human moon landing program, and the opportunity to be a 'world boss', even if it is worth a lifetime." 」 Peng Bo said.
509 pulsars have been discovered
As of December 20, 2021, 509 pulsars have been discovered, more than 4 times the total number of pulsars found in all other telescopes in the world.
A pulsar is a high-speed spinning neutron star that is a star formed after a massive star explodes. The Earth rotates for 24 hours, while pulsars can rotate tens of thousands of times per second. Pulsars were one of the "Four Discoveries" in astronomy in the 1960s, and their research was at the forefront of astronomy, and in 1974 Anthony Hueish, a professor at the Cavendish Laboratory at the University of Cambridge, was awarded the Nobel Prize in Physics for the discovery of pulsars.
Pulsars have magnetic fields that exceed Earth's magnetic field by 10 trillion times, a super-strong magnetic field that simply cannot be created in natural laboratories, Peng Bo said. Scientists through fast observation of pulsars found that gravitational waves, black holes and other major breakthroughs won the Nobel Prize in Physics, are directly or indirectly related to pulsars, and gravitational waves in the future are likely to benefit humans like the current electromagnetic waves.
FAST can search not only for interstellar communications, but also for extraterrestrial civilizations. To date, humans have discovered more than 4,500 extrasolar planets, with extraterrestrial water found on Europa, Mars and Saturn. In addition, the extreme environment for the survival of life on Earth is also constantly rewriting. Located at a depth of 3,800 meters in the Cortez Sea in southern California, there are hundreds of hydrothermal vents, and the surrounding temperature reaches 287 degrees Celsius, but scientists still find microbes inside, one of which is the blue microbe, which was first discovered by humans. In 2012, an international team of scientists used the Earth Deep Exploration Vessel "Earth" to dig further down the seabed of Aomori Prefecture, Japan, at a depth of 1180 meters, and then conducted stratigraphic analysis, and found that each cubic centimeter of sediment contained less than 100 tiny microbial cells.
Peng Bo said that these new discoveries on Earth and outside the solar system have made the possibility of life outside the earth continue to be supported, "FAST received signals are also likely to be the signal of extraterrestrial civilizations, but we don't have time to identify it now, the United States did it in the 60s of the last century."
What if I do find it?
Although radio telescopes only passively receive signals and do not emit radio signals, exploring extraterrestrial civilizations has always been one of its missions. The scientific community also has differences on whether to do extraterrestrial civilization exploration, and the core of the disagreement focuses on whether to actively launch radios from outer space.
In the book "Exploration of Extraterrestrial Civilizations: From Science to Fantasy", co-written by historians of science Mu Yunqiu and Jiang Xiaoyuan, it is mentioned that on November 16, 1974, after the first interstellar radio information was sent to the M13 globular cluster through the Arecibo radio telescope, Martin Ryle, the Nobel Laureate and radio astronomer of the year, issued a statement of opposition, warning that "any creature in outer space may be full of malice and hungry". It also called for an international ban on any attempt to connect with and transmit signals to extraterrestrial life on Earth.
Ryle's views have had supporters for decades, especially in science fiction films and novels. After the terrifying-looking alien creatures in the movie "Alien" came to Earth, they brought countless nightmares to mankind; in the novel "Three-Body", Ye Wenjie continued to send signals to space despite the warnings of aliens, and finally attracted the Trisolarans, and the Earth was also hit by the dimensionality reduction of the more powerful Trisolaran Civilization. "Extraterrestrial Civilization Exploration" also proposes that in the search for extraterrestrial civilizations, the more important question for human beings should be: What if it is really found?
"In fact, the signal sent by the Arecibo Radio Telescope to the M13 globular cluster is emitted more than 25,000 light-years away, so the discussion of whether it will attract aliens is a bit of a 'alarmist' reason, which is why humans are looking for extraterrestrial civilizations in the nearby universe." Peng Bo said that the probability of events in the nearby universe, such as asteroids hitting the earth, is still quite large, and astronomy is even more needed.
On October 31, 2021, Wu Xiangping also revealed that China will build another five telescopes of the same level, and now FAST will form a huge array, at which time, China's astronomical exploration will lead the world by 50 years.
"Sky Eye Project: Big Radio Telescope FAST Dream Record"
Peng Bo
Shanghai Science and Technology Education Press, September 2021 edition