Ever since humans learned to think, the study of the universe has never stopped. From ancient celestial observation to modern space exploration, the mysteries of the universe are being unveiled step by step.
What we are most concerned about is, in addition to human beings, are there any intelligent life in the universe? As the world's largest radio telescope, the China Sky Eye in Guizhou, has only been in use for more than two years, and in June 2022, its research team revealed that several cases of possible candidate signals from outside the Earth have been found, and are being further screened and investigated, will these signals become a major breakthrough in the search for alien civilizations?
Chinese Sky Eye
In fact, the most efficient way to search for extraterrestrial civilizations is to observe and collect information through astronomical telescopes, whose observation range and efficiency are far greater than those of various probes launched into space. From 1609 , Galileo Galilei made the first optical astronomical telescope to observe the starry sky. Up to now, astronomical telescopes have carried out full-band coverage, including radio, neutrinos, gravitational waves, cosmic rays and other types.
We have not only built a large number of large astronomical telescopes on Earth, but also deployed space telescopes in space, and launched hundreds of space probes. Let's find out.
- Project Ozma
On April 11, 1960, mankind launched the first planned extraterrestrial search "Ozma Project", using radio waves to search for biomarker signals in the neighboring solar system. The project is run by American radio astronomer Drake and is located at the National Radio Astronomy Observatory near the town of Green Bank in western West Virginia. The observatory uses a radio telescope with a 26-meter aperture that selects a wavelength of 21 centimeters to receive external signals. The main reason for choosing this wavelength is that the most important element in the universe is hydrogen, and 21 centimeters is the microwave wavelength emitted by hydrogen atoms, which is most likely to be used by intelligent life. Drake and others used radio telescopes to search for the sun-like star Cetus Celestial V, which is 11.9 light-years from Earth and found nothing. Then, they pointed the antenna at Eridanus IV, 10.7 light-years from Earth, and they were excited that they received a strong radio signal of 8 pulses per second, but soon they fell into disappointment, which was analyzed as a false signal caused by a plane flying high in the sky, not from aliens.
Astronomical telescopes scan space
The first phase of the Ozma program searched for 150 hours and found no valuable information. In the second phase of the 1972-1975 program, Drake observed 650 planets near Earth, but found nothing. Drake believes that the limitation of the number and scope of searches is the main reason why alien civilizations cannot be found. He calculated that even if he wanted to search the entire sky through the Arecibo telescope, the largest telescope at the time, he would have to point at at least 20 million units. At that time, scientists only searched for a few thousand planets, and most of them were relatively close to Earth. Will there be new discoveries after expanding the search? On August 16, 1977, the Big Ear radio telescope at Ohio State University received a strong narrowband signal for 72 seconds, which astronomer Ayman circled on a printed report and wrote "WOW!" next to it. The signal has been studied to come from the constellation Sagittarius, possibly in one of these two red bands, 1800 light-years from Earth. However, during the subsequent search, no similar signal was detected.
WOW signal emission coordinates
- SETI program
In 1984, the University of California, Berkeley, officially launched the Search for Extraterrestrial Civilizations (SETI Program). It is planned to detect signals from space through large astronomical telescopes. Scientists selected 1,000 solar system-like objects closest to Earth for signal detection and monitoring.
Due to limited computing power, the massive amount of data collected by the Arecibo radio telescope alone is seriously backlogged and cannot be analyzed in time. Since May 1999, the SETI@HOME project has been launched, and the University of California, Berkeley SETI@home project team divides the collected data into small data packets, and volunteers around the world can use the idle computing power of their computers, automatically download data through free programs, and participate in data analysis in the form of screensavers or background. More than 5 million users have participated in this program in more than 226 countries and regions around the world, and the cumulative CPU running time has exceeded 2 million years. In 2003, the project discovered a suspected extraterrestrial signal (SHGb02+14a). This signal has been observed three times, and the signal frequency is 1420 megahertz, which is one of the main characteristic frequencies of hydrogen, and it is likely to be emitted by extraterrestrial life. But strangely, the source of the signal is located between the constellations Pisces and the constellation Aries, and no stars have been observed in this region within 1,000 light-years, and the source of the signal may be farther away in interstellar space, which needs to be further studied.
SETI plans telescopes
Since the SETI program can only use traditional astronomical telescopes intermittently, the organization has also built a telescope dedicated to searching for alien civilizations, the Allen Telescope. The original plan was to build 350 antennas, 42 of which were completed and commissioned in 2007, but due to lack of funds, the telescope has not been operating smoothly. Due to funding problems, at the end of March 2020, the SETI@home project was also terminated and the distribution of data to users stopped. Several suspected signals have been found throughout the SETI@HOME project that there may be candidate target planets for alien civilizations, pending further analysis.
An era of research has come to an end, and new research projects are constantly emerging. With a diameter of 500 meters, China's Sky Eye has become the world's largest radio telescope, and when it entered service in 2020, it is more than 2.5 times more sensitive than the Arecibo telescope, and possible extraterrestrial civilization signals have been discovered. The next-generation space telescope, James Webb, launched on December 25, 2021, has returned full-color images of the universe. What will these new generation astronomical telescopes find? We'll see.
- Exposing the civilization of Earth
Whether it is the Ozma project or the SETI program, it is a search for the sky of alien civilizations. Since alien civilizations could not be found, scientists began to plan for alien civilizations to discover Earth. Of course, according to the laws of the dark forest, such a plan has certain risks, once alien civilizations discover human beings, it may be a disaster for us, and human beings will be colonized or destroyed. The famous physicist Hawking has repeatedly warned against trying to find aliens. However, such a plan was implemented.
In 1972, the Pioneer 10 space probe was launched, carrying a metal plate depicting the planetary distribution of the solar system and the position of the Earth, as well as a sketch of a man and woman, and Pioneer 11, launched in 1973, also carried the same metal plate. In 1983, Pioneer 10 had already flown out of the solar system and lost contact with Earth in 2003.
Pioneer 10
In 1974, to celebrate the completion of the Arecibo radio telescope, binary information consisting of 1679 numbers was sent to the M13 star cluster, 25,000 light-years away from Earth. This piece of information contains the structure of human DNA, the location of the Earth, and more.
In 1977, NASA's Voyager 1 and 2 probes both carried a gold-plated copper disk record and a diamond gramophone needle, and the sound quality of the record has not changed even after hundreds of millions of years. The disk contains pictures of the planets of the solar system, the current state of human civilization, greetings in 55 human languages, 90 minutes of vocal highlights, etc. At the same time, there is also a piece of high-purity uranium-238 on the record sleeve, and the alien life that captures the record can determine the time of the probe launch based on the decay of the uranium.
Records carried by the Voyager
Voyager 1 and 2 also flew out of the solar system to interstellar space in 2014 and 2018, respectively.
Whether it is Arecibo information, or these probes flying out of the solar system, as long as they encounter alien civilizations, the information of the earth will be undoubtedly exposed, and it is difficult to say whether it is a blessing or a curse. Do you think it is worth it to expose yourself in search of an alien civilization? To be honest, I don't agree with this approach. Just as the great European voyages discovered the American continent and the Europeans conquered the Indians with artillery, isolation is not necessarily a bad thing.
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