Hua Feng sometimes wonders, then, if we meet aliens, what language should we use? Most likely mathematics. Chinese mathematician Hua Luogeng believes that we can use two figures as a medium to talk to aliens, one is "number" and the other is "number-form relationship" (Pythagorean theorem).

As early as the beginning of the 17th century, the Italian philosopher and astronomer Galileo Galilei believed that the language of mathematics was the key to interpreting the language of the universe. Carl Sagan, a contemporary American astronomer, is convinced that the technological civilizations in the universe, no matter how different they may be, have a common language – the language of mathematics. Zhou Haizhong, a Chinese mathematician and linguist, pointed out in his paper "The Language of the Universe: Design, Transmission and Listening" that mathematical language has the advantages of explicitness, monosemy, compactness, universality, abstraction, and logic, and is an ideal tool for interstellar communication.

Why does the language of the universe use the words "number" and "number relation"? Because no matter what the alien civilization is, the rules of counting should be similar. Alien civilizations should have the same rules for counting stars and other things, and if they have 12 or 5 fingers, they will be 12 or 5 and not 10 for humans. Another example is the Pythagorean theorem: the square of the hypotenuse of a right triangle is equal to the sum of the squares of two right angles. The "number-shape relationship" of this natural shape is universal throughout the universe. Then we use "numbers" and "number relationships" as the basis to express some complex operations and pictures, hoping that they can "read pictures" and understand what we mean.

American scientists used this method to send a short telegram to the constellation Hercules, but have not yet received a response. Due to the distance between the stars, if there is a return signal, you have to be patient.

The book "The Mystery of the Ancient Past" co-authored by American scholars Creshysum and Eric believes that in ancient times, some aliens from another galaxy came to the solar system to mine minerals, and they used Planet X as a base and sent some people to the earth to investigate. But mining failed, causing Planet X to explode 60-700,000 years ago. Starship was also destroyed. So these aliens who stayed on the earth had to combine with some flying people on the earth. It is also said that these aliens did not come to open mines, but that there was a war between aliens, and the losing side fled to Earth, and set up a false target on Planet X, and the winning side blew up Planet X in pursuit. In short, once the hypothesis of Planet X was proposed, it was related to aliens, and it has not yet been clarified.

According to the American space network, aliens may exist in the solar system, or we may need more telescopes to discover their existence. At present, many scientists say that a new network of radio astronomy observatories in Europe will have the potential to discover extraterrestrial life outside the solar system.

The radio astronomy network, called the Low Frequency Array (LOFAR), is a network of 25,000 small antennas. In order to obtain sufficiently clear and sharp radio images, the antennas were built in the Netherlands, Germany, Sweden, France, and the United Kingdom, covering an area with a diameter of 350 km. When the antennas are built in 2009, these distributed radio arrays will work together to scan the universe for low-frequency rays. Michael Garrett of the Netherlands Radio Astronomy Association said, "LOFAR can extend the search for extraterrestrial intelligent life by surveying a completely unsurveyed low-frequency radio spectrum, which is mainly in the Earth's civil and military communication bands." In addition, LOFAR is also capable of simultaneously measuring large areas of space, which are difficult for SETI (Search for Extraterrestrial Civilizations) signals to travel to such a wide area of space. It is reported that Garrett is a professor of astronomy and radio technology at Leiden University in the Netherlands.

So far, the world's most famous extraterrestrial search telescope, the Arecivo Observatory in Puerto Rico, USA, has successfully located and found intelligent extraterrestrial life. The massive disk telescope has been receiving radio waves from the universe since 1963, but due to the decision of the National Science Foundation to reduce the budget of the observatory, it is likely that the observatory will be closed in the near future if it does not solve its financial difficulties. In contrast, LOFAR will scan the electromagnetic spectrum at a lower frequency level than the Arecivo Observatory, which covers the Earth's television broadcasts and radio signals.

But other scientists are skeptical, with Seth Shostark, a senior astronomer at the SETI Society in California, saying that LOFAR will probably not be sensitive enough to detect alien television unless aliens emit more powerful television broadcasts than humans. He theorized that the alien version of LOFAR would have to be within 1 light-year of Earth in order to detect Earth's television signal, meaning that the alien star would have to be closer than the star currently closest to Earth.

At present, "SETI@home" is conducive to the exploration and exploration of extraterrestrial civilizations, and this tool can search for the existence of extraterrestrial civilizations on personal computers by analyzing data transmitted from radio telescopes. Dan Wassimo, a SETI@home project scientist at the University of California, Berkeley, said, "The SETI search is still a long way off, and we need many different telescopes and as many techniques and strategies as possible to maximize the success of our search for aliens." ”

From the original "Star Trek" to "Fly to Space" to the most classic "E.T", human exploration of space has never stopped, and people have always wanted to find a trace of life in outer space, hoping to communicate with it for mutual benefit. However, recently, physicist Stephen Hawking has made a surprising statement that it is best not to actively contact aliens.

On April 26, the famous British physicist Stephen Hawking said in a documentary broadcast on the 25th that the existence of aliens is very likely, but human beings should not actively look for them and should make every effort to avoid contact with them.

The American Discovery Channel began to broadcast the documentary series "Follow Stephen Hawking into the Universe" on the 25th. In the film, Hawking introduces his views on the unsolved mysteries of the universe such as the existence of aliens. The British "Sunday Times" quoted Hawking as saying on the 25th that there are more than 100 billion galaxies in the universe, and each galaxy contains at least a large number of planets. Based on this number alone, the existence of extraterrestrial life can almost be concluded.

"The real challenge is figuring out what aliens look like," Hawking said. In his opinion, extraterrestrial life is highly likely to exist in the form of microorganisms or primary organisms, but the existence of intelligent beings that can threaten humans cannot be ruled out.

"I think some of them have exhausted the resources on their planet and may be living on huge spaceships," he said, "and these advanced aliens may become nomads trying to conquer and colonize all the planets they can reach." ”

Hawking argues that it is "a little too risky" for humans to actively seek to engage with them, given that aliens may loot the Earth's resources and then fly away.

"If aliens visit us, I think the outcome would probably be similar to Christopher Columbus's footing on the American continent. That wasn't a good thing for the local Indians. ”

Stephen Hawking (1942-2018) was diagnosed with motor neurone disease at the age of 21 and was almost completely paralyzed, relying on a talking machine and a speech synthesizer to communicate with people. He is well-known in the scientific community for his research on black holes and quantum cosmology, and is the author of popular science works such as "A Brief History of Time" and "The Universe in the Shell". I wonder what kind of ripples Hawking's words will cause in the scientific community? Let's wait and see.

According to the theory of the dark forest proposed in the three-body series of the famous science fiction writer Liu Cixin, it consists of two important concepts: the chain of suspicion and the explosion of technology

"Good will and bad faith among civilizations. Words like good and evil are not rigorous in science, so their meanings need to be limited: good intentions mean not actively attacking and destroying other civilizations, while malice is the opposite. That's the lowest kindness. ——Liu Cixin, "Three-Body Problem 2: Dark Forest"

One civilization cannot judge whether another civilization is good or evil

One civilization cannot judge whether another civilization thinks that this civilization is a good civilization or an evil civilization

One civilization cannot judge whether another civilization will attack its own

One civilization cannot judge whether another civilization is benevolent or malicious towards itself

One civilization cannot judge what another civilization considers itself to be benevolent or malicious

One civilization cannot judge another civilization to judge itself as benevolent or malicious towards her

......

(1) Due to the distance and cultural and species differences, the chain of suspicion between cosmic civilizations is indestructible once formed. (2) The chain of suspicion leads to the inability of civilizations to judge each other's good and evil, and ultimately drives the two sides to be hostile to each other. (3) The result of the chain of suspicion has nothing to do with the specific moral orientation of the two civilizations.

"In an environment where human beings share a common species, a similar culture, an interdependent ecosystem, and close proximity, the chain of suspicion can only be dissolved by communication if it extends only one or two levels. But in space, the chain of suspicion can stretch very long, and before it is dissolved by communication, something like the Battle of Darkness has already happened. ...... In a true cosmic civilization, the biological differences between different races may reach the level of the gate or even the realm, and the cultural differences are even more unimaginable, and they are separated by incomparably long distances, and the chain of suspicion between them is almost indestructible. ...... Regardless of whether civilization is benign or malicious within itself, it becomes the same thing when it enters the web of suspicion chains. ——Liu Cixin, "Three-Body Problem 2: Dark Forest"

The speed and acceleration of civilization progress are not necessarily the same, and weak civilizations are likely to surpass powerful civilizations in a short period of time. It may be caused by internal or external factors (e.g., the exchange of civilizations in the universe). In the original book, it is believed that the huge technological leap in the short period of more than 200 years after the industrial revolution of mankind (compared to the 3 million years and the civilization of more than 7,000 years since the existence of the human species) is an example.