"Aliens take me to Star Trek!" "When will the mother star send a spaceship to take me home?" On Wednesday, guided by the topic of "confirming the existence of the source of life outside the earth for the first time" on Weibo, netizens released themselves and imagined a life with the participation of alien creatures. However, good things always have twists and turns, and this time is no exception. Facts have proved that everyone is probably excited for nothing. The statement that "the source of life has been confirmed outside the earth for the first time" is essentially a misreading of the latest research progress of the asteroid probe "falcon 2".
On June 8, the hot search of "confirming the existence of the source of life outside the earth for the first time" showed "explosion".
It is neither "the first time" nor "the source of life"
It all comes from a report in Japanese media:
On June 6, the Ministry of education, culture, sports, science and technology of Japan said that scientists detected more than 20 kinds of amino acids in the samples collected by the asteroid probe "falcon 2".
Amino acid is a component of protein and an indispensable organic molecule for life. Kyodo news agency of Japanese media reported the interpretation of Kensei Kobayashi, Honorary Professor of astrobiology at Yokohama National University, and wrote: the discovery of a variety of amino acids on extraterrestrial is unprecedented, which may even imply the existence of life beyond the earth.
In 2010, when the "falcon 2" passed the funding application, the Japan Aerospace Exploration Agency (JAXA) set a high goal for it: "to help scientists solve the mystery of the origin of the solar system and the origin of life". To this end, it selected a planet Longgong star, which is more than 300 million kilometers away from the earth, as the sample collection object, and released the impactor 500 meters away from the asteroid, so as to create a crater up to 1 meter deep, so as to ensure that the collected samples of underground materials in outer space are least affected by solar radiation or cosmic ray weathering.
Rock collected by Falcon 2 on Dragon Palace star, provided by JAXA, Kyodo.
In november2019, after completing the measurement and sampling, Falcon 2 left Longgong with more than 5.4 grams of asteroid material. It took more than a year to reach the earth. The project director said: "the capsule with samples is in good condition.". In 2021, JAXA and Japanese research institutions launched a comprehensive investigation and Research on the sample, and published some research results a few days ago, which began to cause extensive discussion.
In fact, there are two major breakthroughs. One is that the amount of amino acids detected has reached more than 20 "unprecedented" (there are 22 amino acids that make up proteins in earth organisms). The other is that the samples of amino acids detected come from under the surface of the planet, which is also the first underground material of an asteroid obtained by human beings, It is proved that amino acids exist underground in asteroids, which increases the possibility of these compounds reaching the earth from space.
However, when the news came back to China, the "variety" before the "unprecedented" disappeared inexplicably, and the time of discovery of amino acids by aliens was forcibly moved back for more than ten years.
In fact, amino acids were found in the dust particles collected by NASA's Stardust probe when it flew over comet Wilder 2 in 2004. In order to rule out the possibility that these samples were contaminated by the ground during the analysis process, researchers spent several years to finally determine that only about one billionth of a gram of glycine (the simplest amino acid) in the samples came from space. In 2009, the website of new scientist published this research result.
Since then, the presence of amino acids has also been detected in the extraterrestrial environment such as comet gas and Venus atmosphere; In 2020, people even found proteins in meteorites, a more complex organic compound composed of amino acids - the so-called "source of life" amino acids, which literally roamed the universe.
On the other hand, the research on "falcon 2" has caused waves on Chinese Internet platforms, partly because some interpretations suggest that amino acid is the "source of life". As long as it is found in outer space, it is basically equivalent to the existence of extraterrestrial life - but so far, "amino acid" and "source of life" cannot be equated.
Amino acid is the "source of life", which mainly comes from some arguments of "chemical evolution". "Chemical evolution theory" is one of the mainstream hypotheses trying to explain the origin of life. It holds that in the natural environment on the earth's surface, nonliving substances can produce a variety of organic substances and biological molecules through chemical action, thus producing life. The general route is: inorganic small molecules → organic small molecules → organic macromolecules → multi molecular system → primitive life. Among them, as the basic composition of protein, amino acid is regarded as the key to the birth of life.
In 1953, Stanley Miller and Harold Yuri of the University of Chicago made a classic experiment on the origin of life. In their experiments, they found that inorganic molecules can synthesize small organic molecules, especially amino acids, in the original earth's reducing atmosphere at normal temperature under the action of lightning, thus providing strong evidence for the "theory of chemical evolution". Since then, scientists have experimented and synthesized many other biological organic molecules, and even artificially synthesized insulin and yeast alanine tRNA, which are the most important components of life.
In the diagram of Miller Yuri experiment, the lower right flask simulates the marine environment, and the upper left flask simulates lightning. Source: Wikipedia
People are encouraged and even believe that the mystery of the origin of life has been solved. However, if you think about it carefully, all this is actually based on a natural imagination, that is, as long as there is amino acid, the basic unit of protein, the process from amino acid to protein, from protein to cell, from cell to organ, and then to a complete life, it is a natural thing. However, the truth is that most of the transformation process is still a black box for us.
In addition, "chemical evolution" is not the only hypothesis of the origin of life, and "cosmological germ theory" is also one of the mainstream hypotheses of the origin of life. According to the "theory of cosmic germ", microorganisms of various forms exist in the whole universe and spread and multiply through meteors, asteroids and comets. The "source of life" of the earth may come from one or more comets that fell into the ocean 4billion years ago.
In recent decades, the discovery of modern astrophysics has provided many bases for the "theory of cosmic germ". Up to now, nearly 100 kinds of "extraterrestrial" organic molecules have been detected in meteorites, comets and interstellar dust, including amino acids, terpenoids, ethanol, purine, pyrimidine, etc. they are likely to come to the earth with meteorites and comets and sow the source of life.
In addition, there are many supporters of the "iron sulfur world hypothesis" (that life is produced in the black chimney wall of the hydrothermal vent, first the chemical changes in the "Fe-S world" and then the changes in life), "mineral crystal origin" hypothesis (life does not come from organic molecules, but from simple mineral crystals) and other hypotheses, and some even support the "silicon-based" hypothesis, This hypothesis holds that alien organisms may exist in a completely different environment from organisms, so they cannot be measured by the criteria of the carbon based world.
The universe was born about 13.77 billion years ago. Source: NASA
Looking for extraterrestrial civilization
Of course, the "first confirmation of the existence of the source of life outside the earth" successfully "cheated" a large number of netizens known as "golden eyes", mainly because people have always been extremely interested in the existence of life outside the earth.
Last month, for the first time in more than 50 years, the US Congress held a public hearing on UFOs, which dominated many headlines. Even if, according to Scott Bray, deputy director of the intelligence agency of the Navy, the US Department of defense did not find anything that "may indicate that there is any non earth origin behind these phenomena", it still triggered a new round of debate about UFOs.
Moreover, ordinary people are interested in aliens, scientists are more interested in aliens than ordinary people, and even generally believe in the existence of aliens. "In the vast universe, we are not alone." Einstein's famous saying can also be seen as the general attitude of the scientific community towards extraterrestrial civilization.
This attitude has its own theoretical support: in the current astronomical system, there are 100billion to 200billion star systems such as the solar system in the Milky Way alone, and there are about 200billion galaxies such as the Milky way in the whole universe. In the face of such astronomical figures as 200billion times 200billion, there must be or have been alien intelligent creatures in the nearly infinite universe, and their types and quantities should be far beyond our imagination.
In the 1960s, American astronomer frankdrake even put forward a formula to speculate on "the number of highly intelligent civilizations on the planets inside and outside the galaxy that may contact us", namely "Drake Equation", namely "n=ng x FP × Ne × Fl × Fi × Fc × FL "(Drake equation has two formulas, just one example here), that is," the number of civilizations that may communicate with us in the Milky way = the number of stars in the Milky way × Proportion of stars with planets × Number of earth like planets in each planetary system × Proportion of habitable planets with living evolution × The probability of evolving intelligent creatures × Probability of intelligent life being able to communicate × The proportion of the duration of scientific and technological civilization in the planetary life cycle ".
Drake equation itself does not pursue accuracy. Its significance lies in summarizing many possible factors that affect radio communication from extraterrestrial detection, and providing theoretical reference and the basis of scientific analysis for it. However, because most of the variables are inferred, resulting in the uncertainty of the final result is too high, Drake Equation still incurs many questions.
In the late 1970s, astronomer jerryayman found that the radio telescope of Ohio State University received a very strange signal from Sagittarius on August 15, 1977. The strength of this signal is 30 times stronger than the ordinary signal. The whole process lasted 72 seconds, and finally left a string of characters "6equj5" on the signal paper tape. In the sparse and random Roman numerals, this orderly and compact character is very abrupt.
The abrupt "6equj5" character on the signal paper, source: bigear org
Iman tried to explain this phenomenon with a popular phenomenon, but after searching for aircraft, meteors, land signal reflection, space gas and bat telephone signals as the source of separation, he failed. The only signal source that cannot be excluded is outer space intelligence. Over the next few years, Iman and other astronomers searched for the signal, but never found it again. "6equj5" is like a beautiful accident made by intelligent creatures in outer space.
Looking back on human efforts to find extraterrestrial life in these years, the most famous are undoubtedly voyager1 and voyager2 launched by the United States more than 40 years ago. According to the speed calculation, the two artificial aircraft have already flown out of the edge of the solar system and are heading for the depths of the universe. It is expected that one day, other civilizations will receive the goodwill and invitation of the earth civilization released by the gold record: "how are you? We all miss you very much. Please come here when you are free."
But so far, the travelers have not returned any information about alien civilization, and it is speculated that in another three years or so, the spacecraft's communication system will stop working due to lack of energy.
However, all setbacks and failures have not fundamentally damaged scientists' confidence in finding extraterrestrial civilizations. As SETI committee chairman SETI, an American astronomer, claimed eight years ago, "in the next 20 years, we are confident to find evidence of the existence of extraterrestrial intelligent civilizations". Of course, the premise is that "the budget is sufficient".
reference material:
The origin of life by fengweimin
Scientific voice: seeking the secret of nature
https://www.youtube.com/watch?v=ND2_aXYZbB0