There are thousands of creatures Earth is the only planet in the universe known to humans so far, There is still life on the planet outside the earth? This is also the most concerned issue for scientists. At present, scientists are looking for alien life based on the standards of life formation on Earth, because this is the most basic and most certain way.
The formation mode of life on Earth is first of all, which requires a planet like the Earth. In astronomy, it is called -type earth planet . However, this kind of life earth planet is different from the earth planets in the planet classification. Instead, several prerequisites are added, that is, it is located in the habitable zone of the stars, the mass is similar to that of the earth, and it has its own atmosphere. These three are conditions that can be achieved in astronomical observations, and even the oxygen content can be analyzed from the chromatography. However, if there is life on such a planet, there is another important condition, that is, there must be water, which cannot be directly observed.
So is there life on such a planet? In fact, scientists do not think so. Many scientists believe that life on other planets in the universe may even be completely different from that on the earth. All organisms on the earth are carbon-based life forms. This kind of life forms cannot be separated from water and almost all cannot be separated from oxygen. However, there are very likely organisms on other planets in the universe that are not carbon-based life forms. According to the analysis of the properties of chemical elements and the characteristics of molecular formulas, scientists believe that in addition to carbon-based life , there may be amino life, silicon-based life , sulfur-based life, arsenic-based life, etc.
Amino life is a living organism that survives by ammonia water . This is easier to understand because ammonia water and water have similar chemical properties, and most things that can be soluble in water can be soluble in ammonia water, and some are even easier to dissolve. Therefore, scientists believe that there is a very likely amino life on some ammonia-rich planets, and ammonia is more likely to form under high pressure, and the chemical properties of ammonia under high pressure are more similar to water. Therefore, there may be no shortage in some gaseous planets with relatively high air pressure, such as Jupiter Saturn Uranus Neptune and Venus (Venus' atmospheric pressure is 96 times that of the earth). Scientists believe that there are conditions for amino life in these planets.
Let me talk about silicon-based life. It was first proposed by British geneticist John Halldan. He believed that living organisms based on semi-melted state silicates may be found deep in a planet, and the oxidation of iron elements can provide them with energy. silicon element is widely distributed in the universe, and in the periodic table, it is just below carbon, so many basic properties of carbon elements are similar. Therefore, some planets in the universe are also likely to form silicon-based life organisms. For example, gaseous planets may be more common, but they may also be formed on planets like Venus, and even on Mars. Scientists believe that the life of this creature may last for 1 million years. In addition, some people believe that if artificial intelligence robots have a life consciousness in the future, they can also be called silicon-based life, because their brains and storage media are based on silicon wafers, and they are likely to become artificial silicon-based life.
sulfur life is a living organism based on sulfur element . As we all know, there is no shortage of sulfur elements on Venus. It is a world of sulfuric acid, so it may not be uncommon for people to discover sulfur-based life on Venus in the future.
Arsenic-based life may also exist, because scientists have found that phosphorus in organisms can be replaced by arsenic element of the same race, so arsenic-based life may also be very common.
In addition to the above four kinds of life, there may also be life living in methane . methane is very common in the universe, and there are many methane planets. There are also many methane oceans on planets such as Iobo , Titan in the solar system. Scientists believe that there may also be organisms in these oceans that use methane as the energy source and metabolic medium.
In addition, scientists have suggested that there may be life on the surface of neutron star . This kind of life uses nuclear energy as its source of energy. It is only half a millimeter in height and has a very short life, only one second, but there are not many life activities. Their time may be calculated based on the time close to Planck.
So, there may be at least these seven kinds of life in the universe, but we only know the carbon-based life on the earth at present.
