The molecular structure of carbon-based organisms is very unstable, and they cannot experience high temperature, low temperature, bacterial erosion and radiation exposure. It is doomed that carbon-based life can only undergo short-term evolution and development in the universe.
The molecular structure of silicon-based organisms is relatively stable, which can adapt to the environment that carbon-based organisms can not adapt to, and such organisms can undergo long-term evolution and development.
All human beings on our planet are carbon-based life. If the matrix does not change greatly, then the existence of human beings on the earth can only be a short-lived behavior.
Fortunately, due to the instability of the molecular structure of carbon-based organisms, carbon-based organisms can also be transformed into silicon matrix through appropriate biochemical reactions.
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When it comes to life forms other than carbon-based life, people who know a little about it first think of silicon-based life. But when did the concept of silicon-based life come into being? Probably, few people know about it. It would be a surprise to say it. It turns out that this concept appeared as early as19th century. 189 1 year, the astrophysicist Julius of Potsdam University? Julius Scheiner discussed the possibility of life based on silicon in one of his articles. He may be the first person to mention silicon-based life. This concept was developed by British chemist James? Emerson? 1893 was accepted by James Emerson Reynolds, who pointed out in a speech of the British Association for the Advancement of Science that the thermal stability of silicon compounds enables life based on it to survive at high temperatures.
Herbert, a famous British science fiction writer? George? Herbert george wells absorbed Reynolds and Bauer's point of view, he wrote:
"People will be shocked by the strange imagination brought by this idea: since there is silicon-aluminum life, why not think of silicon-aluminum people immediately? Let's just say that they walk in the atmosphere of sulfur-containing gas and wander in the ocean of molten steel whose temperature is several thousand degrees higher than that of the furnace. "
Thirty years later, the British geneticist John? Burton? Sanderson? John Burdon Sanderson Haldane suggested that life based on semi-molten silicate may be found deep in the planet, and the oxidation of iron provides them with energy.
At first glance, silicon is indeed a promising element, which can be used as a substitute for carbon to form life. It is widely distributed in the universe, and its position is just below carbon in the periodic table of elements, so it is similar to many basic properties of carbon. For example, just as carbon can combine with four hydrogen atoms to form methane (CH4), silicon can also form silane (SiH4), silicate is an analog of carbonate, trichlorosilane (HSiCl3) is an analog of chloroform (CHCl3), and so on. In addition, these two elements can form long chains or polymers, in which they are arranged alternately with oxygen. In the simplest case, the carbon-oxygen chain forms polyacetal, which is usually used to synthesize fibers, while the skeleton formed by silicon and oxygen produces polysiloxane.
Based on the above situation, some specific life forms may be composed of silicon-like substances. Silicon-based animals probably look like active crystals, just like Dickinson and skyler drew the following imaginary picture. This is a silicon-based animal wandering among silicon-based plants. The structural parts of this creature may be strung together with silk threads similar to glass fibers and connected by muscle blocks in the middle, forming a flexible, exquisite and even thin and transparent structure.
Silicon-based animals walking among silicon-based plants
It seems that these crystalline creatures are very beautiful. If they can survive at room temperature, probably many people on earth are willing to keep a few for decoration at home. One obvious advantage of keeping this pet is that it will not spread bacteria and parasites, because bacteria and parasites, as carbon-based life, are powerless to this completely different life. However, the possibility of life on silicon is threatened by many defects.
A big disadvantage is the strong binding force between silicon and oxygen. When carbon is oxidized during the respiration of living things on earth, it will form carbon dioxide gas, which is a kind of waste that can be easily removed from living things. But the oxidation of silicon will form a solid, because when silicon dioxide is first formed, it will form a lattice, so that each silicon atom is surrounded by four oxygen atoms, instead of each molecule being independent and free like carbon dioxide. Dealing with such solid substances will bring great challenges to the breathing process of silicon-based life.
As long as it is a life form, it is necessary to collect, store and use energy from the external environment. In carbon-based organisms, the most basic compound for storing energy is carbohydrate. In carbohydrates, carbon atoms are linked into chains by single bonds. A series of oxidation steps of carbohydrates controlled by enzymes will release energy, and waste will produce water and carbon dioxide. These enzymes are large and complex molecules, which catalyze specific reactions according to their shape and left and right rotation. Here, the left-handed and right-handed molecules are caused by the asymmetry of carbon contained in the molecules, which is shown by most substances in carbon-based organisms, which enables enzymes to recognize and regulate a large number of different metabolic processes in carbon-based organisms. However, unlike carbon, silicon can not produce many levorotatory and dextrorotatory compounds, and it is difficult to become a supporting element for a large number of interconnected chain reactions needed by life.
In addition, silicon chains are unstable in water and easy to break, unlike carbon chains, which remain stable in dry and humid environments. Although this will not rule out the possibility of silicon-based life, a planet with a lot of liquid water will definitely rule out silicon-based life.
The existence of silicon-based life, even the possibility of early biochemical evolution before the emergence of silicon-based life, is very low, which is also verified by astronomical observations. No matter where astronomers search-meteorites, comets, the atmosphere of giant planets, interstellar matter, the outer layer of cooling stars-they can only find silicon oxide (silicon dioxide and silicate), but can't find substances like silane and silicone as precursors of silicon biochemical existence. On the contrary, it is not difficult to find carbon-based organic molecules such as amino acids in meteorites when we look for signs of carbon-based life. As for methane, it exists not only in many planets and satellites in the solar system, but also in interstellar matter and nebulae. Even in interstellar matter, complex molecules such as methylacetylene and cyanopentyne can be found.
Even so, it is necessary to point out that silicon may have played a certain role in the origin of life on earth. There is a strange phenomenon that life on earth especially likes to use dextrose and L-amino acids. One theoretical explanation for this is that the first batch of carbon compounds in the early stage of life evolution were formed in a "primitive soup" with a specific rotation (optical rotation) on the surface of silicon dioxide, and the rotation of this silicon compound determines the rotation of carbon compounds that we now find in life on earth.
Although from the biochemical point of view, the possibility of finding silicon-based life is very small. But silicon-based life is very prosperous in science fiction, and many descriptions by science fiction writers will put forward many useful ideas about silicon-based life. In Stanley? In Stanley Weisbaum's A Roaming on Mars, the age of life is 1 long live, and a stone will be deposited every ten minutes, which is exactly Weisbaum's answer to a major problem facing silicon-based life. A scientist observed in this paper observed:
"Those bricks and stones are its waste ... we are made of carbon, our waste is carbon dioxide, this thing is made of silicon, and its waste is silicon dioxide-silicon dioxide. But silica is solid, so it is masonry. In this way, it covers itself, and when it is covered, it moves to a new place to start again. "
In the Star Trek series "Devil in the Dark", miners in Janus IV discovered a silicon-based life form-Horta. Every 50,000 years, all Hota will die, leaving only one living individual to look after the eggs of the next generation.
Silicon-based Life in Star Trek Series
It seems that an important idea of life on silicon is longevity, which probably comes from the impression that human beings get from the permanence of natural rocks. Another common view is that silicon-based life is likely to appear on planets with higher temperatures, such as planets full of volcanoes, because many silicon-based compounds are more stable than carbon-based, for example, silicon-oxygen bonds can withstand temperatures of about 600K, while silicon-aluminum bonds can withstand temperatures of nearly 900K, so they have better high-temperature resistance, are relatively stable at high temperatures, and have better activity. For silicon-based life, it takes 200 degrees or even 400 degrees to make them feel comfortable, and they are likely to freeze to death at room temperature where we feel comfortable. That's why when I mentioned raising silicon-based pets, I specifically mentioned the phrase "if they can survive at room temperature".