Yesterday you and I discussed the "cosmic infection", namely how we can protect ourselves from extraterrestrial microbes, extraterrestrial life, and how not to bring our bacteria and microbes to distant planets ourselves. While searching for material on this topic, I came across an interesting theory from Alexander Ezhik about the chiral castle of our biosphere. I cannot judge its sufficient scientific validity. Perhaps this is just a hypothetical theory, not confirmed by deep knowledge, or maybe there really is something in it.
In any case, it was interesting for me to read it and I advise you.
Often science fiction writers describe the capture of our planet by aliens with the destruction of the entire biosphere. But it is not harmless even for us - its original inhabitants, and even more so for them. Danger awaits at every turn. Around many organisms of different hierarchical levels of organization of matter permeate all bodies on the earth's surface. They can be found in every drop of water, every grain of sand. The waste products of the inhabitants of the Earth are deadly for aliens.
Chirality (English chirality, from the Greek chéir - hand) is a concept in chemistry that characterizes the property of an object to be incompatible with its reflection in an ideal flat mirror. It was first formulated in 1884 by W. Thomson, but became widespread only after 1966, when it was introduced into stereochemistry by W. Prelog.
People who grew up in Siberia turn out to be aliens in humid tropical Africa, due to the inability of their organisms to this climate and African parasites. And you need to get a bunch of vaccinations to feel safe there.
It's much more difficult for aliens on Earth than even in space. For most of the developmental history (90%), the Earth's atmosphere was anaerobic (without oxygen). It is therefore more likely that the aliens are not breathing high oxygenated air. Oxygen is a powerful oxidizing agent and is a poison for many inhabitants of the earth's biosphere. It took bacteria hundreds of millions of years to find their place in this new oxygen environment. The fact is that they originated and lived in another in an oxygen-free atmosphere, so bacterial preparations have to be blown off with nitrogen or oxygen-free air so that they do not die. The bacteria turned out to be aliens on their planet. But there are many places on Earth where very little oxygen gets, and there they find their home.
There is a completely objective reason why the Earth cannot be captured by extraterrestrial intelligence. This is not an alien "nobility", but the symmetry of the structure of organic molecules produced by living organisms in our biosphere.
Jean-Baptiste Bio, a member of the Paris Academy, established in 1815 that tartaric acid polarizes light. But, if this acid (racemate) is artificially obtained, then there is no polarization of light. At that time it was already known that it was living organisms that produce tartaric acid, which has polarizing activity.
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An explanation of this property was given by his young student Louis Pasteur. He discovered the principle of asymmetry of crystals of tartaric acid (in shape). They were different as a real object with its mirror image. This genius guess!
L. Pasteur, in the presence of his teacher, manually separated the crystals formed from the racemate during its evaporation. If one separates crystals from others on this basis and then dissolves in different flasks, then it is found that they polarize light in different directions as it passes through the solution. When mixed, a racemate is obtained, which does not possess the property of polarization.
It turned out that living organisms consistently produce only one form of the molecule, which, while chemically in solution, only racemate could be obtained. It is easy to understand if one imagines that organisms make an organic molecule “by hand” one piece at a time, like right or left gloves. Under artificial conditions, a chemical reaction occurs in the volume of a solution with all the variety of levorotatory and dextrorotatory light molecules at the same time, where, in addition to the necessary ones, unnecessary ones are formed. L. Pasteur also discovered that certain microorganisms eat only one specific type of sugar with the same polarizing properties.
Subsequently, it turned out that crystals of different shapes form isomers (enantiomers) differing in the principle of symmetry. Isomers are identical in composition and structure, except for one property - they are mirror-symmetrical, i.e. their images cannot be aligned without mirroring one of the objects.
Symmetry is the main concept of modern stereochemistry, which makes it possible to understand the structure of biopolymers. The point is not in the polarization of light, but something else is important - molecules of the same composition can differ in the symmetry of the arrangement of their parts (radicals). Living organisms always make only one type of molecule symmetry. Natural proteins contain mainly levogyrate amino acids, while complex carbohydrates and nucleotides (DNA and RNA monomers) include dextrorotatory sugars.
Now, this principle is based on the determination of the biomorphism of the organic matter of meteorites, oil and the like.
This property arose at the earliest stages of the development of the biosphere. Let us imagine that by the time the biosphere was formed, many organisms with various methods of biopolymer production and different types of symmetry of the initial components approached. On different planets, due to the difference in prehistory and specificity of the chemical composition, the same molecules will differ in shape. As a result, one of the many biopolymer formation processes is randomly selected, which is then used by all other cellular organisms. A random set of biopolymer symmetry shapes creates a unique lock secret in each biosphere.
For example, the chirality of tartaric acid molecules with a certain probability will be different for us and for them, since the choice of the process of its formation follows from the randomness of the choice of the "molecular pattern", even if the laws of nature are similar. As a result, in the universe, each biosphere must have its own secret lock.
The term chirality was subsequently introduced by Lord Kelvin (William Thomson), who presented the isomers of racemate molecules as two hands that cannot be superimposed on each other. It is chirality that underlies the cellular synthesis of highly specific enzymatic systems and immune reactions, that is, all the most important processes in a living organism.
The chiral lock of the biosphere should be understood as a set of isomeric substances formed by living organisms of the planet's biosphere with a specific structure (asymmetry). For example, proteins synthesized artificially from D-amino acids are not assimilated by the body; bacteria ferment only one of the isomers without affecting the other. It has been proven that L-nicotine is several times more toxic than D-nicotine (L - left, D - right). The amazing phenomenon of the predominant role of only one of the forms of symmetry of biomolecules in biological processes may be of fundamental importance for us. Our "passport" is the chirality of the molecules of our body.
Modern research confirms the possibility of panspermia. Let's say that creatures formed on another planet can end up on Earth, for example, by flying inside a meteorite. The fall of fragments of a hot meteorite into the lake is described. It falls with a hiss, but until it reaches the bottom, a ball of ice freezes on it. Ice forms due to the deep space cold inside a meteorite that comes to the surface, freezing the water. Inside the meteorite, red-hot from the surface, conditions are acceptable for migrants. In the process of weathering of the meteorite minerals, aliens can enter our biosphere. What awaits them?
They will collide with organic substances of a completely different nature, which are poison for them. Another biosphere has other laws of symmetry of biomolecules, different from those of the earth, i.e. they have a different chiral key that does not fit our chiral lock. There are known examples of the use of racemic medicines by humans, when one of the isomers had a pronounced toxic effect, which led to tragic consequences. Therefore, alien beings, including intelligent ones, will perceive the organic substances of our biosphere as toxic, and they may have the same reaction as in the case of racemic medicinal preparations in humans.
The chirality lock of the biosphere is laid at the initial moment of its development. If the key of their biosphere does not coincide with the lock of ours, then the use of biological resources for aliens becomes impossible. There is only one way to acquire a chiral key - to evolve. TO EVOLVE TOGETHER WITH THE EARTH'S BIOSPHERE, MEANING TO BE ITS RESIDENT. The entirety of the biosphere on the surface of the Earth is a shield in relation to any other organisms that have penetrated into the biosphere, but have not passed through its evolution, and are not physiologically adapted to it. One can imagine an extraterrestrial being capable of rapid evolution, but it will face the need to change the most fundamental processes of its body, i.e. it will become earthly.
All living organisms of our planet and products of their vital activity, falling into the body of an alien alien, are deadly agents. Therefore, chirality can be viewed as a shield against extraterrestrial invasions, since it is impossible to remake the biosphere in this respect, and creating another in its place is pointless. Any biosphere has a right to exist. Aborigines are always right. Extraterrestrial intelligence can develop natural resources only on uninhabited planets that do not have a chiral castle, like on the Moon.
When exploring other planets, the presumption is used: the chiral lock of the alien biosphere does not correspond to our key until the opposite is proven. A complete coincidence speaks of our relationship, we are of the same blood, therefore, we can exploit and destroy their nature as our own, but this is possible only on the closest neighbors Venus and Mars. Our earthly civilization must also fulfill this presumption.
It is impossible to occupy another biosphere because of the chiral castle that closed our biosphere 3.8 billion years ago. And the key lies in every cell of our being.
Alexander Yozhik