Life on other planets. Does life exist on other planets

Over time, ideas about the diversity of worlds began to be supported by a theoretical basis. Astronomer Francis Drake proposed the famous formula by which one can calculate the number of civilizations with a high level of technological development.

Drake determines the number of such civilizations in the observable Universe by ten thousand. However, there are other assumptions. For example, astronomer Carl Sagan believed that only in our galaxy there are a million highly developed civilizations (!). According to the theory of John Oro, one of the first researchers to comets, the Milky Way contains no more than a hundred “intelligent” planets. And skeptics claim that the Earth, with its diverse life forms, has no analogues in the world of Cosmos.

However, science now knows that a lifecan exist even without sunlight and photosynthesis. In the early 90s, researchers found in a basalt slab, hidden deep underground in the state of Washington, a huge number of microorganisms, completely isolated from the outside world. Life is discovered in the most incredible conditions., so its existence, say, on Mars, no longer seems impossible.

Probably, in the history of searches for extraterrestrial civilizations there is no more acute topic than the problem life on mars. The history of a close study of the Red Planet began in 1877. It was then that the Italian astronomer Giovanni Schiaparelli discovered that the surface of the planet is dotted with lines that he mistook for channels. The idea of \u200b\u200bthe Italian was picked up by the American astronomer Percival Lovell. In the last years of the 19th century, he announced that the channels he opened were the work of a rational Martian civilization, which surpasses us in development. In his opinion, the construction of a system of engineering structures covering the entire planet indicates an unattainable level of technology for us, to harmonize the situation on the planet - a proof of the high moral character of the Martians. Herbert Wells somewhat re-imagined this idea, depicting the Martians in the novel “War of the Worlds”, published in 1898, bloodthirsty monsters seeking to conquer the Earth.

However, the advent of more powerful telescopes closed the channel problem - they turned out to be only a figment of the imagination. Until 1960, hopes of discovering life on Mars associated with another phenomenon - seasonal darkening of the planet’s surface. There was a theory that these are signs of vegetation. Martian forests and steppes receded into the world of myths in 1965, when the Mariner 4 space probe took 22 photographs of the surface of the Red Planet. Mars turned out to be a desert with craters resembling the moon.

When the Viking-1 and Viking-2 ships reached the Martian surface in 1976, they found no signs of life or traces of organic molecules on the Red Planet. True, the results of the expedition cannot be considered final. “You can put the Vikings on Earth and get into a place where there is also no life,” says astronomer Jack Farmer. The whole thing, he believes, is to identify areas of the Martian surface where, with the greatest degree of probability, footprints of life. One of these places may be the Gusev crater, which was once filled with water.

Nevertheless, the absence of visible on Mars signs of lifepredetermined the decline of exobiology (the science of alien life forms), which lasted two decades.
The situation changed in the 90s. Biologists began to find living organisms in such exotic corners of the Earth and in such harsh conditions that this gave a new impetus to the search life on the planets of the solar system.

It is curious that at a time when life was emerging on Earth, Mars looked much more welcoming. About 3.8 billion years ago, the Martian climate was warmer and wetter. The red planet was similar to Earth - it had water supplies and atmosphere. Evidence that water once existed on Mars has survived to this day. Scientists believe that the canyon Nanedi Vallis, spread over a width of almost three kilometers, was once a full-flowing river. It coils like a river bed and has a branch in the form of a narrow channel through which water once flowed.

Over time, Mars has lost surface water and atmosphere. As the Sun got hotter, the zone suitable for living in our Solar system shifted further and further from the central luminary. Mars is still within this zone, but its atmosphere, with a density of only one percent of the Earth’s, cannot retain enough heat to keep water in a liquid state.

However, if billions of years ago rivers flowed on Mars, and perhaps the ocean was raging, life could well exist there. It can even be assumed that life originated on Mars, and then was transferred to Earth using meteorites.

In 1996, a team of scientists from NASA announced that traces resembling fossilized microorganisms were found in the famous Martian meteorite found in Antarctica and known as ALH84001. This discovery was officially announced at a press conference in Washington on August 7, 1996.

Researchers prepared a spectacular presentation that showed graphics and sensational photographs of fossils, one of which resembled a worm in shape. However, skeptics immediately raised their voices. They referred to the fact that all the facts presented by scientists in evidence of organic
The evidence of fossils may also indicate their inorganic nature. In addition to everything inside the meteorite, particles were found that had already fallen on Earth.

Everett Gibson, a member of NASA's research team, believes that the skeptics' arguments are a typical example of a rejection of a revolutionary idea by the scientific community. “Science,” he says, “cannot accept a radical idea instantly. There was a time when scientists did not believe that meteorites could fall from the sky. There was a time when the theory of the tectonic movement of the earth plates was considered very strange. ”

Another celestial body, with which there are hopes of finding traces of life, is the satellite of Jupiter, Europe. Photos taken by NASA show that the surface of Europe resembles the frozen expanse of the earth's sea! It is dotted with furrows and cracks. Along with the other three Galilean moons of Jupiter, Europe is connected to this planet by gravity. Scientists suggest that the gravitational effect of Jupiter can create enough heat so that the water under the satellite’s ice cap does not freeze. If volcanic activity exists in addition to this in Europe, the chances of finding signs of life on it increase.

Optimism of exobiologists seeking find life on other planets, supported by the well-known fact that living organisms are composed mainly of hydrogen, nitrogen, carbon and oxygen, and these four chemically active elements are most common in the universe. However, the very origin of life, even on Earth, remains a great mystery. How can a set of chemical elements turn into a living entity without outside interference? “There is no principle that states that matter must come to life. Humanity has not yet discovered the Life Principle, ”says physicist and writer Paul Davis.

Suppose life nevertheless arose in several corners of the universe. The next question will be - how likely is its evolution to a reasonable level? Some scientists believe that the development of the mind is programmed even in the simplest organisms that can sense the environment and seek food. Thus, they argue, if we find an alien essence that is looking for food, at some point a rational creature can develop from it.

It is also interesting to what extent the appearance of living beings from different worlds can be similar. How likely is it to meet an alien with eyes, wings or a tail? Although reality can mix all the cards: the physical and chemical properties are universal, and it is logical to assume that any intelligent life should repeat the basic features of the earth. For example, aliens should have a head on which (near the brain) the organs of vision, touch and smell are located in order to perceive light, sound and smells. To maintain and protect internal organs, alien creatures will need a skeleton, and limbs will be needed to move around. Naturally, all these are just assumptions. Nature can be much more inventive than us.

The scientific community continues to seek confirmation of the idea that we are not alone in the universe. In the near future, NASA plans to build a telescope - “Earth Type Planet Detector”, which will search for planets similar to the Earth, and examine them for detection signs of life. In 2008, Martian rock samples are expected to be delivered from the Red Planet, which will be sent for research to various laboratories. In the coming years, space probe flights are scheduled for the region of Jupiter’s satellite in Europe.

Along with the search for primitive alien organisms, scientists are looking for ways to get in touch with highly developed intelligent civilizations. Radio signals are emitted into space, which, moving at the speed of light, have already reached 1,500 stars within a radius of fifty light years. The world-famous SETI project (“Search for an Alien Mind”) tracks signals from outer space in the hope of catching an artificial message. Forty years of experiments have not yet brought the long-awaited result, but optimists are confident that receiving a signal from our distant brothers in mind is only a matter of time.

Most recently, the idea of \u200b\u200ba possible existence has prevailed. intelligent lifein distant stellar systems, and much more advanced in its development of terrestrial civilization. It is not ruled out that such a large gap in the level of understanding of the world and knowledge of the laws of nature is the reason for the "radio silence" of our distant "brothers in mind."

Of course, it is impossible to directly observe the activities of extraterrestrial civilizations because of their vast remoteness. However, the consequences of such activities can probably be seen by terrestrial astronomical instruments. At least, the Lithuanian astronomer V. Streisis adheres to just such a point of view.

He drew attention to some stars, called “blue stragglers”, which are found in different types of star communities (hence their name “stragglers”, which means “wanderers”). These stars, unlike “normal” stars, do not spend their matter on radiation, as if someone continuously replenishes their “fuel” to maintain acceptable temperature conditions on nearby planets.

Such an operation would be completely within the powers of supercivilization adjacent to this star. In some ordinary stars, chemical elements are present in concentrations thousands of times higher than their contents in ordinary stars. Moreover, they are located "spots", reminiscent of landfills of industrial waste. And, finally, stars with a significant amount of radioactive elements with a half-life of hundreds of thousands of years attract special attention of researchers. How did they get there if the stars are billions of years old? It is possible that these are products of the nuclear industry.

Progress in the creation of new means of astronomical research on our planet, including the construction of space observatories, inspires hope for the discovery sooner or later of clear evidence of the existence of a different mind in the universe.

In contact with

Recently I came across an interesting idea about life on other planets, and in particular why we still have not found anything like it. Someone Schneiderman in his book “Beyond the Horizon of an Aware World”, referring to an article from the distant 90, talks about the concept natural cosmic frequency, which is abbreviated as SKH.

According to the academician, each body of the Universe has its own cosmic frequency. And it is the SKH that determines the nature of the space and time in which this body is located. For the Earth, this indicator is 365, 25, that is, the number of revolutions around its own axis during the passage around the central luminary - the Sun. For every planet, the SKH is unique and inimitable. And precisely in this lies the answer to the question of why we feel so alone in the space of the Universe.

The natural cosmic frequency in which we are born forms for us a certain individual pattern, through the prism of which we look at the world. All we can see is just a materialized image.transformed to our perception.

This is similar to how we perceive colors. After all, flowers, as such, do not exist. We see waves of different lengths, which the brain interprets as color. And another interesting nuance is that in our spectrum there is far from all of their possible range. There are vibrations that the eye simply cannot recognize. We do not see ultraviolet and infrared, and many more emissions are inaccessible to our perception.

By analogy, it is also impossible to recognize life on other planets in its real and objective existence through the filters of an alien CPS. And even that which scientists will probably be able to find, according to this theory, will be very far from the truth and true only in a system where planet Earth is the central reference point and the individual pattern or view of the Universe given by its sphere.

Contact with an objective alien is possible only through a change in its own cosmic frequency, through its adjustment and alignment with the object of study. However, this cannot be achieved by technical means alone. Moreover, adherents of the concept argue that such an artificial change in human HCR, if possible, will certainly lead to tragic consequences. The reason is that an unprepared mind is not able to endure such a transformation, so that after returning to its original state without frustration and damage.

Thus, extraterrestrial contacts will become possible only through the development of consciousness through cognition and mystical practice. Today, for humanity as a whole, these techniques are not available, because the main measure of their accessibility is the level of ethics. And while on our planet there is “at least one military man, eager to seize power”, high knowledge will remain hidden from the world community behind seven castles.

This question excites the minds of scientists for more than four centuries. The existence of life on other planets.

Hypotheses of the existence of life on other planets

The first to express the idea of the existence of life on other planets, and many inhabited worlds, the famous Italian scientist Giordano Bruno. He was the first to consider in distant stars formations like the Sun.

There are countless suns, countless earths that circle around their suns, just as our seven planets circle around our sun.

he wrote. On February 17, 1600, Giordano Bruno was burned at the stake. This was the argument in the argument of the then omnipotent Catholic Church against a bold thinker. But no one has ever managed to burn an idea at the stake. And still this debate continues: both about the multiplicity of inhabited worlds, and about the possibility of communication or meeting with representatives of the unearthly mind.

Kant's hypothesis - Laplace

This debate involves many areas of knowledge. For example, cosmogony. While the graceful reigned hypothesis origin Kant - Laplace, even the question did not arise about the exclusivity of the planetary system, however, this hypothesis was rejected by mathematicians.

Immanuel Kant is one of the founders of the hypothesis of the existence of the solar system.

Jeans hypothesis

It was replaced by a gloomy and pessimistic jeans hypothesismaking our solar system almost unique. And immediately the chances of a cosmic meeting with a foreign culture fell. However, the Jeans hypothesis suffered the same fate - and it did not pass the test of mathematics.

Agrest Hypothesis

Today, the presence of large planets in some stars is confirmed by direct observations. And again, the scientists' view of the possibility of space connections has become more optimistic. for instance Agrest hypothesis about the arrival of foreign wanderers, allegedly already taking place in the early youth of mankind. The data of history and archeology, ethnography and petrography were used by him to confirm his point of view.

Hypothesis of I. S. Shklovsky

The professor's reasoning seemed mathematically immaculate I. S. Shklovsky about the artificial origin of the satellites of Mars, but they did not stand the mathematical verification carried out by S. Vashkovyak. No, over the past four hundred years it has been argued whether Life exists on other planets, not only does not subside, but, on the contrary, is becoming more and more hot and interesting.

Professor I. S. Shklovsky is the founder of the hypothesis about the artificial origin of the moons of Mars.

New source of radio waves STA-102

Here are the most interesting facts that were hotly discussed by scientists both on the pages of the press and at special meetings. All-Union meetings on the issue were held in Byurakan (Armenia) Extraterrestrial civilizations. What are these facts that have attracted the attention of scientists? In 1960, California Institute of Radio astronomers discovered in the sky new source of radio waves. This source was not very strong, but strange in character. It was cataloged under the designation STA-102. The study of his oddities engaged scientists in many countries. A group of Moscow radio astronomers led by G. B. Sholomitsky was also interested in him. Day after day, observation of a point in the sky continued, from where mysterious radio waves weakened by distance reached the Earth to the limit. The fruits of these observations were summarized in graphs, which were then published for general information. The graphs turned out to be extremely interesting and completely unusual.

Sky as a source of new radio waves according to radio astronomers of the California Institute of Technology. The first one depicted a curve showing that the intensity of a mysterious space radio station is changing. At first it works at full capacity. Then it begins to weaken, reaches a certain minimum and for some time works on it. Then its power again grows to its original value. The full cycle of this change is one hundred days. This is the first feature of the radio emission of the STA-102 facility. But not the only one. The second graph depicts the STA-102 radio spectrum. The vertical intensity is the intensity of radio emission in the appropriate units, and the horizontal is the length of the radio waves. Here you can see a distinct peak in power at waves about 30 centimeters long. Scientists have never seen cosmic radio sources having such a radio spectrum curve. The same graph depicted the radio spectrum of an ordinary cosmic source located in the constellation Virgo. They were completely different.

Source of space radio emission STA-21

In 1963, American scientists discovered another equally strange space radio source, designated STA-21. His radio spectrum was also depicted on the graph. It turned out to be similar to the STA-102 spectrum. The shift between them can be attributed to the so-called redshift, depending on the difference in the speeds of removal of both of the considered objects from us. And so STA-21 also attracted the general attention of researchers. One more detail should be noted. The fact is that in outer space there is continuous radio noise. The most diverse natural processes - from lightning strikes in planetary atmospheres to gas clouds flying after supernova explosions - give rise to these noises.

A lightning strike generates radio noise in outer space. A minimum of space radio noise occurs in radio waves with a length of 7-15 centimeters. The radio emission maxima of the mysterious objects STA-102, STA-21 almost coincide with this minimum. But if life existed on other planets, it was the waves of this minimum that sentient beings would have tuned their transmitters, if they faced the task of creating interstellar radio communications. It was these oddities of unknown cosmic radio sources that allowed the scientist astronomer N. S. Kardashev to speculate that these mysterious objects are possibly radio noise created by intelligent creatures that have reached an extremely high level of development. Kardashev did not find any other, more natural phenomenon or process taking place in the inanimate Universe that could produce radio emission similar to that emitted by STA-102 and STA-21. He published his hypothesis in the Astronomical Journal, published by the USSR Academy of Sciences (2nd edition, 1964). It is difficult to say anything about the distance to the STA-102 and STA-21 objects, especially since until recently they were not detected using optical methods. Only with the help of the giant Palomar telescope did American scientists manage to photograph the optical spectrum of the star identified with the STA-102 object. According to the magnitude of the redshift, scientists came to the conclusion that this is a superstar, located at a distance of billions of light years from us, however, the identification of the STA-102 object with this superstar is by no means necessary. It is possible that just two astronomical objects are located in the same direction from us. And yet, both STA-102 and STA-21, of course, are thousands of thousands of light years from us. The gigantic power of space radio beacons is striking, since we are considering the hypothesis of their artificial nature. If we accept that the STA-102 object is several billion light-years away from us, then the power of radio emission, given its wide spectrum and the fact that it does not have a narrowly directed character, is comparable with the power of an entire star system similar to our Galaxy. If the STA-102 is incomparably closer, then the energy of one Sun would be enough to power its transmitter. Now the capacity of all power plants in the world is about 4 billion kilowatts. The amount of energy produced by humanity is growing at 3-4 percent per year. If this growth rate does not change, then after 3200 years, humanity will produce as much energy as the sun radiates. This means that this mankind will already be able to light a radio beacon to send signals to other intelligent beings for tens of thousands of light years to the other end of our Galaxy.

Scientist F. Drake on life on other planets

In 1967, the American scientist F. Drake for three months tried using a radio telescope to pick up the signals of intelligent creatures that could inhabit the planets of nearby stars. The scientist was not able to get such signals. However, this did not surprise him. He wittily remarked that the existence of another world inhabited by intelligent beings at a distance of only 11 light-years from Earth would indicate an extreme overpopulation of space. In early 1973, the US National Aeronautics and Space Administration published a statement of intent to seriously study interstellar communications. It is supposed to build a giant radio earmade up of one hundred meter discs that form a circle with a diameter of about 5 kilometers. The radio telescope, which is planned to be created at the same time, will be 4 million times more sensitive than the radio telescope that F. Drake previously used to listen to space. Well, maybe this time we will hear the signals of sentient beings.

Broadcast of intelligent creatures from space

Now let's try to approach the question from the other side: how likely is it to expect broadcast of intelligent creatures from space? Let's say right away: in answering this question we will come across a whole series of dubious and not very accurate provisions.

The broadcast of intelligent creatures from outer space. First of all, where can the signals of sentient beings be expected? According to the almost unanimous opinion of scientists, the Earth is the only bearer of intelligent life in our planetary system. But, in any case, it will not be long to wait for verification of this point of view: already during this century and at the very beginning of the next expedition of scientists, all the worlds of our Sun will be studied in sufficient detail. So far, nothing like the signals of intelligent creatures from the planets of the solar system has been received. Even the very mysterious radio emission of Jupiter, in all likelihood, has a purely natural origin. On the other hand, it is hardly possible to establish communication with intelligent beings from other galaxies. For example, the distance to one of the nearest galaxies to us - the famous Andromeda Nebula is about two million light years. Earthlings will not be satisfied with a conversation in which the answer to the question posed can be obtained in 4 million years. Too many events will take time from question to answer ... Therefore, it is advisable to look for brothers in reason only in the section of our Galaxy closest to us. Scientists estimate that there are about 150 billion stars in the galaxy. Not everyone is suitable to create conditions for an inhabited planet. Not all planets can become a refuge of life - some may be too close to their star, and its flame will burn all life, others, on the contrary, will freeze in the darkness of space. And yet, according to the calculations of the American scientist Dowell, there should be about 640 million planets like Earth in our Galaxy. Provided that they are evenly distributed, the distance between such planets should be about 27 light years. This means that within a radius of 100 light-years from Earth there should be about 50 planets of the same type. Well, this is a very optimistic result, giving all the chances for the possibility of radio communication between neighboring worlds.

The history of the development of planet Earth

Has life arisen on all of these planets? This is not such a simple question, as it seems at first glance. Recall the geological the history of planet Earth. Several billion years passed before the first protozoa appeared on its surface.

The history of the development of planet Earth. Roughly life exists on our planet for only about 3 billion years. Why, during the long series of preceding millions of years, did not life arise on Earth? And are all life-like planets obligatory for the same length of a lifeless period? Or could it be bigger? Or less? Currently, biochemists believe that living matter must inevitably arise in large quantities under conditions similar to the conditions of the primeval Earth. It can be assumed that life exists on all such other planets. But this question is especially dark and unclear: what period of life must exist for its amazing flower to grow and flourish - the mind? And is it necessary that the development of the living should lead to the appearance of reason? So far, naturalists do not even have approximate hypotheses in this regard. But as to whether life exists on other planets, there are hypotheses that civilization on some inhabited planets is at an incomparably higher level of development than ours.

The probability of the existence of life on other planets is determined by the scale of the universe. That is, the larger the Universe, the greater the likelihood of accidental occurrence of life somewhere in its remote corners. Since according to modern classical models of the Universe it is infinite in space, it seems that the likelihood of life on other planets is growing rapidly. This issue will be considered in more detail near the end of the article, since it will have to start with a presentation of the extraterrestrial life itself, the definition of which is rather vague.

For some reason, until recently, mankind has developed a clear view of alien life in the form of gray humanoids with large heads. However, modern films, literary works, following the development of the most scientific approach to this issue, increasingly go beyond the framework of the above ideas. Indeed, the Universe is quite diverse and, given the complex evolution of the human species, the likelihood of similar life forms on different planets with different physical conditions is extremely small.

First of all, it is necessary to go beyond the framework of representing life as it is on Earth, since we consider life on other planets. Looking around, we understand that all the earthly forms of life known to us are just such not just like that, but because of the existence of some physical conditions on Earth, a couple of which we will consider further.

Gravity

The first and most obvious earthly physical condition is. For gravity on another planet to be exactly the same, it will need exactly the same mass and the same radius. To make this possible, probably another planet should consist of the same elements as the Earth. This will also require a number of other conditions, as a result of which the probability of detecting such a “clone of the Earth” is rapidly falling. For this reason, if we intend to find all possible extraterrestrial life forms, we should assume the possibility of their existence on planets with a slightly different gravity. Of course, for gravity, a certain range must be defined, such as to hold the atmosphere and at the same time to flatten all life on the planet.

Within this range, a wide variety of life forms are possible. First of all, gravity affects the growth of living organisms. Remembering the most famous gorilla in the world - King Kong, it should be noted that he would not have survived on Earth, since he would have died under the pressure of his own weight. The reason for this is the law of the square-cube, according to which with an increase in the body by a factor of two, its mass increases by 8 times. Therefore, if we consider a planet with reduced gravity, we should expect the discovery of life forms in large sizes.

Also, the strength of the skeleton and muscles depends on the force of gravity on the planet. Recalling another example from the animal world, namely the largest animal - the blue whale, we note that if it gets on land, the whale suffocates. However, this does not happen because they choke like fish (whales are mammals, and therefore they breathe not in the gills, but in the lungs, like humans), but because gravity prevents their lungs from expanding. It follows that in conditions of increased gravity, a person would have stronger bones capable of holding body weight, stronger muscles capable of counteracting gravity, and smaller growth to lower the actual body weight itself according to the square-cube law.

The listed physical characteristics of the body, depending on gravity, are just our ideas about the effect of gravity on the body. In fact, gravity can determine a much wider range of body parameters.

Atmosphere

Another global physical condition that determines the shape of living organisms is the atmosphere. First of all, by the presence of the atmosphere, we consciously narrow the circle of planets with the possibility of life, since scientists are unable to imagine organisms that can survive without auxiliary elements of the atmosphere and with the killing influence of cosmic radiation. Therefore, suppose a planet with living organisms must have an atmosphere. First, consider the atmosphere with oxygen, which we are all so used to.

Consider, for example, insects whose size is clearly limited due to the characteristics of the respiratory system. It does not include the lungs and consists of tunnels of the trachea that go out in the form of holes - spiracles. This type of oxygen transportation does not allow insects to have a mass of more than 100 grams, since with large sizes it loses its effectiveness.

The Carboniferous period (350-300 million years BC) was characterized by an increased oxygen content in the atmosphere (by 30-35%), and the animals inherent in that time may surprise you. Namely, giant air-breathing insects. For example, a Meganeura dragonfly could have a wingspan of more than 65 cm, a Pulmonoscorpius scorpion up to 70 cm, and an Arthropleura millipede - 2.3 meters in length.

Thus, the effect of the concentration of oxygen in the atmosphere on the range of different life forms becomes apparent. In addition, the presence of oxygen in the atmosphere is not a solid condition for the existence of life, since anaerobes are known to mankind - organisms that can live without oxygen consumption. Then if the effect of oxygen on organisms is so high, what will be the life form on planets with a completely different composition of the atmosphere? - hard to imagine.

So we are faced with an incredibly large set of life forms that can expect us on another planet, given only the two factors listed above. If we consider other conditions, such as temperature or atmospheric pressure, then the diversity of living organisms goes beyond perception. But even in this case, scientists are not afraid to make bolder assumptions defined in alternative biochemistry:

Many are convinced that all life forms can exist only if they contain carbon, as this is observed on Earth. Karl Sagan called this phenomenon in due time as “carbon chauvinism”. But in fact, the main building element of alien life may not be carbon at all. Among alternatives to carbon, scientists distinguish silicon, nitrogen and phosphorus, or nitrogen and boron.
Phosphorus is also one of the main elements that make up a living organism, as it is part of nucleotides, nucleic acids (DNA and RNA) and other compounds. However, in 2010, the astrobiologist Felisa Wolf-Simon discovered a bacterium in all of the cellular components of which phosphorus is replaced by arsenic, which is toxic to all other organisms.
Water is one of the most important components for life on Earth. However, water can also be replaced with another solvent, according to scientists, it can be ammonia, fluorine hydrogen, hydrogen cyanide and even sulfuric acid.

Why did we consider the above-described possible life forms on other planets? The fact is that with an increase in the diversity of living organisms, the boundaries of the very term of life are blurred, which, by the way, still does not have an explicit definition.

The concept of alien life

Since the subject of this article is not sentient beings, but living organisms, the concept of “living” should be defined. As it turned out, this is a rather difficult task and there are more than 100 definitions of life. But, in order not to delve into philosophy, let us follow the trail of scientists. Chemists and biologists must have the broadest concept of life. Based on the usual signs of life, such as reproduction or nutrition, some crystals, prions (infectious proteins), or viruses can be attributed to living things.

An authentic definition of the boundary between living and nonliving organisms must be formulated before the question arises of the existence of life on other planets. Biologists consider viruses to be such a borderline form. By themselves, without interacting with the cells of living organisms, viruses do not possess most of the characteristics of a living organism that are familiar to us and are only particles of biopolymers (complexes of organic molecules). For example, they do not have a metabolism, for their further reproduction some kind of host cell belonging to another organism will be required.

Thus, it is possible to conditionally draw a line between living and non-living organisms passes through an extensive layer of viruses. That is, the detection of a virus-like organism on another planet can be both confirmation of the existence of life on other planets, and another useful discovery, but not confirming this assumption.

According to the above, most chemists and biologists are inclined to believe that the main sign of life is DNA replication - the synthesis of a daughter molecule based on the parent DNA molecule. Having such views on alien life, we are significantly distant from the already battered images of green (gray) men.

However, the problems of defining an object as a living organism can arise not only with viruses. Given the previously indicated variety of possible types of living creatures, it is possible to imagine a situation when a person encounters some alien substance (for simplicity of presentation - the size of a person’s order) and poses a question about the life of this substance - finding an answer to this question can be just as difficult. as is the case with viruses. This problem can be seen in the work of Stanislav Lem “Solaris”.

Extraterrestrial Life in the Solar System

Kepler - 22b planet with a possible life

Today, the criteria for finding life on other planets are quite strict. Among them, in priority: the presence of water, atmosphere, and temperature regimes similar to terrestrial ones. To possess these characteristics, the planet must be in the so-called "inhabited zone of the star" - that is, at a certain distance from the star, depending on the type of this star. Among the most popular can be noted: Gliese 581 g, Kepler-22 b, Kepler-186 f, Kepler-452 b and others. However, today one can only speculate about the existence of life on such planets, since it will not be possible to fly to them very soon, due to the great distance to them (one of the closest Glieses is 581 g, which is 20 light-years away). Therefore, we will return to our solar system, where in fact there are also signs of an unearthly life.

Mars

According to the criteria for the existence of life, some of the planets of the solar system have suitable conditions. For example, sublimating (evaporating) was discovered on Mars - a step on the path to detecting liquid water. In addition, methane was found in the atmosphere of the red planet - a well-known vital product of living organisms. Thus, even on Mars, there is a possibility of the existence of living organisms, albeit the simplest ones, in certain warm places with less aggressive conditions, such as polar caps.

Europe

The well-known satellite of Jupiter is a rather cold (-160 ° C - -220 ° C) celestial body covered with a thick layer of ice. However, a number of research results (the movement of the crust of Europe, the presence of induced currents in the core) are increasingly leading scientists to think of the existence of a liquid ocean of water under surface ice. Moreover, if it exists, the size of this ocean exceeds the size of the world’s ocean of the Earth. The warming up of this liquid water layer in Europe most likely occurs through the gravitational influence, which compresses and stretches the satellite, causing tides. As a result of observing the satellite, signs of water vapor emissions from geysers at a speed of approximately 700 m / s to a height of up to 200 km were also recorded. In 2009, the American scientist Richard Greenberg showed that under the surface of Europe there is oxygen in volumes sufficient for the existence of complex organisms. Considering the other indicated data on Europe, it is safe to assume that complex organisms can exist, albeit similar to fish, which live closer to the bottom of the subsurface ocean, where there are apparently hydrothermal springs.

Enceladus

The most promising place for living organisms is the satellite of Saturn -. Somewhat similar to Europe, this satellite nevertheless differs from all other cosmic bodies of the solar system in that it has detected liquid water, carbon, oxygen and nitrogen in the form of ammonia. Moreover, the sounding results are confirmed by real photographs of huge fountains of water spurting from the cracks of the ice surface of Enceladus. By gathering the evidence together, scientists claim the presence of a subsurface ocean under the south pole of Enceladus, whose temperature ranges from -45 ° C to + 1 ° C. Although there are estimates according to which the temperature of the ocean can reach even +90. Even if the ocean temperature is not high, we still know the fish living in the Antarctic waters at zero temperature (White-blooded fish).

In addition, the data obtained by the apparatus, and processed by scientists from the Carnegie Institute, made it possible to determine the alkalinity of the ocean environment, which is 11-12 pH. This indicator is quite favorable for the origin, as well as maintaining life.

Is there life on other planets?

So we got to the assessment of the probability of the existence of an alien life. Everything written above is optimistic. Based on the wide variety of terrestrial living organisms, we can conclude that even on the "harshest" twin planet of the Earth, a living organism can arise, even if it is completely different from what is usual for us. Even exploring the cosmic bodies of the solar system, we find the nooks and crannies of a dead world, unlike the Earth, in which there are still favorable conditions for carbon forms of life. Strengthens our beliefs about the prevalence of life in the Universe even more strongly than the possibility of the existence of carbon forms of life, but of some alternative ones, which use instead of carbon, water and other organic substances some other substances, such as silicon or ammonia. Thus, the permissible conditions for life on another planet are expanding significantly. Multiplying all this by the dimensions of the Universe, more specifically by the number of planets, we get a rather high probability of the appearance and maintenance of alien life.

There is only one problem that arises for astrobiologists, as well as for all of humanity - we do not know how life arises. That is, how and where do even the simplest microorganisms on other planets come from? The probability of the origin of life itself, even under favorable conditions, we can not assess. Therefore, the assessment of the probability of the existence of living alien organisms is extremely difficult.

If the transition from chemical compounds to living organisms is defined as a natural biological phenomenon, such as the unauthorized unification of a complex of organic elements into a living organism, then the likelihood of such an organism is high. In this case, we can say that life would somehow have appeared on Earth, if it had those organic compounds that it had, and observing the physical conditions that it observed. However, scientists have not yet figured out the nature of this transition and the factors that may affect it. Therefore, among the factors influencing the very emergence of life, there can be anything, such as the temperature of the solar wind or the distance to a neighboring star system.

Assuming that the emergence and existence of life in livable conditions requires only time, and no more unexplored interactions with external forces, we can say that the probability of detecting living organisms in our galaxy is quite high, this probability exists even in our solar system. If we consider the Universe as a whole, proceeding from the above, we can say with great certainty that there is life on other planets.

Scientists have experimentally proven that life can be found in our solar system. For example, on Saturn’s satellite, Titan.

But let's talk about everything in order.

Everyone knows that such cells as exosmos and endosmos are necessary for cell life. These are processes that provide a living cell with water exchange. And water is the basis of life. It is in water that all vital processes for molecules occur. And for any, even the smallest organism, to be considered as an independent, separate system, it must have borders that separate it from everything else. This is precisely the boundary of the cell membrane. It consists of molecules - lipids. Consider a lipid molecule. Their uniqueness lies in the fact that they have a non-polar tail and a polar head. If, for example, we consider water, alcohol and oil molecules, then it turns out that water and alcohol are polar, and oil molecules are non-polar.

Therefore, alcohol and water dissolve in each other, but oil does not. But, again, a feature of lipids is that their non-polar and polar parts are interconnected. If such molecules are immersed in water (polar medium), then these lipids will begin to group into a structure called a lipid bilayer. The molecules line up so that the heads (polar parts) will be outside in the aquatic environment (polar), and the tails inside. Having formed such a double layer of lipid molecules, we get a cell membrane. You can give an example with a fleecy carpet: the pile of the carpet is the lipid tails, and its flat surface is the head. We bend the carpet so that the hairy part is inside, and the smooth part is outside, and we form a ball in our imagination from this carpet. So much for the molecule with the carpet membrane.

Let us return to the research of scientists. As mentioned earlier, water is the basis of life. In our solar system, there is only one planet with livable water - this is the Earth. On other planets, it is in a solid state, but life requires a liquid medium. But astronomers have discovered that on the surface of Saturn’s satellite there are seas and oceans, which means that perhaps there is life. But this is not water, but liquid hydrocarbons, including ethane and methane. Scientists from Cornell University conducted a study to find out which structures can live in unusual conditions?

The task of scientists was to find the structure that can fulfill the function of a cell membrane. They immersed the lipid bilayer in a liquid hydrocarbon medium. We return to polarity and non-polarity. Water, as we recall, is not polar, but methane is polar. So, in the seas of Titan (Saturn’s satellite), the intercellular membrane should be non-polar on the outside (turn our carpet ball with a pile outward). And since the temperature in these seas is 180 degrees Celsius, the membrane should still remain elastic.

A - Acrylonitrile molecules in a liquid are interconnected by hydrogen bonds between a nitrogen atom and hydrogen of an ethylene group. Molecules are disordered

B is a crystal fragment of solid acrylonitrile. Nitrile groups are oriented apart

C - in the presence of liquid methane, it becomes more advantageous for the acrylonitrile molecules to orient the polar nitrile groups into the particles so that they do not come into contact with nonpolar ethane molecules

D is a spherical structure formed by a double layer. Nitrile groups are oriented inside the layer, and ethylene tails are oriented outside and inside the sphere.

And after computer calculations, modeling the behavior of various substances in liquid methane, chemists discovered an amazing fact! Acrylonitrile molecule was able to form the structure of cell membranes! As expected, the membrane was non-polar on the outside (tails outward) and polar on the inside (head inward). The size of these structures was similar to the size of the terrestrial virus. This completely changes the view of what “life” means!

If water is so vital for cells on earth, is it possible for other forms just as necessary in our case, liquid hydrocarbon? Probably other planets, and even intercosmic space are inhabited by life, which we do not even know about! Indeed, if this or that environment is habitual and necessary for us, then for other organisms this environment will be mortally dangerous, and vice versa. In life there is still so much unknown, that we still can not even imagine. For example, until now, some people believe that the Earth is the only planet on which intelligent life lives. And imagine, one small Earth among a great many stars and planets of the Milky Way galaxy. And how many more galaxies are there and how many planets are included in their composition! Are we the one and only in our intelligence? Perhaps ahead of us are great, epoch-making discoveries concerning the discovery of new life forms in space.

If you are interested in the topic of extraterrestrial life - that is, very interesting information that can be found in the books of Anastasia Novykh. For example, the book “Ezoosmos” tells in detail and in simple language about alternative, non-protein life, as well as what the human body consists of, how time and gravity are related, and what is the main role of gravity in the structure of the entire Universe, as well as about what life is in its true sense and what is called the “first brick” of all matter. You can download the books of this author for free from our website by clicking on the quote below, or by clicking.