Extraterrestrial life. Do aliens really exist? Living planets

Encounter with an alien in a fairy forest

Aliens can be everywhere. There are at least 100 billion planets in our galaxy, and at least 20% of them could be habitable. Even if on a small fraction of these planets, say less than one hundredth of a percent, life has evolved, there will be tens of thousands of alien planets in our galaxy. And if we want to figure out where to start looking for these neighbors of ours, we need to understand what exactly they can be and where they can exist.

Ultimately, we need to understand as much as possible about extraterrestrial species before we encounter them.

But making predictions is relatively difficult. The reason is simple: we have only one sample to study - life on Earth, and we will have to build on that. It is not simple. Because, for example, if animals developed eyes and limbs on Earth, this does not mean at all that they will appear even one day in another place. Just because we're made of carbon and coded by DNA doesn't mean that aliens will be the same - they could be based on silicon and coded "XNA" (synthetic analogue of human DNA).

A new study published in the International Journal of Astrobiology shows another approach to alien prediction that gets around this problem. The researchers used evolutionary theory as a guiding principle. The theory of natural selection allows predictions that do not depend on the details of evolution on , and therefore would be applicable even to eyeless, airborne aliens.

Darwin formulated his theory of natural selection long before we knew what DNA was, how mutations appeared, or even how hereditary traits were passed on. It's surprisingly simple, and requires only a few ingredients to work: variation (some giraffes have longer necks than others), heritability of that variation (long-haired giraffes have children with long necks), and differential success associated with variation (long-necked giraffes eat more leaves and have more children).

Aliens Darwin

Scientists have used evolutionary theory to make a number of predictions about aliens. Aliens are said to be subject to natural selection. This is often taken for granted but is considered unproven. The researchers argue that there are solid theoretical grounds for believing that aliens will be (or have been) subjected to natural selection.

Difficulty levels illustration. A) A simple replicating molecule. B) An object like a cell. C) Alien cell. Helen S. Cooper

Living beings have many complex "details" that are well adjusted to each other in order to achieve a common goal for all - copying and multiplying their organism. The only way to achieve the optimal “design” or adaptation for this environment is through natural selection.

Since aliens are highly likely to be subjected to natural selection, some predictions can be made about what they will look like. In particular, these predictions concern "complex" aliens. By "complexity" we mean something more complex than, say, a virus.

Even a bacterial cell has intricate parts that work together to accomplish goals like locomotion and nutrition. In other words, most of the "aliens" we would like to find are complex.

Complexity on Earth arose as a result of a process called "major transitions in personality." This happens when independent organisms come together to form a new type of individual. On Earth, genes came together to form genomes, single cell organisms formed multicellular organisms such as humans. In some rare cases, multicellular organisms such as insects form societies that act as "super organisms". These events are rare and require extreme evolutionary conditions.

Complex aliens have also undergone major transitions, as this is probably the only way to evolve beyond a simple replicating molecule. Because the conditions for major transitions are rare, and because they are fairly well understood from an evolutionary standpoint, this allows us to get some idea of ​​the makeup of the aliens.

Illustration of a complex alien that contains a hierarchy of entities, where each collection of objects of the lower level unites evolutionary interests. Helen S. Cooper

We are all made up of cells, which are made up of nuclei, and mitochondria (the respiratory engine of the cell), which are made up of genes. Complex aliens will also be overwhelmed by a similar nested hierarchy of constituent parts. The aliens may not be made of "cells" as we sometimes think of them, but they may be made up of parts that were once free, and these parts, in turn, will contain anything, down to hereditary material. Our life has mechanisms that allow all these parts to work together so as to be a single organism.

For example, all of our cells are clones, so they interact to make up a single organism. The aliens will have the same ways of ensuring interaction between their internal parts at every level of a complex organism.

Aliens may have two legs or no legs at all, but their structure from an evolutionary standpoint will be much more familiar than we might think. At first glance, of course, they can be seriously different from everything that we see on Earth. But at the same time they will be similar on a more fundamental level: their bodies will be built in the same way and they will be subjected to a similar evolutionary history (independent organisms interacting with new ones, and organisms of a higher level arising from this).

Much more work needs to be done to understand who the aliens are and where we can find them. And the agonizing question - "?" — so far remains unanswered.

Incredible Facts

A team of scientists from the UK is confident that they have found evidence of the existence of extraterrestrial life, having received strange organisms from outer space.

Researchers have made an incredible discovery after a balloon sent 27km into the stratosphere returned with tiny biological organisms they believe came from outer space.

Professor Milton Wainwright(Milton Wainwright) of University of Sheffield "95 percent sure that these organisms are not from Earth.

"Judging by the information available in science, they came from outer space," he said. "There is no mechanism by which these life forms could reach such a height. If they came from Earth, we would see things that are found on Earth, such as pollen."

Alien creatures (photo)

A microscopic fragment of a diatom that scientists believe came from outer space

The samples taken during the meteor shower were covered in cosmic dust. The group of scientists who participated in the study believe that these particles came to us from comets- huge ice balls moving in space at great speed.

"The particles are all very clean," said Professor Wainwright. "Cosmic dust stuck to them, and we think they came from the water environment, and the most obvious water environment in space is a comet."

Organisms may contain DNA that may support the theory that life on Earth is of extraterrestrial origin.

The particles, which included a fragment of a diatom and "unusual biological entities", were too large for them to rise from Earth to such a height.

The only exception would be a very violent volcanic eruption. But for the last three years, no such eruptions have been recorded.

The balloons were launched on July 31 near the city of Chester in the UK. On board were microscopic pins that trap particles at an altitude of 27 km above the Earth.

Some samples will be placed in a machine that measures the ratio of certain isotopes to find out where these organisms came from.

The team of scientists plans to send another balloon in October during a meteor shower associated with the passage of Halley's Comet.

alien life

Microbes in meteorites

In March 2011, a NASA scientist Richard Hoover(Richard Hoover) published a paper in which he claimed to have found evidence of the presence of cyanobacteria in carbon meteorites from space. He observed sections of meteorites through a scanning electron microscope and found fibers and structures resembling single-celled algae.

Results of the Viking program

In 1976, two Viking spacecraft landed on Mars. They conducted a series of biological experiments, collecting samples of the Martian soil to check for organic compounds and biological signs.

The spacecraft found no evidence of organics, but during the experiments they identified reactive agents in the surface material of Mars, which released a large amount of carbon dioxide. Scientists concluded that such activity was caused by microorganisms living in the Martian soil. However, this interpretation was not accepted in the scientific community.

Arthur Clarke and bushes on Mars

Science fiction writer Sir Arthur Clark stated in 2001 that photographs taken by the Mars Global Surveyor showed trees and bushes on the Red Planet.

"Something moves and changes seasonally, which indicates at least the presence of vegetation," he argued.

Alan Hills meteorite

In 1996, NASA scientists said they had found evidence fossilized microbial life in a meteorite from Mars.

The meteorite, named ALH 84001, has generated much controversy, with many experts claiming that the fossils were created by non-living processes.

The results caused a great resonance, and the meteorite remains the subject of research by researchers.

Extraterrestrial life is life that does not come from earth. These life forms so far hypothetically range from simple organisms in the form of bacteria to creatures with a civilization much more advanced than humanity.

Although many scientists expect unequivocal confirmation of extraterrestrial life, there is not yet unambiguous evidence for its existence.

Exobiology about extraterrestrial life

The science of extraterrestrial life is known as exobiology. A science like Astrobiology also considers life on earth, and in a broader astronomical context. science leads search for life forms. Meteorites that occasionally fall to earth are studied for signs of microscopic life. Now the phenomena of biotic life (inherent in living organisms) that have an impact on other organisms with their vital activity, originated 4.1 billion years ago in Western Australia, when the age of the young earth was about 400 million years old, have been studied. And scientists are getting closer and closer to the answer.

According to researchers, if life arose relatively quickly on earth, then it can be common in the universe.

Each of us is made up of atoms that were once part of an exploding star, including carbon, nitrogen, and oxygen—some of the essential ingredients for life. Over billions of years, these ingredients condense to form a cloud of gas, new stars and planets, which means that the ingredients, and therefore the potential, for life beyond Earth are scattered throughout the universe.

Since the middle of the 20th century, a search has been carried out and scientists have been looking for extraterrestrial life forms and extraterrestrial civilizations, from identifying possible extraterrestrial radio signals, to observing through telescopes used to search for potentially habitable exoplanets.

How exoplanets are studied

Scientists suggest that there are more habitable planets in the universe than we thought. An analysis of data from the Kepler space telescope has identified 20 promising worlds that can and are able to host life.

The list of potential worlds includes several planets orbiting stars like our sun. Some of them take a relatively long time of rotation in one orbit - about 395 Earth days, others weeks or months. The fastest orbit is 18 Earth days. This is very different from the very short "years" we see around small stars.

The exoplanet with a 395-day year is one of the most promising worlds for life on the list. Called KOI-7923.01, 97 percent the size of Earth, but slightly colder.

Its cool temperature is due to the distance from the star and the fact that the star around which revolves is slightly cooler than our sun. This means it may be a little more like a tundra region on Earth than a temperate region, but still warm enough and large enough to hold the liquid water needed for life.

The short observation period is also the reason why planets are difficult to identify: scientists need more datasets to allow comparisons that these hidden planets have produced and separate real signals from false warnings on some of the noisiest datasets.

In order to compile a list of possible candidates for extraterrestrial life, scientists are studying signals from potential exoplanets. Different planetary signals are compared and interference signals are excluded. Twenty candidates have now been identified, including only one slightly larger than Mercury.

Interest in the possibility of another life

Extraterrestrial life also plays an important role in science fiction. Over the years, science fiction works, especially those involving Hollywood, have grown in public interest in the possibility of another life. Some people encourage aggressive methods to try to get in touch with life in outer space. At the time, other people argued that it could be dangerous to actively draw attention to the Earth. What's more, a number of recent discoveries also strongly recommend accepting that alien life exists, either in our own solar system or beyond.

However (except for Mars) in the foreseeable future are impossible.

Of course the question Is there life beyond Earth?, does it exist " extraterrestrial life«, « Eat whether life? important for human development in the future.

NASA predicts that we will find life outside of our planet, and maybe even outside of our solar system, as early as this century. But where? What will this life be like? Would it be wise to make contact with aliens? The search for life will be difficult, but finding the answers to these questions in theory could be even longer. Here are ten points, one way or another related to the search for extraterrestrial life.

NASA believes that extraterrestrial life will be discovered within 20 years

Matt Mountain, director of the Space Telescope Science Institute in Baltimore, says:

“Imagine the moment when the world wakes up and the human race realizes that they are no longer alone in space and time. It is in our power to make a discovery that will change the world forever.”

Using ground and space technologies, NASA scientists predict that we will find extraterrestrial life in the Milky Way galaxy within the next 20 years. Launched in 2009, the Kepler space telescope has helped scientists find thousands of exoplanets (planets outside the solar system). Kepler detects a planet as it passes in front of its star, causing a slight dip in the star's brightness.

Based on the Kepler data, NASA scientists believe that 100 million planets in our galaxy alone could be home to extraterrestrial life. But only with the launch of the James Webb Space Telescope (scheduled for launch in 2018) will we get the first opportunity to indirectly detect life on other planets. The Webb Telescope will look for gases in planetary atmospheres generated by life. The ultimate goal is to find Earth 2.0, the twin of our own planet.

Extraterrestrial life may not be intelligent

The Webb telescope and its successors will look for biosignatures in the atmospheres of exoplanets, namely molecular water, oxygen and carbon dioxide. But even if the biosignatures are found, they won't tell us if life is intelligent on an exoplanet. Alien life may be represented by single-celled organisms like amoebas, rather than complex creatures that can communicate with us.

We are also limited in our search for life by our prejudice and lack of imagination. We assume that there must be carbon-based life like us, with a mind similar to ours. Explaining this glitch in creative thinking, Carolyn Porco of the Space Science Institute says, “Scientists don’t start thinking about completely crazy and incredible things until some circumstances force them to.”

Other scientists like Peter Ward believe that intelligent alien life will be short-lived. Ward admits that other species could endure global warming, overpopulation, starvation, and the ultimate chaos that will destroy civilization. The same thing awaits us, he believes.

At present, Mars is too cold for liquid water to exist and life to be sustained. But NASA's rovers Opportunity and Curiosity, which analyze the rocks of Mars, have shown that four billion years ago there was fresh water and mud on the planet in which life could flourish.

Another possible source of water and life is Arsia Mons, the third highest volcano on Mars. 210 million years ago, this volcano erupted under a huge glacier. The heat of the volcano caused the ice to melt, forming lakes in the glacier, like liquid bubbles in partially frozen ice cubes. These lakes may have existed long enough for microbial life to form in them.

It is possible that some of Earth's simplest organisms could survive on Mars today. Methanogens, for example, use hydrogen and carbon dioxide to produce methane and do not require oxygen, organic nutrients, or light. They are ways of surviving temperature extremes like those on Mars. So when scientists discovered methane in the atmosphere of Mars in 2004, they assumed that methanogens were already living below the surface of the planet.

When we go to Mars, we can pollute the planet's environment with microorganisms from Earth. This worries scientists as it could complicate the task of finding life forms on Mars.

NASA plans to launch a mission in the 2020s to Europa, one of Jupiter's moons. Among the primary goals of the mission is to determine whether the surface of the moon is habitable, as well as to determine the places where the spacecraft of the future will be able to land.

In addition to this, NASA plans to look for life (possibly intelligent) under the thick ice sheet of Europa. In an interview with The Guardian, NASA lead scientist Dr Ellen Stofan said: “We know that there is an ocean under this ice crust. Water foam emerges from cracks in the south polar region. There are orange stains all over the surface. What is it, after all?

The spacecraft that will go to Europa will make several flybys around the moon or stay in its orbit, perhaps studying foam plumes in the southern region. This will allow scientists to collect samples of Europa's interior without the risky and expensive spacecraft landing. But any mission must provide for the protection of the ship and its instruments from the radioactive environment. NASA also wants us not to pollute Europe with terrestrial organisms.

Until now, scientists have been technologically limited in their search for life outside our solar system. They could only look for exoplanets. But physicists at the University of Texas believe they have found a way to detect exomoons (moons orbiting exoplanets) via radio waves. This search method could greatly increase the number of potentially habitable bodies on which we can find extraterrestrial life.

Using knowledge of the radio waves emitted during the interaction between Jupiter's magnetic field and its moon Io, these scientists were able to extrapolate formulas to search for such emissions by exomoons. They also believe that Alfven waves (plasma ripples caused by the interaction between the planet's magnetic field and its moon) could also help detect exomoons.

In our solar system, moons like Europa and Enceladus have the potential to support life, depending on their distance from the Sun, atmosphere, and the possible existence of water. But as our telescopes become more powerful and farsighted, scientists hope to study similar moons in other systems.

There are currently two exoplanets with suitable habitable exomoons: Gliese 876b (about 15 light-years from Earth) and Epsilon Eridani b (about 11 light-years from Earth). Both planets are gas giants, like most of the exoplanets we have discovered, but are in potentially habitable zones. Any exomoons around such planets could also have the potential to support life.

Until now, scientists have looked for extraterrestrial life by looking for exoplanets rich in oxygen, carbon dioxide, or methane. But since the Webb telescope will be able to detect ozone-destroying chlorofluorocarbons, scientists suggest looking for intelligent extraterrestrial life in such “industrial” pollution.

While we hope to discover an extraterrestrial civilization that is still alive, it is likely that we will find an extinct culture that destroyed itself. Scientists believe that the best way to find out if a planet could have had a civilization is to find long-lived pollutants (which stay in the atmosphere for tens of thousands of years) and short-lived pollutants (which disappear in ten years). If the Webb telescope detects only long-lived contaminants, there is a high chance that civilization has disappeared.

This method has its limitations. So far, the Webb telescope can only detect contaminants on exoplanets orbiting white dwarfs (the remnants of a dead star the size of our Sun). But dead stars mean dead civilizations, so the search for actively polluting life may be delayed until our technology becomes more advanced.

To determine which planets could support intelligent life, scientists typically base their computer models on the planet's atmosphere in a potentially habitable zone. Recent studies have shown that these models may also include the influence of large liquid oceans.

Let's take our own solar system as an example. Earth has a stable environment that supports life, but Mars - which sits on the outer edge of a potentially habitable zone - is a frozen planet. The temperature on the surface of Mars can fluctuate within 100 degrees Celsius. There is also Venus, which is within the habitable zone and unbearably hot. Neither planet is a good candidate for supporting intelligent life, although both could be inhabited by microorganisms capable of surviving extreme conditions.

Unlike Earth, neither Mars nor Venus has a liquid ocean. According to David Stevens of the University of East Anglia, “The oceans have enormous potential for climate control. They are useful because they allow surface temperatures to respond extremely slowly to seasonal changes in solar heating. And they help keep temperature changes around the planet within acceptable limits.”

Stevens is absolutely convinced that we need to include possible oceans in models of planets with potential life, thereby expanding the search range.

Oscillating exoplanets can support life where fixed-axis planets like Earth can't. This is because such "top worlds" have a different relationship with the planets around them.

The Earth and its planetary neighbors revolve around the Sun in the same plane. But the top worlds and their neighboring planets rotate at angles, influencing each other's orbits so that the former can sometimes rotate with the pole facing the star.

Such worlds are more likely than planets with a fixed axis to have liquid water on the surface. This is because the heat from the mother star will be evenly distributed over the surface of an unstable world, especially if it is facing the star at the pole. The planet's ice caps will melt quickly, forming the world's oceans, and where there is an ocean, there is potential life.

Most often, astronomers look for life on exoplanets that are within the habitable zone of their star. But some "eccentric" exoplanets stay in the habitable zone only part of the time. Being out of the zone, they can strongly melt or freeze.

Even under such conditions, these planets can support life. Scientists point out that some microscopic life forms on Earth can survive in extreme conditions - both on Earth and in space - bacteria, lichens and spores. This suggests that the star's habitable zone may extend much further than thought. Only we will have to come to terms with the fact that extraterrestrial life can not only flourish, as it does here on Earth, but also endure harsh conditions where it seemed that no life could exist.

NASA is taking an aggressive approach to searching for extraterrestrial life in our universe. The SETI Extraterrestrial Intelligence Project is also becoming more ambitious in its attempts to contact extraterrestrial civilizations. SETI wants to go beyond just looking for and tracking extraterrestrial signals and start actively sending messages into space to determine our position relative to the rest.

But contact with intelligent alien life could pose a danger that we may not be able to handle. Stephen Hawking warned that the dominant civilization is likely to use its power to subdue us. There is also an opinion that NASA and SETI are transgressing ethical boundaries. Neuropsychologist Gabriel de la Torre asks:

“Can such a decision be made by the entire planet? What happens if someone receives our signal? Are we ready for this form of communication?

De la Torre believes that the general public currently lacks the knowledge and training necessary to interact with intelligent aliens. The point of view of most people is also seriously influenced by religion.

The search for extraterrestrial life is not as easy as it seems

The technology we use to search for extraterrestrial life has improved a lot, but the search is still far from being as easy as we would like. For example, biosignatures are usually considered evidence of life, past or present. But scientists have found lifeless planets with lifeless moons that have the same biosignatures that we normally see signs of life. This means that our current methods for detecting life often fail.

In addition, the existence of life on other planets may be much more incredible than we thought. Red dwarf stars, which are smaller and cooler than our Sun, are the most common stars in our universe.

But, according to the latest information, exoplanets in the habitable zones of red dwarfs may have an atmosphere destroyed by severe weather conditions. These and many other problems significantly complicate the search for extraterrestrial life. But you really want to know if we are alone in the universe.

Are we alone in the universe? Scientists give an unequivocal answer: no. The number of possible shelters for life is so great that there is definitely life somewhere. The only question is in what form. The Fermi Paradox says that we do not see any traces of aliens and extraterrestrial life, although we believe that there is, therefore, scientists and organizations around the world are staring into space, hoping to capture, catch, see, feel the trace of someone else in space except us.

Scientists may need to rethink their estimates of the number of planets outside the solar system that could be habitable. A new study from the University of California at Riverside reports that the presence of toxic gases in the atmospheres of most planets makes them unsuitable for complex life as we know it. The researchers share their findings in an article in The Astrophysical Journal. Press release of the study by Phys.org.

Where are all the aliens? The difficulty in detecting them may lie in ourselves, according to a group of psychologists from the University of Cadiz (Spain). In an article by scientists published in the journal Acta Astronautica, it is said that we could simply overlook signs of the presence of intelligent extraterrestrial civilizations. Moreover, there is nothing surprising in this, since this is one of the features of the work of our consciousness, which has a scientific explanation.