General

Earth is unique: perhaps life on other planets quickly died

"The mystery of why we have not yet found signsaliens may not be so much associated with the likelihood of life or intelligence, but with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surfaces, ”says Aditya Chopra of Australian National University. "The first life is fragile, so we believe that it rarely develops fast enough to survive."

How did life come about?

In short, life on other planets is probablywill be very short-lived and will disappear very quickly, astrobiologists from the Australian National University believe. In a study aimed at understanding how life could develop, scientists realized that a new life is usually dying out because of increasing warming or cooling of its own planet. A group of scientists found the answer in the so-called “theory of Gaia” by James Lovelock.

In the 1970s, chemist Lovelock and biologist LynnMargulis developed the idea that our Earth could be like a living organism, a self-regulating entity that uses feedback loops to maintain conditions suitable for life. They dubbed the potentially living planet Gaia - in honor of the Greek goddess of the Earth.

Search for "other lands" in many waysis a search for "other gay", and NASA's plans to find other planets similar to Earth are very much dependent on understanding the relationship between life and the Universe, developed by Lovelock in the context of Gaia's theory.

Life has captured the Earth with almost irrepressible haste. When the Earth was young, debris fell on it, remaining from the formation of the Solar System, creating an extreme environment in which life could not last long. This lasted for 600 million years after the formation of the solar system. However, we have evidence that as soon as the bombing was over, life began.

According to John Gribbin, author of the book ‘Alone inthe Universe ’, the Earth’s orbit is located in an extremely fortunate place in the solar system in terms of the development of intelligence. But the situation is not as obvious as it seems at first glance. The presence of life on Earth plays a role in regulating our planet through the greenhouse effect. So gases like carbon dioxide heat the surface of the Earth, retaining heat that might otherwise have gone into space.

Today, this natural greenhouse effectmakes the Earth 33 degrees warmer than the surface of the airless Moon, although the Earth and the Moon are almost the same distance from the Sun. When the Earth first formed, Gribbin writes, the atmosphere was rich in such greenhouse gases and did not allow the planet to freeze, although the sun was colder. As the sun warmed and life appeared on Earth, living beings pulled carbon dioxide out of the air and laid it in the form of carbonate rocks, reducing the greenhouse effect. Life changes the amount of carbon dioxide in the air, thanks to feedback processes that support heat on the planet when the sun cools and prevents it from overheating when heated.

This is the basis of the theory of Gaia, developed by JamesLovelock, which gives us the space to search for life outside the solar system. Lovelock's main question was: what makes the Earth special? “The air we breathe can only be an artifact that is maintained in a steady state by biological processes that are far from chemical equilibrium. Living beings must regulate the composition of the atmosphere not only today, but throughout the entire history of life on Earth - literally over billions of years. ”

But then a mystery arises: why the greenhouse effect didn’t go all bad, when the sun warmed up, why didn’t the same thing happen that happened to Venus? The answer, according to Lovelock, is that life regulates the composition of the atmosphere, gradually removing carbon dioxide when the sun heats up, maintaining the temperature on Earth comfortable for life.

Australian National University scientistsbelieve that the reason why we did not find signs of an advanced technological life may be that all the aliens became extinct. “Extinction is the cosmic order for most of life that has ever appeared,” the study authors write.

"Probably, the Universe is full of potentially habitableplanets, so many scientists believe that they must be crawling with aliens, ”says Chopra. “Most early planetary environments are unstable. To create a habitable planet, life forms need to regulate greenhouse gases, such as water and carbon dioxide, to maintain a stable surface temperature. ”

About four billion years ago, Earth, Venus and Mars, could be inhabited. However, a billion years after the formation of Venus turned into a greenhouse, and Mars froze in the ice.

Early microbial life on Venus and Mars, ifsuch was not able to stabilize a rapidly changing environment, says co-author Charlie Lineweaver from the Institute of Planetology, ANU. "Life on Earth probably played a leading role in stabilizing the planet's climate."

Wet, solid planets with ingredients andthe energy sources necessary for life seem ubiquitous, however, as the physicist Enrico Fermi noted in 1950, no signs of the survival of extraterrestrial life were found.

Probable solution to the Fermi paradox, they sayscientists, there will be an almost universal early extinction, which they dubbed the “Gaia bottleneck” (as any bottleneck is called). “One curious prediction of Gaia's bottleneck is that the vast majority of fossils in the universe will consist of extinct microbial life, not multi-cellular species such as dinosaurs or humanoids, which require billions of years to develop,” says Lineweaver.

“Can a planet, in a sense, be alive?”“, Wonders NASA astrobiologist David Greenspun. He is not the first time to put forward such a concept. In his 2003 book, ‘Lonely Planets’, Greenspun presented the “living world” hypothesis, a small variation of the well-known Gaia hypothesis.

Since then, this idea has been vividly debated,however, it was considered more philosophical than scientific. Nevertheless, many researchers agree that this concept has helped the science of the Earth system to move forward, has allowed us to understand that many of the Earth’s cycles are water, nitrogen and carbon cycles; plate tectonics; climate - deeply interconnected and modulated, or modulated by life on Earth.

“A gay may just be a good metaphor,” says Greenspun. "But I wonder if life can be considered something that not only happened on our planet, but what happens to our planet."

“It’s not so easy to separate living and non-livingparts of the earth, ”he adds. “Life has made the Earth what it is, to a large extent. This is the general meaning of the Gaia hypothesis, and the hypothesis of the Living Worlds simply transports this idea to other planets. ”

"The idea of ​​the origin of life, separated from birthliving world has interesting implications for living elsewhere, ”writes Greenspun. "If the self-regulation of Gaia is responsible for the longevity of the Earth, then we need to find other places where this global organism has evolved, and not just places where life could once arise."

In other words, our search for life should be aimed at places with active geological and meteorological cycles, potentially signaling a living biosphere.

By the present moment we have found almost 2000 planets,revolve around distant stars, and continue to find new ones. Although these worlds may be too far away for us to find any direct evidence of life in the near future, scientists are becoming more and more experienced in determining the composition of their atmospheres. Perhaps one day this skill will allow us to distinguish between a “failed biosphere” and potentially living worlds.

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