Humans are the only advanced civilization in the Universe?

Perhaps in the entire history of the Universe, there was no other intelligent, technologically advanced species of creatures, besides humans. When you take into consideration that in the milky Way may be 400 billion stars, each with three potentially habitable worlds, and in the Universe — about two trillion galaxies, intelligent life seems quite common. But intuition may let us down, because our assumptions are often unscientific. The value of the unknown, which can be hidden in abiogenesis, evolution, long-term adaptation and other factors, does not allow us to have an accurate equation of life. There are an astronomical number of opportunities for the development of intelligent, technologically advanced life, but the huge uncertainty makes it is quite possible that humans are the only inhabitants of the space.

In 1961, scientist Frank Drake presented the first equation that predicts how much in the Universe can be endearing space civilizations. He relied on a series of unknown quantities that could approximately estimate, and eventually called the approximate number of technologically advanced civilizations that existed in the past and in the present, in our galaxy and in the observable Universe. It's been 55 years, and today some of these values allow us to make more accurate forecasts.

First, has greatly improved our understanding of the size and scale of the Universe. Now we know, thanks to observations from space and ground observatories covering the whole spectrum of electromagnetic wavelengths, how big the universe is and how many galaxies. We better understand how to form and operate the stars, and the deeper we peer into the abyss of space, the more accurate the estimated number of stars in the Universe. Stars in the Universe were many — of the order of 10²⁴ — and, based on this number, it is possible to assess the chances of emergence of life for 13.8 billion years.

We used to wonder how many stars have planets near by, while solid and quite interesting atmosphere, similar to ours, and how many of such planets are the right distance from its star that the surface was liquid water. For a long time we were wondering just that. But thanks to the space telescope "Kepler", we learned a lot,

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• 80-100% of stars have planetary systems or planets;
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• 20-25% of these systems have a planet in the "habitable zone" where water will remain liquid on the surface;
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• 10-20% of these planets similar to Earth in size and mass;

Thus, the Universe will be about 10²² potentially habitable earth-like planets with suitable conditions.

Moreover, nearly all these planets are enriched in heavy elements and ingredients necessary for life. Looking at the interstellar medium, clouds of molecular gas at the centers of distant galaxies, we see all the elements of the periodic table — carbon, nitrogen, oxygen, silicon, sulfur, phosphorus, copper, iron and more. Looking at the meteors and asteroids in our own Solar system, we find not only these elements but also their organic formation — sugar, a benzene ring, and even amino acids. In other words, the Universe should not be just 10²² potentially habitable planets, and 10²² planets necessary for life elements.

But our optimism ends. Of course, if we are honest and thorough. Because in order to have an advanced civilization, should be three monumental events:

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• Abiogenesis — when the raw material is associated with organic processes, suddenly turns into a "life".

Life must exist and survive billions of years on the planet to acquire properties such as complexity, mnogoletnei, differentiation and "reason". the

• Finally, intelligent life must become a technological civilization, to either announce your presence in the Universe or beyond your own home and explore the Universe, or to hear and discover other forms of intelligence in the Universe.

When Carl Sagan presented Cosmos in 1980, he said that it would be reasonable to give each of these three steps for 10% chance of success. If it were correct, the milky Way galaxy, there would be over 10 million intelligent alien civilizations.

There are those who argue that together, these three steps have a probability to happen less than 10^-22. But that in itself is a ridiculous statement based on nothing. Abiogenesis can be common; it might happen many times on Earth, Mars, Titan, Europe, Venus, Enceladus, or even outside our Solar system. But it can be such a rare process, even if we made a hundred clones of the young Earth — or a thousand, or a million, or more — our world would be the only planet on which life arose.

And even if life did appear, how high is the probability that she will survive and will thrive for billions of years? Will there be a scenario of catastrophic warming, as on Venus, the norm? Or the scenario of a catastrophic freeze and atmospheric loss on Mars? Or life will eventually poison itself with its existence, as it was on Earth two billion years ago? And even if life will survive for billions of years, with what frequency will occur in the Cambrian explosion, when a huge, multicellular, macroscopic plants, animals and fungi become dominant on the planet? It can be relatively common or rare scenario occurring in 10% of cases, or generally what is happening.

And even assuming all this, how high is the probability of occurrence of technologically advanced, using tools and launching rockets the kind of kind person? Complex reptiles, birds and mammals, which can be considered smart by many indicators exist for tens and hundreds of millions of years, but modern humans appeared less than one million years ago, and "technologically advanced" have become in the last century. Will there be a 10% chance, breaking the previous stages of development, you will become a space civilization? It's hard to believe. And we don't know the truth.

We know that intelligent life in the Universe should appear quite often (10²²). And we know that there is a small chance to become a conquering space civilization. But we do not know what this chance is 10^-3, 10^-20 or 10^-50. We need the data. And no assumptions or statements will not replace them. We need to find life, to find out for sure about its existence. Everything else — not that other, as the usual speculation....