The scale of the question does not allow answering simply, if by chance there is an answer. Because this question concerns the philosophic aspect on the one hand and the chemical aspect of the life, on the other hand. We notice that the life evolves in time taking a way defined by infinity of parameters, what makes it indefinable and unpredictable. Nevertheless, there is a biological definition of the life:
"an organism is said in life when it exchanges matter and energy with its environment, by preserving its autonomy, when it reproduces and evolves by natural selection. »
All the organisms alive as ensure their stability by reacting to the environment changes. Then, the life has an adaptation and a learning ability. Isn’t rather that the life? | | But, we also notice, by observing the galaxies, the stars and the planets that the matter is quite capable to auto-getting organized without being alive for all that. However, a good definition of the life has to take into account this concept, the matter ability to climb gradually the grades of the complexity.  We recognize the life when we see it!
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Are we thus alone? | | | | category: extraterrestrial life |
As long as we did not discover an extraterrestrial life, we are effectively alone. Let us take into account the chances which we have to discover a life somewhere else. Since 1995, the astronomers began looking for exoplanets and discovered several hundreds, and it is going to accelerate.
Our chances grow every day...
The physical conditions are the same everywhere in the Universe: the galaxies contain stars, stars have gaseous or / and telluric planets, planets are constituted by infinity of chemical elements as hydrogen, carbon, water...
Take only one galaxy among the billions existing, our, the Milky Way. In the Milky Way, there are 100 to 300 billion stars, what produce a considerable number of planets.
Even if the necessary conditions to the emergence of the life are difficult to combine, the number of existing planets allows us to think that the life develops or develops probably somewhere else. The astronomy progresses are going to show that the favorable sites and conditions to the life are universals, and that, the chemistry of the carbon (at the origin of the life) meets itself everywhere in the Universe.
Today, we haven’t any formal proofs of this other life, but I think that it must have a large number of places where the life abounds, from the primary state to the advanced state as our and certainly beyond. | | At present, our imagination is blocked by our egocentric vision of the world, which persuades us that the humanity is the unique and extraordinary product of the intelligence, but the given time to the evolution is infinite. The life needs time to reach the complexity, and it is the result of an adaptation pressure to the environment. This pressure engenders the fact that living cells are what they are at a moment: the result of millions of different random phenomena (meteorite impacts, global cataclysms) which modify the evolution road towards the complexity. These phenomena are real contingencies that the chronology is almost impossible to reproduce. What makes say to certain astronomers that the life on Earth is unique. It is sure that it is unique seemingly, we will not discover the other men somewhere else, but the life seems to be strength, present in the Universe, as contingencies the contingency is the negation of the necessity. A proposition is the contingent if it is not necessary (she could be false). Situation where the state of a system is determined by the value of independent, even contradictory internal and external parameters. the strength of gravitation, the electromagnetic strength, the strong nuclear strength and the weak nuclear strength (see the article of the big bang). (see the article on the big bang). The proof of the extraterrestrial life can arrive in one minute or in several million years but the life on Earth has 5 billion years in front of and the present intelligence on Earth at this moment there will see these other lives. | | 
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