The idea of the existence of alien life in other planets, galaxies or whatever far in the distance, it’s taking root in the mind of modern and technological societies. See this article, Does alien life exits?, with excellent references of experts discussing the point. Watch also this very illustrative video by In a Nutshell on the Fermi Paradox, where it is possible to see that the old questions of physicists Enrico Fermi and Michael H. Hart still unanswered today. The paradox puts in contradiction two points: the many evidences we have now about the immensity of the universe – or universes – and the fact that we do not have yet an evidence of the existence of life outside Planet Earth.
There are billions of billions of stars like our Sun in billions of galaxies much older than our Milky Way, increasing infinitely the probability of trillions of trillions of planets with the same conditions of Earth to generate life and probably intelligent life. It is also possible that some of those alien civilizations have developed such a technology to made them able to navigate the Universe. In the face of all these evidences, Fermi argued that by now the Earth could be already visited by alien intelligence or, at least, we could register any radial activity. But it never has happened. Right in this moment, we never have gotten any sign of alien life – out of myths and visions from ideological groups. The question is, therefore, Where is everybody?
There are many probabilities also:
- There is alien life, but it is so primitive and far from us that we cannot reach them. Just imagine a planet inhabited by bacteria. Such living form would be so silent that we will not get to know it, specially if it is billion of light years far from us. Even if it is a superior life such as sort of insects or superior animals and plants. In that case, they will be peaceful ignored by us in the deep of the Universe.
- There is alien life, even intelligent, but not inside our Universe, but in another universe. We are now sure of the probability of the existence of other Universes. It is also possible that our Universe is inside another, etc. To understand it, we can compare with the parallel words. Right inside our planet, a ‘single’ word as it has unity, we can discover many real words. For example, the microorganism constitutes a parallel word to us. Let us imagine that inside that microbiological word, in a certain manner, a particular being developed intelligence without gaining in grandeur like the animals and plants we know as multi-cellular beings. A micro-being with a certain intelligence, could develop a micro-civilization that could live inside a rock pending over a mountain. The rock is on our planet, but the micro-civilization does not know it, because they would be so small, that they could appreciate hardly very few meters out of the pending rock, even with the most sophisticated micro-technology. They could not see things that animals or humans see of the big ‘Universe’ where their rock is. Could it be our case?
- There is intelligent alien life but they are in the same paradox of us. They could be in our same situation. If a planet like Earth is trillions of years far from us and they have similar technological advance like us, it is very much possible that they also are not ready to cross the Universe. Sadly, maybe in a far future they could do, but the Universe is so vast, that to meet our Earth would be too low in probabilities. Just a radio signal spends much time to reach so far. If one day we could get a radio signal, such message could be transmitted centuries before. Our reply would reach them back centuries in the future and maybe when they will be extincted.
- We are really alone. We will be the aliens when we will reach other planets and spread life. The Earth could be the first celestial body to shelter life and its duty would be to spread it to the farthest region of the Universe. This idea would be also beautiful. We all, inhabitants of the Planet Earth, children of our Sun Start, bacteria, animals, plants, humans, the first successful experiment of life and, among all these living creatures, we, the apes, the first to develop intelligence. It would mean a unique experience in the whole Universe, done in our tiny Star, done in our Galaxy. From here, life should spread… it would be our mission.