Mediocrity principle

At the end of the day, the question of extraterrestrial life is based on two principles the Copernican principle and the mediocrity principle. The first states that the Earth is not in a central, specially favoured position. The mediocrity principle states that life on Earth is nothing special, so that life (in whatever form) could evolve in many places in the universe. 

Philosophically, the known as Principle of Mediocrity tell us about the possible fact that Earth is not a special place in the universe, and life on it is just the coincidence of some environmental conditions that could be found elsewhere in the universe [1]. Furthermore, from a scientific point of view, the recent development in Astrometry and Planetary Search has led to the discovery of Jupiter-like planets so far, but Earth-like planets are expected to be also detected. In the same way, recent studies have pointed to the fact that life can also evolve in different environments taking profit of some different energy sources, enhancing the probability of planets evolving life [2],... 

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