The probability of extraterrestrial life

Since beginning of times, human beings need to live in the company of other humans, beings developing what we now know as human societies. According to this idea there has been speculation, specially in the present century, about the possibility that human society has company of the other thinking creatures living in other planets somewhere in our galaxy. In this talk we will only use reliable data from scientific observers in order to establish a probability. We will explain the analysis on the physico-chemical principles which allow the evolution of organic molecules in our planet and establish these as the forerunners of life in our planet. On the other hand, the physical process governing stars, their characteristics and their effects on planets will also be explained as well as the amount of energy that a planet receives, its mass, atmosphere and kind of orbit. Finally, considering all this information, a probability of life from outer space will be given. (Author)