Extraterrestrial life is real

The theoretical possibility that life could exist beyond Earth, is discussed for centuries. In the words for example, already Giordano Bruno in the 16th Century that the universe is infinite and that there are infinitely many creatures on other planets in the universe exist. Even Immanuel Kant in 1755 it employed in his work from the residents of the stars. The speculation increased especially in the second half of the 19th Century, as the theory of evolution gained more widespread, which says that life has on the Earth over periods of billions of natural mutation and selection processes from the simplest life forms to ever greater diversity, more complexity and eventually developed into intelligence. This idea, it was possible to appear that could have evolved on other planets in a similar way of life - especially after both the traditional biblical Christian worldview increasingly lost importance and pointed out the astronomy that our sun is a star similar to the billions star is. It is clear that extraterrestrial life that has, regardless of life developed on Earth, could lead to life forms that differ more or less distinct from those known to us of life forms on Earth (plants, animals, humans) and we thus seem strange would. The speculation about extraterrestrial life may be divided roughly into three groups:Life forms that resemble life on Earth, especially in humans (humanoids), principallyLife forms that are completely different than any on Earth occurringlow forms of lifeExtraterrestrial life may in principle to life on earth will be very dissimilar. It could even be based on entirely different chemical elements. The assumption that alien life is conceivable only on carbon-based, is referred polemically as carbon chauvinism.Especially fascinating and frightening at the same time is not only the supposed strangeness, but also the idea that alien life forms of a similar (or even totally different kind), we humans could potentially have superior intelligence and technology.Furthermore, it was speculated that extraterrestrial life forms, especially those that are superior to humanity, in the event of contact, go out a potential hazard. Researchers such as Stephen Hawking and Simon Conway Morris expressed their fears about a contact with intelligent extraterrestrial beings. The astronomer Alexander Zaitsev, coined name for a possible threat scenario, the concept of Darth Vader scenario, after a character in the sci-fi movie Star Wars. There are theoretical considerations for a planetary defense.