Impact of extraterrestrial contact
Scientific literature and science fiction put forward various models of the ways in which extraterrestrial and human civilizations might interact. Their predictions range widely, from sophisticated civilizations that could advance human civilization in many areas to imperial powers that might draw upon the forces necessary to subjugate humanity. Some theories suggest that an extraterrestrial civilization could be advanced enough to dispense with biology, living instead inside of advanced computers.
The implications of discovery depend very much on the level of aggressiveness of the civilization interacting with humanity, its ethics, and how much human and extraterrestrial biologies have in common. These factors will govern the quantity and type of dialogue that can take place. The question of whether contact is physical or through electromagnetic signals will also govern the magnitude of the long-term implications of contact. [Via: wikipedia]