In a universe bustling with trillions of galaxies, and in our Milky Way alone thousands if not millions of potentially habitable planets, it’s almost troubling that we have yet to see one shred of evidence that might prove that we are not alone out there. The Fermi’s Paradox named after Enrico Fermi is this apparent contradiction between what is the high estimates or probability of existence of intelligent civilizations and the complete lack of any evidence for such civilizations. This is something that has puzzled humans since we were able to ponder such things.
Here are some of the possible explanations for the Fermi’s Paradox.
- Other Intelligent life has not arisen: It is possible that even if complex life turns out to be common in the galaxy, this does not necessarily mean that it will always evolve into intelligent life. The dinosaurs roamed the earth for hundreds of millions of years without any of them ever developing intelligence or self awareness.
- Extraterrestrial life is rare or non-existent: It is possible that although simple life might be common in the galaxy, complex life might be a whole different story. We know that simple life began very early on in earth’s history, however complex-life had to overcome a series of bottlenecks before it emerged. It is possible that this may have only ever happened on earth.
- The Nature of intelligent life is to destroy itself: As we have seen on earth, we are reaching a point in human existence where our desire for economic growth clouds our awareness of the damage we are inflicting on the planet that sustains us. It is possible that once intelligent life reaches a certain point in it’s evolution, it eventually destroys the planet that it originated from.
- It is the Nature of intelligent life to destroy others: Intelligent life that already exists in the galaxy might be monitoring all new intelligent species as they develop. Once they have reached a point in their development where they might pose as a threat, they might then be eradicated. A species might undertake such extermination out of expansionist motives, paranoia, or aggression.
- Periodic extinction by natural events: On earth there have been multiple major extinction events. With the extinction of the dinosaurs being the best known example. These extinction events wipe out most of the complex life on the planet. It is possible that these events are what prevents intelligent life from ever developing to a point where they can leave their home planet or explore the galaxy.
- Intelligent civilizations are too far apart in the universe: Even if there was only intelligent species per galaxy, there would be trillions of intelligent species in the universe. The problem would then become one of distance. Even if humans were able to travel at the speed of light, it would take us 2.5 million years to travel to the next galaxy, Andromeda. So it would be very unlikely that we would ever come face to face with our cosmic neighbours even if they were living in the nearest galaxy to the milky way.
- Human beings might not be listening properly: Although we have the SETI program that listens for alien activity in the galaxy it remains a possibility that the technology required to pick up alien communications has not yet been invented. By comparison to the age of the Milky Way the human race is very young and intelligent species might use communication technologies that we could not yet comprehend with our current advancements.
- Intelligent life deliberately does not contact earth: A possible hypothesis is that earth is known to other intelligent species, and they deliberately have not made contact with earth to allow it’s natural evolution and development. Similar to how NASA scientists try to not contaminate other planets with samples from earth when launching probes and the Rover program on Mars.
- They are already here: A significant portion of the human population believes that we have already been visited by aliens. While most alien sightings are explained away by mistaken interpretations or mundane phenomena, there are those that remain baffling even after investigations. It is also possible that SETI groups or governments are suppressing alien contact in the interest of potential use of the advanced alien technology.