The Fermi Paradox: The Great Filter Theory

There is a dozen of popular possibilities which explain the Fermi Paradox, each may seem impossible, but they are actually more likely than one would think. These are best split into two main groups. Group one possibilities explain that we have had no contact from higher life forms because they don't exist due to something else that must be going on. This something else is often referred to as The Great Filter. (Urban) The Great Filter Theory states that all life has many "filters" to pass through in its journey from pre-life to being a Type III Civilization. Most of these filters are easy to pass though and only kill off a few species of the millions that attempt to pass through. One of these filters is different, it is almost impossible to

The first possibility is that other civilizations have already visited Earth, but long before we were around. Considering that sentient humans have been around for 50,000 years and we have had recorded history for 5,500 years, in the context of millions or billions of years, this is nothing, so they could have visited prior to our existence and never had a need to come back. This is also one of the most popular in pop fiction, with multiple movies being based around the theory that what the ancients thought were gods were actually aliens. The second possibility says that our galaxy is already colonized, but we are a rural area in which no one has any use of coming to. Many cases of this have been found in Europe's colonization of the Americas. Many small northern tribes had no idea that their whole continent had been colonized until a century later. The third possibility is that the whole concept of physical colonization would be an impractical use of resources to a Type III Civilization. They might build an empire around a small group of stars and build their perfect utopia. The fourth possibility is definitely one of the scariest. In this possibility, one predator civilization roams the galaxy looking for resources and life on other planets only to destroy them for their own benefit. This theory has led many scientists to suggest against sending messages out into the galaxy so others might find us. Much like Columbus's discovery of the Americas, it may not end well for the natives. This is again a possibility often referenced in pop culture. The fifth possibility is much like the fourth, except the predator civilization does not destroy other life for resources, but to keep its rule over the galaxy. It makes sure no other civilizations get to their level, or they risk being crowded out. The sixth possibility