While discussing UFOs on a walk to lunch in 1950, physicist Enrico Fermi famously (reportedly) asked, “But where is everybody?” In current times, scientists call that riddle Fermi’s Paradox. The answer to this paradox may be the Great Filter. Why haven’t we encountered intelligent life in our Milky Way galaxy? This article sheds more light on the Great Filter theory.
What is the Great Filter?
Economist Robin Hanson first proposed the Great Filter in the late 1990s. It’s the idea that even if life forms abundantly in our Milky Way galaxy, each extraterrestrial civilization ultimately faces some barrier to its survival- from within or without.
The main conclusion is that the easier it was for life to evolve to the present stage, the bleaker the future chances of humanity. Many scientists believe the Great Filter is why we don’t see nearby star systems.
The Karshashev scale and the Great Filter
This scale categorizes the stages of a planet’s development. A Type I civilization can access all the energy on its planet. A Type II civilization can consume the energy of a star. A Type III civilization can capture the energy emitted by its galaxy.
The Great Filter theory holds that extinction possibly occurs at the end of this scale. Scientists believe humans may attain Type I status in 100–200 years, Type II in a few thousand years, and Type III in 100,000 to a million years.
Has Earth faced some filters before?
The Permian-Triassic extinction, also called the Great Dying, occurred about 250 million years ago. The event nearly ended all life on the planet, wiping out about 96% of marine life and 70% of land species. Was this a form of filter?
The Great Dying and other extinction events were natural from the evolution of our planet and solar system. This points to the fact that the Earth has survived some previous filters; it can occur again from natural causes like giant asteroids or volcanic eruptions.
Is the Great Filter still ahead of us?
While we can’t do much about the external causes of extinction, some factors can end life on Earth from within. Scary enough, these factors of Earth’s doom are already in motion, and they are moving very fast.
In plain words, we may be making our type of Great Filter. From the looming computer rivalry with humans via AI to nuclear war effects, some issues may lead to our undoing. Although we can’t be totally sure, different theories tell us that the Great Filter may be looming.
What are critics saying?
Some critics think it is possible we haven’t met aliens yet because the universe is vast, not because they’re all dead (according to the Great Filter theory). According to these critics, thriving intelligent civilizations may be very far from us.
They believe it’s too early to be sure these civilizations have become extinct. To them, the theory that there is nobody or advanced technology out there is based on an assumed observational result. It’s probably safe to say time will tell.
