In Part 1 of our exploration of the Fermi Paradox we explained the problematic math that gave rise to the paradox. Essentially, the statistics just doesn't work out. Considering all the elements needed to produce advanced intelligent civilizations, they should be more common in the Universe.
The question remains: Why are we apparently alone?
Answers to this question can be more terrifying than losing your job to a particularly plucky Venusian. So let's get into the possible explanations for our silent universe.
Life Exists, But We Suck at Finding it
First, we should temper our egos. Humanity has come ridiculously far in the last 150 years. Discovering flight and landing on the moon are closer together in time than the building of the pyramids and Cleopatra.
Having said that, we are still little more than babies learning to crawl. Our technology might be impressive to us, but we can still imagine far greater achievements.
The theory here is that we just haven't tried hard enough to find an extraterrestrial civilization. Finding planets outside our solar system is tough, but we are getting better at it.
We still can't visit every planet in our solar system (in person). So it might also just be impossible to travel the stars.
According to this theory, we'll find the aliens soon enough.
We're the First, or the Last
The Firstborn hypothesis states that we might be the very first intelligent civilization in the universe. This idea doesn't discount the existence of possible extraterrestrials, it does however, leave us in the unenviable position of being the first to 'wake up'.
We could be tasked with the duty to spread our civilization into the galaxy. Doing this could have the side effect of eliminating species that could in the future evolve into intelligent life.
The flip side is that we have arrived fashionably late to the galactic stage. Every other intelligent species has gone extinct long ago.
They could also have put themselves into hibernation a long time ago. Having learned that they were the first to 'wake', they might have chosen to sleep until the universe becomes a bit more populated.
The Aestivation Hypothesis suggests that aliens are hibernating until a time when the universe has cooled. This colder universe would be perfect for maximizing computing power.
Great Filter Hypothesis
One of the hypotheses that gets the most traction in astronomy media, is the Great Filter hypothesis. According to this idea, there are certain hurdles that all life must leap over in order to survive.
We can look at these filters as natural progression points along the path to becoming a truly advanced galactic civilization. With every new technology comes the risk of self-destruction.
Nuclear weapons are often brought up here. Humanity has the power to make this world uninhabitable for our species. All it takes is for one of the insane old-people that run the world to decide they want to go out with a bang, and poof, we are gone. Lost in an irradiated hell of our own creation.
Climate Change is another possible Great Filter. We as a species might be failing the self-preservation test in favor of the Capitalistic ideology. If it wasn't for corporate influence on world governments, humanity could have 'gone green' a long time ago.
That means that we might still be approaching our Great Filter, and that no civilization has ever made it past all the Filters.
Imagine if we evolved on a planet that was all ocean. The planet is covered in an ice sheath, which keeps uncaring space out. Volcanic activity warms our ocean, and keeps the chemical reactions going to keep the ocean habitable.
Our biosignature would be all but undetectable to outside civilizations. We wouldn't even know what space was.
It would be a bit like what Flat-Earthers think our world is, a disk surrounded by an insurmountable ice-wall (like Game of Thrones). The only difference is that it is even remotely possible in this scenario.
Next time we'll take a look at some scarier hypotheses. Check it out in Part 3.