Have you ever looked at the sky, full of stars, and wondered “Are we really the only ones here?”
I mean, the universe has 2 trillion galaxies, according to a new study. Yet, here we are stuck on one planet, that isn’t even the largest in our own solar system. We can’t be the only ones here, right?
But here’s another thing to think about, if there are other intelligent life forms out there, why haven’t they visited us yet?
That’s what physicist Enrico Fermi asked while wondering during lunchtime one day. He was sitting with his colleagues and chatting about a cartoon in the New York Times with an alien in it, when Fermi asked, “Where is everybody?”
A Huge Universe All For Ourselves?
There are 100 billion stars in the Milky Way alone, and almost 2 trillion galaxies and 1024 planets in the universe.
Of those planets there are 50 sextillion (sextillion= 1021) Earth-like planets in the universe. In our galaxy alone, there are 100 billion planets that can support life.
Our sun is young. There are stars much older than the sun and much older earth-like planets. Aliens, if they exist on one of those earth-like planets, should be more advanced than us.
There should be intelligent life form civilizations older than ours with much more knowledge. They should be billions of years ahead of us. In other words, they should be capable of interstellar travel.
Interstellar travel is the ability to travel between stars and galaxies. We aren’t there yet, but remember only 100 years stand between when we were traveling by wagons and the time we landed on the moon.
According to the Search for Extraterrestrial Intelligence or SETI for short, any civilization with a modest amount of rocket technology and an immodest about of imperial incentive could rapidly colonize the entire galaxy.
It would take them only ten million years to take over every single star system. Ten million years isn’t much when you compare it with the age of the galaxy, which is about ten thousand million years.
Until this day, we haven’t seen any aliens. We haven’t seen any evidence to prove their existence. However, according the Drake Equation, there are other alien civilizations out there.
Where Is Everybody?
There are two explanations for the Fermi paradox:
The first is we haven’t seen any aliens simply because they don’t exist.
Earth might be one of a kind. We assume that just because life started here on Earth, other planets with properties similar to Earth (ones that have water and an atmosphere and other things that ensure life on earth) should have life that started there too.
But that doesn’t necessarily have to be true. We could be rare. According to a paper published by astrophysicists David Spiegel and Edwin Turner at Princeton University, they argue that life here on Earth arose quickly. The researchers pointed out that if it hadn’t done so, there might not have been time for humans to evolve.
But there is also the other explanation to why there would be no other intelligent civilizations even though the math says there should be others.
The Great Filter
This theory suggests that there is something stopping the formation of intelligent life. It could be something behind us such as the evolution from the simple single-cell life to the complex single cell life.
If it’s behind us, that means we are past the great filter and there is nothing to stop our evolution further. We are in no risk of becoming extinct.
The problem is if it’s in front of us. Robin Hanson wrote in an essay titled “The Great Filter – Are we almost past it?” a list of nine steps in an evolutionary path that results in the colonization of the universe:
- The right star system
- Reproductive molecules
- Simple single-cell life
- Complex single-cell life
- Sexual reproduction
- Multi-cell life
- Tool-using animals with big brains
- Where we are now
- Colonization explosion
If we found simple single-cell life on Mars, that would mean the Great Filter is after step 3. If we found Multi-cell life, the Great Filter is after step 6. The more advanced life form we find raises the probability that the Great Filter is in our future.
So we should hope to never find aliens.
The other possibility is that aliens do exist, they just aren’t contacting us.
But why aren’t they contacting us? There are several theories explaining that, here are a few.
- We are like animals in a zoo. The aliens know we are here and are watching us from afar. However, to watch us in our natural habitat, they are following the strict rule “Look, but don’t touch.”
- Aliens visited Earth before we were here or they visited us back before there were any methods to write it for future humans to find. Modern humans only evolved 200,000 years ago. Aliens could have visited Earth before that time.
- Aliens are contacting us, but we don’t know how to hear it. Aliens could be broadcasting to us in frequencies the SETI isn’t looking for or using lasers or gamma ray bursts. We might be looking for the wrong things.
Or as Carl Sagan said, maybe aliens communicate slower or faster than we do and take years to say a single word, and what we are hearing is only white noise.
- We live in a rural area of the galaxy. The universe could be colonized, but we are in a rural area that no one bothers to come to.
- Aliens are all over the place, but we are too primitive to see perceive them. If you were building a mall next to a goldfish, would the goldfish understand what you are doing?
Aliens could be all around us but we are too primitive to understand what aliens are or what they are trying to do.
- We live in a stimulated universe and whoever put us here didn’t bother to put any other creatures out here.
We still don’t know for sure whether or not aliens exist. The Fermi paradox suggests they don’t. Other people are giving us explanations to the Fermi paradox. We’ll never know if aliens exist for sure until we find one.