The Great Filter


Hello, I was doing some research about The Great Filter theory because it interests me. But there is something I can’t find answer to. So I hope you will help me clear my head with this. What would mean if some inteligent form of life visited us? Like bilion or more years old civilization from the other end of the galaxy. Would that mean that filter is in front of us or behind us? I can’t get my head around it..

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Well, if they told us there are a bunch of planets with intelligent life like ours that are stuck in their solar system, that would imply the filter is ahead of us. Intelligent life happens a lot, but interstellar transit is hard to achieve, and that’s the filter.

If they tell us we are the first other intelligent life they’ve met after a lot of exploring, that means we’re probably past the filter, one of the few survivors.

If they say there are a ton of other civilizations that can travel interstellar distances, we can’t conclude much. Maybe the filter doesn’t exist in that case, or still lies ahead of everyone.

That specific scenario wouldn’t say much about the filter one way or another. It could mean the filter is behind us and we are the only two civilizations to punch through. It could also mean the filter is ahead of us, but not the aliens, meaning they punched through and everyone else at our level hits the wall at some point in between. It could also mean a number of other things. With a billion-year head start, the aliens would hopefully have a clearer understanding of how the universe works.

Imagine a coin that someone lost in a forest. The forest is the filter, it prevents us from seeing the coin.

Exept if we find the coin. But the forest is still there.

It would mean there is no filter.

Back in the early days of rockets, a bunch of scientists sat around talking about the possibility of alien life. Being nerds, they wanted aliens to be real. They shared their own predictions for how many alien civilizations there might be in the galaxy. Most of the people agreed that there were so many stars out there, and the universe was so old, that there basically *had to be* advanced civilizations out there.

This led to a question by physicist Enrico Fermi, who said “well then where is everybody?” This is known as the Fermi Paradox. It looks like there should be a bunch of life out there, and we should probably be able to detect some of it, but we don’t see anything.

One of the proposed solutions to this paradox is called the Great Filter, the idea that there’s some kind of barrier that prevents interstellar civilizations from arising. Maybe the filter is early (the creation of life is so rare it almost never happens, or maybe life is common but intelligence never develops), or maybe the filter is late (intelligence is common but people nuke each other to extinction as soon as they get nukes). Nobody knows which, if any, of these filters are correct.

If aliens show up tomorrow, it answers the Fermi Paradox. “Well then where is everybody?” The answer is “over there. The aliens are right over there.”

Let’s start by walking back the question a bit. Why does the Great Filter hypothesis even exist? Well, it’s proposed as a possible solution to the Fermi paradox. Now, if we are visited by Aliens, then Fermi paradox has been answered. If Fermi paradox has been answered, then is the Great Filter hypothesis still relevant? So that’s the first answer.

Next, we could modify Fermi paradox just a little bit. Instead of asking why we have seen no evidence of ET, to asking why we have seen only one? And why now?

Here, we could have some fun and imagine a few scenarios, starting with the simplest.

The simplest scenario is if the Aliens are hostile, and we are annihilated. I know, it’s a bummer, but it does tell us something about the nature of the filter in the Great Filter hypothesis, that there is this advanced civilization going around the universe destroying nascent civilizations on first contact.

Next, in a more hopeful scenario, the aliens are friendly and willing to exchange information with us. Now, we can simply ask them about whether there is a great filter, whether we’ve past it, etc. Good deal!

The aliens may have a Star Trek style prime directive that prevents them from sharing any information with us. In that case, we are no further along on solving the modified Fermi paradox or learning about the Great Filter, but I think knowing that We Are Not Alone must change our human species somehow, hopefully for the better.

Last scenario that I’ll mention would be: what if we are also the only other intelligent life that this alien civilization has ever met? Well, in this case, we can use the information that we’ve gathered to further refine our hypothesis, testing them; then gather more info, refine some more, and test again… in other word, continue on our quest to understand the universe around us, just like we’ve been doing all along.