The Great Filter is the idea that, in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there is a barrier to development that makes detectable extraterrestrial life exceedingly rare. The Great Filter is one possible resolution of the Fermi paradox.
https://en.wikipedia.org/wiki/Great_Filter
The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. As a 2015 article put it, “If life is so easy, someone from somewhere must have come calling by now.”
https://en.wikipedia.org/wiki/Fermi_paradox
Personally I think it’s photosynthesis. Life itself developed and spread but photosynthesis started an inevitable chain of ever-greater and more-efficient life. I think a random chain of mutations that turns carbon-based proto-life into something that can harvest light energy is wildly unlikely, even after the wildly unlikely event of life beginning in the first place.
I have no data to back that up, just a guess.
I don’t think there is a great filter. I think there’s an easy solution to the fermi paradox that doesn’t require great filters, we’re just the first intelligence in this galaxy.
Here’s my reasoning: intelligent species that manage to develop space travel probably do tend to expand out into their galaxy. When they achieve this level of technology they can settle most of all of their galaxy in a matter of 10,000 years or so. That time period is very brief on an evolutionary scale. It’s estimated that life began on earth 3.7 billion years ago. That means it took about 3.7 billion years for earth to produce intelligent life, and then from that point it would take a mere 10,000 years to reach modern day, and 10,000 more years to settle the whole galaxy. That expansion happens so quickly compared to how long it took the planet to develop intelligent life, that the chance of two civilizations rising at the same time becomes very small.
It all boils down to this: there are no intelligent aliens out there in our galaxy, because we are the first intelligent species in our galaxy. We know we’re the first because if we were second, then aliens would already have settled this star system.
Probably there are lots of alien civilizations out there in the universe, but they’re in different galaxies.
and the ones finding apes on a planet just short ahead or into the beginning of those 10000 years might think “well lets teach them how to stack stones and let them call us gods for just showing some of our million years old and cheap replicated tech gadgets pewpew, how amusing! but now lets go on, this planet has water but way too much oxygen and also there is axial precession that would change weather over only few hundrets of thousands of years if not less, not the planet of choice for eternals like us, duh!”
Or we just don’t know, because every possible indicator is gone after a few hundred million years or our star system was still a proto disk when they were around.
That assumes that interstellar travel is possible. Physically, economically, socially, there’s a lot of boxes to check for near-light extrasolar expansion (let alone FTL, which probably is impossible)
I think the easy solution to the Fermi Paradox is that we’re stuck in our fish bowl and so is everyone else.
That’s true, it does assume interstellar travel is physically possible, but at this point there are forms of interstellar travel that we know are possible.
Solar sails for instance, we know those work, we’ve tried it. Now if you wanted to travel to another star system with a solar sail, it’s just a matter of scaling that proven technology way up. We’re not ready to do that today, and we won’t be ready in the next 20 years, but to think that we wouldn’t be ready in 500 years, I find that idea far fetched.
But a much better technology would be fusion propulsion. With fusion drives you could get your cruising speed up to a meaningful fraction of the speed of light (perhaps 5-10%). At that rate you can make it to the closest stars in less than 100 years. And that technology is not at all far fetched. We truly are approaching working fusion power plants, it’s extremely likely that we can eventually develop fusion propulsion, or at the very least, fusion powered electrical propulsion (ion drive).
As for if it will ever be economically possible, I’m not at all worried about that. The fact is, there are a lot of resources and opportunities right here in our solar system, just waiting for people to utilize them. So people definitely will start mining and manufacturing in space eventually. And as we start to operate more in space, we will naturally continue to iterate and improve our methods of getting around. In short, over time it’s going to get cheaper and cheaper to make space ships and we’re going to get better and better at doing it. The economic factors are likely to fall into place eventually.
And finally, will interstellar travel ever be possible socially? Hey, your guess is as good as mine. I don’t think we have any way to answer that…
The Milky Way is 100,000 light years across. It’s physically impossible to settle that in 10,000 years
But why are we the first. That’s the question. Given the age of the universe, statistically it should have already happened by now. Unless something was stopping it.
Statistically I shouldn’t fail a 99% roll 7 times during a single mission in XCOM and yet here we are.
“weird coincidence” is one potential solution to the Fermi paradox.
It could simply be that the rise of life is wildly more rare than we think.
Yeah, it totally could be.
That’s definitely the right question! And honestly we don’t know, but it’s evident that we are first.
I’m not sure that’s true… I’m pretty sure that our sun is old for a main sequence yellow star in our galaxy. When you compare how long it takes for a star to get to the point ours is now, compared to the age of our galaxy, I believe it suggests that sol is part of a first wave of stars of its type. So if life really requires a star like this one to start up, then intelligent life starting just now could be right on time.
Now why is our start perfect for life? Again, we don’t know, but evidently it is. Sadly we only have this one data point, this is the only star where we know there’s life. So assuming that something about our type of star is perfect is about as sensible as assuming that life could start around any star. Is it that other kinds of stars produce too much radiation in the Goldilocks zone? Or is it that other kinds of stars are too variable in the amount of heat they produce? Or that other kinds of stars don’t tend to have rocky planets? We don’t know, but something about main sequence yellow stars could be special, and we have one of the first of those stars in this galaxy.
So declaring “we’re the first” requires some assumptions, but they aren’t crazy assumptions, and a lack of evidence of other older civilizations makes those assumptions stronger.
And to your point, the universe is much older than this our star, so I suspect intelligent life has developed many times before us, at least in older galaxies. But sadly I don’t expect us to ever meet life from another galaxy. While I think stars within a galaxy are close enough for travel between them, galaxies are very, very far apart. I don’t think life has much chance of traveling to other galaxies, at least not without some method of ftl travel (which I am also not optimistic about).
It might have something to do with the available elements.
We live in a population I star system, full of crap spewed out from long dead stars. Perhaps it is exactly this crap (like copper, iron, nickle, manganese, and possibly the bulk of carbon and nitrogen) that allow life to develop with enough agility to survive mass extiction events with any kind of complexity.
Or perhaps it’s exactly those mass extiction events that have allowed enough breathing room for new paradigms to take hold. Maybe our 5-7 mass extictions that didn’t end life entirely are exactly what is needed to prevent stagnation. We just happen to be on the edge of dead and too slow.
In my sci Fi that I’ve been working on has this theory being true but I also play with asking what is the point of colonization. In my story humans have colonized mars to study the fossils and what life used to be like on Mars. However the people there after a few generations separate from earth. Earth doesn’t do anything about it because not only can mars use telescopes to see our ipbm years before it arrives and have that time to shoot our ipbm before it arrives but invasion will destroy the fossils we care about. And that’s all assuming history won’t just repeat itself. Eventually the mars colony expands until it breaks into different nations all fighting echother to become the first martin superpower. So everything that earth cares about gets destroyed by war anyway and earth is pointless to mars without life and water. Eventually the sun becomes so old that everyone feels the need to move their populations to another solar system. And only then de humans discover alien life. Only to discover that it’s currently 900 billion years beyond 2024 and aliens are just now figuring out radio waves and rockets and are more concerned about developing eugenics than discovering humans.