Dissolving the Fermi Paradox

[Skelm]

A recent arxiv preprint has, so far as I can tell, completely resolved the Fermi paradox.

Article:

The Fermi paradox is the conflict between an expectation of a high ex ante probability of intelligent life elsewhere in the universe and the apparently lifeless universe we in fact observe. The expectation that the universe should be teeming with intelligent life is linked to models like the Drake equation, which suggest that even if the probability of intelligent life developing at a given site is small, the sheer multitude of possible sites should nonetheless yield a large number of potentially observable civilizations. We show that this conflict arises from the use of Drake-like equations, which implicitly assume certainty regarding highly uncertain parameters. We examine these parameters, incorporating models of chemical and genetic transitions on paths to the origin of life, and show that extant scientific knowledge corresponds to uncertainties that span multiple orders of magnitude. This makes a stark difference. When the model is recast to represent realistic distributions of uncertainty, we find a substantial ex ante probability of there being no other intelligent life in our observable universe, and thus that there should be little surprise when we fail to detect any signs of it. This result dissolves the Fermi paradox, and in doing so removes any need to invoke speculative mechanisms by which civilizations would inevitably fail to have observable effects upon the universe.

Source: https://arxiv.org/abs/1806.02404

Basically, people were making the argument that there should be lots of alien civilizations by taking the Drake equation, plugging in some reasonable sounding values, and seeing that the expected number of alien civilizations is very large. This is actually a valid way to find the expected number of alien civilizations, since the expected value operator is linear (i.e. the expected value of the product of two variables is the product of the expected values of each variable), but what we care about is actually the probability of there being very few alien civilizations.

If your range of possible values for some parameters covers multiple orders of magnitude, then there is a high probability of getting an actual outcome multiple orders of magnitude lower (or higher) then the expected value would lead you to think, just because some parameters happened to have values much lower (or higher) then the midpoint.

The authors make an attempt to estimate the actual scientific uncertainty in each parameter and come up with an a priori ~30% chance of us being the only civilization in the observable universe. Therefore, there is no particular reason to be surprised that there are no alien civilizations.

 

[Mechasaurian]

The Rare Earth Hypothesis is not new. These three randos at some university have not "solved" anything.

 

[Skelm]

The Rare Earth Hypothesis is not new. These three randos at some university have not "solved" anything.

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People making informal claims that Earth is rare aren't new, a formal argument for why this should be a high probability outcome is.

Consider the difference between a conjecture and a proof, and who deserves more credit.

 

[Vyslanté]

I've always assumed that the solution to that "Paradox" was simply a question of time-scale.
The universe has been around for a dozen billion years, and we've been able to detect radiowaves for not even two centuries.

Obviously we aren't going to see anything. The odds for multiple civilizations existing are what they are, but the odds of them existing exactly in the same insignificant time-frame are ridiculous.

 

[RRoan]

The Rare Earth Hypothesis is not new. These three randos at some university have not "solved" anything.

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They've shown that, based on the level of uncertainty in our knowledge, it is entirely credible for Earth to be rare or even unique. That's something that a lot of people will just dismiss out of hand.

I've always assumed that the solution to that "Paradox" was simply a question of time-scale.
The universe has been around for a dozen billion years, and we've been able to detect radiowaves for not even two centuries.

Obviously we aren't going to see anything. The odds for multiple civilizations existing are what they are, but the odds of them existing exactly in the same insignificant time-frame are ridiculous.

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You're assuming that species like ours die out rapidly (or at all).

 

[Vyslanté]

You're assuming that species like ours die out rapidly (or at all).

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Civilizations, not species.

(or at all).

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I don't think it's an unreasonable assumption to make.

 

[tankdrop24]

I've always assumed that the solution to that "Paradox" was simply a question of time-scale.
The universe has been around for a dozen billion years, and we've been able to detect radiowaves for not even two centuries.

Obviously we aren't going to see anything. The odds for multiple civilizations existing are what they are, but the odds of them existing exactly in the same insignificant time-frame are ridiculous.

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Also, Earth is apparently among the first planets to be habitable in the lifespan of the universe.

We haven't found sapient life out there because the life hasn't evolved to the point where it can be detected yet.

 

[Mandemon]

Also, Earth is apparently among the first planets to be habitable in the lifespan of the universe.

We haven't found sapient life out there because the life hasn't evolved to the point where it can be detected yet.

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This is kinda my believe too. Instead of assuming that universe instantly formed with perfectly habitable planets and life instantly started, it's more like that it's only now that universe has calmed down that entire planets don't get casually wiped out every two days that life has even time to form and evolve.

 

[RRoan]

Civilizations, not species.

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There's not really a meaningful difference. The fall of a civilization similar to ours, or earlier, will not substantially impede the development of further civilizations. The fall of a civilization substantially more advanced than ours will in all likelihood require a disaster so extreme that it would end the species as well. The fall of a civilization much more advanced than ours and substantially more widespread seems rather implausible.

I don't think it's an unreasonable assumption to make.

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Well sure, even the black holes will evaporate in the far-off future. I'm speaking of timescales relevant to the current age of the universe.

This is kinda my believe too. Instead of assuming that universe instantly formed with perfectly habitable planets and life instantly started, it's more like that it's only now that universe has calmed down that entire planets don't get casually wiped out every two days that life has even time to form and evolve.

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Conditions in the universe have been broadly similar to today for all except the first few billion years.

 

[Flare]

I've always assumed that the solution to that "Paradox" was simply a question of time-scale.
The universe has been around for a dozen billion years, and we've been able to detect radiowaves for not even two centuries.

Obviously we aren't going to see anything. The odds for multiple civilizations existing are what they are, but the odds of them existing exactly in the same insignificant time-frame are ridiculous.

Click to shrink...

There's also a question of plain scale. If there's a civilization in the Andromeda galaxy now it's at least 2 million years before a signal could be recived here. Even if it's "only" on the other side of the galaxy it's giong to take a truckload of time to have a hint of their existance.

 

[Kaiya]

There's not really a meaningful difference. The fall of a civilization similar to ours, or earlier, will not substantially impede the development of further civilizations. The fall of a civilization substantially more advanced than ours will in all likelihood require a disaster so extreme that it would end the species as well. The fall of a civilization much more advanced than ours and substantially more widespread seems rather implausible.



Well sure, even the black holes will evaporate in the far-off future. I'm speaking of timescales relevant to the current age of the universe.



Conditions in the universe have been broadly similar to today for all except the first few billion years.

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Most civilizations have failed to last more than a thousand years. By all evidence, yes. Most civilizations won't exist for any meaningful length of time.

 

[firefossil]

The essence of the Fermi paradox is that if:

A: Life has a non-negligible chance of existing.
B: Existing life has a non-negligible chance of reaching sapience.
C: Sapient life has a non-negligible chance of being willing and able to expand in a manner visible to us.

Then we should already have encountered aliens, because when it comes to galactic scales of hundreds of billions of stars over billions of years events which are non-negligible might as well be certain, and that billions of year timescale also gives tremendous amounts of time for C for those that get a head start on us. It doesn't matter if 99% of worlds are barren and 99% of life-bearing worlds don't achieve sapience and 99% of those worlds don't give birth to Space Mormons, then we'd still have already been colonized by Space Mormons. So the question is which of those assumptions is false. The OP article is just the latest tired attempt to feed numbers into a Drake-esque equation so that A+B's probabilities add up to just low enough to justify us existing but being largely alone in that existence.

 

[Kaiya]

Honestly, though, like...there's plenty of intelligent life here. Octopi, elephants, dolphins, apes. Of all the life on Earth, there's been literally less than a century of actually trying to contact the wider universe. Of these species, only we actually have developed technology, all the others seem pretty fine to exist as they are now. And we've, in the century or so we've had of higher tech stuff like cars and electricity, already invented several means of reducing ourselves way the hell back (Global warming+nuclear war being the big two). There's no particular reason the galaxy might not be full of intelligent beings at the bottom of oceans or wandering big alien fields, blissfully ignorant of things like radiosignaling and rockets.

 

[PhoenixMercurous]

The essence of the Fermi paradox is that if:

A: Life has a non-negligible chance of existing.
B: Existing life has a non-negligible chance of reaching sapience.
C: Sapient life has a non-negligible chance of being willing and able to expand in a manner visible to us.

Then we should already have encountered aliens, because when it comes to galactic scales of hundreds of billions of stars over billions of years events which are non-negligible might as well be certain, and that billions of year timescale also gives tremendous amounts of time for C for those that get a head start on us. It doesn't matter if 99% of worlds are barren and 99% of life-bearing worlds don't achieve sapience and 99% of those worlds don't give birth to Space Mormons, then we'd still have already been colonized by Space Mormons. So the question is which of those assumptions is false. The OP article is just the latest tired attempt to feed numbers into a Drake-esque equation so that A+B's probabilities add up to just low enough to justify us existing but being largely alone in that existence.

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Have you read or even skimmed the paper linked in the OP? Arxiv papers are freely available AFAIK.

 

[Mandemon]

Conditions in the universe have been broadly similar to today for all except the first few billion years.

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And how long did it for Earth to develop life and then how long did it take for it reach a civilization?

For all we know, galaxy is full of intelligent life, but due to everyone's short time on universe nobody has yet managed to even get a simple "beep" across the vast distances between stars, never mind have someone else realize that the said beep was actual message rather than some background noise.

The Wow-signal might have been some alien sputnik signal that finally reached Earth... and then they nuked themselves.

 

[Vehrec]

The crux of their arguement is the vastly huge uncertainty they assign to the arising of life, to the point where it swamps out all other factors, even with a normal as opposed to uniform distribution. I have no idea why they decided that 50 orders of magnitude was an appropriate measure of our understanding, nor why they seem to discount alternative biologies as impediments to this, rather than the next stage of the assessment. We have no way of knowing if Abioogenesis occurred once on earth, or millions of times, followed by a winnowing and amalgamation of the survivors. The study of the origins of life is based on scant evidence and poor understanding of the topic of study, of course the uncertainties are immense, but they should be a double-tailed immensity.

I think they are right that we are hugely ignorant of the probabilities of life arising and life achieving intelligence, but I think they're using that ignorance to push, well, a dubious conclusion. We need better studies of the origins of life and perhaps more importantly, we need to step up our searches for martian fossils and perhaps even consider seriously a mission to Europa to look for signs of life. Extra data points are sorely needed here, because without them we have no data to feed into our estimates.

 

[Havock]

Not to mention that even if life, intelligent life, is "common" it would only be relative to the vastness of space.

Couple that with it probably not being netly organized; if there are other civilizations you might see entire regions of the galaxy (nearly) devoid of complex life, with others teeming. Not unlike places on earth.
We could simply be in a dry patch.

There's a ton of possibilities that even if we have the know-how to look into, we simply haven't had the time yet.

 

[Mandemon]

Fermi Paradox also assumes that there is rather constant rate of expansion by whatever species that reach planet, when ever our own history is full of empires and populations growing, shrinking, surging and collapsing, migrations and emigrations, etc.

To assume that "There is intelligent life and they intentionally try to spread everywhere... Where is life might go "...Nah, that neutron star ain't a place we want to settle" and stop colonizing in that direction. Colony might also fail or civilization might decide to pull inwards.

 

[Havock]

Fermi Paradox also assumes that there is rather constant rate of expansion by whatever species that reach planet, when ever our own history is full of empires and populations growing, shrinking, surging and collapsing, migrations and emigrations, etc.

To assume that "There is intelligent life and they intentionally try to spread everywhere... Where is life might go "...Nah, that neutron star ain't a place we want to settle" and stop colonizing in that direction. Colony might also fail or civilization might decide to pull inwards.

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And we still don't know if it is posssible, and if then feasible to actually project outwards.
Not to mention we have very limited sample size to work with, for all we know the vast majority of intelligent life develops in oceans. Such beings would need to take another hurdle when developing a tech base, let alone shooting stuff into space.

 

[Mandemon]

And we still don't know if it is posssible, and if then feasible to actually project outwards.
Not to mention we have very limited sample size to work with, for all we know the vast majority of intelligent life develops in oceans. Such beings would need to take another hurdle when developing a tech base, let alone shooting stuff into space.

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And this is even assuming the species does leave their home planet. Up until humans showed up nobody on Earth was in hurry to leave and even to us it took something off an accident to even go "You know, what if we could travel across the stars?"

Basically, Fermi Paradox relies far, far too much on idealized model of species expansion and evolution.

 

[Navarro_Refugee]

Fermi Paradox also assumes that there is rather constant rate of expansion by whatever species that reach planet, when ever our own history is full of empires and populations growing, shrinking, surging and collapsing, migrations and emigrations, etc.

To assume that "There is intelligent life and they intentionally try to spread everywhere... Where is life might go "...Nah, that neutron star ain't a place we want to settle" and stop colonizing in that direction. Colony might also fail or civilization might decide to pull inwards.

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This argument isn't a very strong one, because for it to work actually requires you to make an even bigger assumption about the behavior of intelligent life than the paradox does. You have to assume that every faction of every species that reaches the point of being capable of interstellar colonization are all going to decide not to expand at all, and stick to that choice forever, because all it takes is just one group within one of those species deciding they want to expand to bring the paradox back in full force. It doesn't even have to be aggressive expansion, even a languid growth rate of launching one new colony every ten thousand years per existing star system would see a galaxy colonized in a relatively short time in cosmic terms.

Second, there is always a reason when expansion stops, usually an economic or population collapse or simply running out of room. Population collapse in particular requires a catastrophe that just doesn't seem believable for a civilization that is capable of interstellar expansion in the first place, and the scales involved in an interstellar civilization would mean that economic collapse could hardly ever be more than a local event affecting a single system. Important to remember that while individual nations may have periods where population shrinks humanity as a whole has been growing nonstop for tens of thousands of years, and that's in spite of the fact we were relatively vulnerable hunter-gatherer societies for the majority of that time.

 

[PhoenixMercurous]

It doesn't even have to be aggressive expansion, even a languid growth rate of launching one new colony every ten thousand years per existing star system would see a galaxy colonized in a relatively short time in cosmic terms.

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Is that growth rate actually on the low end of expected rates, or did you just make up a number that sounded low?

 

[Whachamacallit]

While I don't necessarily agree with these researchers, it is interesting none-of-the-less. Although, I'm surprised there are people here who claim that the Rare Earth Hypothesis is the most likely reason for the lack of observable intelligent life. We only got a sample size of one, but I would argue it shows the complete opposite proposition.

Like let's consider the history of Earth. Earth formed around 4.5 billion years ago, and, based off fossil evidence, life appeared 3.7 billion years ago, with a potential of it starting 4.1 billion years ago if the C13​/C12​ ratio of that time is anything to go by. Let's just assume it started 4 billion years ago, for the sake of my conclusion. Either way, life formed when Earth was more of a barely habitable hellscape than what we have today.

For around 2.5 billion years, life on Earth was nothing more than microscopic soup, until 1.5 billion years ago, when multicellularity evolved. Even so, multicellular organisms didn't become prolific until ~750 million years ago(+or- a few hundred million years), with the potential occurence of the Snowball/Slushball Earth. Then 541 million years ago (we'll generalize it to 500 million years), the Cambrian Explosion happens and complex mulitcellular life evolves.

Following that, it's not until the last 300,000 years that a sapient, prolific tool-user evolved (I'm specifying this since there are plenty of brainy animals). And even so, it wasn't until the last 12,000 years that this species developed a method of living that boosted technological advancement, and it wasn't until the last 200 years that this species even had the most remote chance of flying off planet. And there are enough risks abound that even that flying off planet isn't guaranteed.

So let's take it all into account. Earth has had life on it for ~8/9s of its history. ~3/9s of it's history had any sort of multicellular life, those multicellular life forms weren't prevalent until the last 1.5/9s of Earth's history, and ~1/9 of its history has had complex multicellular life. Finally, 67/1000000 of Earth's history has had an intelligent super tool-user that hasn't spread through the stars and may never do so.

I would argue that using the argument "life in general is rare/unique" to explain the Fermi Paradox/Observation is a bit of an odd thing to focus on, since with our sample size of one, it seems like that may be the easiest step.

 

[Mandemon]

Population collapse in particular requires a catastrophe that just doesn't seem believable for a civilization that is capable of interstellar expansion in the first place, and the scales involved in an interstellar civilization would mean that economic collapse could hardly ever be more than a local event affecting a single system.

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You would be correct if we assume that every colony is a self-sustaining and requires no support from anyone. However, our own history has shown that it is actually very easy to have a colony fail due to lack of support. Consider Bronze Age Collapse, for example. Civilization basically went poof and it took centuries to start to recover. If a central government suddenly collapses and various supply lines are cut-off, it is far more likely that colonies start to fail due to hostile worlds combined with lack of support. We have yet to find a world that can support human life without any sort of aid: why are we assuming that aliens would find constant influx of "garden worlds"?

 

[Navarro_Refugee]

Is that growth rate actually on the low end of expected rates, or did you just make up a number that sounded low?

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The later. I don't know that "expected rates" even really exist in the form of meaningful studies or anything like that. I will note however, that needing ten thousand years to become established and launch a new colony is extremely pessimistic. Ten thousand years saw human population on earth go from a couple million to seven billion and from primitive agriculture to computers, with most of that growth occurring in the last two hundred years. It seems a touch absurd to think that a hypothetical interstellar civilization could need longer than that to build a ship, gather people, and launch a colony, or that it would take longer than that for a newly established colony to grow the population and build the infrastructure needed to launch colonies of their own.

You would be correct if we assume that every colony is a self-sustaining and requires no support from anyone. However, our own history has shown that it is actually very easy to have a colony fail due to lack of support. Consider Bronze Age Collapse, for example. Civilization basically went poof and it took centuries to start to recover. If a central government suddenly collapses and various supply lines are cut-off, it is far more likely that colonies start to fail due to hostile worlds combined with lack of support. We have yet to find a world that can support human life without any sort of aid: why are we assuming that aliens would find constant influx of "garden worlds"?

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The logistics of interstellar travel very nearly forbid the kind of trade between systems that we are familiar with here on earth, at least if FTL is impossible (which it probably is). How reliant can you really become on shipments from another system when you could be looking at a minimum transit time of at least several years and probably more like decades, centuries, or millennia to move material from one system to another? The fairly uniform distribution of matter in the universe means there shouldn't ever be a case where one system has some abundance of any material thing that another system lacks (outside of infrastructure, and that has to be built anyways).

It's also wrong to think that garden worlds are a prerequisite for interstellar colonization, since anything like a world well suited for life from another planet would be so rare that there are probably only a handful in the entire galaxy if even that many. Habitation space would like be primarily in the form of megastructures, like Oneill or McKendree cylinders, and perhaps terraforming if suitable planets are present.