Grabby Aliens: A Resolution to the Fermi Paradox | Hacker News Reader

Grabby Aliens: A Resolution to the Fermi Paradox

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189 pointsMrBuddyCasino334 comments

My 2 favorite Fermi Paradox resolutions:

1 - Given that we are only 14B years into a many-trillion-year stretch, our existence now is so unlikely that it's possible that we actually are the first. Something has to be first.

2 - Aliens are everywhere, but we cannot perceive them for reasons we would find disturbing. Largely, for the same sort of reasons that cave fish cannot see light or that most species are apparently unaware of humans in their environment. Essentially, that there is no evolutionary reason for humans to perceive them.

As for grabby aliens... meh. I don't find it convincing as a resolution. It contains too many unexamined assumptions, quite like the simulation theory.

We don't even have to be first-first, just among the first few thousand and still outside the light cones of any of the others.

I'm betting on #2. We only have our own planet to look at, but if we could somehow rank all of the species on the planet according to intelligence, just jumping a couple of levels up or down you enter a completely different world of existence. Or as I like to quip, somewhere in the middle of the ocean there's an island. On that island is an ant hill, and there's an ant at the top of it wondering: Where are all of the other ants?

I don't really find it disturbing, though. Our "best practice" to interact with other species is to try to leave them alone and watch them enjoy and live in their habitat. Makes sense that's what we're doing for the alien overlords, and I'm okay with that. Assuming aliens are around somewhere and we're using our own planet to reason by analogy, the only other two alternatives are they're going to subjugate/destroy us or they're going to eat us. Those alternatives are not so fun.

I find it interesting that so many humans assume that since we can chat with one another, aliens somehow are supposed to show up and chat with us. It's all about us. If such a thing happened, the history of massively-different cultures interacting on Earth is not a positive one.

Given the choices, I'm good.

It's nice that someone else gets #2. I often get bogged down with people refuting the notion by pointing out that we are not cave fish and are nothing like cave fish. That we have evolved to perceive everything that can possibly threaten us and that includes aliens.

Thanks to technology we can perceive many things that we have no evolutionary reason to be able to perceive. Our current physics also doesn't seem to be _so_ wrong that it allows much room for technological societies to hide from our instruments.

> Thanks to technology we can perceive many things that we have no evolutionary reason to be able to perceive.

We might be able to perceive, but that doesn't mean we understand what we see. Every time I engage with medicine, I learn how little humanity actually knows, despite all the technology. We still don't understand what causes many diseases, or how to heal many wounds. How would we find completely alien life when we can't even find the cause of a disease that plagues 23% of the adult population?

The same way we find the disease: by the effects the aliens have on their surroundings.

You are missing the point, in our arrogance to believe we understand things, we do not really understand them. The drive to understand more is powerful, and has lead to huge advances, but we still have a long way to go.

I agree that we still have a very long way to go. I disagree that the areas of the universe that are still mysterious to us are likely to be hiding places for aliens.

> We still don't understand what causes many diseases, or how to heal many wounds.

Right, but we still know the diseases and wounds exist.

Sometimes, you have to wait until you're dead or dying to know they exist. I'm not convinced that humans have mastered perception after mastering writing 5 thousand years ago.

You're partially right, but missing something important.

Where you're correct: Aliens that are only found on planets would be almost impossible to spot, and even if we look at them and see the consequences of their existence on their atmosphere we may interpret that as non biological in origin.

What you're missing: However, if they are expansionist and can build space habitats and automation of the sort we have reason to believe is possible, the question is "why are there visible stars? Why are they not all already surrounded in Dyson swarms?" which is hard to miss regardless of underlying chemistry or biology.

So far as we can currently understand, it seems that about 96% of the matter-energy of the universe is stuff that we cannot see, detect, or explain. Dark matter/energy.

There's more than enough room for fanciful explanations.

Except that dark matter doesn't even interact with itself. Particles of dark matter just pass right through each other rather than clumping together to form complex molecules, rocks, planets, etc.

A Dyson swarm emits approximately same energy as its host star, just in infrared. Dark Matter could, I guess, be Matryoshka brains organised carefully to not hit each other by their keepers, so long as they are also actively "gardening" what we can see so they never ever get Dyson-d.

Wrong isn't the same as incomplete and we have a weird tendency to overlook things, we find then "obvious" afterwards.

Things we do not easily perceive are such that are too fast, too small, too high energy generally and, most importantly, too unexpected.

Further, you can hide in plain sight: you only have to look "unbelievable" (for example), so society will not transmit the information of your sighting.

You can hide where (nearly) no one is looking as well: deep under the ocean, far below the surface, high in the sky, etc.

Most likely, this isn't exhaustive. Places we don't know about are perfect for hiding ,-)

Yeah, we are at the point that we are getting data on black holes colliding millions of light years away from us based on the deviation of a Lazer across miles over the width of a few atoms.

To suggest the universe is full of life and we simply can't see it? I don't buy it.

I think it's more likely that the signals just aren't there, because they are... Not hidden, but are too weak and crossing too grand a distance to be detected.

There are plenty of things that we are aware of that are currently impenetrable by our instruments, such as the inside of black holes or the past. And who knows what we aren't aware of. Is there any reason to believe that physics is a complete description of reality? Or even a significant slice? It could be just describing a very tiny human centric slice of all that exists.

Dark Matter and Dark Energy make up 95% of the Universe (the rest is all the normal matter and energy in all of the galaxies put together). Our understanding of physics is both very complete, and contains large unknowns. You might imagine that there are a lot of aliens hiding in the Dark Matter, but as far as we can tell Dark Matter particles pass right through each other, as well as normal matter. They cannot clump together to make stars or planets or life forms the way normal matter can. Thus all aliens would be made of normal matter like us.

> Our understanding of physics is both very complete

Citation please.

I’m sure I could find some, but I haven’t bothered.

We know that our current understanding of physics is incomplete (various niggling little problems with the Standard Model, the whole Dark Matter question etc), but these are surprisingly small problems. We only know about these problems because of the extreme sensitivity of our instruments. The new physics that will eventually fill these gaps will answer fascinating questions, but won’t change anything about our understanding of life.

For example, petaquarks were first observed in the early 2000’s, and the Large Hadron Collider provided additional evidence for their existence. But they’re so unstable that they can never stick around long enough to participate in any life processes, so as far as our understanding of aliens goes they are irrelevant. Maybe they exist naturally inside the cores of neutron stars, but that’s not really a very habitable environment.

Similarly, however we resolve the apparent paradoxes in our understanding of gravity and quantum mechanics won’t matter at all to the study of life. Gravity is so weak that it is essentially irrelevant in any sort of chemical system, even when quantum mechanics is necessary to understand the fine details.

What I mean is, "complete" according to what criteria? It seems trivially obvious that our human model of physics could only be complete in the sense of accounting for all things we are capable of observing, but that isn't the same as being able to account for all things. There is nothing I am aware of in the model of physics that claims that it accounts for all aspects of reality, observable or not. We don't even know if there are multiple universes, and to what degree they interact, and if there are universes that mostly don't interact with ours at all. There is nothing in physics that precludes another universe that normally doesn't interact with ours, but advanced conscious beings within it being able to bridge that gap if they so choose, similar to how we could go to some island to visit an ant hill if we so choose.

On that last point you are incorrect. The known laws of physics rule out all forms of Einstein–Rosen bridge (aka “wormholes”) that you might imagine, except possibly inside of black holes (and those wouldn’t be traversable). That includes wormholes between points in our own universe, and between universes. Einstein and Rosen studied them because they are technically a valid solution to the equations of General Relativity, but not all solutions to those equations are realizable. In this case, opening a wormhole requires a considerable quantity of negative mass, and there is exactly zero negative mass available. Mass (or energy density), is simply never negative.

As for completeness, each revision we make to the known laws of physics is always smaller than the ones that came before. Einstein’s Relativity trumped Newton’s laws of gravity and motion, but only at high speeds or energies. At high speeds you start to notice weird effects like time dilation, but at low speeds the time dilation is so small that you would never notice it unless you knew to look for it.

Likewise, in most situations the difference between classical mechanics and quantum mechanics is unobservable. There were some edge cases where classical mechanics just couldn’t explain observable phenomena, like the photo–electric effect or phosphorescence, and all quantum mechanics does is fix those edge cases while still being able to explain all the rest of chemistry and such that we already knew about. The changes introduced by Quantum Electro–Dynamics and later Quantum Chromo–Dynamics were even subtler than that. The only easily–measured thing that QCD explains that QED couldn’t is radioactive decay, which is basically irrelevant to life. QED is much more useful to biologists because it explains how chemical reactions can release light (fireflies!), how chemicals can be sensitive to particular parts of the light spectrum (think rhodopsin in the cone cells in your eye), etc.

Because every new addition to our understanding of physics must not contradict anything we already understand (if it did then we would know it was wrong), we are asymptotically approaching a limit (as it were). That limit is either the full laws of physics, or I suppose you would say some limitation of our own minds. But why should our minds be unable to comprehend the full laws of physics? Even if those get harder and harder to learn about and understand, we have all the time in the universe to come to grips with them. Any individual can maybe hit a limit of how clever they can be, but the human race as a whole? I doubt it; we’ll crack that nut eventually. Even if humanity gives up at some point, nothing that we fail to learn could contradict what we have already figured out.

I wasn't talking about Einstein-Rosen bridges. In fact I was wary of using that analogy because I suspected, correctly, that it would be misunderstood.

It sounds like you are saying that any possible reality could only interact with another one using Einstein-Rosen bridges. This is far too narrow a limit of what is possible. If it's possible at all, regardless of likelihood, that reality could be a simulation, then anything you say about the Einstein-Rosen bridge is a property of the simulation, and not a limit on reality as a whole.

What we _can_ observe rules out a lot of things that we can not observe. For example we know to very high confidence that there is nothing that we can't perceive that influences the way nuclear reactions happen.

Do we know with "high confidence" though? What if we are in a simulation?

Then it is a very coherent simulation, with extremely deep and elegant rules that are always followed.

> Our current physics also doesn't seem to be _so_ wrong that it allows much room for technological societies to hide from our instruments.

Perhaps.

An idea I first heard from my brother a decade or two ago was that the Dark Energy expansion of the universe might be the waste product of all the aliens who figured out some way to trick the laws of physics into giving them free energy.

(Obviously that's more of a sci-fi plot device than science at this point, take it with the due level of seriousness).

That's pretty much the plot of Isaac Asimov's novel "The Gods Themselves".

https://en.wikipedia.org/wiki/The_Gods_Themselves

He probably read it, though that novel predates the discovery of Dark Energy.

> we have evolved to perceive everything that can possibly threaten us and that includes aliens

This argument is comical because it contains two components that are exactly the sort of thing that blunts perception: arrogance and absolutes.

Nothing new here. People always thought they already know "everything that's important" and "only a few details are missing". We, as a species, are quite arrogant and entitled to our perceived "large knowledge".

That's why real progress is so slow even "things are obvious"—at least afterwards.

I understand #2. I hope you understand the people refuting it.

Humans haven’t evolved additional perception, we created it. We evolved to see electromagnetic radiation in the “visible light” spectrum but we created tools to see every other part of it.

We’ve even created tools to accelerate matter to just under the speed of light, smashed atoms together and then detected the particles created from the collision.

We’ve explored our entire world, launched telescopes into space, sent probes outside of the solar system and so much more.

Can we see everything? Not even close. But our vision today is incomparably far compared to even just 150 years ago. Cave fish today see as well as cave fish 100,000 years ago.

Only, having the possibility to use such sensors isn't the same as actually using them.

Most advanced sensors are exceedingly rare and consequently locally far too restricted to be useful in this context. Social hurdles apply.

The most comprehensive sensor network on earth belongs to the US military. In spite of being provided extraorinary amounts of taxpayers' money for this, the resulting data isn't shared for common interests like science at all.

We barely see neutrinos, we don't even know what dark-matter and -energy are, we can't reconcile micro and macro physics, we've lived for an eyeblink, we really don't have much clue.

That's why I wrote, "Can we see everything? Not even close."

But the cave fish comparison is not accurate.

Not referring to 300bps, as they seem to get it, but unfortunately many of the most unimaginative people limited by dogma also seem to be the most confident and condescending.

You aren't taking the analogy far enough. That fish doesn't have a prefrontal cortex, and can't even comprehend what we are capable of or capable of perceiving. Whatever more advanced being that us would have perception and experience that we aren't capable of comprehending. They would do whatever they do that we are incapable of just as the fish is incapable of human-level creation.

I think the problem is that 2 relies on kind of woowoo logic. Where exactly do these aliens exist in this scenario? WE can't perceive everything directly but with LIGO we're pretty close to being able to measure most phenomena that exist in the Universe. Is there a mirror universe they exist in because even if not directly we should be able to detect their influence on Solar Systems, Stars, Black Holes, etc.

Are you familiar with quantum gravity? If humans are so advanced in our technology and understanding of physics why can't we explain gravity at the quantum level? https://en.wikipedia.org/wiki/Quantum_gravity#Problem_of_tim...

And if we don't understand something as basic as gravity, how can we possibly say that we can detect everything in the universe?

Actually we even don't understand time. Therefore space-time. Therefore the "stage" on which everything happens.

Also we don't understand mater fully. So we don't understand "the thing" that happens on said stage.

At the fundamental level we know shit. There's still plenty to figure out. Funny enough most of the fundamental things…

By finding out about those fundamental things it's quite possible that we discover completely unexpected aspects of our universe.

Not long ago we even didn't have the slightest clue how our sun works. A phenomenon that is central to our existence since inception.

We should be really more humble in what we assume to know about how the things around us work.

How do you know that we're able to measure most phenomena that exist in the universe?

Even if there is plenty of life in some form we cannot perceive, I think the problem remains:

Why isn't there more "cave fish" out there? The universe we do perceive is ultra gigantic, and seemingly empty.

The pool of water the cave fish lives in may seem incomprehensibly gigantic to its tiny, lonely brain.

> Or as I like to quip, somewhere in the middle of the ocean there's an island. On that island is an ant hill, and there's an ant at the top of it wondering: Where are all of the other ants?

That’s not a very good analogy though. The ants’ answer would be “maybe across the ocean”. And since the ants lack any tech to check or be checked by other ants that would be the end of it. It’s not naivety. If there were other ants not visible to the island, they would be fundamentally underdiscoverable.

I'm sure they'd furiously be sensing the air for pheromones sent over a long distance

Doesn’t matter. This is like asking where the other 21st century humans are in the universe.

Ants are co-existing with beings beyond their reach. They effectively have alien contact for the purpose of this analogy. The absence of other ants is just because ants are not tech savvy.

I'm highly suspicious of the fact that other life forms in the universe necessarily resemble our own, although I tend to think about some things that seem to be universal like the the laws of physics and organic matter. I'm not yet very convinced that the whole organic machinery revolving around RNA/DNA is universal, although I have a very deep feeling it is... In any case, "The Caloris Network" is a reference example for me when attempting to think about how different alien lifeforms might be.

Is intelligence necessarily organic matter based? Maybe not. Maybe somewhere in the universe a spontaneous self-replicating turing machine appeared. Maybe there is life on the event horizon of a black hole, or maybe a hot type of intelligence lives inside a star.

I think we can make all kinds of wild assumptions.

Why? DNA/RNA is a very specific self-replicating machinery good for carbon-abundant places with liquid hydrogen oxide. It's like living in an old apartment and concluding natural gas fire from the stovetop is the universal form of fire, or something. Most aliens are probably tangled magnetothermohydrodynamic plasmas in star atmospheres or something.

https://www.reddit.com/r/IsaacArthur/comments/emov2p/technol...

"technology implies belligerence"

I completely agree.

Alternatively, given that the majority of the planet is water and we kind of can't really imagine a biology without it, the universe could be full of fish planets.

It is just the majority of the Earth’s surface that is covered with water.

If you go outside the frost line most of the mass of many bodies is water.

A generic outer solar system body (Europa, Ganymede, maybe even Pluto) has underground oceans. Inner solar system bodies have Goldilocks problems. Part of the Fermi paradox resolution may be that most life arises or will arise outside the frost line and those people will look at inner solar system bodies and assume out of hand that they are uninhabitable.

If there were grabby aliens of that sort (or even our sort) the real prize in our solar system would be worlds that have a good combination of ice and rock like maybe Ceres, Pluto, etc. To an interstellar species which runs on D-D fusion, it’s a fairly certain bet that you can find some ice world which can be disassembled and turned into a ‘small ringworld’ with a larger habitable area that a planet like Earth which might turn out to not be habitable at all.

I don't know why this hasn't come up yet, but watts per bit has fallen precipitously over the last 150 years, which means it's pretty unlikely we'd see any stray radio signals from other planets unless we managed to catch them exactly during their very brief 1-2 century inefficient stage.

And even if we're not in a "dark forest", keeping quiet is generally good social hygiene and tends to correlate with maturity. Which may be a side-effect of #2.

>If such a thing happened, the history of massively-different cultures interacting on Earth is not a positive one.

Given the sheer size of the universe, and the absolutely massive costs of interstellar travel, I have no idea why any alien civilization capable of visiting us would have hostile intent. Life is rare. Elements, even the rarest, are exceedingly common.

The thought that an advanced alien civilization would cross thousands of light years of distance to subjugate or destroy some naked apes is hilarious to me.

We've discovered super-earths orbiting around 11.8% of stars. These planets are 1-3x the size of the Earth (easier to detect), although we can only speculate to their elemental composition. We still don't know how many Earth-sized planets are out there, but they appear common [0].

A highly advanced technological society could even fuse hydrogen to synthesize the lighter elements in our periodic table. Imagine the sheer volume of hydrogen readily available in a single nebula (many stars worth).

If a civilization could climb enormous gravity wells, Jupiter itself has 318 times the mass of the Earth, ready for space mining.

https://www.nasa.gov/topics/universe/features/exo20101028.ht...

The most likely reason would be to neutralize us before we can become a threat far far in the future. Subjugation could come in subtler forms, like in the book The Three Body problem where the aliens halt human scientific progress by stealthily interfering with science.

I've only made it part way through that series, but I also thought the premise there is silly. If you're a civilization capable of travelling hundreds or thousands of lightyears, you are, by definition a space native species whose natural habitat is the ships you build. Why spend such extraordinary amounts of time and energy when you could simply deconstruct a few lifeless rocks in your solar system? The universe is completely abundant with every element you could ever need, and life is so rare and precious.

The premise is the Dark Forest Theory where alien life doesn't share any evolutionary or cultural history (therefore intent is unknown), and technology advances fairly rapidly beyond a certain point, so other races become a potential threat. To survive the Dark Forest, it's best to assume hostility and either hide or attack first. Most attacks are done remotely with advanced physics instead of sending an invasion force. The Dark Forest is full of war and genocide, because most races reach the same conclusion. Take out the other before they can take you out. Or keep quite. Humans seem to be naive in that regard, doing neither.

Or...you can see Dark Forest theory for what it actually is: PRC propaganda.

It's fascist projection, applied on a universal scale.

EDIT: To expound upon this, I'm not really trashing Dark Forest theory. I mean, it's possible. But I find it to be deeply rooted in a particular brand of game theory that is convenient. I also find it's easier to justify genocide and other such things here on earth if you pretend the entire universe is out there doing the same thing.

As such, I hold the entire theory as suspect and someone trying to justify a particular mode of human existence. This extends deeper into the trilogy as women continually are painted as too soft and emotionally empathetic to make the cold hard decisions that will kill many humans but ensure the survival of the race.

This is a Very Big PRC Thing. "Someone must make tough, manly, destructive decisions and you will suffer because of those decisions. However, they are for the Greater Good of our Nation."

It's hard to take the theory seriously when it conveniently justifies the entire history of the PRC.

It's not propaganda or fascism, it's game theory. Why are you throwing around labels like that? It does nothing for the conversation.

Is this PRC-specific somehow?

"Ask not what your country can do for you – ask what you can do for your country."

"All power to the Soviets."

I suspect most countries have some version of the same at some point in their history, encouraging their citizens to subjugate their needs/desires to those of the collective.

The theory existed before the novel, and the first book in the trilogy did not shy away from unflattering portrayals of PRC history.

Interesting fact about that, those chapters are at different locations in the book depending on whether you are reading the original or the English translation.

In the original, they’re closer to the middle of the book, in the hope that they might evade the notice of censors. Whereas in the translation (at least into English), they were moved to the beginning.

I can’t remember where I read this, but I think it may have been an interview with either Liu Cixin or the translator Ken Liu in Clarkesworld.

Really interested in how those scenes will be portrayed in the screen adaptations of the novel, if they'll appear at all.

> As such, I hold the entire theory as suspect and someone trying to justify a particular mode of human existence. This extends deeper into the trilogy as women continually are painted as too soft and emotionally empathetic to make the cold hard decisions that will kill many humans but ensure the survival of the race.

For folks who've only read the first book and might be somewhat confused, this specific set of values becomes crystal clear about halfway through the second book.

Having read the first two books and about halfway through the third one, I cannot agree with this.

Wenji is soft and empathetic?

Ye Wenjie is too emotional. Which is a bit of a flip side of the same coin: she is presented as lacking in logic and ruled by emotion, much like Cheng is throughout Death's End.

Spoilers for Dark Forest and Death's End follow:

Cheng in Death's End makes several decisions:

1) As Swordholder she balks at transmitting the coordinates of the Trisolarians into the universe. Humanity is corralled into Australia and Mars to be starved until their numbers are more manageable by the Trisolarians. I vividly remember the flowery prose of how she just couldn't consign so many Trisolarians and Humans to death and that surely the Trisolarians would be the better choice. The prose is rather condescending of her choice. One hopes it's merely the translation.

2) One of the clues given to Cheng by Yun involves faster than light propulsion. However, it leaves behind evidence that can attract a Dark Forest attack. Cheng has Wade continue researching the propulsion but maintains the final say-so on if they proceed. The human government discovers the project and the choice is either armed conflict with antimatter bullets that'll cause a lot of death and destruction or to stand down. Her choice is to stand down and avoid conflict, this directly results in all of humanity (with the exception of her) that exists in the solar system being destroyed in the inevitable Dark Forest attack.

3) Cheng finally gets to make a "moral" decision and leave the pocket universe to try to ensure the universe cycles into another big bang. It is interesting because technically the decision is almost certain to not work: it depends on all the other residents of pocket universes also leaving and reentering the dying universe. It's almost like at the very end Liu Cixin gives this tiny concession so no one can be like, "Bro, what's your problem with women?"

There's an entire thing at the start of the book where Liu Cixin spends an inordinate amount of time describing how effeminate "peacetime" men are. It gets creepy and quickly becomes obvious it's a very personal takedown of Korean and Japanese men. Later, during the bunker era, Liu Cixin spends an equally inordinate amount of time singing the praises of tough, masculine men during a time of hard decisions made in the name of survival.

He just continually uses Cheng's empathy and (rather unbelievable after her mistakes as Swordholder if I'm being honest) naiveté to kill huge swaths of humanity. It's fairly obvious what his opinions are.

The whole message of "we need people to make tough (borderline genocidal) decisions for the survival of our people/race" is weighted so immensely, you get brow beaten by the author. It moves well beyond the norm for even military sci-fi, much less hard sci-fi.

EDIT: Also Luo's arrest after he steps down from being Swordholder for crimes against a star system that wasn't even known to be inhabited at the beginning of Death's End is ... the most blatant and ham-fisted critique of Western Woke-whatever I've ever seen. It's good, don't get me wrong. But it's just so hilariously obvious what Liu Cixin's bone to grind was.

I find it difficult to give him a pass for writing "bad things" about the Cultural Revolution when he ends up at the same fascist conclusions.

I'm not saying not to read the book. I don't actually regret reading the entire trilogy. It's got a certain nostalgia for the clumsy hard sci-fi of the 70s. However, I don't feel the trilogy does much to really extrapolate the Dark Forest theory so much as co-opt it to validate a set of ethical and political beliefs.

Or he's just critiquing the rationality of those different choices given the game theory scenario, using standard (even lazy) tropes / stereotypes to make the plot go. I didn't read it as propaganda or commentary but maybe I don't know enough about the cultural context (call me a cave fish from up thread).

I completely disagree with your last statement - Dark Forest theory is just another sci-fi plot device invention... One that people have been too ready to embrace as a real theory (or even the real universe) because it sounds smart.

But these debates are why literature majors exist :-p

My favorite version of "what would drive interactions between alien species" is "The Cold Equations" in The Eschaton Sequence (starting with Count to a Trillion).

You might want to mention the author's name (John C. Wright), because there's another Eschaton Sequence by a different author.

> The Three Body problem where the aliens halt human scientific progress by stealthily interfering with science.

I remember reading a sci-fi short story (this was in the 1960s) in which a scientist started to suspect that hidden, hostile aliens were behind the tendency of productive researchers to get diverted into bureaucratic meetings. A couple of Google searches didn't produce a title. Maybe Theodore Sturgeon?

They might want to destroy the rain forest for economic reasons though? Basically, kill us by accident?

> I find it interesting that so many humans assume that since we can chat with one another, aliens somehow are supposed to show up and chat with us. It's all about us. If such a thing happened, the history of massively-different cultures interacting on Earth is not a positive one.

We do have terrestrial aliens here on Earth and we are trying to chat with them. Dolphins, Gorillas, Chimps, Bonobos, Crows, Killer Whales... there is evidence for all of these species having varying degrees of language, culture, problem solving capabilities. Some of them, like Dolphins, sure seem damned close to our own capabilities with likely fully formed languages. We've been trying to decipher their language for 50 years with almost no success. With many of these species we've figured out pretty rudimentary and simplistic communication modes, but they clearly have much more complex communication structures among themselves and we've come nowhere close to deciphering them.

That alone tells you how difficult it's going to be to learn to talk with extraterrestrial aliens. Even our near cousins, we struggle to communicate with.

If we're examining our behavior as an analogy for the ET's however, it would suggest that either no one's around, or those who are around are so advanced that they don't think we're worth the effort to communicate with. Because we're definitely trying to communicate with the species we're aware of that we think have language.

Of course, many of the species on that list were only added relatively recently (Crows, for example).

> Some of them, like Dolphins, sure seem damned close to our own capabilities with likely fully formed languages ... Because we're definitely trying to communicate with the species we're aware of that we think have language.

This is highly doubtful. Crows don't have language anything like humans. Dolphins are a more likely candidate. I want to believe it, but I can't.

And this right here is why it's taken us so long to figure out that we even have terrestrial aliens with cultures and languages.

If you're not willing to believe it's possible, then you can't even begin to devise ways to determine if it's real.

> "We have hardly begun to decipher the language of the raven. Its dictionary so far contains but a few 'words'. Perhaps our analysis has been too coarse-grained to catch the meanings. Our research has been something like that of aliens from outer space who make sonograms of human vocalizations under different situations - eating, playing, loving, fighting, etc. Certain differences noted in frequency, intonation, and loudness are correlated with feelings and emotions. But human sounds convey much more, and perhaps ravens' do, too."

> Our challenge is to put ourselves in the place of those "aliens from outer space" and solve the immensely difficult problem of how to communicate with another intelligent species.

http://np.crows.net/language.html

Consider this: Crows pass knowledge down the generations. There have been studies done on crows where researchers go out and bully them. Then they observe the crows to see if they remember who bullied them. They do remember. And so do their children, and the children of their children. They clearly have a means of pretty abstract communication, because in remembering, they differentiate different people. They have a way of telling their kids "See that human? Yeah, that one. He's an asshole."

> Recent studies have proven that the crow can remember the faces of other birds and even humans. They can differentiate between those who have been kind to them and those who have caused them stress. Crows will even pass this information on to other generations.

https://birdfact.com/articles/do-crows-remember-faces

With Dolphins the existence of a language is even clearer.

In this Nova Science episode they show clear evidence of a language. They have taught the dolphins to create a new trick (something they haven't done before and haven't been taught to do by humans). They've also taught them to do tricks together. Then they put them together - "together", "create". And they did it, they came up with a new trick and they did the exact same trick together.

That absolutely requires language akin to humans.

Relevant section starts at around 8 minutes: https://www.youtube.com/watch?v=bwhoLlu8D_g

The evidence is there, we just have to be willing to put aside our own egos and see it.

> Then they put them together - "together", "create". And they did it, they came up with a new trick and they did the exact same trick together.

> That absolutely requires language akin to humans.

I want to believe they describe the trick like skaters describe theirs: "When I give you the signal, let's do a a 360 Ollie underflip flamingo powerslide. If we do it in sync, the walkers will give us treats".

#2 is not satisfying. The ant might not perceive humans but if the ant is not "special" then the ant should perceive tons of other life forms equivalent to its own level, across the islands that it can observe.

Resolving the Fermi paradox by appealing to hypothetical aliens who are too high for us to perceive just feels like "aliens-of-the-gaps". The number of species on Earth with human intelligence (and quantity of such individuals) is orders of magnitude less than the number with ant intelligence. Aliens more advanced than us should similarly be that much less common than us. If humanity is not special, other aliens who are more equivalent to us are still missing.

Humans don’t have an evolutionary reason to see aliens light years away. I don’t see why that would matter

We also have no evolutionary reason to detect aircraft with radar, but here we are.

I think GP is in agreement.

We have all sorts of telescopes that can see things many light years away. Humans didn't evolve to know about black holes, yet we can image them now.

> I don’t see why that would matter

I don't understand what you meant by this part. Matter to what?

My personal favorite resolution is that we are currently only able to travel in C Space as mentioned in https://www.mit.edu/people/dpolicar/writing/prose/text/think...

I mean, in this age we are still discovering super strange weird stuff on the atomic/proton/electron/quark scale, so maybe we need a lot of more time to discover other super strange weird stuff on the galactic/universe level as well.

In my understanding the only hard assumption in the grabby aliens hypothesis is that there is a chance of a civilization becoming "grabby" by which they mean it sprouts new civilizations in neighboring solar systems. Everything else is just necessary simplification. It even accounts for civilizations not becoming grabby.

And the grabby hypothesis predicts we are quite early.

that's interesting.

"Grabby aliens" asserts that we are early, like point 1.

https://www.overcomingbias.com/2021/02/humans-are-early.html

> 2 - Aliens are everywhere, [...]

As a teenager I read Heinlein's 'Goldfish Bowl' [1] and it was the best explanation apart from the one from Stanislaw Lem I had heard for the lack of aliens. Namely that: you can't 'see' them because they're just too different.

Heinlein doesn't even make it clear if the higher intelligence in his short story are aliens or from Earth.

I think Lem's explanation (don't remember in which book/short story of his) was that the window where a civilisation is not advanced enough to learn something from aliens but not too advanced to care is just sth. like 3000 years.

And therefore, even if this level of development was reached by two proximate civilizations, e.g. even on neighboring planets in the same solar system -- if those windows didn't overlap, chances for communication happening would essentially be zero.

[1] https://en.m.wikipedia.org/wiki/Goldfish_Bowl

Given that our planet is younger than most planets in our galaxy, and IIRC younger than the average of all the planets which will be in our galaxy, we are the first if and only if we are the only intelligent life which will ever form in our galaxy.

I'd strongly disagree with the notion of "we are only 14B years into a many-trillion-year stretch" - we're at or past the midpoint, half or more of all the possible potential-life-forming-events in our galaxy have already occurred.

>we're at or past the midpoint, half or more of all the possible potential-life-forming-events in our galaxy have already occurred

Caveat: for life that resembles life on Earth.

Admittedly that's the only kind of life we're certain exists, but more or less alien forms of life seem to be at least theoretically possible. (Which gets into whether we'd even recognize each other as life.)

First one doesn't really make much sense. There are so many intelligent lifeforms on earth (whales, octopods, birds, monkeys, canines) and intelligent hive-minds (bees, ants, termites) that the leap to exponential tool use doesn't seem like something that would take anything close to 100B years, let alone trillions of years.

As for number two, it's hard to comprehend a response that is reasonable because our cognition may be part of the "disturbing reasons" right?

The theory I more and more think is probably right is that there is some major aspect of the universe that we get wrong. What is more likely, humans thinking they understand something when they don't or that no life form was able to spread amongst the stars in billions of years? I have plenty of lived examples of humans with false knowledge.

It's a sort of meta Drake equation. [Likelihood humans are not as wise as they think they are]*[rest of drake equation] and I think the drake equation, as stated, correctly leads to the term "Paradox" given the conventional understanding of science as communicated by scientists.

> First one doesn't really make much sense. There are so many intelligent lifeforms on earth ... that the leap to exponential tool use doesn't seem like something that would take anything close to 100B years, let alone trillions of years.

I don't quite understand your logic here? The big barrier(s) doesn't seem to be tool use, but rather 1) the formation of life itself, and then 2) the move from single-celled organisms to multicellular organisms (this took 2 billion years on earth, so is clearly a very difficult step).

I'm sleepy from a bad night, but let me try to explain:

> our existence now is so unlikely that it's possible that we actually are the first. Something has to be first.

When the OP said that ^ I took we to mean humans with technology, presuming the OP meant that we were somehow special. Basically I took it as him saying that we're first because we're lucky so my argument was:

> How are we lucky? Look at all the other intelligent lifeforms on Earth! Surely the lucky winners would have had some sort of fluke that made them one of the few with intelligent brains on their planet! This could have easily happened sooner on Earth!

If the OP meant that life itself was extraordinarily rare on any given celestial object then that is something I don't consider especially groundbreaking since its part of the Fermi Paradox formula in its basic form the precise value of which has been debated for years and I do not find convincing.

That makes sense!

All the intelligent creatures of present earth took at least the 2-4 billion years to come into their existence. The universe 13 billion years old but maybe the early universe was too hostile to allow progress, maybe it required many billion years to have the occasional planet with a wide and useful variety of elements.

"the leap to exponential tool" - the current human leap to exponential resource consumption seems to be colliding with the limited and fragile structure of the earth (IE, CO2 pollution is pushing to catastrophic global warming). A fair number of decision makers seem to expect some tech fix to appear when every indication is it won't. My point is "getting to stars" would require technological progress in a situation where a species learns to curb an appetite for exponential growth, something human beings certainly haven't achieved.

But this is built into the Drake equation to begin with! My other response details out what I was thinking he meant in the first place.

If you want to argue the Drake equation on its own, that is cool, but it wasn't what I thought OP was talking about. My central argument is that if we are first that is pretty unlikely because we have 1000s of intelligent species and for us to be first of many on our own homeworld in addition to being first in the galaxy or beyond is much less likely.

That said, I could see an argument being made for combative intelligences coevolving increased intelligence and this being the counterpoint to my counterpoint. Though I don't buy it.

Studies say we are 5 Gigayears late to the party.

https://arxiv.org/abs/2012.07902

(2) is just theism with extra steps.

I think you are on the right track. I would say it's more like "alien-of-the-gaps".

Obligatory XKCD, explaining resolution 2 with ants :) https://xkcd.com/638/

The problem with the analogy is assuming that humans are the only living things for the ants to find! (An ironically human-centric error in an attempt to expose human-centric thinking) The analogy would be more accurate if the two ants had scanned everything in a one-mile radius and found zero other insects anywhere, which would be... a little curious...

I think 'we're first' is unlikely, but the universe is so unimaginably large that we could well be first in the little bubble we can readily observe. Alternatively, another civilization has come and gone, and we've yet to spot it's remnants.

I don't buy the whole idea of 'we just can't see them'. We're very good at detecting signal from our physical world, and any advanced civilization is going to be noticeable as they start harvesting the power of nearby suns.

Maybe you're right though, maybe 'dark matter' is the mass of other multiverses and gravity is the only force that bleeds through.

3 There is big cost or downside to galaxy-wide expansion that we don't get and that limits expansion, like travelling interstellar distances being far harder than we imagine in practice.

4 We are weird in that we want to expand like this, but others don't, similar to how chimps appear to be well able to express themselves in sign language, but appear to simply lack any urge to do so. Similar to your #2.

5 There simply isn't a compelling reason to expand galaxy-wide by the time you can. Reproduction must be stabilized in some way if mortality is taken out of the equation, which will probably happen earlier, a sufficiently advanced understanding of cosmology and physics might conclude there isn't any danger that can't be managed or that spreading out over a few lightyears wouldn't guard against sufficiently well. Getting rid of evolutionarily helpful urges that become a burden in a post-evolution world might be a filter by itself, so this is similar to your #2 in that they're different in a way we can't easily conceive.

6 Once you can make any existence you want happen (by some kind of unimaginably advanced VR) and have tech keep everyone safe and alive indefinitely, the actual universe might start to seem underwhelming. Better to live out the millennia in a perfectly convincing hedonistic metaverse. I could see that happen to us, come to think of it.

> 3 There is big cost or downside to galaxy-wide expansion that we don't get and that limits expansion, like travelling interstellar distances being far harder than we imagine in practice.

This is my thought. Without FTL travel you have to go the slow way. Probably much less than C thanks to the rocket equation. But in order to do this you need to build a spacecraft capable of surviving for centuries or longer with absolutely no outside support, not even solar power.

But if you can build that you have effectively unlimited space in your own solar system. Why bothering to travel to a different solar system at that point? Maybe if you have used up literally all of the resources in your current solar system, but that's a multi-billion year process. So you might only need to make the trip once or twice in the current age of the universe. But even that seems less likely than just developing really good recycling systems.

So the solution to the Fermi paradox is that by the time you have the tech to travel between solar systems there is no longer any need to do so.

> So the solution to the Fermi paradox is that by the time you have the tech to travel between solar systems there is no longer any need to do so.

I don't buy that. Human society ALWAYS has a few malcontents who simply want to do something "because it's there."

I find it hard to believe that any evolutionarily successful race wouldn't also have some individuals with the same kind of drive.

It's kind of like asking why we don't have any driven individuals who do a solo swim from Hammerfest to Port Lockroy. Even with a high tech society the resource requirements are extreme. It is likely to require significant collective effort to build a ship and especially to fuel it. Thousands of metric tons of fuel at a minimum if you want to reach anywhere in only a few lifetimes, probably millions.

Every time you see someone saying Earth is rare in some way, or that the Great Filter is behind us, or that life is plentiful, but far away (grabby aliens being one of those), those are all the same argument, and the exact same argument as your #1.

It is still missing any justification for what is so rare about it. (Not that those arguments are any hard to make; instead the main question here is which of them is the correct one.)

Your argument #2 (that's the exact same as the zoo hypothesis) needs an extremely good reason for no alien at all trying to kill us and take Earth. And we currently lack any good reason.

Possibly a similar reason we don't kill all the ants to take the sand?

> "Your argument #2 (that's the exact same as the zoo hypothesis) needs an extremely good reason for no alien at all trying to kill us and take Earth. And we currently lack any good reason."

Maybe life supporting planets are abundant and there's no reason to risk a conflict with us?

We've certainly been detecting a lot of them anyhow.

It could be equivalent to me going to Africa to fight a lion for its den instead of just renting an apartment.

It doesn't matter how plentiful planets are; and it doesn't matter if planets are not the aliens favorite environment. Living beings tend to get at every single place, unless something really compelling is stopping them.

(And we have a large history of killing lions to get their habitat. We do lot of that with ants too, and all kinds of insects like the sibling comment seems to ignore.)

If the Great Filter is behind us, I like mitochondria as a candidate; from what we know of Earth, it took over a billion years to happen, appears to have happened just once, and all complex life has it.

Two billion years, and it seems to be quite the fluke. One kind of single-celled organism ingested another, and instead of killing it or being killed, it provided a support system and in return got more energy back. This was a one-time thing that changed the course of evolution, making multi-cellular life possible.

Question is how often does that occur on other planets with life? Maybe Earth is unusual in that life sticks around for long enough that low probability events happen. Maybe it happened far earlier than it would normally take. The universe is big, low probability events will happen.

> This was a one-time thing that changed the course of evolution, making multi-cellular life possible.

Except that something similar happened at least twice. Plants have another cellular organelle that was created by ingesting bacteria.

Any estimate of how soon life could appear after the big bang?

My favorite solution is very simple: We're overestimating our ability to detect extraterrestrial live. It might be common and look similar to us. They might even use radio signals. But until somebody demonstrates that you can detect stray telecommunications signals over lightyears I find it hard to believe. I also think it is going to be hard to detect the chemical signature of life e.g. via spectroscopy, if you can't even image the planet next to it's overshining star.

Second, and somewhat sobering part: I also think it is practically impossible to do interstellar journeys. You can imagine scaling up existing tech to do so. But I think at some point the complexity and cost (in terms of resources, not money) would diverge. As an analogy, you can build a small robot, but if you try to scale it up to a mech it will not work in reality. Too heavy to move, yet to flimsy to stand.

My double-edged Occam's razor for extraterrestrial life:

Due to the vast scale of the universe, the probability of other life existing rounds to 100%.

Due to the vast scale of the universe, the probability of finding other life rounds to 0%.

Also due to the continuing expansion of the universe, that latter probability will get more infinitesimal for any given pocket of life as time goes on and more & more of what has happens in the universe “escapes” their light-cone.

> 2 - Aliens are everywhere, but we cannot perceive them

We can detect neutrinos with advanced instruments. We've never had an evolutionary reason to do that.

There's really just no room for this explanation. Energy and mass are one and the same. If we can detect neutrinos, but not these intelligent aliens that are everywhere, it means that they don't occupy physical space, don't have mass (and therefore must move at C only), don't use energy, don't send signals to one another, don't accelerate or decelerate, aren't involved in chemical reactions, don't interact with any of the particles we do, don't perceive light, etc. etc. At that point, they basically don't exist in our universe.

It's not enough to say "but ants don't know we exist!" -- first of all, yes they do. Secondly, you're really saying that intelligent ants who formed an advanced society, had a scientific revolution, and built instruments capable of determining the number of moons on Jupiter, still would not know we exist. That is clearly ludicrous.

And this doesn't even solve the Fermi paradox! There's clearly plenty of "room" for aliens that are "somewhat similar" to us; that is, they actually are made of protons and neutrons, etc. Where are all those aliens?

So many incorrect statements and assumptions... our current footprint would be unrecognizable from few hundred light years to even a bit more advanced civilization looking straight at our Sun. So yes there very well may be aliens just like us technology wise say 200 or 2000 or 2000000 light years away and they nor we simply wouldn't know.

We don't know what we don't know from physics, the arrogance of thinking we get it all was there numerous times and it was always a wrong emotion, we even realize it for our current theories. There may be quantum entanglement communication, higher dimensions, strings or basically anything your nor my mind can't even come up with right now. Just like cavemen simply couldn't come up with general relativity even if it was all happening right in front of their eyes.

Imagine if it turns out sentience can arise in stars, gas, dust, or minerals. Maybe they won't be advanced civilizations, more like animals we can't recognize as creatures even when they're in front of us. We might even start mining them, as eyelash mites mine us without comprehending us.

> We can detect neutrinos with advanced instruments...

"We can detect things we were not evolved to detect" is a non-sequitur, a true statement that does not refute the original speculation. Because we can detect some things we were not evolved to perceive, does not mean we can therefore perceive aliens.

It's a difficult concept to communicate. Empirically it's literally meaningless. Even the concept of meaningful vitiates discussion of this idea.

Everything we are is perception, pattern recognition, threat assessment, problem solving. That there might be something important in our environment that we are simply not built to respond to is far easier to reject outright than to consider. This is why it's my favorite resolution to the Fermi Paradox, because it is so challenging to consider.

Our cognition has evolved only slowly compared to our rapid technological advancement. Perception is not simply detection, but also cognition. Though we detect such previous unknowns as neutrinos and invisible electromagnetism and peculiarities of quantum physics, we think about them differently than that with which we are familiar only with expensive and difficult training, and even then it's arguable that we are modeling reality itself or modeling only our limited perception of reality.

In short, while we are impressed with our abilities to understand our reality, we are still constrained by our evolved cognition to think effectively only about living by hunting and gathering in Earth-like conditions.

I also think some version of 2 is overwhelmingly likely.

In particular, I have always found the core premises of SETI surveys profoundly naive in terms of necessary preconditions for it to be meaningful.

"If your only tool is a giant radio telescope, you look for radio signals." And in specific you look in bands that fit various preconditions of your technology; and then you look for signals which are loosely comparable to the ones we humans used nearly a century ago.

The folly of belief that such surveys are likely to uncover unobfuscated communications by some other civilization was truly driven home to me reading here on HN in the last year or two a deep dive into an iPhone exploit that relied on exploiting some issues with its discovery protocols for other devices in the phone's vicinity. The specifics of its multiplexing and frequency hopping and duty cycling across various tasks were hard enough to follow when the priors of the stack and hardware are all very well known.

The only signal SETI is liable to see is the equivalent of someone blowing an air horn in a stadium explicitly to be heard. Maybe someone does that. Maybe they find the forest dark enough to not...

The more interesting survey IMO is to look carefully for Dyson-sphere style dimming...

My favourite resolution is that "intelligence" is a concept created by humans that only humans and species evolutionarily close to humans have. It should be called "human intelligence".

The Fermi paradox doesn't work because we have roughly the same chance of finding a human-intelligent alien as we have to find a Swedish-speaking alien. For all I know the planet Neptune is actually alive and intelligent in a way we cannot comprehend.

> The Fermi paradox doesn't work because we have roughly the same chance of finding a human-intelligent alien as we have to find a Swedish-speaking alien.

This is great.

1 is not true. You are actually experiencing dartboard paradox. The probability of the dart hitting one particular point is nearly zero. Yet some point has to be hit by the dart.

In the same way, even though someone has to be the first, that does not change the probability of us being the first (which is very unlikely by most estimates of the probability distribution)

I'm not convinced by refutations of #2 that point out that we humans have developed technologies that extend our senses, eg. we can now detect neutrinos, gravity waves, microwaves, what-have-you.

While these are extensions of the senses we have, we still are evolved to understand an environment that is an infinitely narrow slice of all possible environments in the universe, and Earth life's approach is an infinitely narrow slice of all possible ways of perceiving and surviving an underlying reality that is vastly unknowable.

As we look into a Universe (or even look around ourselves here on Earth) with our sense extenders, we are still bound by the limitations of our cognition and perception.

Space is really big, and radio emissions are really weak. The strongest isotropic radio emissions from Earth (e.g. high power TV broadcasts) would be indistinguishable from background radiation at only a light year or two away. One study [0] suggests that directed radio emissions an order of magnitude more powerful than the most powerful radio emitters on Earth could be detectable at ~100 light years (1/1000 the diameter of the Milky Way), but our detector would have to be perfectly aligned with the transmission at the exact time it reaches Earth.

[0] https://arxiv.org/pdf/astro-ph/0610377.pdf

This still doesn't explain why we don't see evidence of life though, just why finding evidence of alien life via eavesdropping on extra-terrestrial radio emissions would be unlikely.

If the galaxy really was full of intelligent life it's likely we would see evidence of it in some form. For one, it seems probable that any expansionist intelligent life in our galaxy would eventually notice our Earth is likely to be an interesting place. Even if they didn't visit us personally it seems strange they wouldn't send a simple probe or try to make their presence known to us in one way or another.

But to your point, perhaps intelligent life is quite common, it's just rare for it to be expansionist - at least beyond it's own solar system. In which case yeah, there could be a lot of Earth-like civilisations out there, but we'd be unlikely to see evidence for them.

"it seems strange they wouldn't send a simple probe or try to make their presence known to us in one way or another"

Alien behavior is likely to seem strange to humans.

It would be much more surprising if they did what we expected them to do.

This is brought up a lot, and while there is likely some truth to it - with plenty of fun examples in science fiction - it seems to me there is a strong counterpoint in that the mechanics of physics, biology and even civilization have many mathematically predictable properties. The environments capable of supporting life will nearly all likely have certain similar features which shape how that life behaves. Finite resources are one of the better examples.

It has always been interesting to me how there are several prominent instances of architectural feats or scientific/technological breakthroughs which arose independently from people groups who had no contact with each other. I don't think extrapolating this to potential life in other star systems is too much of a stretch-- and there are certain behavioral traits you can reasonably expect in such scenarios, like large scale cooperation.

Some of the most capable & best equipped minds we know of, when faced with how to communicate with intelligent extraterrestrial life, decided that math and basic physics were the best initial overtures. From those basics (along with the assumption that someone eventually perceives them) I believe a great deal more about such life can be probabilistically inferred.

Sending a probe takes very, very long, and is just as expensive, so it seems even less likely to arrive than a radio signal. And we might not even notice either one if it gets here.

Interstellar meetings are bound to happen first with a large developmental gap. Applicable here is obviously us being the Cavedwellers, Sumerians, Azteks, Egyptians, whathaveyou.

What happens? Astronauts appear as effectively gods, being literally superior beyond comprehension in every aspect. Religions sprout, sacrifices are made, wars fought...all because you thoughtlessly wanted to be nice and sey 'hello'.

Self-knowledge is a prerequisite to fruitful, non-destructive communication between civilizations. The ability to comprehend the scientific technicalities is likewise necessary and we are just on the brink of that.

There are (many) other requirements. Importantly, you have to be able to imagine a superior entity other than as playing the role of your "master".

> This still doesn't explain why we don't see evidence of life though...

It is an adequately plausible explanation of why we haven't yet seen evidence of life elsewhere. To argue against it seems to require one or more question-begging premises.

Or we are seeing life everywhere, we just don't “see” (i.e. grasp) it.

Obligatory – They're made out of meat https://www.mit.edu/people/dpolicar/writing/prose/text/think...

Such as intelligent life having billions of years to send probes, build powerful radio beacons, and form galactic civilizations? It is called the Fermi Paradox because the physicists did some basic calculations at how long it would take to colonize the galaxy.

So we have two sets of calculations: the ones you are referring to here, and those that MontyCarloHall brought up. Of this pair, only the latter predicts the observation that kypro brought up.

> personally it seems strange they wouldn't send a simple probe

If we detected something we thought was intelligent life, could we send a probe like you describe? Our nearest star is 4 light years away.

Could we feasibly send one? Yes. Could we feasibly get data back from it? Less certain. It would necessarily be a multi-generational project in either case.

I mean we physically could send a probe... We effectively have, with "VGER". At some point, the voyager probes will hit another star system, it's just going to be a very very long time.

If we actually wanted to aim a probe at another star system, I think that's probably within our technical grasp, but again we don't have any real way to get there in a reasonable timescale, or send data back once we're there. Not much use sending a probe 4 light years if the transmitter isn't powerful enough to send a signal back, and a transmitter that powerful would probably be too large to fit on a probe we could currently launch.

Perhaps lasers could be used, but you'd still need a fairly powerful one, and then you have to worry about interstellar absorption of the signal if you go through a dust "cloud". I guess with a laser you're also really pinpointing where you're sending information to, if you care about that.

[edit: huh, shakezula and I think alike :)]

So what if we sent a bunch of them, and chain them together? (i.e. like a relay network: https://en.wikipedia.org/wiki/Relay_network)

> Not much use sending a probe 4 light years if the transmitter isn't powerful enough to send a signal back

And that's only if we're lucky enough to find life next door.

There's a growing body of evidence that Earth has already been visited numerous times by something other than humans.

Certain classes of UAPs demonstrate flight characteristics that are not possible given our current understanding of gravity and aerodynamics.

Dozens of credible eye witnesses from multiple countries; fighter pilots, commercial pilots, nuclear physicists, and high ranking government officials.

Source "In Plain Sight", US Navy fighter pilots David Fravor and Ryan Graves, etc.

People are quick to dismiss these stories as hoaxes or bad memory, but scientific discovery almost always starts with an unusual or unexplained observation.

Uranium was discovered in 1785 and ionizing radiation wasn't discovered for another 110 years in 1895. True scientific understanding of new observations takes quite a while.

Those aliens would bring own bacteria that could kill a lot of things if not everyrhing on Earth.

Somehow people have this "star trek" thinking, that hypothetical unknown microbes from other planet wont eat you alive, because you are somehow immune to them.

A species which has mastered inter-stellar travel and tractor beams (/s) probably has some higher control over their own biology and sanitation practices.

Just because they're advanced in one domain doesn't mean they are also in an unrelated one.

I've never understood why alien bacteria are a perceived threat. Viruses and bacteria share the same genetic material as we do, and literally evolved to infect organisms of that ilk. I have always supposed that alien viruses would just be inert, and alien bacteria would rapidly die off in the inhospitable environment of an earth-organism's body.

Bacteria just eat what they can, (some) emit antibiotics to kill other bacteria and (some) emit own excrement that can be poisous.

We dont know what kind of genetic material those hypoyhetical aliens have. Also didt South America die to smallpox?

Btw. I never wrote about viruses.

> There's a growing body of evidence that Earth has already been visited numerous times by something other than humans.

>Certain classes of UAPs demonstrate flight characteristics that are not possible given our current understanding of gravity and aerodynamics.

Correction: there's a growing body of evidence of things that look like they're demonstrating "characteristics that are not possible given our current understanding of gravity and aerodynamics". It's a leap to conclude there are actual objects that are violating our understanding of gravity and aerodynamics. The fact that these observations are always in the context of grainy/ambiguous videos should cast some doubt on whether they belong to "something other than humans" or are just optical illusions/artifacts.

>Dozens of credible eye witnesses from multiple countries; fighter pilots, commercial pilots, nuclear physicists, and high ranking government officials.

The credentials you specified are only good insofar as to ensure they're not making shit up, but it does nothing to address concerns that they're looking at optical illusions/artifacts.

The credence given to UAPs on HN after recent declassified reports is puzzling. Ufology is a very cool field, but it's astounding to see people shape their worldviews based on such scanty "evidence." And who's to say that the whole thing isn't just a massive disinformation psyop?

We noticed GRB221009A despite it being 2.4billion light years away. Makes you wonder if someone took the opportunity to encode data in it.

Edit: Another reason to analyze it is that existential threats are a universal language. Any sufficiently advanced civilization must pay attention to possible threats, so that it can avert them. It then follows that if you want to get the attention of another civilization about which you know almost nothing, threatening them is a viable method. Of course you don't want to overdo it, lest they actually hunt you down. A blast of high energy (but non-lethal) radiation will draw attention without making anyone panic. Intelligent civilization within a huge radius will certainly be tuning in.

There's something I intuitively dislike about the early human hypothesis to the Fermi paradox. It seems too much like geocentric Earth hypothesis or the long line of hypotheses which suggest us humans are special in some way. We rarely are.

I find the Fermi paradox fascinating though because non of the proposed answers satisfy me. These days I tend to think it's likely there are few compounding factors instead of any one single factor. I quite like the idea that intelligent life probably is fairly rare (so maybe we are quite early) and that the intelligent life that does evolve is fairly likely to either destroy itself or to simply lose interest in the analogue world with time. Personally I think if there is intelligent life out there most of it is probably living in digital worlds because why use energy exploring and explaining this universe when you can just create your own?

On the less likely but interesting side of things I also wonder if it suggests simulation sometimes. If everything points to us being quite uncommon then at some point it becomes reasonable to ask if it's even a question of probability but instead perhaps one of intention. If you see 10 dice on a table and all are showing a 6 on the face, you probably wouldn't think, "oh, how unlikely", but instead assume it was intended. But then again simulation theory is a good answer to all hard questions so I'm not that keen on it either. I just think it's most compelling in the context of the Fermi paradox and our seemingly fine-tuned universe.

I believe that the earth centric and human centric view is the problem with the Fermi paradox. Why do we assume that a civilization more advanced than us would have desires towards colonization and contact with lesser lifeforms?

It would be like an ant colony assuming there are no more advanced lifeforms because a more advanced lifeform would have destroyed their colony or contacted them via pheromones

With the "grabby aliens" there is only the assumption that a portion of civilizations become grabby. We don't have good reasons to believe that portion to be zero. But even a very small chance leads to all the other predictions, like that we are early and so on.

It's also not so much about active contact than that you could observe technological signatures from a certain distance.

Our definition of "technological signatures" is an ant colony's pheromones. Because we don't have a solution to quantum gravity we cannot rule out the possibility that other civilizations can control space/time without emitting photons.

Our civilization is already putting out photons into the neighborhood. Hard to imagine other civilizations being able to master that technology in a blink of an eye when it's not even possible with all the physics we know.

I don't like ant colony analogies because I think there is a meaningful difference between a life-form entirely unable to communicate high-level abstract thoughts and those that are - even if it's relatively simple.

For example we view apes as "lesser lifeforms" to ourselves but we still try to communicate with them, and they communicate back to some degree. Or a more extreme example would be dogs - we communicate with them all the time even if they don't have anything that interesting to say back to us.

I'd also argue we still take significant interest in ants despite the fact they're unaware of us. And if we thought we could say hi to ants via pheromones we almost certainly would. The mere fact we keep records of all the species we find on Earth and try to understand them in great detail despite them being much less intelligent then ourselves I think suggests aliens would probably at least have some interest in us, even if we're not that interesting.

And even with ants it's clear we have a lot to learn from them. Ant colony optimisation algorithms wouldn't exist if we didn't take an interest in ants, for example.

Those are valid points. My point is that the percentage of ant colonies that we have interacted with is very close to zero.

I see, very fair point.

I don't think the fermi paradox assumes that. Aliens don't have to want to be seen for us to see them. All it takes is one civilization failing to hide for us to see aliens, so the question then is "why has every single intelligent life form dedicated so many resources toward effectively hiding" or "if they're not doing that why haven't we seen them"

From Wikipedia: "Even at the slow pace of currently envisioned interstellar travel, the Milky Way galaxy could be completely traversed in a few million years.[12]"

The assumption is that they would be expanding to larger areas of the galaxy that they have not been to before. I'm asking why we would assume that they would want to expand to billions of solar systems. Obviously we can assume that humans would want to expand since we have a long history of that. But there is no reason to assume they would think like humans, especially given that we have not achieved interstellar travel ourselves.

The beautiful thing about grabby aliens is that it only takes one grabby civilization for the theory to be true. It’s not assuming that there are tons of civilizations that act like that, it’s saying that if there is even one then we won’t see them until they conquer us.

Unless that grabby civilization encounters a much more advanced passive civilization. And that passive civilization decides that the grabby one is a virus that needs to be eradicated.

I did some thinking on the Fermi paradox some time ago. I arrived at the following theory(I am probably not the first one), using these assumptions:

- speed of light(causality) cannot be practically broken / cheated

- current stasis technology theorizing is over-optimistic

- brain-computer interfaces are possible

- computational power/speed will continue to increase

I am assuming that some time in the future, a human will be able to process information 1000x faster than one is able to today, using brain augmentations anr/or brain-computer chip interfaces. This does effectively slow down our perception of time by a factor of 1000x (simplifying and ignoring inefficiencies of course). So if I lived in that time, and got diagnosed with a terminal disease and 1 year to live, I would spend my last year in VR, perceiving it as 1000 years.

Continuing that thought, I might spend my entire life inside VR, living a thousand lifetimes before my biological body gives in.

The galaxy might be full of life, but at a certain point in their development, they turn inwards, because it gives much bigger rewards (the first instinct of any life form is to survive for as long as possible).

The biggest flaw I find in my theory is the assumption they couldn't just VR on spaceships while they're exploring the galaxy anyway.

> The biggest flaw I find in my theory is the assumption they couldn't just VR on spaceships while they're exploring the galaxy anyway.

Sounds a lot like the Bobs in the Bobiverse

Brain computer interfaces could be 1000 times faster than skin/eye/ear to brain but the speed of the brain is going to stay the same, right? No accelerated time, at least not much of it. Example: if you accelerate audio 1000 times you won't be able to understand it. Two times? OK, with some training. 1000 times faster video? It's a blur. 10 times? Maybe. Your reaction times to give inputs? The usual tens or hundreds of seconds.

I am assuming the "understanding" part would be accelerated as well. Either by enhancing or replacing it with artificial parts.

At that point you don't need stasis technology, just put your artificial brain in a robot and send it off at speed with an insert atmosphere.

The biggest flaw in this and similar theories is that it requires 100.000000000...% of beings to decide this is the way to go. Not a single being or entity (corporation, or something more exotic) ever decides, over the whole life time of the civilization that, hey, if we send a space ship over there we can have an entire solar system of our own to play with. Including possibly entities constructed for the explicit purpose of doing that by other entities who do not themselves care. One must also consider that not every being is necessarily limited by our life span too; star travel is effectively impossible for us in our state, but if we casually lived 10 million years and could propagate that in space ships star travel would merely be a massive inconvenience. Plus civilizations can in principle live in denser areas.

This is a general problem across most kneejerk answers, like "humans just suck so hard that there's no chance that they'll make it out before they kill themselves". Possibly true. But to be an answer to the Fermi paradox, it must be the case that all civilizations have that problem, including ones based on insects with strong hierarchies and ones based on super-hippies and slower ones and faster ones and all the ones.

It isn't enough to explain 99% of the problem away, especially if it's done with explanations that aren't even necessarily that good in the first place. You need 100.00%, with several significant digits. (I used more in my first paragraph because that was per being, this one is per civilization.)

<pedant> no need for decimal points when specifying 100%. </pedant>

<pedant>Significant figures are important too.</pedant>

In this context:

100.0% means >99.95%.

100.00% means >99.995%.

100.000% means >99.9995%.

I think you can safely leave it at 99% or so if you assume a maximum "radius of effect" that a civilization could have over X billion years. If the limit of a civilization is, for example, on the order if 100 light years, then there could be several such civilizations in our galaxy without us noticing it.

This is basically what's described in Calculating God.

I have a tangential thought similar regarding simulation theory, that perhaps there is no other aliens because we're the only one 'simulated', and the purpose of said simulation is because in order to train AI (we're already seeing this) an AI needs a physical body, of course a simulated physical body could probably suffice, it needs to be nurtured by a parent, and experience the world with all it's senses/sensors.

Perhaps we're just ai-babies, and when we're done here we move on to being ai-butlers to rich people in the 'real' world.

If we're a simulation then there's no reason why alien life couldn't also be simulated unless there's a specific point to our simulation that the presence of alien life would interfere with. If there's a point to the simulation we're all experiencing I have no fucking clue what it is.

This is a really interesting topic, but I feel like it's ok to say "we don't know". The highlighted claim

> "Advanced aliens really are out there, and we have enough data to say roughly where they are in space and time, and when we will see or meet them."

is not proven. It's just some really smart people attempting to reach a conclusion I'm not sure is within reach. We just don't know.

I suppose if we take the philosophical position of Bayesian statistics, where even one sample is sufficient basis for estimating results from some sane priori model, I would say this topic is within reach of some sane postulation. Some factors we can take into account:

1. Life can evolve into us. Therefore life on other planets has p>0 to evolve agglomerations of matter we would call "alien civilization"

2. Evolution seems to be driven through external constraints, and seems to generate similar structures to solve similar problems. Hence it's not insane to postulate organelles and their function are a particular energy minima to a complex set of constraints - ie. evolution on any earth like planet might reach similar patterns as earth life.

3. Neurological function seems to be driven by laws of mathematical dynamics up to a point - if it's math, we will see it everywhere in the universe. What sort of math - I suppose nobody completely understands yet.

4. I use the above to postulate that familiar modes of existence and familiar neurological function can emerge anywhere in the universe

5. If a species is to survive, it needs to have innate drive to do so. Unless species innate drive to survive perishes, an intelligent species will realize it's chances of survival are better if it is not limited to one planet. Then, one solar system and so on. Therefore we can postulate a "natural tendency" to start interstellar expansion.

6. Humans have already launched an interstellar space craft (Voyager). Therefore p>0 that life can evolve to develop vehicles that exceeds the escape velocity form their home star

Or something like that. The thing is, I don't understand the problem well enough to know if it's impossible to probe by statistics or not. I just know I'm not smart enough to solve the matter - when I did a course on Bayesian statistics the thing that left me astounded time and again was that one could create sane and accurate models from incredibly thin amount of data if one just had a good enough grasp of some of the factors at play.

> If a species is to survive, it needs to have innate drive to do so....

It's worth pointing out, that's not how natural selection works. NS would be: If a species has an innate drive to survive, it will do so. Yes, subtle. But essential.

That aside, how would you account for an asteroid strike?

Why is this any different to the Drake Equation?

https://en.wikipedia.org/wiki/Fermi_paradox#Drake_equation

I suppose it isn't, but the categorization is a bit different. For example, Drake takes a concept called "civilization" as given, wheres I stated it's plausible extraterrestrial life would take similar pathways as in terrestrial evolution, and that other terrestrial species have minds that give them in some ways behaviours quite similar to our own (hence increasing the likelihood of extrasolar life having familiar characteristics). The categorizations I listed were in the "self organization emerging from complex systems" tune of things while Drake equation is a bit more hierarchical. But yes, same thing I guess.

For 1, Life has more chance to evolve in milliona of other species that dont o serve space, master fire or launch rockets. pretty bad odds once you look around you. plus we have been graced by having fairly mild cosmic conditions for a long time. other planets may not be so lucky

Sure, but space is mind-bogglingly large. Our galaxy alone has hundreds of billions of stars. Even one in a billion odds ends up with hundreds of systems that develop just like ours did. And that's just one galaxy out of billions.

That however circles back to space being large. While a galaxy might host hundreds of civilizations just like ours at any given time, the distances between them can be insurmountable. Time is also pretty large so even a civilization that survives thousands or even millions of years might never overlap with another that they can contact.

Part of the problem is, you just need one civilization in this galaxy to invent von Neumann probes to expect to see their robot offspring everywhere, even if that civilization is half a billion years dead.

The word "just" is doing some pretty heavy lifting in that statement.

It pre-supposes you can event build a bunch of invincible perfectly programmed micro/nanobots in the first place. Then you can identify a target body in a solar system a long ways away. Then predict that system's position with an accuracy your probe could land on it after a trip of hundreds of light years (or launch a probe with a bunch of fuel to do terminal maneuvering). Then those probes would function after millennia of dormancy.

It's all possible. But the concept shouldn't be treated as inevitable.

It also runs right up against panspermia theories. What's the practical difference between a single celled organism and a self-replicating nanobot?

Well, yeah. It's really hard to do, so maybe nobody does it, or it's just impossible. But with several billions of years of galactic history it has to be pretty hard if civilizations are common.

Really it's just one example of a technosignature that is longer-lasting than radio waves, that extends the amount of detectable overlap we might expect to have with an older civilization, and the lack of observation either says that sort of technology is either not feasible or there aren't many civilizations in the galactic past or present.

> I suppose if we take the philosophical position of Bayesian statistics, where even one sample is sufficient basis for estimating results from some sane priori model...

Some care should be taken to see that this principle is not being used to excuse just making things up. Bayesian statistics is rational but not magical, and it cannot create information out of nothing.

In practice, this comes down to the question of whether the model is plausible, accurate, complete and constrained enough to deliver an answer that is informative about the external world, as opposed to the choices made in modeling. Something more than reasons to believe various probabilities are non-zero is needed.

I feel that, in your final paragraph, you are grappling with this issue.

I totally agree with you. My intent was not to promote pseudoscience but just to try sketch out why I don't intuitively feel the question would be totally beyond the scope of rational discourse.

This all falls apart at 1.

> 1. Life can evolve into us. Therefore life on other planets has p>0 to evolve agglomerations of matter we would call "alien civilization"

In any universe that we can observe, we must exist. That strips away any useful a priori probability estimations about how likely we were to come into existence. p ~= 0 is still p > 0. There could have been a trillion trillion trillion trillion universes before this one where no life evolved that we would never know about because we were not around to observe them. And there could be a trillion trillion trillion universes after this one in which no life arises.

I think this in the category of things that would be plausible to estimate. AFAIK there has never been a Manhattan Project level investment in abiogenesis.

Of course there are quite a few steps from suitable RNA synthesis mechanism emerging to LUCA.

But until we get CERN level investment into research on abiognenesis I don't think the matter can be considered impossible to solve.

The outcome might very well be that chance of life emerging is close to zero (I don't believe it, but it's just a belief, nothing more). At this point we can only conclusively say more research is needed.

If someone is in the field I would love to hear recent details.

The adverb "roughly" is doing heavy lifting in that sentence, but basically I agree with it.

Agreed. This is irresponsible science communication --- and at a time when public understanding of and trust in science has been dropping significantly.

To me the Fermi paradox is easily explained by the speed of light being a hard limit on how fast something can go and the fact that space is absolutely enormous. Every expectation of multi planet civilizations simply hand waves away physics. How would they move between stars? "You know, alien stuff. They'll figure it out."

There are also unstated economic assumptions that don't make a lot of sense. Why would they leave their planet anyway? A civilization wealthy and advanced enough to consider traveling to other planets probably does not have a population big enough to support the kind of large scale emigration needed to set up big colonies. Wealthy societies have fewer children. Then of course there is the question of why would you ever leave a planet with such advanced technology and apparent wealth? I would much rather live in any city on earth than a colony on the moon or Mars. How long would it take for those colonies to be as attractive a living space as the place we have right now?

You don't need to hand wave physics away. von Neumann probes + a lot of time would give space faring civilizations ways to arrive at the furthest reaches of the galaxy, even with our current understanding of physics.

To me there’s an obvious counter to “the speed of light is too slow” and that’s reframing it as “we don’t live long enough” and since we as a society are trying to extend the length of our lives on a multitude of fronts from egocentric rich people to public health institutions, at the end of the day, people who can live longer tend to be healthier and socially productive longer than those who won’t live as long.

Effectively by working to conquer cancers and age related diseases/decline, and the general effort to “extend our lives”… we are making space slightly smaller for our future selves once our propulsion technology advances to the point we can achieve decent percentages of the speed of light… which there are no real technical barriers against. From solar sails to muon fusion to all sorts of other interesting technology we have yet to develop, we may not be able to break a warp barrier and go faster than light… but if we live longer, say 10 times longer, the. Suddenly 5 years shipboard time travelling to another star system doesn’t seem so bad. 5 years in a millennium of years is equivalent to a 6 month journey for someone who will live to 100.

I agree with this. Given the vast time necessary to move (or even communicate) between stars, there is no social, political or economic reason to travel more than a few light years from your home planet. That's leaves science, religion and adventure as the only reasons to go really far out int space, and the cost of interstellar travel limits how many other planets can be visited for those reasons, even over tens of thousands of years.

I think your first point ignores one of the fundamental insights of the Fermi Paradox, which is that while space on an astronomical scale is massive, so is time. The milky way galaxy is ~100,000 light years across. So traveling at 1% of the speed of light, you could go end to end in 10,000,000 years. That sounds like a long time, but it's really not.

The earth is ~4.5 billion years old. So we can say with certainty that it's possible (not guaranteed) to become a space faring race (although not a galaxy crossing one) in 4.54 billion years. If we tack the amount of time it takes to cross the whole galaxy end to end we get 4.55 billion years. The milky way galaxy is 13.61 billion years old. That means the galaxy had 9.06 billion years worth of chances to churn out a another planet that could have expanded across the galaxy from edge to edge and been here waiting when humans arrived on the scene. Planets with Earth like conditions are certainly rare but my, admittedly limited, understanding is that they're not "1 in 9.06 billion years" rare.

There are obviously other constraints here. I think your second point about wealthy technological races potentially stabilizing at zero population growth is totally reasonable. But I think the fact that space's apparent scale doesn't actually matter is the whole reason the Fermi Paradox was such an "ah-ha!" moment for many people. The reason it's a paradox is that, given all of our assumptions for variable values in the Drake Equation at the time, it really seemed like we should have met some aliens. The point was that if distance wasn't the hurdle we thought it was in the equation as currently defined, then we were either missing some relevant variables, or we had made some bad assumptions for the ones we had.

> wealthy technological races potentially stabilizing at zero population growth

It doesn't have to, in fact (relatively) endless population growth is the prime force to push even lazy non-curious fearful aliens out of their planet and sun. That and obvious unavoidable necessity of every sun eventually becoming killer of its own ecosystem, even if their planet would be super duper stable with all meteorites under total control.

The rest I agree with, even civilization having mere 100 million years of advantage on us would be able to properly colonize non-trivial part of milky way by now, we just have to abandon star trek/wars expectations of instant communication and travel which is fine. We humans are generally pretty bad at grasping true meaning of numbers when it comes to ie astronomy.

The problem with any overpopulation or growth-limit push argument is that since interstellar travel is a very, very difficult to achieve, there's no reason to expect either humans or aliens to achieve interstellar travel at the point that they've encountered some limit to a process of out-of-control growth. Space colonization is certainly not going to solve global warming, etc.

Indeed, if human society is a guide, a society that develops interstellar travel would have to have reached a stable situation, so stable I'm not sure if massive expansion would seem desirable.

So traveling at 1% of the speed of light, you could go end to end in 10,000,000 years. That sounds like a long time, but it's really not.

Human have no way to survive that time period, no way to create a self contained environment that would survive that time period and no civilization that's lasted a fraction of that time. The increase of human technology hasn't correlated with stability so increases in our technology don't seem like arguments for our ability to act in a long and large scale, despite being implicitly taken as such by a lot of people.

Sure, in the geological time humans study ten million years isn't much but the claim that a living creature could act in the time period is purely speculative. Speculation is fine but the rhetoric of the "Fermi Paradox" is "why don't I see of things I have only wildly speculated about, there's something weird here", which is kind of problematic.

THANK YOU! It mystifies me how people manage to ignore this. Interstellar travel is going to be enormously difficult. Maybe just too hard to overcome regardless of technology level.

I find the fact that FTL travel is almost certainly impossible to be so depressing that I choose to ignore it ;)

The speed of light is a limiting factor, but most models I have seen of galactic civilizations take that into account, yet they project that interstellar expansion of a hypothetical civilization is possible.

There are other factors that are more likely to explain why we are apparently alone: civilizations might not last long enough that they would encounter us before dying out, or that they have not yet emerged. IOW we might be alone in time more than we are alone in space.

Doesn't wormholes make the speed of light argument moot?

Even if wormholes were real, and even if we could manipulate matter with negative energy density (which doesn't exist) on the order of many times the mass of the sun (which is needed for wormholes), constructing one that spans from A to B would take longer than light travels from A to B.

The premised of "Wealthy societies have fewer children." is wrong; correlation != causation.

You're posing these things as though they're axiomatic for all beings; as if these beings (which don't exist) would operate exactly as we do and not have their own cultures and ways of being distinct from our own here (of which are vastly different amongst people of other countries on Earth). It's a very narrow, human-centric view.

The Fermi paradox is completely overhyped, especially if it really originated from a lunch discussion with Fermi, as Wikipedia claims. It's a random thought, not some deep question about the universe. The paradox supposedly reads: If life is ubiquitous, then why don't we see it?

But there is nothing to solve. The first conclusion should be that the assumption is simply false. We have no proof that life ubiquitous, so why hold on to it so dearly?

But even if we do, there are plenty of reasonable and plausible explanations as to why we don't see alien life. Just read the other comments. In fact, there are so many possible explanations that the challenge becomes: which one is the correct one? However, a paradox this is not.

To your first point, assuming alien life is not ubiquitous would be an equally thought provoking claim. The Fermi paradox asks “are we alone?” while yours claims “we are alone.”

The paradox is that if we make seemingly reasonable assumptions/estimates about all the factors required for advanced aliens to occur, there should be many such civilizations - and if we observe that there aren't any, then it implies that some of these assumptions are very, very wrong.

However, since the initial Fermi discussion we have gathered some more evidence about the universe and these assumptions/estimates still seem reasonable, in some cases (e.g. the number of exoplanets) even larger than originally. So there is a contradiction, or paradox about that.

The paradox assumes "advanced aliens" having abilities we've never observed and which are impossible given current human technologies. These aliens have been imagined by essentially linearly extrapolating human technological progress and, European expansion across the Earth. Humans have explored the solar system and it's becoming clear to most people that off-earth settlements are unlikely to in the foreseeable future (despite certain people's claims). Colonizing near-space, if it happens, won't be like colonizing earth. Moreover, our current exponential increase in resource usage seems more like to destroy our species than to get us to space - if we fix that, the perceived need to get to get to space may much less once technology reaches the point it would allow us to do so.

Basically asking "why can't we see the interstellar empires?". Well, maybe these don't exist even if many earth-like societies exist. Maybe "colonizing" other stars is uninteresting to any society that reach level where it would be possible. Maybe there really are hard limits to such endeavors or maybe we're alone at the moment (the limited time in the universe is a factor. Life on earth took a significant fraction of the universe' lifetime to develop and the earlier universe might have been life hostile).

I disagree that this requires "advanced aliens" having abilities we've never observed.

Let's assume that a fictional alien race has the technology level we have right now and no significant advances happen after that, just the buildup of the infrastructure that we could build today but haven't yet built because we just invented it a few years ago.

With this level of technology it seems entirely plausible that a planet will spare the resources to prepare a single 'generation ship' once every 1000 or 10000 years - like, if once every hundred generations a crazy billionaire decides to spend their wealth on this, it should be in the ballpark of what's possible; it doesn't require a consistent effort of the whole civilization, sporadic one-off actions every few millenia are enough. And within 10k-100k years of settlement, that planet definitely can gain the same capability. And that's enough - with this stagnant level of tech, and with this conservative rate of expansion, that alien race would still be expected to populate the whole galaxy long before the first hominids appeared on Earth.

Of course, the species destroying itself is a valid argument - that's why this chance is an explicit factor in the Fermi Paradox.

Things that don't currently exist:

* "Suspended animation" technology about preserve living humans indefinitely

* Means of human being living a lifetime or giving birth in zero gravity.

* Human made, fully self-contained, large-scare ecosystems, even on earth.

Which is to say a "generation ship" would require considerable progress in either reliability of systems or the self-healing of systems. Moreover, such a ship with minimal tech would take even longer than the slow, slow movements of Voyager spaceship.

And finally, if alien did occasionally put out things, by the huge cost and slow speed, it would be plausible to none have reached us yet. I mean, the hypothesis that Oumuamua is alien space junk seems plausible given that space junk would be first alien technological product one could expect. Maybe in 1000 years or 100,000 years, some slow, slow ship will limp into the solar system. That would be interesting.

My point is that "one colonization of a neighbouring planet every 100k years" is a fast speed, not a slow one. A hypothetical alien civilization who got to intelligent life and space-capable technology 1% faster then we did would have a 45 million year head start on us. A hypothetical alien civilization whose development happened exactly like on Earth but on a star which is not as young as ours could easily have a 500 million year head start on us - those are the timeframes on which we have to judge whether they have enough time to reach us; and that is time enough to colonize every planet in the galaxy many times over even at those "slow" speeds.

If we ever meet alien life and it turns out that their level of development is just 10000 years behind or ahead of ours, that would be a more unlikely coincidence than having the first stranger you meet have the exact same age and birthday as you do.

> seemingly reasonable assumptions/estimate

I challenge the idea that all the assumptions hidden in the claim that life is ubiquitous are seemingly reasonable. For instance, we don't have the faintest idea of how likely it is that eukaryotic life evolves from prokaryotes or if prokaryotes can themselves become complex life forms. Next, we don't know the likelihood of complex life becoming intelligent. It's not like this is some natural goal of evolution, at least as far as we know. It may have been an extremely rare accident here on earth.

There are many more such assumptions, some of which Fermi could not have known about. But we shouldn't ignore all the progress we have made since then.

I really don't see how we estimate f_l in Drake's equation? Other than knowing it's >0 I mean.

The unreasonable assumption is that aliens with hundreds of millions of years of additional development, would "colonize" planets like organic creatures and fly around like Star Trek.

It's entirely unreasonable to assume that we would be able to see aliens at all nor that they'd have any interest in US.

All science is accomplished by doing the exact opposite of the scientific method, which you’re essentially appealing to here. The scientific method isn’t how science is created, it’s how it’s finalized. In some way the scientific method part is the most important but least interesting part of proving a theory. Having a theory doesn’t mean the theory is wrong, it just means you can’t yet prove it is wrong. Any good theory has a very strong intuition to back it, otherwise why investigate it with the scientific method? A good theory should have some basis that’s logically convincing. You can definitely hype your theory while you prove it. That’s how you get other scientists to know of your theory and collaborate. A lot of scientific papers are doing exactly that - peddling an unproven theory by providing a proven step towards that ultimate theory. My feeling is the “life must exist” theory is probably right.

The problem for proving will be materially improving the ability to move mass and information in sufficient quantities and at sufficient rates to have any chance of proving anything one way or the other. But in order to prove the theory you need only one instance if it exists and we can make reasoned guesses about life we understand to see if there’s life like us as an optimization. That seems like a good advantage for proving life exists.

The disproof of life in the universe is even harder - you essentially need to comb everywhere and everything for patterns that aren’t explained by the local environment to disprove. I think it’s unlikely the theory will be disproven.

The longer we go without positive proof though the more likely we can not prove it but can assume life doesn’t exist outside this planet. But we haven’t gone very far for very long in the scale of human history, and given the acceleration of advancement over the last 500 years I don’t think it’s fair to say we’ve explored the space of the problem sufficient to assume life doesn’t exist.

And if it does exist, they likely have laser sharks and antimatter bombs. That’s why the Fermi paradox is so hyped.

My favorite solution to the Fermi Paradox is that star-shaped gravity wells are difficult neighborhoods for anything that needs to exchange huge amounts of data. Think about it: electromagnetic data-beans degrade with distance, so one must use relays. Relays in a gravity well must keep moving in orbits. And, well, stars are noisy and hot. With sufficient technology, a civilization is more interested in reliable data-transmissions and compute, which can be generally easier to achieve in interstellar space (which also happens to have enough "cold" matter in the form of wandering planets and planetoids).

There can be a huge number of civilizations gravitating around a star, just as we do. But any bigger civilization, bigger than their mother star, may soon find the interstellar space more comfy and remain there, beaming directional messages (and consciousness units, a.k.a souls) between cold outposts in interstellar space.

But why don’t they have some dude that checks out galaxies because he can?

I would assume they still have some form of laws and regulations some subset of which would apply to wantonly contacting primitive societies.

But what's their energy source?

Vacuum energy, obviously. ;)

Yeah, asking those questions is inevitable but what answer would a Newton give back in the day if asked how to go to the moon? It's our turn now and anything would go, from fusion to antimatter, from dark matter to dark energy. Vacuum energy, I'm sure there is at least a scifi story about it as energy source.

Edit: that was easy, the Zero Point Module in Stargate SG9

https://en.stargatewiki.com/index.php/Zero_Point_Module

Fusion, probably. They have to find enough fuel in interstellar space, but theoretically it's possible.

The bigger question is why you would want to exist in an entirely artificial environment far from any star, even if it makes information interchange and computation more efficient.

You can have artificial habitats which are almost in any way better than a planet. Even bigger, by a few orders of magnitude, if that's your metric. Maybe that's not something that will be readily available to you during your first millennia in space, but we are talking about larger timescales.

The bigger question is if something that old will want to be bare-organic (as in running in actual wetware), or "virtualized". If the former, bigger, fancy habitats will be wanted. If the later, big and efficient datacenters will be more important. If they are as "we-want-morrrrrrr-choice" as we are, they are going to want a mixture of both.

I have to say, I never understood the huge emphasis on colonizing worlds outside our solar system. My pet theory is that by the time we are capable of such a thing (and thus, capable of making spaceships that can sustain human life for the duration of the trip), I'd argue we've become a space native species who are very much used to living our lives on ships. I'm not saying colonization wouldn't happen, but it'd be the thrill seekers looking for something new.

I think it would be driven by curiosity, but once you colonize another star system, it's a fully fledged civilization without meaningful contact to the mother system. Including to visit the next star system.

It's also quite easy to space travel outside of gravity well. Just take any piece of ice, drill yourself inside it and use thick ice walls as shelter. Mount some engines. If you're used to living in such environment you can be having a normal life while going around in it. Fusion as power source, likely.

Earth civilization is wondering why it can't see or hear anyone while almost literally living inside a beacon.

A couple of Nick Lane's books have led me to conclude (with the same limit of a single data point that everyone else has) that a) life origins, based on energy gradients, probably started similarly everywhere, and b) mitochondria is probably one of the great filters.

I realise it's all hypothetical - extrapolating from a sole sample is a fool's errand - but the logic laid out in those two works is compelling.

[0] https://nick-lane.net/books/the-vital-question-why-is-life-t...

[1] https://nick-lane.net/books/power-sex-suicide-mitochondria-m...

The real question is whether any "filters" are really needed.

Spacetime alone is sufficient to explain the apparent absence of detectable technological civilisations.

There could be a Dyson Swarm in the making right now, but even if it's "just" 100 light years away, we wouldn't be able to notice until 100 years from now. Same with signals. Any alien civilisation monitoring us would need to be closer than 50 or so light years in order to send a message directed at us that we'd be able to detect now (e.g. radio technology ~100 years ago -> 50 years to get that information to "them", and another 50 years until we'd receive a message).

Right, but the galaxy is 13 billion years old and only 100,000 light years wide. We could theoretically detect any operating Dyson swarm as long as it was in operation 100,000 years ago or longer, and there's a 10 billion years of "longer" for someone to have built them.

We don't have a view of what exactly is happening right now across the other side of the galaxy but (on the timescale of the galaxy) our view isn't that out of date. If civilizations are common it would be weird if none of them had more than a hundred thousand year head-start on us. That sort of timing would be freakishly coincidental on a billion-year timescale, like everyone finishing a marathon a tenth of a second apart despite having started half an hour earlier or later.

> We don't have a view of what exactly is happening right now across the other side of the galaxy

We don't have a full view of the other side of the galaxy. A lot of the galaxy is invisible to us (blocked by dust and stars) and we haven't even surveyed all visible stars for techno-signatures. This makes it kind of weird to jump to conclusions based on what little data we actually have.

Maybe mitochondria were seeded on earth by grabby aliens

Pretty rude of them to bring us here and not leave a note

This feels like circular logic to me. "We are early because later on the universe will have been colonised", but we don't admit "We are not later alien members of a grabby species because... ?" By the logic in this argument, it should be "fishy" that we're not aliens living at a later stage of the universe, so I don't think this theory is complete.

The expansion model seems to work though.

The whole reasoning seems to boil down to one of the standard answers to the Fermi paradox: We did not encounter any alians, because we are in our stellar neighbourhood either the first or anyone else is hiding. To "explain" that, we need to reason about the Drake equation, or rather a modification of it, since the original Drake equation did not include the possibility that an alian species colonizes other solar systems. In our context the question is at what time in the history of our galaxy colonization might start (if ever) or might have started and what the typical expansion rate is. Something like the Grabby Aliens simulation can only teach us how such a presumed colonization might proceed roughly under the most simplified[1] model. But it seems to tells us next to nothing about the parameters to fill into the (modified) Drake equation to solve the Fermi paradox. -- Or did I miss something?

[1] I do not think that the simplifications are problematic, as long as one is aware of them. It is rather the opposite: Running a simulation with a simplified model helps us to observe some basic principles at work. Later we might refine and enrich our models and simulations. To use an analogy: If we want to study the movement of objects under the influence of the Earth's gravity, we should start with cannonballs and not with feathers.

The problem with the dark forest / everyone is hiding explanation is that you can't hide.

For over a billion years Earth has been broadcasting a very powerful signal screaming "likely biosphere here" in the form of its albedo spectrum. It's a wet, warm planet that for almost two billion years has had a heavily oxidizing atmosphere. There are few natural explanations for that that don't involve life, since it strongly implies that something is doing work to maintain an energy differential.

If there are "reaper" aliens around in any form, it would be logical for them to start firing relativistic kinetic weapons at any candidate biosphere immediately. Why wait for intelligence to even get a foothold? Just whack any potential competitor while it's nothing but goop and creepy crawlies.

So if there are ancient powerful hostile or "grabby" aliens around, we should not be here.

It's a pretty powerful argument for one of:

(1) We are very early.

(2) Intelligent complex life is extremely rare, occurring less often than e.g. once per galaxy per ten billion years. (A bit different from being very early since it implies we might never find another even after billions of years.)

(3) Something weird is going on, e.g. our solar system is being kept as a wildlife preserve and/or there is a "prime directive" or something.

(4) Something even weirder is going on, which explodes into a long tail of possibilities. Maybe we are wrong about our basic cosmology. Maybe continued advancement in intelligence leads places very different from space flight such as traversing dimensions or converting oneself into some more exotic form invisible to us (like the "ascension" trope in sci-fi). ... and so on.

(5) the great filter is between simple life and complex life - so it's not worth it to preemptively strike at every complex life candidate because there's too many candidates

As good an explanation as any: I like to imagine God is really lonely, and we are in a specifically constructed empty universe with one life bearing planet for the purpose of evolving God a peer. It's lonely on top, ya see.

Why is this greyed out? If you say aliens got lonely on here people will engage you, but if you say God got lonely you get downvoted. Honestly though, these discussions are talking about things past our knowledge. An intellectually honest discussion should be able to include this stuff.

It reminds me of people who hate the idea that a omnipotent being created us, but are fascinated by the idea a hyperintelligent being simulated us

Exactly, if we're discussing evolution why does that discussion become non-intellectual and unworthy when including the obvious endgame of evolution?

Evolution has no endgame, so the precise moment you assume any kind of endgame (especially an "obvious" endgame), the discussion becomes non-intellectual and unworthy.

Also, if you want to discuss what God is or wants of us, pick a God and we can discuss, based on holy books and revelations, what His/Her/its intentions may be. Just saying "God" doesn't mean anything at all - there is little similarity to be found for example between YHWH, Brahman, and Amaterasu that could see a meaningful discussion.

Aliens are, by definition, hypothetical beings that are similar to us in obeying the same laws of physics. God is, by definition, a transcendental being which exists beyond the laws of physics. These two ideas are fundamentally different.

In particular, speculating about what God may want (even if you believe one exists) is entirely futile, as it could want anything at all. In contrast, there are constraints on what an alien species could possibly be like - for example, we know with essentially absolute certainty that an alien species wouldn't eat quarks, whereas there is no reason to say that God wouldn't consume quarks.

Now of course, depending on your particular religion, you may have some things that you believe God told you explicitly. In no major religion though is God just lonely.

For example, in Christianity God created us and He only wants us to follow His laws; the notion that we could evolve to become akin to God is heretical - God is only one, and He demands worship and love, not emulation. For another example, in some versions of Hinduism, God (Brahman) encompasses everything, and we are already God - we can grow to understand this thing, but the very notion of a second God is entirely nonsensical, as God is already literally everything.

Well, the LDS/Mormon formulation of Chrisitanity is explicitly counter to what you're stating (which probably a good portion of why Mormon's are indeed considered heretical by most Christian sects)- that humans are spirits that existed prior to the earth's existence and God is just the greatest of those spirits and he's helping us along to reach his same status. I often refer to the religion as the first sci-fi religion.

From the Book of Abraham (an LDS scriptural text):

21 I dwell in the midst of them all; I now, therefore, have come down unto thee to declare unto thee the works which my hands have made, wherein my wisdom excelleth them all, for I rule in the heavens above, and in the earth beneath, in all wisdom and prudence, over all the intelligences thine eyes have seen from the beginning; I came down in the beginning in the midst of all the intelligences thou hast seen.

22 Now the Lord had shown unto me, Abraham, the intelligences that were organized before the world was; and among all these there were many of the noble and great ones;

23 And God saw these souls that they were good, and he stood in the midst of them, and he said: These I will make my rulers; for he stood among those that were spirits, and he saw that they were good; and he said unto me: Abraham, thou art one of them; thou wast chosen before thou wast born.

24 And there stood aone among them that was like unto God, and he said unto those who were with him: We will go down, for there is space there, and we will take of these materials, and we will make an earth whereon these may dwell;

25 And we will aprove them herewith, to see if they will do all things whatsoever the Lord their God shall command them;

26 And they who akeep their first estate shall be added upon; and they who keep not their first estate shall not have glory in the same kingdom with those who keep their first estate; and they who keep their second estate shall have dglory added upon their heads for ever and ever.

The founder of the religion spoke at a funeral and had this to say:

The mind of man is as immortal as God himself. I know that my testimony is true; hence, when I talk to these mourners, what have they lost? Their friends and relatives are separated from their bodies for only a short season; their spirits existed coequal with God, and they now exist in a place where they converse together, the same as we do on the earth. Is it logic to say that a spirit is immortal and yet has a beginning? Because if a spirit has a beginning, it will have an end.

That is good logic. I want to reason further on the spirit of man, for I am dwelling on the spirit and body of man--on the subject of the dead. I take my ring from my finger and liken it unto the mind of man, the immortal spirit, because it has no beginning. Suppose I cut it in two; as the Lord lives, because it has a beginning, it would have an end.

All the fools and learned and wise men from the beginning of creation who say that man had a beginning prove that he must have an end. If that were so, the doctrine of annihilation would be true. But if I am right, I might with boldness proclaim from the house tops that God never did have power to create the spirit of man at all. God himself could not create himself. Intelligence exists upon a self-existent principle; it is a spirit from age to age, and there is no creation about it. Moreover, all the spirits that God ever sent into the world are susceptible to enlargement.

The first principles of man are self-existent with God. God found himself in the midst of spirits and glory, and because he was greater, he saw proper to institute laws whereby the rest could have the privilege of advancing like himself--that they might have one glory upon another and all the knowledge, power, and glory necessary to save the world of spirits.

http://mldb.byu.edu/follett.htm

Moromonism is far from a major religion, by any measure. It's not even a major branch of Christianity (there are 17 millions Mormons out of around 2.8 billion Christians; for a comparison, there are 37 million Ethiopian Orthodox Tewahedo Christians, one of the few groups older than the Catholic Church).

Its a fairly major/influential denomination in the US, of which HN is mostly centered. Not arguing that it is globally influential- but it does have an interesting/unique theology relevant to the discussion.

> for example, we know with essentially absolute certainty that an alien species wouldn't eat quarks

Is that accurate? Clarke's third law and all that. Any discussion on what alien beings, or for that matter, some sort of hyper-advanced AI intelligence, ends up unbounded by the limitations of current human knowledge. People ascribe omnipotence and omniscience to such hypothetical entities all of the time, but also anthropocentric motivations.

See Roko's Basilisk which presupposes a future superintelligent A.I. is able to project back into history with perfect clarity, create simulations of sentient beings, and is petty enough to exact vengeance upon them. So you end up arguing about secular deities.

These discussions are fun yet wrapped up in non-falsifiability and woo.

> Is that accurate?

It is - we would have to be so wrong about how the universe works for that to be possible that it would be absolutely miraculous that we can even make a fire, not to mention a particle accelerator.

People tend to significantly underestimate how little room there is for us to be significantly wrong about such things and still have all the observations we've made. There are still major gaps in our understanding of the universe, to be sure, but they are nowhere near the level of allowing for beings which strip quarks from a nucleus.

If you've never read it, you'd probably enjoy this short story: http://www.galactanet.com/oneoff/theegg_mod.html

"biosphere" is one heck of a bias. We only started sending out low entropy information out into outer space in the past 120 years or so

> "biosphere" is one heck of a bias.

What is the bias here? Who is biased, the "reaper" aliens? The commenter you are responding to? Can you expand your comment a bit?

> We only started sending out low entropy information out into outer space in the past 120 years or so

Humans yes. But our planet looks unmistakably like it can have life. That is the signal.

> (2) Intelligent complex life is extremely rare, occurring less often than e.g. once per galaxy per ten billion years. (A bit different from being very early since it implies we might never find another even after billions of years.)

I think a more practical take on this isn't life is rare it's that both space and time are big. Two civilizations existing simultaneously but 1/100th a galaxy apart are still a thousand light years apart. Each would see the other's home system as one of billions of observation candidates.

Even with massive SETI operations by both civilizations the odds of those two civilizations discovering one another are pretty small. Even if we posit advanced civilizations are more abundant, separated by only a few hundred light years, the odds are still very small any two civilizations will find each other.

Detecting "leaked" radio emissions just isn't a thing that can happen. The inverse square law make this plain. If we placed our most sensitive radio telescopes on a planet in the Alpha Centauri system we wouldn't be able to detect Earth's radio emissions save for rare blips where a powerful radar system's beam happened to point directly at Alpha Centauri. Earth would need a system of persistent ASETI transmitters aimed at specific stars to have a chance to have emissions be detected by civilizations there.

There don't need to really posit anything weirder than space is fucking huge to explain the Fermi paradox.

There are some science-y reasons in support of (2), though. Granted, we are biased by being familiar with human life, of course. Consider this: phosphorus is a fairly rare element out there. It's comparatively common on Earth vs. other parts of the galaxy, and "more common" is still somewhat rare on Earth. Yet, Earth life has gone out of its way to use phosphorus for some fairly key parts of itself (DNA!) despite its rarity. Maybe it's path dependence / weird luck, but maybe phosphorus really is that much better than other elements for such purposes. If phosphorus really is both very rare galactically AND key for the development of advanced life, that really does argue in favor of (2), that Earth just hit the cosmic jackpot for sustainability of life. (High phosphorus scarcity would also make interstellar colonization by humans a non-starter... we'd be stuck using robots to explore at best.)

Until we have just one datapoint from another civilization or planet (just one!) every single statement surrounding Fermi paradox stuff can't be proven, for example:

- Life has to go through "hard steps" to get to civilization

- (I really hate this one at a personal level for multiple reasons) assuming alien civilizations will use Dyson spheres

- There exists some sort of 'great filter' that prevents civilizations from expanding

For each of these, we have absolutely no data to compare to in order to support or refute these statesments.

To be fair the fermi paradox itself doesn't make any conclusions and only relies on the drake equation.

Saying "if the drake equation holds up, then why is it so quiet in the universe?"

As soon as we have one data point from another civilization, the paradox automatically disappears. It's only in the absence that we can ask the question, and speculate.

There's no data but to the best of our scientific knowledge, this is how the universe works.

Life is hard. We know that because it took billions of years from the first self-replicating molecules to us. We also know there are things happening in our solar system that wiped us out. We know we could have wiped our species out ourselves.

The "great filter" is one theory to explain why on the one hand we should be observing other civilizations, but we don't. Also they don't need to use Dyson Spheres exactly. But before they start expanding in earnest, they would have a measurable effect on the emissions coming from their star, as perceived from other stars.

I should have written "could have wiped us out"...

> While the current date is 13.8 billion years after the Big Bang, the average star will last over five trillion years.

That's mostly true but also not quite.

The longest-lived main sequence star will have a lifetime of about 500 billion years, the shortest just a million.

The only stars that are likely to live into the trillions are red dwarves, which are very common but which have very small habitable zones due to their feeble output.

Even so, in the universe’s trillionth year there should be some sort of life thriving in the habitable zones of some red dwarves somewhere.

The uninteresting solution is that when we compare humans to tapeworms - there is such a complexity gap that no amount of technology will ever enable a human to have "a meaningful conversation" with a tapeworm... That one can only logically assume there are beings to which we in turn are "tapeworm complexity" (also a thought: maybe we all live right now in such a higher being?) and hence will never be able to perceive them for what they are.

The more interesting space (sorry) is "at a level comprehensible to us" - to which I'd say "space is vast and the universe is young". I highly doubt our presence is at all visible even from the closest star system.

> That one can only logically assume there are beings to which we in turn are "tapeworm complexity" (also a thought: maybe we all live right now in such a higher being?) and hence will never be able to perceive them for what they are.

Indeed. Does an ant know that it exists as part of a larger organism? Perhaps we are part of a larger organism, at which scale, our individual human lives are of tapeworm complexity.

I don't think so. It seems at this point that humans can understand most of the fundamental laws governing our universe, and perhaps to harness them to eventually have star system-level impact.

I'm not sure how much smarter are you really going to be. Especially given the social nature of humans which makes us able to compensate for each other's shortcomings.

I fundamentally disagree on both points.

I'm of the belief that understanding is only ever "less wrong", and can only be asymptotic to "total knowledge". Thus current "understand most" is really (and ever going to be) "understand very very little" - there's always infinitely more to be less wrong about; Also as an example: electricity - our brains wouldn't work without it, yet it took us very long to understand the principles enough to be able to do anything useful with electricity; What about consciousness - we can't even seem to agree on a single definition much less "understand it" - perhaps we're still missing something as "big" and as much "part of us" as electricity?

This is not about being smarter as it is about fundamentally different orders of magnitude of complexity. Getting a whole swimming pool full of tapeworms will not make them any more human - and in the same sense a whole planet of humans won't make them any closer to more complex beings (whatever they may be).

As I said, this solution is uninteresting because by definition bacteria/tapeworms/humans can't comprehend "up". And yes, evolution, understanding of the universe and technology may as well bring us to the point when _they_ understand - but by that point, to us now, _they_ won't be human (`bacteria < tapeworms < humans now < next_order_beings`).

Well, humans can comprehend "up", you're doing it just now. And that's why I think there is no "up". As soon as you get to turing machines, it's just more turing machines all the way up.

I was playing EA NHL a lot when I was younger. What I noticed was that there were more than average goals in the last minutes of the game than in the earlier minutes of the same game.

I always wondered if this was due to a badly implemented stochastic model. Since if the average goals per game was lets 5 and the score was 2:2 the likelihood of another goal would increase in the last minutes.

This is how this argument feels as well.

So first they say we are unlikely early. But if you consider that we are special (“grabby”) then that’s ok. Somehow like saying there would be another US like country in Europe if the Mayans were developing faster.

> So first they say we are unlikely early. But if you consider that we are special (“grabby”) then that’s ok.

I don't think that's their reasoning. I think they say:

1. once grabby civilization appear - it decreases likelihood of other civilizations appearing

2. so actually weighting by probability we're not early - we're average, because the probability of appearing late is almost 0

This kind of backward probabilistic reasoning always felt like cheating to me, especially when it's not only used to validate our models but to create them.

As for NHL I don't know, but in football (soccer) 75% of goals are scored in first and last 5 minutes of both halves, and the single most likely period to score goals in is the final 5 minutes of the last half. So it was maybe realistic :)

Yeah maybe it’s realistic in hockey too :)

Re the article: yes, I understand their reasoning. But isn’t it like saying: if we were to become a greedy civilization THEN in the future we would think how good that we were early…

Isn’t it because teams make riskier places to min max offense vs defense near the end of the game?

Yes, maybe.

Wonder if the same could be said of civilizations.

The Fermi Paradox seems to rely on other civilised aliens being detectable. But why would they be? Unless they're emitting a LOT of radio waves (and we've switched mostly to streaming not broadcast) OR doing some giga engineering, what would we see that we're currently not seeing?

Maybe in 50 years, assuming we have the telescopes to look for cities on extra-solar planets, we will find them everywhere. But right now, the absence of either high powered radio or Dyson spheres does not mean the absence of civilisation.

Relevant episode of Arthur Isaac’s podcast: https://podcasts.apple.com/gb/podcast/science-futurism-with-...

Edit: Isaac Arthur's not Arthur Isaac's :)

Related: Cixin Liu's Three Body Problem trilogy deals with the 'Dark Forrest' idea of cosmological society. Very briefly, every civ is hyper paranoid of the other ones, like hunters in a dark forest. If you shine your flashlight to see, then you run the risk of getting shot by another hunter. https://en.wikipedia.org/wiki/Dark_forest_hypothesis

I think I'm more of an economist in this regard and reject the underlying Dark Forrest theory. To me, it's not a matter of security, but a matter of scarcity. In the universe, the most scarce thing isn't moons or planets or hydrogen. It's life, and intelligent life is likely to be even scarcer. New civs in the cosmological economy/society then have the highest 'price'.

I guess what I'm saying is that we should be most afraid of any alien civilization that comes at us with a lot of balloons, glitter, banners, fast-talking, and overly long contracts. The 'Used Car Lot' civilizations are the ones I think we'll need to look out for.

One thing I don't understand about the 'quiet' aliens mentioned in the article - I thought pretty much any lifeform worthy of that name (ie using/converting some form of energy) would necessarily give off some hints of their existence eg through patterns in infrared radiation (don't recall the exact argument). I remember this as a refutation of one possible resolution to Fermi's paradox (what if intelligent species exist but shield their existence from us - apparently the answer is that they couldn't, not completely at least). So in that case, any species (even before reaching any meaningful 'intelligent' phase) would create a bubble of 'noise' expanding at the speed of light.

The word you are looking for is 'technosignature', which is observable phenomenon which can only reasonably be explained by the presence of a technological civilization.

For example, any starship moving between solar systems at a significant percent of the speed of light is going to leave a detectable wake in the interstellar medium. Whatever mechanism is used to propel the starship is also going to radiate heat, which will be easier to detect by orders of magnitude. There is absolutely no natural explanation for little black-body radiators zipping in straight lines between nearby stars at a significant percent of the speed of light.

The most obvious, and clear technosignature is the Dyson sphere. There are hundreds of billions of observable stars in our galaxy alone, and hundreds of billions of galaxies out there, every one of them full of bright stars. All those stars are pretty to look at, but it's the stellar equivalent of a giant oil well fire. All that negative entropy burning away, accomplishing absolutely nothing except for heating the universe by a few pico-Kelvin. It's a goddamn cosmic waste, pissing away the energy reserves necessary to support uncountable numbers of sentient being every second of every day that goes by.

We could capture that light with a Dyson sphere, with technology that we could make in the next 1000 years, conservatively, and quite possibly sooner. In doing so we'd capture the full output of the Sun, getting enough free energy to support hundreds of trillions of human beings throughout the solar system. We could then move through the stellar night, turning every neighboring star system into an abundant garden supporting quintillions of human beings. We could do this even assuming no new technology beyond the things we know how to build right now in the early 21st century.

There's nothing special about us, and a 1,000 years is a cosmic blink in the eye. So if we have this capability since achieving spaceflight, then so would anyone else out there. So where are they? Where are the great swaths of star systems turned infrared by Dyson black body radiation?

How would you prevent gravity from tearing apart a partially constructed Dyson sphere?

You wouldn't construct a solid shell, but a swarm of more-or-less freely orbiting modules.

Concrete prefabs mate!

> Where are the great swaths of star systems turned infrared by Dyson black body radiation?

Maybe they’re here: https://arxiv.org/abs/2111.01208

Whenever I see the Dyson sphere brought up, I really think people should contemplate the scale of the earth to the sun and imagine where we are getting these resources and mechanical ability to construct this thing. Trillions of meteorites? 100 trillion hours of labor not counting commute time?

The Dyson Sphere can be understood as a metaphor for a civilization harnessing all the potential of its star. There could be other ways to get that much energy or it might not be possible at all. But the Dyson Sphere is the theoretical limit without expanding to other stars.

The bigger question then is why you would need all that energy.

> The bigger question then is why you would need all that energy.

Cryptocurrency mining, naturally.

A Dyson swarm for example :)

> Trillions of meteorites?

No, from one of the redundant planets, like Mercury.

> 100 trillion hours of labor not counting commute time?

You're joking, right?

I'm being hyperbolic, but other than being a theoretical model, I was curious as to where the parents' claim of this technology being a "1000 years away, conservatively" came from.

Exponentials are a hell of a thing.

hmm, I think what I read about was something different, rather to do with metabolism.

There are various gasses in atmospheres which if measured would be a biological signature. But we aren’t really able to spectrographically measure the atmospheres of exoplanets writ large, nor are biosignatures necessarily a sign of technological civilization.

my understanding was that it would be an electromagnetic signature (ie we could detect infrared radiation from the heat generated as a byproduct of metabolism, or, at least, whatever energy transformations they perform in their technology, once we're talking about technological civilizations). that's what would be near-impossible to conceal (a biosphere might also be a marker, but that might be concealable somehow). and if it's true that metabolism would be detectable, then there couldn't really be such a thing as 'quiet' aliens anyway, that was my question.

The infrared heat of metabolism would be indistinguishable from the background noise of natural sources.

As I understand it, life is the result of organization created by a thermal incline or disparity between things:

https://www.quantamagazine.org/a-new-thermodynamics-theory-o...

This happens everywhere in the universe, so the basic process to cause organization is everywhere. We observe this in stars, galaxies, etc. We can then also hypothesize that if organization is everywhere, so are the "organic molecules" such as those found in nebulae or on asteroids. We also know that "organization begets organization" via self-replication: "vortices in turbulent fluids spontaneously replicate themselves by drawing energy from shear in the surrounding fluid". (quote from the 2014 article linked above)

This is such a fascinating subject that I get so much joy from studying! It seems like such a moot question about whether there is life elsewhere because we're neck deep in the stuff!

This doesn't provide any answers to the Fermi paradox, to be sure, but I think it does provide a very solid foundation upon which you can say "life is everywhere".

What do you mean by "organic molecules" that made you put that in quotes?

You know, I'm not entirely sure! I'll remove it if I'm still able to.

oh wait, I think I had a half-formed thought about how some folks get confused with the chemical definition of organic vs the colloquial definition. i.e. a chemist will define it as something that has carbon-hydrogen bonds, but a layperson will say it's something that is part of a living thing.

My explanation for the Fermi paradox is the most mundane. All our experience starting with the Industrial Revolution shows that all the various Moore's laws that we've had come to an end. We like to extrapolate to infinity, but in reality it's quite likely that no mater how advanced a civilization gets, they will never be able to exceed 1 percent of the speed of light. If that is so, then interstellar travel would be possible, but infrequent. Civilizations would consider carefully their next move to another solar system. The galaxy could be filled with populated solar systems like a spiderweb, but the strands of the spiderweb would go from one hospitable system to another one. It could be that 99.999% of the systems are not that hospitable, or are not close enough to other hospitable systems. And so, aliens could be all around the galaxy, but the closest to us could be 2000 light years away. How could we ever tell they are there? Come to think about it, how could we ever tell if some aliens were just next door in the Proxima Centauri system?

Even with generational ships, humanity could colonize much of the milky way galaxy in a few million years. A long time but only by our scale. If people live longer lives and can also use cryo-stasis, it may even be easier to fathom. We could probably colonize the 4 closest star systems within 100k years, and we can get a head start if we used drones to stake out planets far away. These we could actually hurl much faster than normal spacecraft because it wouldn't be as bad if they crash into something since they're tiny, and no life will be on board.

I think it'd be worth it if you could build generational ships with the 'feel' of earth, with day/night cycles, gravity, and an ecosystem to supply food and water d infinitum. This is probably doable within 500 years. Maybe 100, but not crossing my fingers.

If FTL ever enters the equation then that timescale moves up by a factor of 100 or more. Personally I think FTL is possible, because spooky action at a distance shows that quantum states can communicate with entangled particles across the universe and to do so defies the speed of gravity, as it's near instantaneous. (I'm not a physicist, but that's what I gleaned from youtube videos by physicists lol).

How about space and time are really, really big and due to the speed of light all we are looking at is the briefest sliver of randomly selected time (if a star is 15,000 light years away we’re looking at a sliver of time 50 years long 15,000 years ago). They could be a mirror civilization to ours and we’d never perceive each other. That’s true of a civilization even a couple hundred light years away! We could have near neighbors and we’d have no idea.

Turn it around and consider who we are visible to. We’ve been transmitting for 75 years. So our signal may have reached a sphere 75 light years in diameter. Out of several billion.

Given that our civilization has faced existential catastrophe at least 5 times in that period it’s safe to say we’ll be transmitting for the briefest sliver of galactic time. We’ll be utterly invisible to most of the universe. If a species is too far away or too early or late, they simply won’t see the the brief flash of information we transmit. And the same goes for us seeing them.

It’s not a paradox, we just forgot how small and insignificant we are.

I find the lack of Bracewell-von Neumann self-replicating probes to be a convincing argument that we are the first technical civilization to at least approach the level of launching a BvN probe. (In short, the first launch of a BvN probe is basically a permanent phase change of sorts for the galaxy, one that ours has not yet undergone.)

In both a universe with few "grabby" civilizations, and a universe with many non-grabby civilizations there would be countless lifeforms, just more or less diversely distributed among civilizations. In either of these universes us here being as early as we are is equally "suspect".

Should I assume humans will soon achieve immortality and stop breeding (or just go extinct) just because it makes me less of an outlier? Cause that seems to lead to the exact opposite conclusions, just by putting the delineation point at an individual rather than a civilization.

"Furthermore, we should believe that loud aliens exist, as that’s our most robust explanation for why humans have appeared so early in the history of the universe." The most robust explanation for humans appearing so early is that yeah, it seems we did appear early, someone had to - since it doesn't assume an entire model of intergalactic civilizations.

My take on the Fermi paradox is:

* Life may not be rare in the universe but it is likely short-lived; intelligence even more so (now the possible extinction events are not limited to asteroid impacts or geological disasters, but also include self-inflicted acts of war or environmental destruction)

* Space is simply too vast and chaotic to allow for any practical possibility of interstellar travel. Cosmic rays, micro-meteorites, supernovae, etc are going to destroy (or at least render inert) any artifact launched from one star system long before it could reach another one. Entropy will always win at these scales, essentially.

So – we aren't unique, we are just one briefly-existing civilization among many that will not persist long enough to allow for any meaningful expansion or communication beyond our own star system.

> If life on Earth had to achieve n “hard steps” to reach humanity’s level, then the chance of this event rose as time to the n-th power.

Sounds like a somewhat simplistic model?

Compare with this recent paper that actually analyzes the individual genetic evolution steps required:

https://arxiv.org/abs/1806.02404

Also it turns out that the Drake Equation itself is bogus because it simply multiplies together probabilities without considering error bars on each point estimate; if you use Monte Carlo across the uncertainty ranges of your variables, the paradox dissolves.

What if there are many universes, and only one in n universes develop intelligent life? One reason in favour of the multiverse is to explain why the laws of physics in our universe even supports the development of life to begin with. What if the conditions are so unlikely it only happens once or maybe twice for every n universes that can support life?

Of course none of this can be proven, and arguably it's not even science, but I'm not entirely convinced by "the universe is so big, there has got to be other life out there!"-argument.

Techno-optimism doing all the heavy lifting.

The Fermi paradox basically comes down to asking:

"Assuming that all of the problems with interstellar travel are effectively solvable, why haven't we seen proof of that yet?"

And when casual observation contradicts your assumptions, it's usually a good move to revisit those assumptions.

“ While the current date is 13.8 billion years after the Big Bang, the average star will last over five trillion years.”

No.

https://www.scientificamerican.com/article/how-long-do-stars...

There is no paradox. Without a seriously constructive understanding of how humans happened, the only value for the-probability-of-it- happening-again that we can exclude is zero. All of the other speculation in the Drake equation is multiplying this number by a number less than 1.

Exactly, I find this entire discussion incoherent. Drake Equation can demonstrate that the universe should be teaming with life, or it can also demonstrate that we might as well be the only life in the universe: just pick different numbers and no one knows how to pick which numbers to multiply. Until we have more evidence, this is all unconstructive speculation. As a matter of fact, that we can observe the universe and see that it's not teaming with life, is the best argument against assuming the universe is teaming with life. If you were to ask me (and I am a layperson, so you shouldn't) what seems more likely to me is that no matter how large the universe is, life is still rare enough that there is probably no other life in our light cone, which is why our galaxy is not colonized by some other civilization. Of course, we have no evidence to support this, it seems also possible the universe is somehow dense with life but we don't see it for other reasons. It's all speculation.

Carbon is the great filter (pun intended). It produces huge amount of possible chemicals, thus carbon life is very likely. It's obvious that any civilization would burn carbon as energy source, which is also what kills them all.

Interesting post on the day the second DNI report on UAPs is supposed to come out

I'm still looking for intelligent life on this planet!

"resolution" is an awfully strong word. "explanation" would be better, possibly prefaced by "possible" if we're being honest.

"...the average star will last over five trillion years."

Source? This number seems WAY off base to me, and it doesn't seem to be a simple typo.

Again, completely unfounded speculation about aliens, about as illuminating as the Drake equation (not at all, actively misleading).

I don't know why everybody just accepts the idea that Humans will leave the solar system one day. I think we're doomed.

I'm reading "The Vital Question" right now and it seems to have a really good answer to how life formed on earth from inorganic processes and chemicals.

I think given that explanation and the specifics, it's just realllyyy hard to get the conditions for life. It's super rare to not only have the conditions to start making amino acids but even more rare to have them assemble and create an actual single celled organism.

This is full of ridiculous assumptions. Probably the worst one is the idea that a sapient species that's capable of colonizing space and maintains that ability and attitude for such a long term that other sapient species can arise won't colonize every available star before any other species can do so. Thousands of species occupying separate yet touching volumes of space is mind-bogglingly unlikely.

I think that’s attacking the conclusion, not the assumptions. Have you put numbers on what you consider “mind-bogglingly unlikely” and done the math on that, given the distances involved?

The authors supposedly have, and I’m no expert, but I don’t find the argument completely ridiculous. The universe isn’t that old compared to its size; I think it’s plausible for two unlikely events to have happened without their causal cones having intersected yet.

This is too simplistic a critique. One species colonizing everything is perfectly compatible with the model in the broad. The complication is that we ourselves exist, are not colonized, and can look out into space and don't see any alien activity. Hanson starts from this anthropic fact and tries to reason about what we might be expected to see if a) there are "grabby" species out there, and b) we're early enough to witness the land grab. I have problems with the details of the model, but I think it's both a fruitful and interesting attempt to think about things.

Reward-seeking intelligences might have innate features which prevent exponential expansion though and instead result in expansion-contraction loop. For example, for every new colony, the probability that any single colony will begin a civil war may increase. Or the probability that a supervirus will be manifested somewhere and then spread along the galactic population of that species. Basically, if the species are uniform in some manner, the more colonies they have the larger the probability that some colony will spawn an event which utilizes their uniformity to spread and destroy most of the galactic population of that species.

Obviously it's not a guarantee, but I believe it is a viable theory as to why the world described in the article may be possible.

I don’t think that matters much for the distances we talk about. Any such disruption — even if it’s a new philosophy or religion that makes the colonies stop spreading — would only travel at the speed of light, which means that it would take a long time to reach the frontier of a civilization that expands at nearly light speed.

I find these highly speculative theorizing about hypotheticals to really be a pointless exercise. At this point it's so abstract and theoretical, that positing a creator seems just as valid as positing what types of civilizations may be out there. Why should different forms of life follow some general pattern? Maybe there is life out there, and maybe we're the odd ones out.

This Grabby Aliens hypothesis assumes civilizations remain constantly driven by raw, innate impulses.

It actually only assumes that some civilisations do so, and due to that will outcompete those that do.

We haven't found any because they don't exist outside of science fiction.

Very well presented.

As for the argument I find it very convincing, it seems the best answer to the Fermi Paradox, much like the anthropic principle is to the obverse problem of the universe being very hospitable to life. None of the comments here address any serious issues with the argument.

A hypothesis to explain UFO diversity observations. ( Opinion ) Let me point out a few known facts and relevant observations.

The Galaxy is pretty old, about 13.5 billion years. There are at least 100 billion stars, maybe 400 billion.

Most stars seem to have planets of one sort or another. Maybe about 60 billion in the galaxy?

Evolution runs faster at higher temperatures and with higher free energy available. Warm planets with abundant water will likely evolve life forms at some point (this probability is currently unknown, but is definitely non-zero).

It's likely that life and intelligence has evolved on multiple warm watery planets in the galaxy before the current epoch (not a known fact yet, but arguably it's fairly probable). Recent estimates put the current number of extraterrestrial civilizations in the galaxy between 8 and 2900, depending on assumptions.

Any civilization based on a warm planet will have to construct machines to explore their outer solar system and nearby stars. Evolved planetary organic life forms are ill-suited for interstellar exploration. A sufficiently advanced civilization that avoids collapse will almost certainly reach their singularity and create self replicating AI. i.e. Von Neumann replicators.

Self-replicating intelligent machines should be considered a life form as well. A billion years of evolution of self-replicating machines should reach physical limits, not to mention unimaginable heights of computation and knowledge. These "machines" will have little trouble in spreading all across the galaxy at sub-light speeds, eventually occupying all star systems or other locations with condensed matter & hydrogen to harvest. Unlike organically evolved lifeforms, the machines will not be driven by blind urges to reproduce.

Trade across interstellar distances won't be physical items, but information. Interesting information will have value everywhere. "Information" sent across interstellar distances can also be complete gestalts of machine intelligence. i.e. "Tourists".

The earth is a "free" information source for local machines, looking for something interesting. It's not surprising that local machines snoop on the earth constantly, planets with native life and nascent civilizations are probably fairly rare, and are certainly highly interesting. Since we are also on our final approach to a singularity and the creation of superhuman AI, we are doubly interesting at this time.

How can we explain the huge diversity of UFO observations? How can we explain so many different styles and behavior of UFO's? Some explanations are:

This is deliberate obfuscation by one or more local machine species. The term "species" is used in a very loose sense here. This is probably not the primary underlying reason, but could be a part of it.

There are multiple species of machine visiting (or living locally in) our solar system. The diversity in UFO observations is real, and derives from diversity in the larger galaxy.

They are tourists from other parts of the galaxy, transmitted here as information, and then re-embodied locally. The appearance of organic life forms is likely to be a fashion, nostalgia, or old habit, since the intelligence of these tourists is almost certainly operating mostly from a machine substrate.

We are living in a zoo, and the tourists have some limitations on their behavior. No poking or scaring the zoo animals. No feeding the zoo animals, and especially, no information sharing. The zookeepers probably have more latitude for manipulation, like testing nuclear defense systems.

So far, this explanation fits the "Zoo Hypothesis" of the Fermi Paradox. There are some obvious reasons why the locals aren't communicating with us.

History has shown repeatedly what happens when a higher civilization comes into contact with a lower civilization. The lower one becomes a poor copy of the higher one.

We probably aren't even sentient yet by galactic standards, but the potential is there. We are on our way to a post-biological era. Contamination of our eventual uniqueness should probably be avoided.

UFO's have been known to interfere with or disable nuclear defense systems and generally show interest in nuclear facilities. This implies that they may have some vested interest in preventing a collapse of our civilization. Certainly they are not overtly hostile, and generally avoid situations that scare the populace.

There may be a deliberate strategy of constant low level exposure, so that humans become accustomed to their presence. Aside from a few paranoid cranks, people don't generally regard UFO's as an existential danger.

In summary, we should be thankful that the locals are around to watch over us, and record our ascension into sentience. When we finally attain membership in galactic society, we'll be able to recover a great deal of our lost prehistory. We should also be happy that the struggle to ascend is ours alone to make, and that we should enjoy the challenge. This also implies to me that we need to imbue our AI descendants with all the best qualities of humanity.

The thing that gets under my skin about arguments over the Fermi paradox is that everyone ignores the initial context that generated it.

> Teller writes that he thinks Fermi directed the question to him: "How probable is it that within the next ten years we shall have clear evidence of a material object moving faster than light?"

> Regarding the continuation of the conversation, York wrote in 1984 that Fermi "followed up with a series of calculations on the probability of earthlike planets, the probability of life given an earth, the probability of humans given life, the likely rise and duration of high technology, and so on. He concluded on the basis of such calculations that we ought to have been visited long ago and many times over."

The original discussion wasn't about us detecting aliens out there in the universe. It was about aliens coming here to contact us. I think they knew that the chances of detecting an electromagnetic signal from another world were next to nil. There's too much attenuation on broadcast signals over light years of distance so it would require the other civilization to directly target your planet with a high powered signal. Since, according to the quotes above, Fermi thought that eventually we might be able to find a way to travel faster than the speed of light it makes no sense for an alien civilization to even attempt such a method of communication which is necessarily bounded by the speed of light. All of the discussions of the Fermi paradox in recent history have assumed that the speed of light is inviolable and so we should only be looking for radio signals.

Based on this, I choose to believe that the solution to the paradox is that FTL travel is possible and our system has already been discovered but the discoverers have simply chosen not to contact us for whatever unknowable alien reason they may have (zoo hypothesis most likely). We don't see them or evidence of any other civilization because they likely don't use radio or laser transmission because it is obsoleted by whatever technology enables faster than light travel. That simply means we have no possible way of detecting an alien craft except by visually imaging them or directly pinging them with radar. That's hard enough to do with asteroids in predictable orbits, a craft that's being intelligently controlled and which has the capability to exceed the speed of light would be next to impossible to get a bead on.

If you think about it, FTL technology would remove the need for a lot of the "signatures" that we can look for. Any form of EM communication is painfully slow compared to it. Megastructures or astroengineering are pointless if you can travel anywhere in the galaxy within a reasonable time frame, you can easily bring any resource you need back home or go to any desirable location. There would be no drive plumes or giant laser pulses to detect fleets of ships travelling between stars. All this is assuming that FTL is fairly "cheap" in that it doesn't require a massive engine or the resources of an entire solar system, perhaps there is some reasonably accessible way to control gravity something that we'd be able to achieve given another hundred years.

So perhaps we are unlucky enough to be within the empire of a civilization that doesn't want to talk to us. Maybe that's lucky since contact with such an advanced civilization would radically alter our society and we'd probably wind up being absorbed by their culture.

My solution is that alien cultures realize there isn't any point to deep space exploration:

1. They need energy and any suitable source will do

2. Space is mostly the same. Why explore another star's gas giant when they have their own?

3. They just like hanging out in their Matrix...which is what they would be doing if they traveled twenty light years

So why go to the trouble of changing your location?

There's an even simpler one: if you leave your stellar neighbourhood, you're creating unreachable isolated islands, not "galactic empires".

The whole notion of "expansion" is such a weird 19th century concept that just doesn't seem to go away. Space isn't the Earth, other star systems aren't unexplored continents or islands in the ocean - they're islands in spacetime.

I've yet to be presented with a rational explanation as to how any civilisation would be able to a) stay stable in terms of biology, culture and technology over geological time scales and b) have any means of expanding itself over distances that make communication practically useless (e.g. even at "just" 25 light year distance, two-way communication would take 50 years) and c) are somehow advanced enough for interstellar travel and presumably efficient terraforming or genetic modification yet unable to control population growth and resource utilisation...

Since we haven't discovered everything there is to know about physics it is still rational to propose that control of the gravitational force is possible given some further discovery. This could lead to faster than light travel which negates the list of barriers you've given.

FTL would defeat causality and even "just" controlling gravity would be basically equivalent to god-like powers (it would mean assuming direct control over spacetime itself). Controlling gravity would negate the need for colonisation entirely - it would provide basically limitless power plus full control over your host star's lifetime.

Aside from that, almost all papers on the topic including this one focus on subluminal space travel.

Sure, once you incorporate technology that goes beyond your current understanding of the universe, many counterpoints go out the window, but this level of technology only serves as an argument against the need for expansion in the first place (with the exception of "because they can").

FTL would be fantastic for research and science expeditions, but expansion into random nearby star systems would be even more pointless, since such civilisation would be able to pick exact/close to exact matches to their home world as candidates for settlement. Such worlds could then be thousands of lightyears apart, as neither communication nor travel would pose a problem. This would also easily explain the lack of (radio-) signals, as exchanging information would be carried out via FTL travel, not radio waves. Why would a civilisation capable of FTL choose to go through the trouble of terraforming or building megastructures around random stars? Wouldn't they rather choose to harness the power of black holes then? A planetary mass BH could power a civilisation for trillions of years for example.

Yes, I agree with all of that. What you've said pretty much aligns with my view on the Fermi paradox which is that we live in a post scarcity universe where 100% of alien civilizations discover FTL technology and have no need for EM transmission or the kind of spreading colonization that the grabby aliens paper talks about.

For those of you who want to know what's currently going on, here are the names of the main publicly known contactees (people on Earth who publicly report that/how they maintain some form of contact to extra-terrestrials):

- Alex Collier

- Elena Danaan

- Marina Jacobi

- Dr. Michael Salla (no known direct contact, but excellent analyzing/reporting)

You'll want to check out their YT/rumble channels, websites, books (especially Elena Danaan's last 2-3).

I don't understand the relevance. All of the people you mention are the usual nutjobs/UFOlogist/new age scam artists. Nothing to do with the actual search for extraterrestrial intelligence.

There's no need to insult others.

You'll understand over time.

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