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.

> 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.

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 interacti with another one using Einstein-Rosen bridges. This is far too narrow a limiting 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.

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.

"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.

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

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.

> 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

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.

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

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?

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...

> 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.

> 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 argument. Because we can detect some things we were not evolved to perceive, does not mean we can therefore perceive aliens.

I mean no condescension when I say that I know that is a difficult concept to grasp. 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. In fact, it is literally meaningless speculation. This is why it's my favorite, because it is so challenging to consider.

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.