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William Boernke
Feb 2
You confuse theory with hypothesis. Theories arise when hypotheses are tested and affirmed while not being falsified. Your Dark Forest hypothesis needs to be tested before you can call it a theory.

What does the low probability of intelligent life evolving tell us?
Evolution is not teleological. Our big brains are flukes. If life evolves, there is no reason to think intelligent life will evolve. This is because there is no selective advantage to having a big brain. Insects have tiny brains and are just as successful as we are.
Humans are arrogant. We were created in God’s image. The reason most science fiction posits intelligent extra-terrestrial life (other than “The Andromeda Strain”) is that who wants to read a book or watch a movie about a planet inhabited by bacteria?

I do like the idea that if a big brain evolves, then the result will be bad. What have we used our big brains to do? We have figured out better ways to kill ourselves. Since the laws of physics exist in the universe, it is reasonable to assume that all intelligent civilizations will discover that E = mc^2. Once we knew this, we built the bomb. As Oppenheimer said when the first atomic bomb was tested: “Now, I have become death.”
我确实喜欢这样的一个想法:即如果一个巨大的大脑进化出来了,那么结果将是很糟糕的。我们用我们的大脑做了什么?我们找到了更好的自杀方式。既然物理定律存在于宇宙中,我们有理由假设所有的智慧文明都会发现E = mc^2。一旦我们知道了这一点,我们就制造了核弹。正如奥本海默在第一颗原子弹试验时所说:“现在,我已经死了”。

Karen Fowler
Feb 4
It makes perfect sense that as a civilization gets more advanced, it should become more, not less, xenophobic.

As you pointed out in your reply to C Stuart Hardwick, we have no way of knowing how good other beings might be at picking out signals from the CMB. Aliens fifty light years away could be trying to decipher the deep meaning in The Beverly Hillbillies as we speak. Furthermore we took the utterly stupid step of sending the gold record into space telling where to find us and more or less how to kill us (not that a civilization capable of finding and reading it would need much help in the latter department, anyway).
正如你在给C Stuart Hardwick的回复中所指出的,我们无法知道其他生物在识别宇宙微波背景辐射信号方面有多擅长。在我们说话的时候,50光年外的外星人可能正在试图破译贝弗利山庄的深层含义。此外,我们采取了极其愚蠢的作法,将黄金唱片送入太空,告诉别人在哪里可以找到我们,这或多或少地就告诉了他们应该如何杀死我们(无论如何,一个能够找到并阅读它的文明在后一方面并不需要太多的帮助)。

Nick Moore
Jan 29
Imagine if the Earth were the universe, and in such a comparison we were an indigenous tribe that hadn’t yet made contact with the “outside world”.
And suppose, for the sake of Fermi’s argument, a well-intentioned alien decided to stop by despite being very adamantly warned against doing so.
We’re not the only species to come up with the Prime Directive. We simply haven’t learned the consequences yet.

Colby Stebbins
Jan 29 · 2 upvotes
That’s not the creepiest solution to the paradox. The creepiest one is that they’re already here.

Justin Di Angelo
Stephen Hawking was always against broadcasting ourselves to the universe, and I have to say, I agree with him. It doesn’t matter if the Dark Forest theory is true or not, it’s foolish to shout into the void with no clue what could hear.

Barry Goldberg
Jan 27 · 2 upvotes
Interestingly, I just finished reading the second book of Cixi Liu’s “Remembrance of Earth’s Past” trilogy (entitled “The Dark Forest”) where this concept is discussed and, in fact, forms the basis for the entire story. Is this where you learned about this theory as well, or did it exist before Cixi Liu used it as a basis for his novel?

Steve Brennan
Jan 27 · 3 upvotes
That book series is how I first heard of it. I actually used pieces of his dialogue as part of my answer, as you may well have recognized. I’m not entirely sure if those books are the origin of the theory, however, I’ve heard the theory speculated by futurists and theorists. It would be interesting to find out whether or not Cixi Liu had already heard of the theory before writing about it.
As other commenters have noted, the theory is not very sound from the standpoint of a highly evolved intelligence. However, from a purely evolutionary, “survival of the fittest” standpoint, it does bring about plenty of speculation!

Barry Goldberg
Jan 27 · 3 upvotes
Yeah, I was shaking my head a bit when reading the book. It assumes too many things, such as how close together highly advanced technological civilizations are in the galaxy and how easy it would be to actually detect evidence of other civilizations. But it was a fun read nevertheless. I’m debating whether to continue on with the third book, though, since the second books seems to have wrapped up the central plot.

Shahbaz Ahmed
Jan 27 · 3 upvotes
I would recommend finishing the trilogy, only because the third book really puts a final rest to the story of humanity. However, many other concepts are introduced in the third book that may seem too outlandish to some. But for me, I love seeing the crazy situations he paints for us and it definitely is worth experiencing.
I will say, be prepared for a lot of head-shaking haha.

Refiz Duro
Jan 27 · 1 upvote
Among the best sci-fi I have ever read — one of the reasons being that it is a plausible scenario.

Carlos Moya
Jan 28 · 2 upvotes
This reminds me of a short sci-fi horror story where SETI received a message back from space; the message pretty much amounted to “chist, they will hear you!”

Vincent Gao
Feb 3
Another problem with Dark Forest is that following such philosophy is simply politically unwise. Historical dialectic shows that the formation of alliances and diplomacy guarantee not only far greater security but also a host of other benefits, both military and economic, that outweighs any perceived good that can come out of isolation. Furthermore, while isolation may sound appealing in the short term, remaining isolationist proves directly detrimental to the country’s security in the long run, as demonstrated by the Humiliation of China and the fall of the Ottoman empire. All said, though the Dark Forest does make some sense, it’s most likely untrue: intelligent beings are smarter than that.

Vova Zakharov
Jan 29
Does The Theory explain why we are the only intelligent form of life stupid enough to “broadcast our presence”?

Tom Lowe
Jan 29
“Every civilization could potentially represent an armed soldier stalking through the trees. Each soldier must be silent and careful, because everywhere in the Dark Forest are stealthy, silent soldiers like himself. Each breath must be silent… each footstep must be silent. If he finds another life- he either risks his own life by trusting it, or he opens fire to eliminate them before they can eliminate him”

This sounds like your imagination going wild. I imagine the name dark forest means just like your standard forest, animals don’t broadcast their presence unless they’re in a safe location. Lizards, deer, rabbits etc tend to be not too loud. It isn’t very frightening, just a somewhat risky waste of energy to be really loud.

Mark Harder
Jan 29
Why did Fermi assume they weren’t already here? What are UFOs, to consider just one possibility? Personally, I’m not convinced that the issue of their existence has been completely settled as yet. What about other animal species on our planet? Do we really know so much about consciousness that we can rule out the possibility that some of the weirder creatures out there have an extraterrestrial origin? Just sayin’…

Semen Maslak
Jan 28 · 1 upvote from Steve Brennan
I heard an interesting continuation of the theory
Any life smart enough to broadcast its existence is smart enough to come to the conclusions of Fermi paradox, Dark Forrest, and this assumption. That would mean that an intelligent civilization will be quite and treat all other civilization as quite. However, civilization that actively broadcasts it's existence must be strong enough not to fear others. For all we know, we are scaring the shit out of every nearby civilization

John Huskins
Feb 12
I always considered another answer to the Fermi paradox far scarier. The possibility that there is intelligent life but they know to keep quite because there is a real threat looking. I don't like many of the possibilities when you consider if we are not alone. I did enjoy your answer, so thank you for that.

Milly Stuchinski
Feb 6
I read this before, maybe from you? But it makes perfect sense to me. We can see it played out in our current culture, when walking down a dark alley, singing. Maybe somebody will jump out and join in harmony, or else they will slit your throat and take all of the ten dollars you have in your pocket.
How to tell the difference? Impossible.

Such a civilization would be so incredibly advanced, self-replicating robots that power themselves by the light of nearby stars would be primitive, creating any sort of advanced compounds directly from available elements would be trivial nanotechnology.

The absolute vastness of space and all the stars and planets possessing no sentient lifeforms would be both well-known and available to harvest for raw materials, water, food, and habitat construction. Any civilization capable of exploiting such vast resources would have long ago learned how and why cooperation gains more capability than subjugation.

The idea that such an advanced civilization would seek to harm sentient life anywhere, or deprive it of resources, seems to me to be paranoia at its darkest.

Gabriel Lewis
Feb 10
“If you were lost in a dark, creepy forest at night… would you scream out to alert all the nearby predators where you were?”
Honestly, yes. My strategy in those situations tends to be intimidation.

Gabriel Lewis
Feb 10
If you don’t know, it is generally recommended to make a lot of noise while hiking in the woods. As nearly every living animal on Earth tends to be afraid of humans. And it’s much better that they know of your presence and are able to leave the area before you arrive.

Steve Brennan
Feb 10
Yeah, that’s a little different than screaming at a predator.

Gabriel Lewis
Feb 10
The recommended action when encountering pretty much any dangerous wild animal is to make noise, appear large, and intimidate.
Google “wolf encounter safety”, “cougar encounter safety”. Hell, it’s even the recommendation for tigers, although I’m not sure it would be quite as effective.

Steve Brennan
Feb 10 · 1 upvote from Gabriel Lewis
I agree. I’ve hiked in many wilderness areas and have heard the whole speech many times… You’re completely right. I guess the better thing to say would be, if you were a soldier in a creepy dark forest at night filled with enemy soldiers, would you scream out?

Andria Duncan
Feb 13
I’ve thought for a long time that any extra-terrestrial civilization would have to be completely insane to make themselves known to humanity, given our long history of murderous xenophobia and genocide. Homo sapiens sapiens survived, but probably by murdering and/or EATING all the other homo species who shared our beginnings — given how we routinely murder and carry out massive genocide against even members of OUR OWN species, it’s really not that big a reach to believe that.

Aniket Salunkhe
Jan 28
Maybe they are seeing us after we got destroyed, resultant of time dilations across the universe and the mass of star they are close to.Maybe they are seeing us in future,just a planet,with ashes around,and not seeing us as living creatures.
Maybe we are dead.For them.And which we will actually will be.

Varun S Rajan
Feb 5
But what if our stupidity is what that have saved us so far? Say that we were silent and one civilisation found us consumed our resources and left us for dead. Nobody notices anything. But since we have been vocal nobody can be sure that they are the only one that keeps track of us. If one made an offensive move it would immediately point out about its whereabouts threatening its own existence. So everyother intelligent life forms stay obsevant. We might never know there might be wars waged on in our names.

William Green
Jan 28
We live in a dialectical universe where all existence no matter how advanced is still endowed with an animal consciousness that seeks to preserve itself, While the dark forest theory is no theory but reality in my view, we need not worry because those of them that have observed us want nothing to do with us. What do you do when you walk down the street at night and see a bunch of rowdy people arguing, fighting, and acting crazy….thats right, you avoid them! You don’t care that you are big and strong or even aggressive. You just don’t need the trouble and walk on by……………..

Kirk Johnson
Jan 29 · 1 upvote
I’m sure many others have pointed this out already, but it seems to me that the missing piece is the implicit assumption that intelligent life always—or even usually—develops advanced technology.
Right here on earth we have Corvids, Cephalopods, and Cetaceans. All of which seem possess intelligence and some of which are tool-using, but none of which have ever developed the sort of advanced technologies that—again, it seems to me—the Fermi Paradox seems to take for granted.

Mark Oakley
Jan 30
Cixin Liu’s “Three Body Problem” was one of the best Sci-Fi stories I’ve ever read, (where I first encountered the Dark Forest Theory). He deservedly wears the badge of, “China’s Asimov”.
I liked how the author demonstrates how the Dark Forest Theory is undone by (a variation) of that other famous Sci-Fi adage: “Life finds a way” -merely by writing the story and its outcome. -That much curiosity and energy put into the writing of a 3 part novel indicates intelligent life really really really wants to reach out to know in spite of the terrors.
It also reminded me of “Watchmen”, where a flawless argument for nihilism is presented and then undone in the last stroke.

Ryan Lolly
2h ago
The other issue is time. The length of time humans have been on the earth, and even a fraction of that have been broadcasting anything is tiny beyond belief in universe time. 100 years out of 13 billion years. It’s almost impossible to align with the timing of another advanced civilization in any “near” system. And considering the vastness of space, by the time any of our transmissions reach any potential intelligent life, either we are gone, or they are, or by the time they attempted any response, we’d almost certainly be gone.

You did kind of address that with the fact that most civilizations will wipe themselves out (as we most likely will). But their time in this universe almost certainly won’t line up with our time. Even if we make it to 1,000 years of technological existence, that’s a fraction of a fraction of a fraction on the universe time clock.

Omkar Kadam
Jan 29
Always assume positive intent, if there are sophisticated individuals more intelligent than humans, they'd be wise enough to know that in war there are no winners, perhaps they'd have had initiated contact yesterday, and lead our lives to faster progress than we could on our own. Bring that goddamn technology bitches, tell us the secret of the universe!

Sarah Giers
Jan 27
The biggest problem I have with this is that the asked asked for a scientific theory. Speculation based on likely faulty reasoning isn’t a scientific theory. It does not fall under either criteria for a scientific method, as its not sound Abduction reasoning nor is it thoroughly tested. It’s a colloquial use of “theory” rather than a scientific theory.

Steve Brennan
Jan 27
There are many theories that can only be indirectly tested. But you’re right, the Dark Forest theory cannot be tested per Scientific Method.

D Clifford
Feb 6
There's also the possibility that we are the most advanced species in the galaxy right now.
We're a rifleman walking through the forest. We don't have night vision goggles, so we can't really see what's out there. We're basically walking into the forest with a flashlight on our rifle, only able to see a tiny way ahead of us, making a lot of noise but not really seeing what's out there.
But, whatever's out there, we have our rifle.

Brian Davis
Feb 1
The Dark Forest hypothesis has some serious flaws. This video could explain it better than I ever could:
The folks on that channel have been discussing the Fermi “Paradox” for a little while now. Like the OP, I considered the Dark Forest conclusions pretty grim… until I consider the reasoning supplied in that video.

Roger Scott
Jan 31
See if this analogy lets a little air out of the Fermi Paradox balloon: before the development of the germ theory of disease there was the “Illness Paradox”; lots of people got sick, all the time, all over the place, but there was zero evidence — none! — for a cause; surely if there were something causing all this disease we’d see it everywhere, all around us, right? Most paradoxes are only paradoxes until someone figures out what the major faulty assumption(s) is(are).

Nitin Shukla
Feb 3
This answer took me back to my childhood which i spent watching numerous documentaries on Discovery and national geographic. Absolutely loved your answer bookmarking it for future readings.

Russell Jurney
Feb 5
Monitor the others? Monitor and then blast the others to holy hell!

John Ramsey
Jan 27 · 1 upvote from Steve Brennan
Maybe they've seen how utterly mad we all are, and they can't reach us before we perfect a means of travelling between stars. Maybe humanity will be the monsters in the closet of the galaxy, and no one can do a thing about it. A dangerous bacteria, thriving in an unreachable culture, about to rupture and spread into the void.
Or maybe we're the dunces skipping about the forest smashing cymbals together and singing Mary had a Little Lamb.
Probably the latter.

Omkar Bapat
Feb 4
We can only hope that the extra terrestrial civilization has got content from ‘The Jerry Springer Show’ as it is the only broadcast that can ensure our survival.

Steven Gibb
Jan 26 · 6 upvotes including Steve Brennan
Could they perhaps think “wow, they are broadcasting where they are, they must be so confident in their power. We should avoid them!” :D

Steve Brennan
Jan 27 · 4 upvotes including Steven Gibb
This reminds me of the Lion King when Simba is trying repeatedly to roar at the evil Hyenas. Eventually, Mustafa comes in from out of the picture and roars while Simba is trying to roar. Perhaps other civilizations seeing how confident we are to display ourselves view us as big, bad Mustafa, when in reality we are merely little Simba!

Steven Gibb
Jan 27
Haha yes i like that. Though in reality we're more like the insects under the rock that simba eats.

John Drew
Feb 8
Thank you everyone for contributing to this discussing. I’m enjoying it. Here are a few of my low-level thoughts on the subject.

Once we find a planet with life on it lets think about the fact that there have been billions of life forms on this planet (99% are extinct) and only one has been intelligent enough to build a bicycle.
The law of large numbers tells us life / intelligent life is out there somewhere but the laws of physics (speed/time/distance) tells us they are not hearing our footsteps in the forest.

Persephone Bell
Feb 6
“If you were lost in a dark, creepy forest at night… would you scream out to alert all the nearby predators where you were? Probably not! But that’s what humanity has been doing for 100 years!”

Actually, ironically, it is often advised by national park staff to carry a bell or to otherwise make loud noise when walking in the woods so that one will not startle bears, etc. They are more likely to go aggro if they are startled, and more likely to simply steer clear if they are not. After all, humans may be physically weak by comparison, but they are the ultimate predators on the planet. Most wild animals prefer not to tangle with us given an alternative.

I think that would extend to this situation with reference to alien life as well. I wouldn’t blame them for steering clear of our species one bit.

Frank Bartlo
Feb 5
The Fermi Paradox certainly interesting philosophical fodder; but as noted in some prior responses, the very distance between solar systems and challenge of being able to bridge such vast distances makes it virtually impossible for us to make contact with such extraterrestrials, even if the universe is teeming with them.

Going with that line of reasoning, it is highly improbable for living beings on any other planets to encounter each other; as they may have to be located on planets of the same solar system whose orbits are relatively close to each other, such as Earth and Mars, but both with habitable climates, both being close enough to the ideal temperatures and compositions to support life. Such conditions are an extreme long shot, to say the least.

Duncan Mc Cornock
Feb 10
This reads like children afraid of boogeymen in the night at times. Intelligence has only been on Earth for 100 of 14 billion years of the Universe’s existence (wrt to hearing/being heard by alien civilizations). Our broadcasts haven’t gone far and would be hard to detect and decode. Assuming it is possible for a civilization say at 400 light years away to detect us, so what? There are no magical warp drives. The cost of sending a spacecraft to our Solar System would be enormous and for what purpose? Say it goes at 1/10 light speed. Okay, it will be here in 7000 years. If our civilization survives, our technology should be good enough to deal with a spacecraft of aliens assuming they were hostile. The aliens happen to know how rapid technological progress is once it gets command of electrical and magnetic knowledge. Moreover, a 4000 year journey for a spacecraft with live aliens aboard has substantial probability of failure. No, the most likely contact we would get if an alien civilization detected our broadcasts is a “Hi, neighbor, let’s start talking. We will be streaming you some designs for transmitters, receivers and information coding as well as pictures, music, art and high tech information. We start now …” and the stream continues for 1000 years, at which time, if we haven’t replied, the aliens sign off.
Why would do that? Because, it would take us 7000 years to reach them if we get their first signal and so what?

Chris Sharp
Feb 1
The simplest, most likely solution to the Fermi paradox is that the joint spatial and temporal cross section required for a successful interaction between ourselves and another intelligent species - especially given technology restrictions - is incredibly small.
It is therefore unsurprising that, as a matter of chance, we should have not yet found evidence for advanced extraterrestrial life.

Victor Grubsky
Jan 28
I don’t really see any paradox in the absence of extraterrestrial signals. There is no point in talking about the size of the Universe and the number of possibilities for life on other planets. Our Milky Way galaxy is something like 100 kly across, and we could practically expect to detect any artificial signals within 100 lay or so, which tremendously reduces our sampling volume. Within that, we probably still have hundreds or thousands of planets, and some of them may have conditions go life to form. But what are the chances that this life is advanced enough to send signals through space? If we take Earth as an example, we have been in the position to do so for less than 100 years, compared to 3 billion years that life existed here. So the probability of hearing from other civilizations within our space neighborhood is tiny.

But you may ask: what about those super-advanced civilizations that can send signals through space over much larger distances? Perhaps such civilizations can operate gigantic transmitters in space that can reach across the whole galaxy?

Well, this is also doubtful. Such super-advanced civilizations probably know a lot more than we do about the Universe. They would probably have technology for interstellar travel, and they could be using such powerful sources to communicate with their colonies long distances away. But these would be highly directional communications, similar to what we use for our faraway probes, to optimize the signal quality. They would not be beaming signals uniformly in all directions because this would just be a waste of power. And in this case, our chance to intercept their communications would be extremely low.

In any case, super-advanced civilizations would have no interest in going out of their ways to announce their presence. They would probably be aware of any other advanced civilizations in their neighborhoods, and trying to engage up-and-coming civilizations like ours would make no more sense to them that for us to try engage potentially intelligent cephalopods in the ocean. For us, squid is simply resource to exploit. We don’t want to talk to them - we want to have them for dinner.

Joe G Kearns
Feb 5
Leaving aside the questionable idea that humans are actually intelligent…..
Another factor in the discussion is time. Not only do we have to try to find other intelligent life but it has to be intelligent at the same time as us. Humans as we are today exist only for about 200,000 years and within that we have only been technologically intelligent for about 100 years. 100 years in the span of the timescale of the universe is effectively non-existent. Ergo, to the universe we really don’t exist.
Somewhat off topic, but I would further argue that not only are we not an intelligent life-form, we are actually rather stupid and deeply flawed. Compared to other lifeforms on our own planet we have existed for a very short time and the way we are headed we wont be around for much longer. We don’t have the “intelligence” to make ourselves sustainable.

Alain Gardner
Feb 3
I like your answer. A nitpick: potential explanations should be referred to as hypothesis, not theories. A theory is “ the best explanation of all the available evidence ”. A hypothesis is still being tested and checked against the available evidence and not yet accepted as the best.
You’re a talented writer with the ability to influence people’s thinking. If you use hypothesis where appropriate you’ll help educate folks.

Lydia Koza
Feb 4
Technically a hypothesis (by all measures), not a theory.

Yonko Avalanche
Jan 27
What should be the parameter while considering whether a planet has life or not?
Maybe due to my naivety I can not completely grasp what people are referring to when they say there is no life on a planet.
Can anyone here explain it or provide any source?

Steve Brennan
Jan 27 · 1 upvote from Yonko Avalanche
When referring to whether or not a planet has life, we are looking for life as we know it. This includes any living organism: Bacteria, plants, fungi, animals. There could be forms of life that we are completely unaware of, and this would be much more difficult for us to identify or relate to.

Also, our scientific instruments can only travel or look so far. If we were to find a single bacterium on Mars, we would say that Mars has life. If we were to one day drill into the ice shell of Europa with one of our probes/rovers and find strange aquatic life there, we would say that Europa has life. Other than planets or moons within our Solar System, though, we have very little capability of confirming living organisms elsewhere.

We must improve the technology of our telescopes, Rockets, etc in order to improve our capabilities of discovering life in other star systems.

Yonko Avalanche
Jan 27 · 1 upvote from Steve Brennan
Exactly! So it would be better to say that we have not interacted with a life form similar to us. There might have been some occasions where our eyes would have been fixated on alien life forms but simply because it is immobile/inorganic/invisible/etc we were not able to confirm their existence.
If this were the case then there are no soldiers hiding in the dark forest but the tree under which we sit, the air which we breath and the darkness are the soldiers itself.
Thanks for the reply.

Steve Brennan
Jan 27 · 1 upvote from Yonko Avalanche
I like how you think! Like I mentioned in my original answer, there are many theories that attempt to answer the Fermi Paradox, and the Dark Forest Theory is merely one of them.
You have shed light on another theory that could explain the Fermi Paradox… perhaps there is life everywhere around us and we just aren’t aware of it because of the way our senses work! Especially considering we can only sense a small percentage of our surroundings at any given moment!

Vlad Miu
Jan 28 · 1 upvote
But if even a tiny fraction of the life forms is as stupid as we are, shouldn’t we find their traces/signals?

Arthur Stepanyan
Feb 1
If electronic transmissions were not enough, we sent the Voyagers out with as much information about human race as we could think of.

Renato Marcos Endrizzi Sabbatini
Feb 3
You all are using the term “theory” wrongly in this debate. You should use “hypothesis”, instead. Theory in science is a different thing altogether.

RB Nerf
Jan 28
As a child, I was taught that Adam & Ever were thrown out of paradise because of disobedience. If on most planets, the Adam & Eves were not disobedient, then they and their progeny still live in paradise, and have little interest in astronomy.

Peter Kinnon
Feb 1
There are more profound ways of resolving the Fermi paradox derived from observed universal evolutionary trends.

From what we know of the emergence of biology on this planet and the evolutionary pattern of the ensuing network with a seemingly unending increase of intricacy, we can reasonably infer that, given half a chance, the directionality this implies will extend to the eventual exploitation of extraterrestrial niches. But not by biological organisms, for whom the adaptations required for such extreme environments are (outside the imaginary realms of science fiction) prohibitive.

However, the symbiont with which we have co-evolved over the last couple of million years, technology, seems to be well placed to eventual spawn rugged inorganic “life-forms” that can permanently escape the constraints of this nursery planet and draw their energy requirements directly from stars. Just as we live far more slowly than hummingbirds, we can expect these new cognitive entities to have metabolisms that are exceedingly slow. Accordingly their communication rates also. Way outside the spectrum of frequencies searched by SETI. Even one bit per year might be adequate for such a community who would also have no use for Von Neumann probes.

The biologically activated radio emanations of active planets such of our’s occur in the blink of an evolutionary eye and are quite weak, so not much chance of picking up those.

The extent to which biology occurs on other worlds and the prerequisite essential features are uncertain. Oceans, plate tectonics, magnetic field, atmosphere, similar size and mineral composition to Earth would seem to be musts. Such things as a single moon of similar size are more speculative. And, again, because of the observed gross directionality (and inevitability) of biological evolution, the hurdle of eukaryotic multicellularity would be similarly overcome.