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There is nothing I enjoy more than pondering on life on other worlds. I have been fascinated by alien life ever since I grew up watching E.T. And Star Wars as a kid. And I like many dream of joining an Interstellar Alliance and seeing the varieties of alien life out there. So it should come as no surprise that one of my most recent endeavors is proving that The Dark Forest Theory doesn’t work.

The Dark Forest Hypothesis in a Nutshell

The dark forest hypothesis is the idea that many alien civilizations exist throughout the universe, but are both silent and paranoid. In this framing, it is presumed that any space-faring civilization would view any other intelligent life as an inevitable threat, and thus destroy any nascent life which makes its presence known. As a result, the electromagnetic spectrum would be relatively silent, without evidence of any intelligent alien life, as in a "dark forest"...filled with "armed hunter(s) stalking through the trees like a ghost". The hypothesis was described by astronomer and author David Brin in his 1983 summary of the arguments for and against the Fermi paradox, for which this hypothesis is one potential solution. (Source)

Kurzgesagt made a video that deftly explains The Dark Forest Hypothesis.

For those of you more familiar with the topic let’s begin. As it stands their are two major problems that poke massive holes in the theory.

Problem I: You Can Run, But You Can’t Hide

Now a lot of the Dark Forest Theory depends on the assumption that the universe is a dark place where eldritch predators can lay in ambush and wait for the perfect moment to strike. But there is a simple rule that everyone I’ve had this debate with seems to either not understand or just outright ignore. There is NO stealth in space. Any technological species can make a telescope, take a look and say, “Oh look, Jupiter has four moons. What’s that big black rectangle doing there?” Now everybody keeps pointing out the radio signals we are blasting into the eternal night are letting everyone know where we are, like a baby crying out attracting the predators lurking in the shadows. But here’s the thing, any predator any good at hunting doesn’t need the baby to cry to know it’s there. They can hear the baby breathing.

See, about a billion years ago, this brand new life form called Cyanobacteria first evolved and became Earths first photosynthesizers. They utilized the light of the sun for energy, and produced a fascinating byproduct that would prove useful in the further development of Earths biosphere. Oxygen. Now because of how sunlight interacts with various gases and molecules on our planet, anyone with a telescope can see that we have an atmosphere that can only be produced by a thriving biosphere. And because of the funny way light lag works, anyone with a big enough telescope within 1 billion light years can look towards our planet and go, “hmm, plentiful water, high concentration of oxygen, large quantities of organic compounds, all right we have a planet with a functioning biosphere. Singer, launch the strike, leave no survivors, I’m going on a coffee break.” So even if all our world leaders decided no more radio signals, it’s already too late, because our own planet has been shouting, “Biosphere! Living thriving biosphere, right here! Come quick and wipe it out before it develops space travel!” Into the void for a billion years before we even started banging rocks together.

Now this sounds like bad news and I suppose in this context, it is. But the good news is that anyone advanced enough to build weapons that can wipe out civilizations with the push of a button, face the exact same problem. In fact, you can say they might have it worse then we do, since they can’t hide all the industrialization of their solar system needed to support their society and their interstellar war effort.

And even if you are sufficiently advanced to completely hide from someone less technologically savvy than you, anyone above your weight class will still be able to find you. The Amun-Ra class stealth frigate is a technological marvel of stealth tech, but I sincerely doubt that it could hide from the sensors of the USS Enterprise.

Now this leads nicely into the next point.

Problem II: We’re Still Here

As I said, Earth has been broadcasting its life-bearing status into the void for a billion years. That means any civilization in the Laniakea Supercluster, all 150,000 GALAXIES, have had plenty of time to check Earth out, and if the mood strikes them, blow it up. And yet, our planet hasn’t been wiped clean of life, torn apart and stripped of everything worthwhile. We are still here having this debate. And so we can confidently say that there is no one within a billion light years participating in the Dark Forest Theory.

Now this sounds fairly conclusive, but recently I was lost in thought and found something that might end the whole debate once and for all. Suicide Pact Technology.

I was going through my audible recently and I remembered a rather poignant passage in the Novel Year Zero that I think sums up this thought experiment perfectly.

“Most society’s destroy themselves with nuclear, biological or nanoweapons long before achieving Refined status. And when this happens, Refined observers do nothing to stop the annihilation. This may sound heartless but it’s actually a prudent form of self-defense-since any society that’s violent and stupid enough to self destruct on H-bombs might easily destroy the entire universe if it survives long enough to invent something with real firepower.” - Year Zero by Rob Reid, Chapter Zero.

Now while Year Zero is meant as a farcical comedy on humans making the best music in the universe, they do bring up a pretty valid point. The Dark Forest theory requires EVERY sentient species to be xenophobic, expansionistic and fanatically dedicated to the elimination of any threat or competition. Except any species that would see the use of WMDs as the only logical conclusion, would naturally wipe themselves out long before they could leave their homeworld or develop the tech necessary to destroy civilizations beyond their Star systems. This isn’t even a new argument, Carl Sagan made the exact same arguments when fears of Nuclear War were at their height. And as for us blowing ourselves up there were plenty of close calls, like a bear tripping the wrong alarm, a flock of geese, a malfunctioning Soviet early warning system showing a full blown attack, a US B-52 bomber breaking in half and dropping two armed nukes over North Carolina,(I’m not kidding, Goldsboro Incident, 1961) and despite all of that, we reframed from pushing the big red button and ending our species. But this restraint is not looked on as the virtue it is in the Dark Forest Theory. So we are faced with a logical problem. The exact thought process necessary for the Dark Forest Theory to work, is also the thought process telling you to push the big red button to blow your own planet straight to hell.

So is the nature of Suicide Pact Technology and Overly Aggressive Species tendency to destroy themselves the final nail in the coffin for the Dark Forest Theory?

Notes: there might be a debate on weather or not nuclear power or weapons count as a Suicide Pact Technology, but I hope that my arguments here will grant me an “eh, close enough” in this case.

JBH
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Jacob Badger
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    It is not clear that this is a worldbuilding question so much as an earnest discussion of some competing, almost game-theoretical analyses of the search for extra-terrestrial life. This might be a better fit for Astronomy.SE or Philosophy.SE. (It might also help to eliminate unnecessary content so it's less a wall of words.) – Tom Oct 31 '22 at 01:55
  • Please make your questions self-contained. You will get better answers if you explain everything yourself rather than linking elsewhere. – Daron Oct 31 '22 at 02:14
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    (a) I edited our post to include the (relatively simple) basics of the dark forest hypothesis (hypothesis, not theory). It is bad grace to not include relevant information in your posts. Posts that rely on links to convey basic and necessary information are closed for "Needs More Details." (b) I voted to close anyway because this isn't a worldbuilding problem. Proving or disproving the dark forest hypothesis is irrelevant to the rules of a fictional world of your own creation as it only relates to Earth. – JBH Oct 31 '22 at 04:57
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    For the record, you can't disprove one hypothetical solution to the Fermi Paradox by promoting another hypothetical solution to the Fermi Paradox. The only way to disprove the dark forest hypothesis would be to factually find friendly aliens who then explain why our rudimentary science couldn't detect them (or explore each and every planet in the galaxy to prove we're truly alone). And if you want to see some clever solutions to stealth in space that might give you pause to think, search for stealth and space on this Stack. – JBH Oct 31 '22 at 05:01
  • Asking just about the hypothesis is more astronomy and -mainly- first contact diplomaty than building a world. In order to prove you're building a world you need to set some world premises you worked on around this hypothesis, or set the hypothesis as a premise itself (e.g. : Dark forest hypothesis is true) and wondering what you can do with it. – Tortliena - inactive Oct 31 '22 at 11:58

3 Answers3

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No nail, no coffin (and barely a theory)

Now a lot of the Dark Forest Theory depends on the assumption that the universe is a dark place where eldritch predators can lay in ambush and wait for the perfect moment to strike.

On the contrary, it depends on the assumption that more advanced civilizations can easily detect life. That is, it's not a dark forest for them, just for us, due to our limited sensing. And they aren't laying in ambush: in the Dark Forest theory, as soon as they spot life, they destroy it. Less an eldritch predator, more a venus fly trap.

But there is a simple rule that everyone I’ve had this debate with seems to either not understand or just outright ignore. There is NO stealth in space.

Space has great stealth, as long as you don't get close to anyone else. Fortunately, most folks are pretty far apart, if they're out there.

Now everybody keeps pointing out the radio signals we are blasting into the eternal night are letting everyone know where we are, like a baby crying out attracting the predators lurking in the shadows

At the moment, only anyone within ~130 LY of us could have possible heard our broadcasts, and even then, in order to hear them, they would need to have a radio telescope pointed directly at us, tuned exactly to the right frequency, and for us to have been using half the power on earth to broadcast a signal directly at them at the exact right time. (see here) for more on that.

"Even a 3000 meter diameter radio telescope could not detect the "I Love Lucy" TV show (re-runs) at a distance of 0.01 Light-Years!"

anyone with a telescope can see that we have an atmosphere that can only be produced by a thriving biosphere

Well, only if they're in a direct path along which our planet transits the sun, which is not even remotely guaranteed. And if they're close enough that they can actually use transit spectroscopy for such a small planet at such a large distance from the Sun. We don't even know the atmospheric composite of Ross 128 b, and it's 11LY away.

And because of the funny way light lag works, anyone with a big enough telescope within 1 billion light years

Only for an insanely generous definition of "big enough".

since they can’t hide all the industrialization of their solar system needed to support their society and their interstellar war effort.

Sure they can, see above.

Problem II: We’re Still Here

I agree, us existing is definitely a problem.

As I said, Earth has been broadcasting its life-bearing status into the void for a billion years. That means any civilization in the Laniakea Supercluster, all 150,000 GALAXIES have had plenty of time to check Earth out, and if the mood strikes them, blow it up.

Chances are, no one outside of ~100LY can even detect earth, much less its atmosphere, and even if they could, assuming they have the capability to hit the earth with a relativistic kill vehicle is... pretty optimistic.

Can you imagine how difficult it would be to hit Proxima Centauri B (< 5LY away) with a projectile? We have its semi-major-axis accurate to only within ~0.005 AU, so we know how far it is from its star... give or take 750,000 kilometers, and its radius to be somewhere between 4400km and 16,000km. So it's like knowing that there is a pencil mark somewhere on yardstick, and trying to hit that pencil mark with a thrown needle from 32,000km away. Oh, and the yardstick is moving. And you have to aim at where it will be four years from now.

(a guided relativistic kill vehicle suffers from many other problems, but the scope of the calculation stands.)

so we can confidently say that there is no one within a billion light years participating in the Dark Forest Theory.

We can't even confidently say this for 'no one within 10 LY".

The Dark Forest theory requires EVERY sentient species to be xenophobic, expansionistic and fanatically dedicated to the elimination of any threat or competition.

Well, no, it just requires enough sentient species with enough motivation to destroy life when they find it.

Except any species that would see the use of WMDs as the only logical conclusion, would naturally wipe themselves out long before they could leave their homeworld or develop the tech necessary to destroy civilizations beyond their Star systems.

I wouldn't feel comfortable speculating about alien biology. Assuming that we would understand alien psychology is nuts. That aside, this is a huge assumption anyways.

despite all of that, we reframed from pushing the big red button and ending our species

Yet. We've only had nuclear weapons for ~0.01% of our recorded history. Don't count your mushrooms before they've sprouted.

The exact thought process necessary for the Dark Forest Theory to work, is also the thought process telling you to push the big red button to blow your own planet straight to hell.

This discounts any number of humanly plausible reasons to destroy other life other than a penchant for violent destruction at every occasion, much less the unimaginable alien motivations.

So is the nature of Suicide Pact Technology and Overly Aggressive Species tendency to destroy themselves the final nail in the coffin for the Dark Forest Theory?

Coming up with philosophical conclusions about a theory based on the Fermi Paradox is like trying to build a skyscraper on the surface of a bottomless pit full of quicksand. Mainly, all you should get is a sinking feeling.

Daniel B
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    +1 just for pointing out that the idea of there being no stealth in space is ridiculous (paint your ship flat black and optically you can only be seen if you happen to fly between Earth and a bright object at the very moment we're looking at it, what are the odds of that?). – JBH Oct 31 '22 at 05:09
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    Oh, good grief. I just read the rest of your answer and happily admit that I couldn't force myself to read through the OP's post. +10. I actually clicked the up button 10 times, but the SE Overlords won't let me upvote more than once. – JBH Oct 31 '22 at 05:15
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No

  • The first argument ("You Can't Hide") grossly mischaracterizes how obvious is the presence of life on Earth. It would take a miracle for anybody to be looking specifically at Earth. It is beyond absurd to imagine that oxygen in our atmosphere makes us stand out. Earth is not a quasar, or a supernova, or a source of any other strong signal. Earth is one small planet in that region of 150,000 galaxies, which could make for a list of 150 quadrillion planets to study. The light reflected from our atmosphere puts us very low on that list of things to look at.

    And even if they knew the exact location of Earth, it is quite possible they would not have the technology to see it. As of today, the furthest exoplanet humans have discovered is only 17,000 ly away, and it's more massive than Jupiter (which is the only reason we were able to detect it). They will face the same difficulties.

    It's also worth noting that a species does not, upon its birth, start searching the skies for victims. There has been life on Earth for about 3.5 billion years, but Earth only started looking for aliens ~100 years ago. It is entirely possible there are murderous aliens out there who haven't started looking yet, or whose search has not been going on long enough to get through a substantial portion of the 150 quadrillion planets within your range.

    Don't you think they would start the search in their own galaxy, as a purely practical matter? Traveling between stars is enormously difficult in an absolute sense; traveling between galaxies is unthinkably harder. Scouring their own galaxy of other life will probably keep a species busy for billions of years.

    The Earth's continued existence is not conclusive evidence that there are no alien species out there who would seek to destroy us. It is overwhelmingly likely that absolutely nobody knows about us.

  • It seems like you use the phrase "suicide pact technology" as a gloss for the assumption that aliens who are violent will necessarily engineer their own extinction before they reach the point of wiping out other species. That is a bad assumption.

    Consider that wars like we have only Earth can only occur in species that have multiple independent individuals who dwell in separate power structures. A planet ruled by a hive species like bees or ants could easily have no wars at all, or an age of war that ended in a total victory for one hive, long before they unlocked destructive tech. From that point on, I'd expect the planet to operate in perfect harmony, and that species to thrive. And they might very well still be bent on exterminating others.

    Or, consider a species like humans who didn't disperse across the whole planet in their infancy, forming separate communities which could develop into separate cultures and nations who could later make war. Instead, they all stayed in a single location long enough for one group to achieve dominance, only venturing forth afterward. Permanent hegemony by a single individual is still a possibility here on Earth, with multiple super-wealthy individuals subverting governments and reducing all of society to the economic domain where they hold sway, while simultaneously investing in robot storm troopers and longevity technology. Humanity might yet be "saved" from such a suicide pact by an immortal billionaire who establishes a global dictatorship in the wreckage of a climate catastrophe, pandemic, or the like.


I don't know that I think much of "dark forest theory," but I would also say that as a matter of pure reason, the arguments you've presented do not do much to defeat that view: it is far from obvious that they are true, and it is obvious they would not shut down the assumptions that underpin the dark forest even if they were.

From a worldbuilding perspective (you do have a worldbuilding goal, right?), I would say: if your world will be more interesting if it's not a dark forest, then simply reject some of the assumptions that drive it. Or, if you want a dark forest but are worried that it won't hold up, do it anyway. You don't need our permission to establish the facts of your world.

Tom
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    Wouldn't it be funny if the reason we can't find any aliens is because they've adopted your solution to this other question: SneakerNet.... It's funny how the best predictions of the past often fall prey to the practical solutions of the present. – JBH Oct 31 '22 at 05:25
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So is the nature of Suicide Pact Technology and Overly Aggressive Species tendency to destroy themselves the final nail in the coffin for the Dark Forest Theory?

No. We have no evidence to believe that advanced civilizations tend to wipe themselves out. We have only one civilization to base our observations on, and as you say we are still here.

Daron
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