Jan 21, 2020 I Brent Swancer

The Dark Forest Theory: A Grim Answer for Where All the Aliens Are

The question of whether we are alone in the universe has swirled around our consciousness since as long as we were able to even comprehend the concept of a universe at all. We have long reached out to the stars, looked out over that vast sea of cosmic mysteries, and wondered if there might be anyone else out there doing the same, looking right back at us. Is there other intelligent life in the universe, or are we truly alone in this cold expanse? There has never been an answer to this, and we continue to try and find one, yet as time goes by it sometimes seems that for all we know there is no one looking out, and that we are the sole consciousness of this universe of ours. We throw out our radio signals, announce our presence, and scour every corner that our technology will allow, but there is nothing, only silence. There have been many ideas on why this should be, and some are far more ominous and sinister than others.

The main problem we face in the end with regards to other intelligent lifeforms is that, although the universe is vast, with the Milky Way alone composed of around 200 billion stars and billions of planets, if even a tiny faction of those have produced intelligent, spacefaring civilizations, then it has been reasoned that we should have definitely heard from them or at least detected them by now. This conundrum was perhaps best illustrated in what has come to be called the Fermi Paradox, which I have covered before but which probably deserves a refresher here. In 1950, influential and notable physicist Enrico Fermi was working for Los Alamos National Laboratory, and one day while having lunch with colleagues Emil Konopinski, Edward Teller and Herbert York, the conversation came around to UFOs and alien life. The group began discussing the possibility of other alien civilizations out there scattered across the galaxy, and that was when Fermi simply and bluntly asked “Where are they?” This generated a bit of laughter around the table, but he was perfectly serious. When the others asked exactly what he had meant, Fermi explained that if there was another civilization or civilizations that had developed out there with the technological ability to traverse space, then eventually they should have already spread out all over the galaxy, and we should have had some brush with them by now in some form.

Fermi reasoned that there had been plenty of time for them to do so, and utilized complicated equations to illustrate that over millions and millions of years, just a drop in the bucket compared to the age of the universe, these hypothetical alien civilizations should have at least found us by now. Fermi explained that with so many stars and potential planets in the observable universe, then if even a fraction of those had produced intelligent, spacefaring life then they would have exponentially broken their barriers and moved out into the galaxy, colonizing new worlds, and we would have surely known about them by now. By Fermi’s various calculations, the probability for intelligent life somewhere in the universe was high considering the sheer scale of it all, and if such advanced societies had developed, then after so much time aliens should be everywhere by now, or at the very least given us some sort of sign of their existence, even if such societies are rare. Yet there is no one, no evidence of such a thing, not a single sign that there is anyone else out there at all. Essentially, like Fermi asked, where is everybody?

This is the main gist of what has gone on to become known as the “Fermi Paradox,” and although it has been criticized by many as being perhaps too simplistic and making too many assumptions based on our own ideas of life, it has nevertheless gone on to become a major cornerstone for debate on the topic of intelligent life elsewhere in the universe, and has inevitably hung over most discussions on the matter. This offhand lunchtime remark has propelled the imagination and driven the efforts of organizations like SETI. No matter what one thinks of the veracity of Fermi’s question, it is a compelling one to say the least, and there have been many numerous and varied theories that have come forth to try and explain just why we have not found anyone else out there in this cold universe of ours.

This is all backed up by what is known as the Drake Equation, which was conceived of in 1961 by a Dr. Frank Drake, of the National Radio Astronomy Observatory in Green Bank, West Virginia. Drake wished to come up with a mathematical formula for calculating the number of possible technologically advanced civilizations in our galaxy and takes into consideration various factors such as the number of stars and their rate of formation, the number of possible planets around these stars, the number which might be inhabitable, and many others. When all of this is plugged into the formula, the result is that there should be around two dozen spacefaring civilizations in our galaxy, yet we have not heard a peep. There have been many reasons for why this might be, some of which I have covered here before, but one of the more sinister and grim of these is what is rather ominously known as the “Dark Forest Theory.”

The depressing idea more or less boils down to that every alien race would naturally put its survival above that of another species, and that considering the chaotic nature of the universe and innate problems with trying to communicate with a completely alien civilization, compounded by the fact that we can never know what the intentions of such a race would be, the best bet is to stay quiet and hope no one finds you, or conversely wipe them out before they do the same to you. The theory was best laid out in the 2008 science fiction novel The Dark Forest, part of the Remembrance of Earth’s Past trilogy by author Lui Cixin, in which the argument is presented that A) All life seeks to ensure its own survival, B) There is no way to know if another lifeform will try to destroy you, and C) Without an assurance that this won’t happen, the safest logical way to avoid termination is to stay hidden or destroy them before they can do the same to you, a sort of preemptive attack. In essence, any alien races that haven’t annihilated each other already are maintaining “radio silence” so to speak, hiding away in a state of paranoia and fear, and so are loathe to make their presence known. Lui would write of this:

The universe is a dark forest. Every civilization is an armed hunter stalking through the trees like a ghost, gently pushing aside branches that block the path and trying to tread without sound. Even breathing is done with care. The hunter has to be careful, because everywhere in the forest are stealthy hunters like him. If he finds other life — another hunter, an angel or a demon, a delicate infant or a tottering old man, a fairy or a demigod — there’s only one thing he can do: open fire and eliminate them. In this forest, hell is other people. An eternal threat that any life that exposes its own existence will be swiftly wiped out. This is the picture of cosmic civilization. It’s the explanation for the Fermi Paradox.

Lui also mentions that resources in the universe would be finite and limited, and so for a civilization to expand across stars they would necessarily have to consume as much as they could and eliminate any competitors. In other words, any other alien race other than one’s own is an unknown competitor at best, and a catastrophic threat at worst. Between members of one species, such as between humans, this might be resolved through diplomatic solutions, although even that doesn't work out a lot of the time, yet with a completely alien race all bets would be off, so the best solution to ensure survival is to hide or destroy the other before they have a chance to pose a threat. This theory was touched on and supported by science fiction writer David Brin as well, of which he rather darkly writes:

It is consistent with all of the facts and philosophical principles described in the first part of this article. There is no need to struggle to suppress the elements of the Drake equation in order to explain the Great Silence, nor need we suggest that no ETIS anywhere would bear the cost of interstellar travel. It need only happen once for the results of this scenario to become the equilibrium condition in the Galaxy. We would not have detected extraterrestrial radio traffic- nor would any ETIS have ever settled on Earth- because all were killed shortly after discovering radio.

If this theory has any merit at all, then it is probably not a good idea that we have been relentlessly announcing our position and existence into the frigid void of space through decades of radio transmissions and space probes, something that has alarmed the more negative of the scientific community. The late physicist Stephen Hawing notoriously opposed contact with extraterrestrials, often lamenting that to make contact would be a death sentence for us, and he once said:

If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans. We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet.

Many other scientists have shared this sentiment. This fits in very well with the Dark Forest Theory, and if it is an accurate solution to the Fermi Paradox, then we are very lucky that no one has been listening, or perhaps there are alien races cowering in the shadows who are indeed listening, and just wishing that we would shut up. Even if the other civilization knows that we are technologically inferior and not a threat now, the distances and time frames involved make sure that there are no guarantees. As one commenter on the site Quora puts it:

You might be thinking that if an advanced civilization detects the radio signals from Earth then they would know that we are less advanced and therefore not a threat. But again you have to consider the vast distance and time it takes for those signals to travel. Even if a nearby civilization (only 10 or 20 light years away) detects us, it would take hundreds or even thousands of years for them to reach us and that is plenty of time for a technological explosion. If they don't attack us at once, then we might develop technology fast enough to catch up and threaten them.


It won't be like Star Trek. Without faster than light travel, there won't be any communication, diplomacy or trade with alien races. It's kill or be killed. So that's why we haven't heard a peep from other civilizations. The universe is a dark forest where every civilization is a silent hunter. They desperately try to stay undetectable while hunting for other planets to colonize and threats to destroy.

It is all about the best interest of one’s own race, every man for himself, and in this theory this is the only way to guarantee that we survive this morass of bleakness. The Dark Forest Theory has drawn comparisons to a thought experiment known as “The Prisoners’ Dilemma,” a paradox in which two individuals acting in their own self-interests do not always produce the optimal outcome that is most beneficial to both. Basically imagine you have two criminal accomplices to a crime being interrogated in two separate rooms, with no way of knowing what the other is up to. Each one is told that if neither of them rats the other out, and they both remain silent, then they will both go to jail for one year on a lesser charge. However, if one of them is to implicate the other, he will walk free while the other does a 3-year sentence, longer than they would have done otherwise. If both of them point the finger, they will both get 2 years. The best outcome for both is obviously to keep quiet, but not knowing what the other will do and without faith that the other will also stay silent, the safe bet is to incriminate the other as soon as possible and avoid jail time altogether just to be safe. This is the general gist of the Dark Forest Theory in essence.

It is all rather pessimistic and morbid for sure, and paints the universe as an innately unfriendly place and all intelligent species as ruthless predators looking to exploit, hide, or kill. It all seems actually pretty possible just from looking at life on earth. Humans have long subjugated and wiped out other tribes and species in an attempt to expand, so mightn’t an alien race be prone to the same sort of behavior, as Hawking pointed out? There seems to be no universal moral code that other cultures must abide by, so in this way of thinking, if we can’t even follow our own moral rules on this planet, then how could we ever expect a positive outcome from an alien race?

In some ways it makes sense, but never fear, because there have been a criticisms aimed at the idea of the Dark Forest as well. The main problem with it is that it takes a very narrow and human-centric view of what an advanced civilization should be like. Who is to say they would have to be aggressive and looking to destroy, or that they would think in any way like us at all? Indeed, there have been a lot of scientists who support the idea that any spacefaring civilization would be hundreds or thousands of years more advanced than us, and so would by definition have by necessity learned to overcome such self-destructive behaviors such as war and murder, and to have mastered universal empathy. One scientist who believes this is Seti’s former director, Jill Tarter, who thinks that such a civilization would have risen above such things and that the very fact that they are advanced enough to come to us means that they would be sophisticated, peaceful, and benevolent. Tarter said of this to Business Insider:

The idea of a civilization which has managed to survive far longer than we have…and the fact that that technology remains an aggressive one, to me, doesn’t make sense. The pressure of long-term survival — of limiting population…I think requires that the evolutionary trends that ratcheted up our intelligence…continues to evolve into something that’s cooperative and take on global scale problems.

With regards to a species hiding out and lying low in the hopes that others don’t come for them, there is the criticism that it would be very hard to advance to this stage of development by remaining completely silent and meek. To reach a state of advanced technology and the ability to cross the sea of stars would be very difficult to do while remaining completely invisible to other such races, so there would be no guaranteed way for them to totally cower in the shadows while simultaneously reaching such a pinnacle of civilization. There is also the fact that for as much as other powers might be a threat, there has always been value in trade, cooperation, and forging alliances as well, which would not be possible in this climate of extreme paranoia. Yet another fact is simply that we cannot possibly know how an alien species would perceive threats or risks, so assuming what they should do is over anthropomorphizing them.

Unfortunately, or perhaps fortunately, depending on how you look at it, we have not yet made alien contact as far as we know, and so the question remains: where are all of the aliens? One would like to think that they are out there and we simply, for some reason haven't found them yet, and one would also hope that if we ever get the opportunity to make their acquaintance that they will be benevolent and friendly. The Dark Forest Theory is in the end just one idea, and one that was originally posited as fiction, so perhaps we can look forward to a more positive outcome, and have hope that the universe is not an inhospitable enemy. Only time will tell, and perhaps one day we will know the answer to the question of whether it was a good idea to shout out our presence, or if we should have hidden in the shadows like everyone else.

Brent Swancer

Brent Swancer is an author and crypto expert living in Japan. Biology, nature, and cryptozoology still remain Brent Swancer’s first intellectual loves. He's written articles for MU and Daily Grail and has been a guest on Coast to Coast AM and Binnal of America.

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