We have no good reason to believe that aliens have ever made contact with Earth. Sure, there are conspiracy theories and some rather strange reports of livestock damage, but nothing credible. Physicist Enrico Fermi found this strange. His formulation of the puzzle, proposed in the 1950s and now known as 'the Fermi paradox', is still the key to the search for extraterrestrial life (Seti) and messaging by sending signals into space (Meti).
The Earth is about 4.5 billion years old and life is at least 3.5 billion years old. The paradox states that, given the size of the universe, favorable conditions for life have likely occurred many times. So where is everyone? We have good reason to believe there must be life out there, but no one has come to call.
This is a problem that the character Ye Wenjie struggles with in the first episode of Netflix's 3 Body Problem. While working at a radio observatory, she finally receives a message from a member of an alien civilization - telling her that they are pacifists and urging her not to respond to the message or Earth will be attacked.
The series will eventually provide a detailed, elegant solution to the Fermi Paradox, but we'll have to wait until the second season.
Or you can read the second book in Cixin Liu's series, The Dark Forest. Without spoilers, the explanation in the books is as follows: "The universe is a dark forest. Every civilization is an armed hunter that stalks like a ghost through the trees, gently pushing aside branches that block the path and trying to tread silently."
In the end, everyone hides from everyone. The varying rates of technological progress make a continued balance of power impossible, leaving the fastest-advancing civilizations in a position to exterminate anyone.
In this increasingly threatening environment, those who play the survival game best are the ones who survive the longest. We joined a game that took place before our arrival, and the strategy everyone has learned is to hide. No one who knows the game will be stupid enough to contact anyone - or respond to a message.
The story continues
Liu has depicted what he calls "the worst of all possible universes," continuing a trend in Chinese science fiction. He does not say that our universe is a real dark forest, in which one survival strategy of silence and predation reigns everywhere, but that such a universe is possible and interesting.
Liu's dark forest theory is also sufficiently plausible to have reinforced a trend in scientific discussion in the West - away from concerns about mutual incomprehensibility, toward concerns about immediate threat.
We can see its potential influence in the protocol for what to do at first contact proposed in 2020 by prominent astrobiologists Kelly Smith and John Traphagan. "First do nothing," they conclude, because doing anything could lead to disaster.
In the event of contact with aliens, Earth should be notified using predetermined signals, rather than something improvised, they say. And we should avoid doing anything that might reveal information about who we are. Defensive behavior would demonstrate our familiarity with conflict, so that wouldn't be a good idea. Recurring messages would reveal Earth's location - also a bad idea.
Again, Smith and Traphagan's idea is not that the dark forest theory is correct. Benevolent aliens could really be there. The idea is simply that first contact would entail a great civilization-level risk.
This departs from the assumptions of much of Russian space literature in the Soviet era, which suggested that advanced civilizations would necessarily have moved beyond conflict and therefore share a comradely attitude. This no longer appears to be considered a plausible guide to contact protocols.
Misinterpreting Darwin
Interestingly, the dark forest theory is almost certainly wrong. Or at least, it's wrong in our universe. It outlines a scenario in which there is a Darwinian process of natural selection, a competition for survival.
Charles Darwin's account of competition for survival is evidence-based. In contrast, we have absolutely no evidence of alien behavior, or of competition within or between other civilizations. This makes for entertaining guesswork rather than good science, even if we accept the idea that natural selection might operate at the group level, at the level of civilizations.
Even if you were to assume that the universe functioned in accordance with Darwinian evolution, the argument is questionable. No real forest is like the dark one. They are noisy places where co-evolution takes place.
Creatures evolve together, in mutual dependence, and not alone. Parasites depend on hosts for pollination, flowers depend on birds. Every creature in a forest depends on insects. Although interconnectedness leads to encounters that are nasty, brutal and short, it also takes other forms. That's how forests work in our world.
Interestingly, Liu recognizes this interdependence as a counterpoint to the dark forest theory. The viewer and reader are repeatedly told that "in nature nothing exists alone" - a quote from Silent Spring by Rachel Carson (1962). This is a text that tells us that insects can be our friends and not our enemies.
In Liu's story, this is used to explain why some people immediately side with the aliens, and why the urge to make contact is so strong, despite all the risks. Ye Wenjie finally answers the alien warning.
Carson's allusions do not restore the old Russian idea that aliens will be progressive and therefore comradely. But they do help paint a more varied and realistic picture than the dark forest theory.
For this reason, the dark forest solution to the Fermi paradox is unconvincing. The fact that we don't hear anyone could just as easily indicate that they are too far away, or that we are listening the wrong way, or that there is no forest and nothing else to hear.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
