Why is annihilating Aliens necessary?

Why is annihilating Aliens necessary?

The existential risks of contacting extraterrestrial civilizations as seen on 3 Body Problem.

The Fermi paradox, named after renowned physicist Enrico Fermi, highlights a perplexing contradiction in our understanding of the universe. Given the immense vastness and age of the cosmos, it seems probable that extraterrestrial life and advanced civilizations should be abundant. The Drake equation, which estimates the number of communicative civilizations in the galaxy, suggests that even with conservative assumptions, the Milky Way should host thousands of advanced species. Yet despite decades of searching using increasingly sophisticated methods such as radio telescopes, optical SETI, and gravitational wave detectors, we observe a "Great Silence" - no definitive signs of alien life or technology. As Fermi famously asked, "Where is everybody?"

One chilling solution proposed to resolve the Fermi paradox is the "Dark Forest" hypothesis, put forth by science fiction author Liu Cixin in his novel of the same name. It posits that the universe is akin to a dark forest filled with hunters (advanced civilizations). To ensure their survival, the hunters must destroy any other life they encounter, or risk being destroyed themselves. This results in an unsettling conclusion: the only civilizations that endure are those that remain undetected. Any that reveal their presence are swiftly annihilated.

Several arguments support the dark forest hypothesis from a game theoretical perspective. Game theory is the mathematical study of strategic interaction and decision-making between rational agents. In the context of cosmic civilizations, we can model the scenario as a sequential game, similar to chess, in which players (i.e., civilizations) choose their actions in response to the other's moves.

Consider two civilizations, A and B, separated by a vast distance, say 100 light-years. Each civilization has three possible actions upon detecting the other:

  1. Ignore the other civilization

  2. Attempt to communicate and establish contact

  3. Launch an attack to preemptively destroy the other civilization

If both civilizations ignore each other, the payoff is zero - neither gains nor loses anything. If one civilization contacts the other, it reveals its presence and technological capabilities. This gives the receiver of the message a distinct advantage. They could choose to reciprocate and establish friendly relations, leading to a positive payoff for both (e.g., through trade or information exchange). However, they could also exploit the information to launch a devastating attack on the sender, resulting in a highly negative payoff for the contacted civilization (potential annihilation) and a moderately positive payoff for the attacker (elimination of a rival).

Crucially, the vast distances between stars force the game to be played sequentially, with long delays between turns. This means civilizations must make their decisions in isolation, unable to gauge the intentions of the other in real-time. Like hunters in a dark forest, the safest strategy is to shoot on sight, as a single technologically advanced adversary could pose an existential threat. Even if the contacted civilization is peaceful, the very act of responding could prompt the original sender to turn hostile, as they cannot be sure of the respondent's intentions. This strategic situation is known as the Hobbesian trap, where conflict arises between rational agents due to mutual distrust, even when cooperation would be mutually beneficial.

The Dark Forest hypothesis is further bolstered by considering the potential destructive capabilities of advanced civilizations and the dynamics of space warfare. The time lag induced by light-years of separation means any civilization could experience rapid, potentially exponential technological progress in the interval between their detection and a reply. Human history shows that enormous scientific and engineering advances can occur on century timescales - Moore's Law, for instance, describes a doubling of computing power every two years, which would result in a staggering quadrillion-fold increase over a century. An apparently primitive civilization could leap ahead to become a formidable threat by the time a message reaches them.

Moreover, the vast distances of space incentivize the development of devastating first-strike weapons. Given the light-speed limit, civilizations would be unable to detect and defend against an incoming attack fleet. The only viable strategy is a preemptive relativistic kill vehicle (RKV) - a dense projectile accelerated to a significant fraction of light speed (~0.1c) and aimed at an enemy planet. The kinetic energy released upon impact would be comparable to the world's nuclear arsenal, capable of sterilizing a planet's surface in seconds. A single large asteroid or spacecraft boosted by a solar sail, fusion drive or antimatter engine could serve as an RKV, making it feasible for even modestly advanced civilizations.

With these offensive capabilities in mind, the structure of the game changes. Detection may be followed by an unstoppable first strike, making the payoff of contact negative infinity (extinction) for the recipient. This dramatically shifts the equilibrium of cosmic diplomacy. The optimal strategy becomes either: A) Preemptive attack: launch RKVs at any other civilization you detect to eliminate the threat B) Absolute stealth: remain completely radio silent to avoid being noticed

In this light, the Great Silence may be a sign that the few surviving civilizations have converged on these strategies. Radio transmissions or other signatures of technology would be a death sentence, as even a single hostile power could effectively sterilize the galaxy of competitors. From a purely game theoretical perspective, attempting to contact alien intelligences is an act of civilizational suicide.

Critics of the Dark Forest hypothesis argue that it projects our own human xenophobia and primitive drives onto hypothetical alien minds. It assumes a universal drive toward "survival of the fittest" that may not apply to advanced intelligence. Perhaps through cultural and technological evolution, civilizations can transcend narrow self-interest and develop cooperative, non-zero-sum ethical systems. Post-scarcity societies with molecular manufacturing, fusion power or Dyson swarms may lack the material incentives for violent expansion.

Some suggest that alien species may even have a strong intrinsic interest in contact and exchange with other intelligences. Scientific curiosity and the thirst for knowledge could compel civilizations to initiate communication despite potential risks. Contacting aliens may be seen as the ultimate intellectual endeavor, promising a wealth of insight into the nature of mind, consciousness and the universe.

However, even if the majority of alien species are peaceful, the Dark Forest hypothesis still holds if a single advanced civilization is motivated by aggression or paranoia. Given the existential stakes and the vast number of potential civilizations, contact remains an unimaginable risk. Curiosity is also more likely an individual than a civilizational trait – the light of alien knowledge may not be worth the potential heat death of an entire species, especially if more conservative voices hold sway. The notion of a harmonious galactic federation may stem more from wishful thinking than hard-headed strategic analysis.

In light of this strategic and technological assessment, the question of whether humanity should attempt to contact alien intelligence appears to have a clear answer. Listening and observing the cosmos is safe and valuable, but transmitting high-powered signals is the equivalent of firing a flare in a forest full of hunters. It invites a deadly first strike by any hostile power that intercepts the message. Even the remote possibility of such a civilization existing makes "active SETI" an unconscionable existential risk.

The current radio signals produced by human activity are relatively faint and unlikely to be detectable by alien receivers more than a few light years away. The 1974 Arecibo message, one of our most powerful intentional transmissions, will take tens of thousands of years to reach its target globular cluster with a signal strength of merely 10^-29 W/m^2. But this grace period may be short-lived. Proposed Kardashev 2 civilizations could use star-powered beacons to send observable signals across the galaxy, and smaller groups may soon be able to access planet-scale energies to power high-gain SETI transmitters or probes. Even if done with peaceful intentions, this massively increases our civilizational risk exposure.

Therefore, the only responsible course of action is comprehensive "technosignature control" - carefully monitoring and restricting any electromagnetic, neutrino, or gravitational wave emissions that could betray our presence to the cosmos. This will require extensive international coordination and regulation of both private and government projects to enforce a shared "no transmit" policy. We may also need to develop active countermeasures to contain unintentional leakage from planetary radar, television broadcasts, and military operations.

Of course, this does not preclude the scientific search for extraterrestrial intelligence. Observing the universe for signs of astroengineering, Dyson spheres, or other anomalous phenomena remains a worthwhile endeavor. Narrow-band signals or other distinctive "beacons" would be particularly revealing. But the moment we detect a confirmed alien civilization, it is imperative that we do not respond, but rather quietly assess their capabilities and possible trajectories. Even if it takes centuries, a Bayesian analysis of their transmissions and astronomical data could give us a probabilistic assessment of their intentions and level of advancement.

Some have proposed using gravitational lensing or neutrino beams to eavesdrop on distant worlds without alerting them to our presence. If feasible, this could provide valuable intelligence while keeping us shrouded in the galactic background. Another option is the construction of a vast network of autonomous "sentinel probes" throughout the solar system and nearby stars. These could serve both as an early warning system for incoming threats and as a dead-hand deterrent – if an extraterrestrial invasion fleet is detected, the probes would broadcast our presence far and wide, ensuring a retaliatory strike even if Earth is destroyed.

Ultimately, the safest long-term strategy may be complete "cosmic isolation" – gradually moving our civilization into stealthy Dyson swarms, hollowed-out asteroids, or other hard-to-detect habitats. This would allow us to expand through the galaxy over eons without betraying our presence. Some futurists even envision "Matrioshka brain" megastructures - concentric layers of planet-sized computers powered by a star, running uploaded minds. These could host unimaginably vast and rich virtual worlds, reducing the need for risky physical travel or expansion.

The Dark Forest hypothesis remains a chilling but logically consistent model for the Fermi Paradox. It suggests that, like overly vocal hunters in a dark wood, civilizations that attempt to contact alien life may be destroyed by more technologically advanced predators. The game theoretical dynamics of distrust and the offensive potential of relativistic weapons make cosmic diplomacy a fool's gamble, with the very survival of a species at stake.

This has sobering implications for humanity's SETI efforts. While the search for technosignatures is scientifically valuable, any attempts at high-powered transmission or probes are an unconscionable existential risk. We cannot gamble our entire future on the benevolence of unknown alien civilizations. Instead, we must quietly listen, assess, and take all possible precautions to avoid detection by hostile eyes.

Yet even in this dark forest, there is still wonder and purpose to be found. We can continue to explore the majestic expanse of the cosmos and the endless frontiers of science, art, and the mind. With care and wisdom, we may yet forge a future where we can step out of the shadows and into the light – either alone, or alongside other patient watchers in the night.