30.11.2021

Shifting the search for extraterrestrial life from biological to technological signs could break us out of anthropocentrism and help guide humanity's future.

BACK IN 1950, Enrico Fermi posed the question now known as the Fermi Paradox: Given the countless galaxies, stars, and planets out there, the odds are that life exists elsewhere—so why haven’t we found it? The size of the universe is only one possible answer. Maybe humans have already encountered extraterrestrial (ET) life but didn’t recognize it. Maybe it doesn’t want to be found. Maybe it’s monitoring Earth without us knowing. Maybe it doesn’t find us interesting.

And there’s another reason: The search for advanced aliens is constrained by human assumptions, including the idea that advanced ET would be “alive.”

Scientists who engage in the search for extraterrestrial life look for what life on Earth needs—carbon and water—as well as for biosignatures: gasses and organic matter, such as methane, that living things exhale, excrete, or secrete. Searching for biosignatures is arduous for many reasons, and biosignatures don’t necessarily indicate the presence of life, as they could come from geological or other natural forces (for instance, a whiff of methane detected on Mars has tantalized scientists for years, but they have yet to reach a consensus). 

The assumption that biological life on other planets would look or function like biological life on Earth is flawed and constrained by anthropocentrism. The same is true of assuming that advanced intelligent life on other planets would be biological just because humans are. Maybe we haven’t found aliens because advanced alien spaces have transcended biology altogether.

IN THE GRAND scheme, Earth is a relatively young planet. If we assume that biological life of some sort emerged on other planets, then we can also make some educated assumptions about how that life evolved—namely, that other species also invented technology, such as tools, transport vehicles, factories, and computers. Maybe those species invented artificial intelligence (AI) or virtual worlds. Advanced ET may have reached the “technological singularity,” the point at which AI exceeds human or biological intelligence. Maybe they experienced what many scientists believe is in store for Homo sapiens—the merging of biological beings and machines. Maybe they’ve become nanosats. Maybe they’re data or are part of a digital network that functions like a collective consciousness. In fact, the last variable of the Drake Equation—a framework for estimating the likelihood of advanced, intelligent species existing in the cosmos—posits that technologically advanced civilizations broadcast detectable signals for a finite amount of time, suggesting they eventually go extinct or become post-biological.

The idea that ET intelligence might exist as “super” AI has been proposed by scientists like Susan Schneider, founding director of the Center for the Future Mind; SETI senior astronomer Seth Shostak; and others. In an op-ed for The Guardian, Shostak posits that aliens intelligent enough to seek out Earth “will probably have gone beyond biological smarts and, indeed, beyond biology itself.” Caleb Scharf, director of Columbia’s Astrobiology Program, argues that “Just as someone living on the steppe in 12th-century Mongolia would find a self-driving car both magical and meaningless, we might be quite incapable of registering or interpreting the presence of billion-year-old machine savants.” 

The potential of AI to become super AI and vastly eclipse the limits of human intelligence has long concerned scientists like Nick Bostrom and entrepreneurs like Elon Musk, and so the possible existence of super AI aliens raises important considerations about the risks of searching for—and finding—them. It also provokes questions about the potential dangers of them finding us. Dark Forest Theory teases out these threats, suggesting that the universe is akin to a dark forest full of predators and prey and that stealth is the best, and perhaps only, survival strategy.

If advanced aliens are nonbiological, searching for biosignatures won’t help scientists find them. Those who continue to search for ET life might instead focus on technosignatures, the chemical, radio, and/or light emissions from technologically sophisticated civilizations. The SETI Institute has long searched for radio waves, as experts struggle to imagine an advanced species not using them. But that’s just the start. Technologically advanced species would produce more than radio waves—they would impact their environments as well. Perhaps even more importantly, focusing specifically on radio waves could constrain scientists’ understanding of other technological emissions and the consequences of them, both for aliens and for humanity.

SHIFTING THE SEARCH for ET life from biological to technological implicitly acknowledges that pollution or the emissions of machinery may be more identifiable hallmarks of an intelligent civilization than the exhalations of biological beings. The word “signature” suggests a unique characteristic that represents a civilization. Super AI aliens may have reached the point at which the technological outputs of their races are more identifiable—and perhaps even more significant—than their biological ones. Given our increasingly techno-centric society, it’s easy to wonder whether the same could (or will) be said of humanity.

One mark of humanity is the impact our species has on the planet. Presumably, that would also apply to intelligent ETs. A NASA study published in February 2021 suggests that the most fruitful technosignatures to look for might come from industrial pollution. Researchers focused on nitrogen dioxide (NO₂), a gas that exists on Earth as a technological, rather than biological, product of human activity—namely, the burning of fossil fuels. Volcanoes and other natural combustion sources also produce NO₂, but scientists can avoid detecting those emissions by searching for the gas in the atmosphere (~6 miles above Earth’s surface), where the vast majority of detectable NO₂ is human and/or factory-produced—an insight gleaned in part from a study about the impact of COVID-19 on pollution. Thus, high concentrations of nitrogen oxide in Earth’s atmosphere signal the presence of human, not just geological, activity, which could be the case on other planets as well. Scientists also consider chlorofluorocarbons (CFCs) used as solvents in hairspray and other aerosols and as refrigerants to be good candidates for technosignature studies.

Searching for technosignatures represents a step toward considering what advanced civilizations invent and produce, as well as humanity’s own future in this era of climate change. The questions and thought experiments prompted by considering that intelligent extraterrestrials may be post-biological can help scientists understand the possible trajectories of humanity, just as studying other planets helps scientists understand the possible trajectories of Earth.

In the story of Homo Sapiens, the creation, manufacture, and use of technology threatens and often eliminates biological—including human—life. Perhaps other intelligent species faced a similar reckoning. And while some might have gone extinct, perhaps others survived. Maybe there exist environments that somehow feed on carbon dioxide, nitrogen oxide, or methane (on Earth there’s bacteria that feeds on arsenic), with which an intelligent ET could achieve a symbiotic, rather than parasitic relationship. Maybe super AI aliens have uploaded their minds into a network that functions like a Jungian collective consciousness. Perhaps environmental degradation has served as an impetus for advanced alien races to evolve out of biology.

Humans don’t have the tools to know for sure, but we can imagine what such races may have learned and what their possible existence and post-biological evolutions might mean for humanity. In the broadest sense, humans might revisit our definitions of life, as well as its relationship to our understanding of intelligence and of ourselves. Considering such paradigm-shifting scenarios helps prompt a cultural relocation of Homo Sapiens from the center of the universe or from the top of the existential food chain. Understanding humanity’s status as a relatively young race among countless others could help us keep our collective ego in check, our minds open, and our future—both planetary and perhaps beyond—malleable enough to accommodate the knowledge and insight gained along the way.

Quelle: WIRED