If there are alien civilizations in the universe, why haven’t we made contact? To provide new guidance to the search for extraterrestrial intelligence (SETI), researchers gathered in Paris to answer a question about extraterrestrials posed by the Italian physicist Enrico Fermi in 1950 when he asked, “Where are they?” This puzzling question is now called the Fermi Paradox. On March 18, 2019, leading researchers from such diverse fields as astrophysics, biology, sociology, psychology, and history met at the Paris science museum Cité des Sciences et de l’Industrie to examine wide-ranging solutions to the Fermi Paradox, including the possibility that extraterrestrials are staying silent out of concern for how contact would impact humanity. Another speaker considered new ways we might make first contact, including sending intentional radio messages to nearby stars to signal humanity’s interest in joining the Galactic Club. Other presenters debated whether extraterrestrial intelligence will be similar to humans.
“Every two years, METI International organizes a one-day workshop in Paris as part of a series of workshops entitled ‘What is Life? An Extraterrestrial Perspective,’” said Florence Raulin Cerceau, co-chair of the workshop and a member of METI’s Board of Directors. “This year, METI collaborated with the Cité des Sciences et de l’Industrie — a huge science museum in Paris — and the Centre Koyré — a research center for historical studies of science and technology — to gather renowned scientists, philosophers, and sociologists to debate the Fermi Paradox. This puzzle of why we haven’t detected extraterrestrial life has been discussed often, but in this workshop’s unique focus, many of the talks tackled a controversial explanation first suggested in the 1970s called the ‘Zoo Hypothesis,’” Raulin Cerceau added.
“Perhaps extraterrestrials are watching humans on Earth, much like we watch animals in a zoo,” explained Douglas Vakoch, president of METI. “How can we get the galactic zookeepers to reveal themselves?” At the workshop, Vakoch proposed that humans should complement the traditional passive SETI with a more active alternative. “If we went to a zoo and suddenly a zebra turned toward us, looked us in the eye, and started pounding out a series of prime numbers with its hoof, that would establish a radically different relationship between us and the zebra, and we would feel compelled to respond. We can do the same with extraterrestrials by transmitting powerful, intentional, information-rich radio signals to nearby stars.”
But if extraterrestrials know we are here, why are they remaining silent? “Past experience shows that any meeting of two civilizations is dangerous for both. Knowing that, civilized extraterrestrials will not try to communicate with us,” said Danielle Briot, an astrophysicist at the Observatoire de Paris.
“It seems likely that extraterrestrials are imposing a ‘galactic quarantine’ because they realize it would be culturally disruptive for us to learn about them,” said Jean-Pierre Rospars, the honorary research director at the Institut National de la Recherche Agronomique and co-chair of the workshop. “Cognitive evolution on Earth shows random features while also following predictable paths. By considering the regular and random components together, we can expect the repeated, independent emergence of intelligent species in the universe, and we should expect to see more or less similar forms of intelligence everywhere, under favorable conditions,” Rospars added. “There’s no reason to think that humans have reached the highest cognitive level possible. Higher levels might evolve on Earth in the future and already be reached elsewhere.”
Roland Lehoucq, an astrophysicist who works at the Commissariat à l’Énergie Atomique (CEA), and Jean-Sébastien Steyer, a paleontologist from the Muséum National d’Histoire Naturelle, were skeptical that humans would have much in common with extraterrestrial life forms. “The environment on an exoplanet will impose its own rules,” Lehocq said, adding that “there is no trend in biological evolution: the huge range of various morphologies observed on Earth renders any exobiological speculation improbable, at least for macroscopic ‘complex’ life.”
Lehocq and Steyer also examined portrayals of aliens in science fiction, demonstrating the challenge of imagining extraterrestrial intelligence that is radically different from ourselves. As one example, they pointed to pictures of lunar “bat-men” from a satirical series of newspaper articles from 1835 that many readers interpreted as an actual account of the discovery of life on the Moon. Lehocq said these depictions “show our persistent anthropocentrism in our understanding and description of alien life.”
Several of the papers presented at the workshop focused on biological and sociological explanations of the Great Silence, while other papers re-examined longstanding topics like interstellar migration, but using novel reformulations of the problem. Nicolas Prantzos, director of research of the Centre National de la Recherche Scientifique (CNRS) who works at the Institut d’Astrophysique de Paris (IAP), recast the Fermi Paradox in terms of the Drake Equation, a formula used to estimate the number of technological civilizations in the Milky Way galaxy. “It appears that although radio communications provide a natural means for SETI for civilizations younger than a few millennia, older civilizations should rather develop extensive programs of interstellar colonization, because this is the only way to achieve undisputable evidence — either for or against the existence of ETI — within their lifetime,” Prantzos said.
“We are very interested in the scientific approach used in the analysis of the Fermi Paradox and the search for intelligent life in the universe,” said Cyril Birnbaum and Brigitte David of the Cité des Sciences et de l’Industrie, Europe’s largest science museum. “The question ‘Are we alone?’ affects us all, because it is directly related to humanity and our place in the cosmos. This is an essential question that will introduce the public to the scientific process in a show being designed at the planetarium.”
President, METI International
Florence Raulin Cerceau
Workshop Co-Chair, METI International
Speaker, Workshop Co-Chair, METI International
+33 6 70 91 19 65
Cité des Sciences et de l’Industrie
Cité des Sciences et de l’Industrie
METI International (http://www.meti.org) is a non-profit scientific and educational organization dedicated to messaging extraterrestrial intelligence — transmitting intentional radio signals to other stars in the hope of receiving a reply. METI is headquartered in San Francisco, California, and its European center is in Paris, France. METI also supports the development of a global network of observatories for optical SETI (search for extraterrestrial intelligence). In addition, METI promotes research on the many factors that influence the origins, evolution, distribution, and future of life in the universe, with a special emphasis on the last three terms of the Drake Equation: (1) the fraction of life-bearing worlds on which intelligence evolves, (2) the fraction of intelligence-bearing worlds with civilizations having the capacity and motivation for interstellar communication, and (3) the longevity of such civilizations.