It’s been seventy years since physicist Enrico Fermi asked his famous question: “Where is everybody?” And yet, the tyranny of the Fermi Paradox is still with us and will continue to be until definitive evidence of Extraterrestrial Intelligence (ETI) is found. In the meantime, scientists are forced to speculate as to why we haven’t found any yet and (more importantly) what we should be looking for. By focusing our search efforts, it is hoped that we may finally determine that we are not alone in the Universe.
In a recent study, two researchers from the University of Liège and the Massachusetts Institute of Technology (MIT) recommended that we look for evidence of transmissions from our Solar System. Based on the theory that ETIs exist and have already established a communications network in our galaxy, the team identified Wolf 359 as the best place to look for possible interstellar communications from an alien probe.
The study, which is being reviewed for publication in the Monthly Notices of the Royal Astronomical Society, was conducted by Michaël Gillon and Artem Burdanov. While Gillion is a professor of astrophysics at the University of Liege, a Senior Research Associate with the Belgian National Fund for Scientific Research (NSRF), and a member of NASA’s Nexus for Exoplanet System Science (NExSS), Burdanov is a Postdoctoral Associate with the Department of Earth, Atmosphere, and Planetary Sciences (EAPS) at MIT.
This illustration shows how gravitational lensing works. The gravity of a large galaxy cluster is so strong, it bends, brightens, and distorts the light of distant galaxies behind it. Credit: NASA/ESA/L. Calcada
Additional insight and support came from Prof. Jason Wright, a Penn State Center for Exoplanets and Habitable Worlds member and director of the Penn State Extraterrestrial Intelligence Center (PSETI). Like many proposed resolutions to the Fermi Paradox, Gillon and Burdanov began their study with the assumption that extraterrestrial life has had a significant head start on humanity. From a cosmological standpoint, this is a pretty safe assumption.
According to accepted models, the Milky Way Galaxy formed roughly 13.51 billion years ago, followed by the first planets 500 million years later. Our Solar System is a relative newcomer, having formed 4.5 billion years ago, and humanity has only existed for the last 200,000 years. It stands to reason that intelligent species have already emerged and have had the necessary time to colonize the Milky Way.
For the sake of their study, the team built upon a 2014 study by Gillon that showed how an ETI could have filled our galaxy with self-replicating probes (von Neumann machines). This idea is similar in theme to the “Berserker Hypothesis,” but with the caveat that these probes were built for peaceful exploration. These probes, he argued, could form a galaxy-spanning communication network using stars as gravitational lenses to maximize their communication efficiency.
As Gillon told Universe Today email, this activity would constitute a viable technosignature that could be detected:
“In this hypothesis, every star of the Milky Way should host such probes, including the Sun. This hypothesis tells us where to look for these probes: at the “solar gravitational line” (SGL) of the nearest stars, i.e., at the opposite coordinates to the nearest stars. I explored this hypothesis further by considering different possible methods to detect these probes.
“The problem is that the SGL is very far from the Sun, as it starts at 550 astronomical units, so any communication device out there would be extremely difficult to detect. This was the main conclusion of my 2014 work: searching for these probes is worth a try, but we would need to be very lucky to detect anything.”
In this study, Gillon, Burdanov, and Wright focused on how humanity might detect interstellar messages coming from these probes – which they refer to as Focal Interstellar Communication Devices (FICDs). For this, they identified Wolf 359 – an M-type (red dwarf) star located with two possible exoplanets – as the best target for such a search. At a distance
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