If life is common in our Universe, and we have every reason to suspect it is, why do we not see evidence of it everywhere? This is the essence of the Fermi Paradox, a question that has plagued astronomers and cosmologists almost since the birth of modern astronomy. It is also the reasoning behind the Hart-TIpler Conjecture, one of the many (many!) proposed resolutions, which asserts that if advanced life had emerged in our galaxy sometime in the past, we would see signs of their activity everywhere we looked. Possible indications include self-replicating probes, megastructures, and other Type III-like activity.
On the other hand, several proposed resolutions challenge the notion that advanced life would operate on such massive scales. Others suggest that advanced extraterrestrial civilizations would be engaged in activities and locales that would make them less noticeable. In a recent study, a German-Georgian team of researchers proposed that advanced extraterrestrial civilizations (ETCs) could use black holes as quantum computers. This makes sense from a computing standpoint and offers an explanation for the apparent lack of activity we see when we look at the cosmos.
For over sixty years, astronomers and astrophysicists have been engaged in the Search for Extraterrestrial Intelligence (SETI). This consists of listening to other star systems for signs of technological activity (or “technosignatures), such as radio transmissions. This first attempt was in 1960, known as Project Ozma, where famed SETI researcher Dr. Frank Drake (father of the Drake Equation) and his colleagues used the radio telescope at the Green Bank Observatory in West Virginia to conduct a radio survey of Tau Ceti and Epsilon Eridani.
Since then, the vast majority of SETI surveys have similarly looked for narrowband radio signals since they are very good at propagating through interstellar space. However, the biggest challenge has always been how to filter out radio transmissions on Earth – aka. radio frequency interference (RFI). In a recent study, an international team led by the Dunlap Institute for Astronomy and Astrophysics (DIAA) applied a new deep-learning algorithm to data collected by the Green Bank Telescope (GBT), which revealed eight promising signals that will be of interest to SETI initiatives like Breakthrough Listen.
The Five-hundred-meter Aperture Spherical Telescope (FAST), located in China, is currently the world’s largest and most sophisticated radio observatory. While its primary purpose is to conduct large-scale neutral hydrogen surveys (the most common element in the Universe), study pulsars, and detect Fast Radio Bursts (FRBs), scientists have planned to use the array in the Search for Extraterrestrial Intelligence (SETI). Integral to this field of study is the search for technosignatures, signs of technological activity that indicate the presence of an advanced civilization.
While many potential technosignatures have been proposed since the first surveys began in the 1960s, radio transmissions are still considered the most likely and remain the most studied. In a recent survey, an international team of SETI researchers conducted a targeted search of 33 exoplanet systems using a new method they call the “MBCM blind search mode.” While the team detected two “special signals” using this mode, they dismissed the idea that they were transmissions from an advanced species. Nevertheless, their survey demonstrated the effectiveness of this new blind mode and could lead to plausible candidate signals in the future.
In a recent paper submitted to The Astronomical Journal in November 2022, a scientist at the Swiss Federal Institute of Technology Lausanne quantifies how the Earth has not heard a radio signal from an extraterrestrial technological civilization over the course of approximately the last 60 years, which is when the Search for Extraterrestrial Intelligence (SETI) began listening for such signals. They also quantify the potential likelihood pertaining to when we might hear a signal, along with recommending potential strategies that could aid in the ongoing search for detecting a signal from an extraterrestrial technological civilization.
The Robert C. Byrd Green Bank Telescope (GBT), part of the Green Bank Observatory in West Virginia, is the world’s premiere single-dish radio telescope. Between its 100-meter dish (328-foot), unblocked aperture, and excellent surface accuracy, the GBT provides unprecedented sensitivity in the millimeter to meter wavelengths – very high to extremely high frequency (VHF to EHF). Since 2017, it also became one of the main instruments used by Breakthrough Listen and other institutes engaged in the Search for Extraterrestrial Intelligence (SETI).
Recently, an international team of researchers from the SETI Institute, Breakthrough Listen, and multiple universities scanned twelve exoplanets for signs of technological activity (aka. “technosignatures”). Their observations were timed to coincide with the planets passing in front of their sun relative to the observer (i.e., making a transit). While the survey did not detect any definitive evidence of technosignatures, they did identify two radio signals of interest that warrant follow-up observation. This new technique could vastly expand the field of SETI and create all kinds of opportunities for future research.
Breakthrough Listen, a privately funded project seeking evidence of extraterrestrial intelligence, has started operations on the MeerKAT radio telescope array in South Africa. Over the next two years, the team will search over a million nearby stars, expanding the number of targets observed by a factor of 1000.
In June, NASA announced that it had commissioned an independent study team to investigate unidentified aerial phenomena (UAPs) from a scientific perspective. Last week, NASA announced the members of the independent team that will study observed events in the sky that cannot be identified as aircraft or natural phenomena. These sixteen individuals, a collection of scientists and researchers from premier institutions across the U.S., will analyze all possible data sources that could help NASA and other agencies learn more about this phenomenon.
Science fiction is the realm where people traditionally wrestle with the idea of contact with an ETI (Extraterrestrial Intelligence.) But now, those discussions are migrating from science fiction into more serious realms. Academics are going back and forth, one paper at a time, concerning the response and geopolitical fallout from potential contact with an ETI.
The discussion is interesting whether you think it’s likely or even remotely possible that humanity ever contacts an ETI. And it might tell us more about humanity than it does about an ETI.
Do aliens exist? Almost certainly. The universe is vast and ancient, and our corner of it is not particularly special. If life emerged here, it probably did elsewhere. Keep in mind this is a super broad assumption. A single instance of fossilized archaebacteria-like organisms five superclusters away would be all it takes to say, “Yes, there are aliens!” …if we could find them somehow.
Legendary astronomer Frank Drake has passed away at the age of 92. Known primarily for his Drake Equation — an estimate of the probability of intelligent extraterrestrial life — he pioneered the field of SETI, the Search for Extraterrestrial Intelligence, and was a noted astronomer and astrophysicist. His work and life have left an indelible mark on humanity and given hope and wonder to all our hearts.