Seventy years ago, Italian-American nuclear physicist Enrico Fermi asked his colleagues a question during a lunchtime conversation. If life is common in our Universe, why can’t we see any evidence of its activity out there (aka. “where is everybody?”) Seventy years later, this question has launched just as many proposed resolutions as to how extraterrestrial intelligence (ETIs) could be common, yet go unnoticed by our instruments.
Some possibilities that have been considered are that humanity might be alone in the Universe, early to the party, or is not in a position to notice any yet. But in a recent study, Robin Hanson (creator of the Great Filter) and an interdisciplinary team offer a new model for determining when the aliens will get here. According to their study, humanity is early to the Universe and will meet others in 200 million to 2 billion years from now.
The search for extraterrestrial intelligence (SETI) has long roots in human history. With the advent of modern technologies, scientists were finally able to start scanning the skies for any sign of life. When the search first started back in the 1960s, it focused almost exclusively on trying to detect radio signals. Over the decades, no irrefutable evidence of any artificial radio signals was ever found. Financial support started to drift away from the discipline, and where the money goes so do many scientists.
But more recently, the spike in interest in exoplanet research has breathed new life into the search for intelligent life, now commonly referred to as the search for “technosignatures”. In 2018, NASA sponsored a conference where scientists who were involved with the field came to discuss its current state. That meeting was followed up by a meeting last year sponsored by the Blue Marble Institute, which NASA also helped to sponsor. Now a working paper has come out from the group of SETI scientists that attended the conference. Numerous potential mission ideas to find technosignatures are described in the paper. It’s clear the search for extraterrestrial intelligence isn’t limited just to radio astronomy anymore.
Upcoming telescopes will give us more power to search for biosignatures on all the exoplanets we’ve found. Much of the biosignature conversation is centred on biogenic chemistry, such as atmospheric gases produced by simple, single-celled creatures. But what if we want to search for technological civilizations that might be out there? Could we find them by searching for their air pollution?
If a distant civilization was giving our planet a cursory glance in its own survey of alien worlds and technosignatures, they couldn’t help but notice our air pollution.
This week we are excited (and honored) to welcome Dr. Jill Tarter to the Weekly Space Hangout. Best known for her work in the field of SETI, tonight Jill will be discussing the search for technosignatures.
In the past five years, the project has made two major data releases (in the June of 2019 and February of 2020) and announced that it found no signs of alien transmissions from the 1,327 nearest star systems. But thanks to an analytical breakthrough recently proposed by researchers from the University of Manchester, it looks as though Breakthrough Listen’s search efforts could be expanded by a factor of more than 200!
In July of 2015, Breakthrough Initiatives announced that it was embarking on a ten-year initiative to conduct the largest Search for Extraterrestrial Intelligence (SETI) to date. This initiative was aptly named Breakthrough Listen, which combines state-of-the-art software and data obtained by premier observatories around the world to look for signs of extraterrestrial technological activity (aka. technosignatures).
To date, astronomers have discovered 4,164 extrasolar planets in 3,085 star systems, with another 5,347 awaiting confirmation. With this many planets available for study, researchers have been able to apply new constraints on how likely habitable planets are. In fact, the latest estimates say there could be 6 billion in the Milky Way alone! Understandably, these discoveries have renewed interest in the Search for Extraterrestrial Intelligence (SETI).
But whereas the search for habitable planets is focused on finding evidence of biological processes (aka. “biosignatures”), SETI has historically been focused on evidence of technological activity – aka. “technosignatures.” With a grant from NASA, researchers from the Harvard-Smithsonian Center for Astrophysics (CfA) and the University of Rochester are gearing up for a new study that will look for different kinds of potential technosignatures.
When it comes to the challenges posed by interstellar travel, there are no easy answers. The distances are immense, the amount of energy needed to make the journey is tremendous, and the time scales involved are (no pun!) astronomical. But what if there was a way to travel between stars using ships that take advantage of natural phenomena to reach relativistic velocities (a fraction of the speed of light).
Already, scientists have identified situations where objects in our Universe are able to do this – including hypervelocity stars and meteors accelerated by supernovae explosions. Delving into this further, Harvard professors Manasvi Lingam and Abraham Loeb recently explored how interstellar spacecraft could harness the waves produced by a supernova explosion in the same way that sailing ships harness the wind.
In 1961, famed astronomer Frank Drake created a formula for estimating the number of extra-terrestrial intelligences (ETIs) that could exist within our galaxy. Known as the “Drake Equation“, this formula demonstrated that even by the most conservative estimates, our galaxy was likely to host at least a few advanced civilizations at any given time. About a decade later, NASA officially kicked of its search for extra-terrestrial intelligence (SETI) program.
These efforts have experienced a major infusion of interest in recent decades thanks to the discovery of thousands of extrasolar planets. To address the possibility that life may exist out there, scientists are also relying on sophisticated tools to search for telltale indicators of biological processes (aka. biosignatures) and technological activity (technosignatures), which could indicate not only life but advanced intelligence.