Radio SETI Archives

January 2, 2024January 3, 2024 by Matt Williams

After all of This Time Searching for Aliens, is it The Zoo Hypothesis or Nothing?

The Karl Jansky Very Large Array at night, with the Milky Way visible in the sky. Credit: NRAO/AUI/NSF; J. Hellerman

In 1950, during a lunchtime conversation with colleagues at the Los Alamos National Laboratory, famed physicist Enrico Fermi asked the question that launched a hundred (or more) proposed resolutions. “Where is Everybody?” In short, given the age of the Universe (13.8 billion years), the fact that the Solar System has only existed for the past 4.5 billion years, and the fact that the ingredients for life are everywhere in abundance, why haven’t we found evidence of extraterrestrial intelligence by now? This came to be the basis of Fermi’s Paradox, which remains unresolved to this day.

Interest in Fermi’s question has been piqued in recent years thanks to the sheer number of “potentially habitable” exoplanets discovered in distant star systems. Despite that, all attempts to find signs of technological activity (“technosignatures”) have come up empty. In a recent study, a team of astrobiologists considered the possible resolutions and concluded that only two possibilities exist. Either extraterrestrial civilizations (ETCs) are incredibly rare (or non-existent), or they are deliberately avoiding contact with us (aka. the “Zoo Hypothesis“).

December 14, 2023December 14, 2023 by Matt Williams

Breakthrough Listen Scans Entire Galaxies for Signals From Extremely Advanced Civilizations

Breakthrough Listen has released the results of its latest survey - the center of 97 galaxies!

In 1960, Dr. Frank Drake led the first Search for Extraterrestrial Intelligence (SETI) experiment at the National Radio Astronomy Observatory in Green Bank, West Virginia. In the more than sixty years that have since passed, astronomers have conducted multiple surveys in search of technological activity (aka. technosignatures). To date, Breakthrough Listen is the most ambitious SETI experiment, combining data from the Robert C. Byrd Green Bank Telescope, the Parkes Murriyang Telescope, the Automated Planet Finder, and the MeerKAT Radio Telescope and advanced analytics.

The program includes a survey of the one million closest stars to Earth, the center of our galaxy and the entire galactic plane, and the 100 closest galaxies to ours. In a recent paper, members of Breakthrough Listen presented the results of their radio technosignature search of the centers of 97 nearby galaxies observed by the Robert C. Byrd Green Bank Telescope. This search was one of the largest and broadest
searches for radio evidence of extraterrestrial intelligence ever undertaken, surveying trillions of stars at four frequency bands. Unfortunately, no compelling candidates were found.

November 3, 2023November 3, 2023 by Matt Williams

SETI Works Best When Telescopes Double-Check Each Other

The LOFAR 'superterp', part of the core of the extended telescope located in the Netherlands. Credit: LOFAR/ASTRON

The Search for Extraterrestrial Intelligence (SETI) has evolved considerably in the past sixty years since the first experiment was conducted. This was Project Ozma, which was conducted in 1960 by Dr. Frank Drake and his colleagues using the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia. While the experiment did not reveal any radio signals from space, it established the foundation upon which all future SETI is based. Like Ozma, the vast majority of these experiments have searched for possible technosignatures in the radio spectrum.

Unfortunately, this search has always been plagued by the problem of radio interference from Earth-based radio antennas and satellites in orbit, which can potentially flood SETI surveys with false positives. In a recent study, an international team of astronomers (including researchers with Breakthrough Listen) recommended that future technosignature searches rely on multi-site simultaneous observations. This has the potential of eliminating interference from terrestrial sources and narrowing the search for extraterrestrial radio signals.

June 2, 2023June 6, 2023 by Matt Williams

Astronomers are Searching for a Galaxy-Wide Transmitter Beacon at the Center of the Milky Way

Artist's impression of a Dyson Sphere, an proposed alien megastructure that is the target of SETI surveys. Finding one of these qualifies in a "first contact" scenario. Credit: Breakthrough Listen / Danielle Futselaar

It has been over sixty years since the first Search for Extraterrestrial Intelligence (SETI) survey occurred. This was Project Ozma, a survey led by Dr. Frank Drake (who devised the Drake Equation) that used the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, to listen for radio transmissions from Epsilon Eridani and Tau Ceti. While the search revealed nothing of interest, it paved the way for decades of research, theory, and attempts to find evidence of technological activity (aka. “technosignatures”).

The search continues today, with researchers using next-generation instruments and analytical methods to find the “needle in the cosmic haystack.” This is the purpose behind Breakthrough Listen Investigation for Periodic Spectral Signals (BLIPSS), a collaborative SETI project led by Cornell graduate student Akshay Suresh to look for technosignatures at the center of the Milky Way. In a recent paper, Suresh and his team shared their initial findings, which were made possible thanks to data obtained by the Greenbank Observatory and a proprietary algorithm they developed.

April 17, 2023April 17, 2023 by Matt Williams

How Many Intergalactic Radio Stations Are Out There?

The Stephans Quintet captured by the James Webb Space Telescope (JWST). Credit: NASA/ESA/CSA

It has been over sixty years since Dr. Frank Drake (father of the Drake Equation) and his colleagues mounted the first Search for Extraterrestrial Intelligence (SETI) survey. This was known as Project Ozma, which relied on the “Big Ear” radio telescope at the National Radio Astronomy Observatory (NRAO) in Greenbank, West Virginia, to look for signs of radio transmissions in Tau Ceti and Epsilon Eridani. Despite the many surveys conducted since then, no definitive evidence of technological activity (i.e., “technosignatures”) has been found.

This naturally raises the all-important question: are we going about the business of SETI wrong? Instead of looking for technosignatures within our galaxy, as all previous SETI surveys have done, should we look for activity beyond our galaxy (from possible Type II and Type III civilizations)? This premise was explored in a recent paper led by researchers from the National Chung Hsing University in Taiwan. Using data from the largest SETI project to date, Breakthrough Listen, the team looked for potential radio technosignatures from extragalactic sources.

October 14, 2021October 14, 2021 by Matthew Cimone

Advanced Civilizations Could use Their Stars to Communicate (and as Telescopes)

A schematic of a on-axis stellar relay transmission system, opening angles, distances, and sizes not to scale. The initial unfocused transmission beam may even have an annular pattern to prevent flux from being lost to the disk of the Sun.A reversed arrangement can be used to receive signals from a distant star by focusing rays onto the spacecraft. c. Kerby and Wright 2021

A Long Distance Call

E.T. managed to call home with a Speak and Spell, buzzsaw blade, and an umbrella. The reality of interstellar communication is a bit more complicated. Space is really, really big. The power needed to transmit a signal across the void is huge. However, rather than using super high power transmitters, recent research by Stephen Kerby and Jason T. Wright shows that we could make use of a natural signal gain boost built into solar systems – the gravitational lensing of a solar system’s star. Networking a series of stars as nodes could get signals across vast tracts of the Milky Way. And we may be able to detect if our Sun is already part of an alien galactic communication network.