“Close Encounters of the First Kind” referred to UFOs seen at close enough range to discern some details. In “Close Encounters of the Second Kind,” the UFO exerted physical influence, such as burning trees, frightening animals, or causing car engines to stall. In “Close Encounters of the Third Kind,” witnesses reported seeing people inside or near the UFO.
The US Department of Defense found no evidence of any connection between UFOs and national security agencies—or, for that matter, evidence of UFOs’ existence. The Anomaly Resolution Office conducted interviews across all disciplines, verified suspected alien materials, and investigated sightings.
A government report published in March 2024 stated that not only is there no evidence of covert U.S. government efforts to collaborate with extraterrestrials or to research alien technology, but there is also no evidence that UFO sightings are the result of visits to Earth by extraterrestrial civilizations. The “Report on the Historical Record of U.S. Government Involvement in Unidentified Anomalous Phenomena (UAP),” prepared by the Office for the Resolution of Anomalous Phenomena in All Fields, refutes all claims of U.S. government involvement in UFOs, arguing that they are the result of declining public trust in government, the prevalence of UFOs in public culture, and excessive government secrecy, writes Popular Mechanics.
The report was compiled by the Office of Anomalous Phenomena Resolution (OAR), a division of the U.S. Department of Defense tasked in 2022 with investigating reports of unidentified aerial phenomena (UFOs) in the U.S. government. The 63-page report details the OAR’s investigation into allegations of a secret UFO program within the U.S. government, covering everything from the government’s possession of classified UFO information to actual connections between the government and extraterrestrial civilizations.
The report, published on March 8, 2024, appears to have a classified version, but it is unlikely to contain anything new or different. AARO suggested that the difference in classification likely relates to discussion of confidential or classified programs, as well as individuals involved in a classified government UFO research program.
A popular theory is that the US government possesses crashed UFOs and has handed some of them over to military contractors to learn their secrets. DigtialStorm/Getty Images
The report attempts to address two main narratives that AARO believes have emerged regarding the US government and UFOs. The first is the conspiracy theory that “the US government and its industrial partners possess and are testing extraterrestrial technologies that have been hidden from Congressional and international scrutiny since approximately 1964, and possibly since 1947 given the events at Roswell.”
AARO claims to have investigated a number of allegations in this vein. One was that named corporations, likely known contractors to the US Department of Defense, were experimenting with alien technology. Another was that the US government possessed exotic, otherworldly materials created by aliens. Other claims included a claim that a former US officer touched a UFO and that a former US service member observed “US Special Forces” uploading materials to a UFO. Those interviewed by AARO claimed that “between 2004 and 2007, the White House commissioned a Virginia-based research institute to study the theoretical social implications of disclosing information about the extraterrestrial origins of UFOs.”
The second theory was that UFOs were somehow interfering with the US nuclear arsenal and that “a series of UFO sightings occurring in close proximity to US nuclear facilities resulted in the malfunction and destruction of nuclear missiles.” If true, this would pose a significant risk to US nuclear deterrence, leaving US nuclear weapons vulnerable to an external force that is at best unknown and at worst hostile.
The AARO report failed to substantiate any of the numerous claims investigated. None of the allegations regarding UFO technology, classified US government programs, or individuals in possession of sensitive information were confirmed. Many of the accusations appear to be based on rumors or misunderstandings, or on second- or third-hand information that ultimately proved unfounded.
The report refuted accusations one after another. The companies mentioned denied any involvement in reverse engineering UFO technology, and the material allegedly obtained from aliens was actually a metal alloy created by humans on Earth. A military official who allegedly touched a UFO denied the event, suggesting that whoever made the accusation was referring to an incident in which he actually touched an F-117A Nighthawk stealth fighter. The report about alien contact, allegedly commissioned by the White House, was real, but the US government had nothing to do with it.
The AARO report does not describe what the agency found when it investigated the report of “special forces” uploading material to UFOs, but suggests that it didn’t work either.
The report’s findings are not surprising. If there were clear and verifiable evidence of US government involvement with extraterrestrials, it likely would have emerged long ago. It’s also possible that such involvement is already being carefully concealed from investigation, and those involved are still bound by secrecy oaths, which in government circles carry serious consequences for violators. Did the AARO report reveal the scale of the military-industrial complex? Perhaps, perhaps not.
Do you think the US government is hiding and possibly reverse-engineering extraterrestrial technology? Think again. Or, better yet, don’t think about it at all. There’s nothing to see here, reports Popular Mechanics.
That’s the main thrust of a report released by the Department of Defense in March 2024. The 63-page “History of U.S. Government Involvement in Unidentified Anomalous Phenomena (UAPs)” concludes that the Defense Anomaly Resolution Office (AARO) “has found no evidence that any U.S. government investigation, academic-sponsored study, or formal peer review has confirmed that any UAP observation constituted extraterrestrial technology.”
As The Guardian summarizes, AARO is “a government agency established in 2022 to detect and, if necessary, mitigate threats, including anomalous, unidentified space, air, underwater, and trans-environmental objects.”
This report came immediately after and in spite of perhaps the most high-profile UFO hearing (formerly known as the UAP) in decades: the August 2023 testimony of “whistleblower” Dave Grash.
During a sensational hearing, Grash, a former member of the Pentagon’s UAP task force, claimed to have been informed of a “multi-year program to find and reverse-engineer failed UAPs.” However, his claims were never substantiated, and while the new report doesn’t name Grash, it offers plausible explanations for the phenomena he described in his testimony.
This is far from the first government report to refute stories about little green men and their strange flying saucers. So why do Americans continue to cling to conspiracy theories about extraterrestrial visitors? Blame science fiction, says the AARO report:
“A persistent theme in popular culture is the particularly persistent narrative that the US government (or a secret organization within it) has discovered several extraterrestrial spacecraft and extraterrestrial biological remains, that it is pursuing a program or programs to reverse engineer the discovered technologies, and that it has been secretly concealing these efforts from the US Congress and the American public since the 1940s.
AARO recognizes that many people sincerely hold various versions of these beliefs based on their perceptions of past experiences, the experiences of others they trust, or media and online resources they consider sources of reliable and verifiable information. The proliferation of television programs, books, films, and a vast amount of online and social media content devoted to UAP-related topics has likely influenced public discussion of this topic and reinforced these beliefs among certain segments of the population.
The X-Files and the internet have helped curious people delve into the fringes of ufology. But to fully understand the public’s persistent skepticism toward government explanations of aliens, it’s necessary to remember the man once responsible for propping up these “official” stories and trace his remarkable evolution from a simple skeptic to the world’s leading proponent of UFO theory.
Joseph Allen Hynek, born May 1, 1910, became interested in space after a childhood illness. The illness distracted him from the work of his mother and father—a schoolteacher and a cigar maker, respectively—and prompted him to explore the universe. His biography reads:
“Hynek’s introduction to the stars came after he contracted scarlet fever at the age of seven: after reading all the children’s books, his mother turned to textbooks, and the boy’s attention was drawn to a school publication on astronomy.”
From an early age, Hynek’s passion for science was combined with a fascination with mystery and philosophical reflection. According to the “Biography,” he “was interested in more esoteric themes, particularly the works of the Rosicrucian secret societies and the Hermetic philosopher Rudolf Steiner.”
At a press conference in 1966, Hynek dismissed the Michigan UFO sighting as glowing swamp gas. Getty Images
In 1934, as a doctoral student, Hynek participated in observations of the Nova Herculis supernova at the Perkins Observatory in Ohio. By 1936, he had joined the Department of Physics and Astronomy at Ohio State University. His research, which continued over the next 12 years, culminated in his appointment as director of the university’s McMillin Observatory. It was then that the US government made an unusual request.
In the final days of World War II, American fighter pilots reported sightings of aircraft unlike any they had ever seen in combat. Some described “orange, streaming lights,” while another pilot “saw a reddish, wingless, cigar-shaped object.”
These reports reached the media, and the war-weary population reacted with bewilderment and alarm to stories of strange flying machines. However, these incidents were ultimately attributed to “electrostatic or electromagnetic phenomena.”
However, the incident involving pilot Kenneth Arnold on June 24, 1947, was not so easily explained and, more importantly, not so easily dismissed. As PopMech previously noted: While searching for a Marine Corps C-46 transport plane, experienced pilot Kenneth Arnold deviated from his original flight path to survey the southwest slope of Mount Rainier. During his search, Arnold spotted nine “strange-looking” and possibly “perfectly round” objects flying in formation, which reminded him of geese. They were later determined to be traveling at over 1,000 miles per hour. When he reported this (speculating that it was a new type of jet or experimental military aircraft), the Army Air Corps dismissed it as a mirage or hallucination.
When Arnold felt the Army was taking his claims too lightly, he went to the press. After a conversation with Bill Beckett of the East Oregonian newspaper, Beckett coined the term “flying saucers” to describe the unusual objects Arnold claimed to have seen.
The US Air Force hired Hynek as an “astronomical consultant” for Project Sign, an initiative aimed at studying numerous reports. During the project, Hynek meticulously analyzed each report of unusual aerial phenomena and classified them accordingly. According to his biography:
“There were simply astronomical observations, such as the appearance of a meteor, explained by meteorological explanations, such as an unusually shaped cloud, and reports of artificial objects, such as hot air balloons. That left about 20 percent of cases that had no clear explanation…”
Hynek’s later work suggests he hoped for additional investigations to answer questions about the remaining 20% of unexplained cases. However, the US government, wary of Cold War-era public fears and the potential for manipulation of those fears, chose to prevent such questions from being asked. Thus, Project Sign became Project Grudge.
“Employees,” concludes the Report on Historical Data on U.S. Government Involvement in Investigating Unidentified Anomalous Phenomena, “particularly those who appeared to be inclined to believe in the ‘interplanetary’ origin of UFOs, were reportedly expelled from the organization.”
Project Grudge published only one report, in August 1949. “There is no evidence that the objects reported are the result of advanced foreign scientific research; therefore, they do not pose a direct threat to national security,” the report stated. It concluded by recommending “a reduction in the scope of investigation and study of reports of unidentified flying objects.”
The findings of Project Grudge failed to allay fears about what are now called “unidentified flying objects” (UFOs). So the US Air Force resumed its investigations, this time in its most famous form: Project Blue Book.
The US Air Force re-engaged Hynek with Project Blue Book, allowing him to independently conduct field research into these phenomena. Hynek’s views on extraterrestrial theories surrounding unexplained sightings were formed during his work on Project Sign. As Biography magazine notes:
“Although he was skeptical at first, he found his assumptions challenged by the rational recollections of witnesses, and began to think about a legitimate scientific study of these ‘unidentified flying objects’ or ‘UFOs.'”
However, Hynek quickly realized he was being perceived more as a tool for dismissing alien speculation than as a scientist exploring such possibilities. As Biography notes, “by the 1960s, Hynek found himself in conflict with the Air Force’s strict controls.”
One particularly embarrassing incident for Hynek occurred in 1966, when he was sent to investigate “reports of unusual lights in various areas of Michigan over several consecutive nights.” Rushing to provide an explanation and avoiding extraterrestrial theories, Hynek was forced to publicly state that the sightings could be related to “swamp gas.”
The term “swamp gas” became a proto-meme in the mid-1960s, and House Minority Leader (and future president) Gerald Ford demanded answers about the seemingly shoddy investigation. “Summoned to testify,” notes Biography, “Hynek seized the opportunity to advocate for a comprehensive and transparent investigation of UFOs.”
Hynek violated Air Force directives, and just three years later, Project Blue Book was completely canceled. But that didn’t stop the astronomer.
Freed from the constraints of the BBC, Hynek initiated a public campaign to promote rigorous scientific study of what he called “ufology.” This initiative first emerged in his 1972 book, “The UFO Experience: A Scientific Investigation.”
Hynek wrote about his philosophy of UFO studies, observations accumulated over decades of work on Projects Sign and Blue Book, and his UFO classification scale, which included both distant and close encounters. He classified distant sightings as “night lights,” “daytime disks,” or, if not directly visible to the human eye, as “radar/visual.”
Other observations—”close encounters”—also fell into three categories. HISTORY summarizes:
“Close Encounters of the First Kind” referred to UFOs seen at close enough range to discern some details. In “Close Encounters of the Second Kind,” the UFO exerted physical influence, such as burning trees, frightening animals, or causing car engines to stall. In “Close Encounters of the Third Kind,” witnesses reported seeing people inside or near the UFO.
This latter category inspired the title of Steven Spielberg’s classic 1977 film, Close Encounters of the Third Kind. Hynek reportedly received royalties for the use of the title and for his role as a consultant on the film, and also made a brief appearance in the Best Picture nomination. Hynek also appeared on shows like The Dick Cavett Show and In Search of…, lectured at universities, and even presented a paper on UFOs at the United Nations. His life’s work inspired a two-season television series, Project Blue Book, that aired in the 2010s.
It’s important to note that while Hynek spoke openly about the limitations he faced during his time in the Air Force and spoke directly about its lack of genuine interest in investigating possible alien contacts, his work never relied entirely on conspiracy theories. The same couldn’t be said of those who came after him.
In 1986, the year Hynek died, conspiracy theorist George C. Andrews published Aliens Among Us, which integrated UFO ideas into existing notions of government conspiracies and secret organizations. In his grandiose concept of a global conspiracy, Andrews claimed that extraterrestrials were behind the assassination of President John F. Kennedy.
In 1991, conspiracy theorist Bill Cooper incorporated Andrews’s theories into his manifesto, “Behold a Pale Horse,” one of the most widely read books on fringe political conspiracies. While Hynek espoused scientific speculation, The New Republic noted that Cooper’s use of ufology was “…the tip of the spear, arguing that the main thing we should fear isn’t little green men, but the government that’s colluding with them and using their technology against us.”
Hynek’s legacy risks being overshadowed by the radical and politically motivated theories of self-proclaimed ufologists who emerged after him. He sought to establish ufology as a legitimate scientific field; however, the subsequent proliferation of conspiracy theories gave the government further grounds to completely ignore the topic.
A new AARO report states that during Hynek’s time on Project Blue Book, “about 75 percent of Americans believed [the U.S. government] ‘almost always or most of the time gets it right.'” However, the report notes, that figure has never exceeded 30 percent since 2007. “This lack of trust likely contributed to the belief among some segments of the U.S. population that the U.S. government was not revealing the truth about the existence of extraterrestrial spacecraft.”
Ultimately, the Air Force’s attempts to suppress Hynek by forcing him to give conventional answers to questions he wasn’t even allowed to ask appear to have backfired.
Ironically, the BBC’s attempts to dispel suspicions only fueled them, leading to new conspiracy theories and mistrust. People began to believe the government was hiding the truth, despite Hynek’s revelations: in fact, finding answers might not be all that important to those at the top.
“I don’t see any evidence of aliens.” SpaceX’s Elon Musk claimed that Starlink satellites have never evaded UFOs. “SpaceX and its Starlink constellation have about 6,000 satellites, and we’ve never had to maneuver near a UFO.”
The CEO and founder of SpaceX participated in a panel discussion titled “How to Save Humanity and Other Bright Topics” at the Milken Institute 2024 Global Conference, which took place in Los Angeles on May 7, 2024. During the discussion, institute chairman Michael Milken began by asking Musk about his take on the famous opening monologue of many Star Trek episodes, which states that the mission of the starship Enterprise is “to find new life forms and new civilizations.” Musk responded, “Yes, that’s exactly the idea.”
Musk clarified that if we send probes into the universe, we might find “the remains of long-dead alien civilizations.” He then began to explain why, in his opinion, aliens have never visited our planet.
Musk told Milken that he’s often asked if he believes aliens exist among us on Earth, and he acknowledged how widespread this belief is. “And for some reason, many of the same people who believe aliens are among us don’t believe we’ve been to the moon. I thought, ‘Think about that for a second,'” Musk said to laughter from the audience.
Musk explained why he doesn’t believe aliens have visited our planet, saying that even with the thousands of high-bandwidth spacecraft SpaceX operates in low Earth orbit, he has never seen compelling evidence of extraterrestrial life or any potential craft controlled by non-human intelligence.
“I haven’t seen any evidence of aliens,” Musk said. “And SpaceX, with its Starlink constellation, has about 6,000 satellites, and we’ve never had to maneuver near a UFO. Ever. So I’m like, okay, I don’t see any evidence of aliens.”
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But, like many, Musk said he’s open to the possibility of an alien visit if there’s truly compelling evidence. “If anyone has evidence of aliens, you know, that’s not just a blur, then I’d love to see it and hear about it,” Musk said. “But I don’t think there is.”
The SpaceX CEO then pointed out how troubling the lack of any evidence of alien civilizations is for the future of humanity, opining that even if an ancient civilization had existed for a million years, it would have easily been able to explore and populate the entire Milky Way galaxy.
The head of SETI stated that the US has no evidence of the existence of alien technology. “And there never has been any.” “The idea that the government would keep something like this a secret is simply absurd. There is no reason for it.” If all reports of mysterious objects flying in our skies are taken as real encounters, then Earth is likely under attack.
“We have no credible evidence of alien technology in our skies. And there never has been,” said Bill Diamond, president and CEO of the SETI Institute, headquartered in Mountain View, California. “The idea that the government would keep something like this a secret is completely absurd. There’s no basis for it.”
The SETI Institute’s Allen Telescopic Array is the first radio telescope designed from the ground up to search for extraterrestrial intelligence. Seth Shostak, SETI Institute
SETI is a key research contractor for NASA and the National Science Foundation, collaborating with industry partners across Silicon Valley. Space.com caught up with Diamond to discuss his views on alien invasion claims and whether there’s any signal amid the UFO noise.
Diamond stated that while we shouldn’t completely rule out the possibility of someday discovering evidence of alien technology in our skies, “we also shouldn’t jump to the conclusion that UFOs are alien technology unless there’s compelling evidence. And there is no compelling evidence,” he asserted.
To clearly understand why this is so, Diamond encourages people to conduct a thought experiment.
For many, the SETI logo symbolizes the universal question: “Are we alone?” SETI Institute/Trevor Beattie
The fastest spacecraft ever built and still moving away from Earth is NASA’s New Horizons spacecraft. It launched into space in January 2006, passing by Pluto, and is still piling up miles.
“If you sent this spacecraft to our nearest neighboring star, Alpha Centauri, it would take it 80,000 years to get there,” Diamond said. “Any civilization that mastered the ability to traverse the unimaginably vast distances of interstellar space would possess technologies so superior to ours that they are beyond our comprehension.”
The closest star system to Earth is the Alpha Centauri group, located 4.3 light-years away. The NASA/ESA Hubble Space Telescope photographed Alpha Centauri A (left) and Alpha Centauri B (right), which appear like cosmic lanterns in the dark. ESA/NASA
Diamond suggested it would be like a smartphone for a Neanderthal.
“If such creatures exist, they would likely send equipment here first, not biology, and they certainly wouldn’t crash-land in our deserts,” he said, as was the case with the alleged and widely publicized 1947 dive of a UFO and its accident-prone occupants near Roswell, New Mexico.
“Long before they ever sent any craft into our skies, they would have some idea of what they were dealing with,” Diamond noted, “since they would already know everything about our atmosphere, our airspace, our technology, and so much more. And if that were the case, they wouldn’t have left them behind. And by the way, if a small craft were passing through our airspace, where would its base be? And if they didn’t want to be observed, they wouldn’t be here!”
Diamond points to revelations from NASA’s Kepler mission, launched in March 2009.
Bill Diamond, President and CEO of the SETI Institute. Bill Diamond
This spacecraft, designed to search for and collect data, has discovered more than 2,700 planets beyond our solar system. For nine years, Kepler has been collecting data on deep space, and here’s what it tells us: there are billions of unseen planets, and there are actually more planets than stars.
“Statistically, every star in the sky is orbited by one or more planets,” Diamond noted. Moreover, 50% or more of them are Earth-like (having a rocky surface and similar sizes) and reside in their star’s habitable zone, he added.
“This implies the existence of tens of billions of potentially habitable worlds in our galaxy alone,” Diamond said. “So the statistical probability that we are alone in the universe is zero. Life beyond Earth certainly exists!”
But the presence of highly advanced alien civilizations, both in space and time and in the immediate vicinity, is a completely different matter, Diamond continued. “There are countless variables, and we’re trying to figure them all out in sciences like astrobiology, planetology, astronomy, and astrophysics.”
Diamond wonders why an alien civilization would send biology when they could send equipment instead.
The Karl G. Jansky Very Large Array is a radio astronomy observatory located in the San Agustin Plains of New Mexico. Getty Images/Feifei Cui-Paoluzzo
“The furthest we’ve ever sent into space is hardware. And that makes sense,” Diamond said. “But if you were actually sending creatures, and the most interesting thing you could do was make crop circles… come on!”
Diamond added another layer of skepticism: all UFOs (now referred to as “unidentified anomalous phenomena”) are “random sightings.”
“That makes them extremely unreliable. They don’t have the instruments, the technology, or the methodology to determine what exactly they’re seeing,” Diamond said.
Finally, the head of the SETI Institute stated that if the government really believes in the existence of aliens flying on our planet, then where is the money for research?
“The lack of government funding for UFO/unidentified flying object research indicates either that the government is completely confident that there are no random sightings, or that the government would prefer that we not use the technology available to closely monitor our skies because of our own technologies, which are being developed by man in secret,” Diamond said.
“I think this is the most compelling evidence against the idea that there are visitors in our skies,” Diamond concluded.
More information about the SETI Institute and its programs can be found at https://www.seti.org/
SETI searches for alien life in over 1,000 galaxies using unexplored radio frequencies. The search for extraterrestrial signals in over 1,300 galaxies has helped narrow expectations regarding the number of communicating and technologically advanced civilizations that may exist beyond Earth.
The search, conducted using the Murchison Widefield Array (MWA) in Australia, focused on low radio frequencies in the 80–300 MHz range. By comparison, SETI (Search for Extraterrestrial Intelligence) typically searches for alien signals at 1420 MHz, a frequency associated with hydrogen radiation. In fact, low frequencies are a relatively unexplored area for SETI. The study was published on August 26, 2025, in The Astrophysical Journal.
The search was led by Chenoa Tremblay of the SETI Institute in California and Stephen Tingay, director of the MWA at Curtin University in Australia. The team focused on a 30-degree field of view in the constellation Vela (Sails), encompassing 2,880 galaxies. The redshifts and, therefore, distances to 1,317 of these galaxies had previously been measured with high accuracy, so Tremblay and Tingay focused specifically on these galaxies. Knowing the distances to the galaxies, they could place constraints on the power of any transmitters in these galaxies.
Although their initial search failed to detect an extraterrestrial signal, Tremblay and Tingay concluded in their paper that they might be able to detect it using a 7 x 10^22 W transmitter at 100 MHz.
This composite image shows the red radio wave signature of the night sky above the Murchison Widefield Array, a radio telescope in the Australian outback. MWA Collaboration/Curtin University
“This work represents a significant step forward in our efforts to detect signals from advanced extraterrestrial civilizations,” Tremblay said. “The large field of view and low-frequency range of the MWA make it an ideal instrument for such studies, and the constraints we establish will guide future research.”
For example, in 2015, the Glimpsing Heat from Alien Technologies (G-HAT) project surveyed 100,000 galaxies using NASA’s Wide-field Infrared Survey Telescope (WISE) to search for civilizations that could create “Dyson swarms” around all the stars in their galaxies. None were found. In 2023, a team led by Yuri Uno of National Chongqing University in Taiwan proposed that there could be no more than one civilization within three billion light-years of us directing a radio transmitter with a power greater than 7.7 x 10^26 W toward the Milky Way.
That same year, Michael Garrett of the Jodrell Bank Center for Astrophysics and Andrew Siemion of Breakthrough Listen searched for background galaxies to constrain the maximum detectable power, arriving at a range of roughly 10^23 W to 10^26 W. (The exact maximum power of the potential signal will depend on the distance to the galaxy in which it originates.) Finally, Carmen Choza of the SETI Institute led a team that conducted a targeted search of 97 galaxies using the Green Bank Telescope but found nothing.
In 1964, Soviet astronomer Nikolai Kardashev developed a classification scale for extraterrestrial civilizations based on the amount of energy they possess. A Type I civilization would utilize the entire available energy of a single planet, amounting to 10^16 watts or more. A Type II civilization would be capable of harnessing the energy of an entire star, which for a star similar to the Sun would amount to 10^26 watts. A Type III civilization would be capable of harnessing the entire output power of every star in its galaxy, amounting to approximately 10^36 watts.
The lack of detections so far doesn’t necessarily mean that technologically advanced extraterrestrial life doesn’t exist; our observations are simply not comprehensive enough to confirm its existence. We’re simply not sure. There are estimated to be up to 2 trillion galaxies in the observable universe, and we’ve only explored a small fraction of them, and for a short period of time.
Launching an intergalactic radio beacon would also be expensive; perhaps some beacons were turned off to save power when we observed them. Or perhaps they were pointed toward other galaxies. Perhaps civilizations like Kardashev 2 and 3 are rare, meaning we won’t see transmitters of such power. Therefore, according to the constraints, radio beacons may exist, but their power is below what we can detect. Furthermore, this new study worked at low frequencies, but transmitters at higher frequencies cannot be ruled out.
Tremblay and Tingay note that several powerful radio emitters on Earth, as well as some of our earliest transmissions, operate at low frequencies, justifying searches in this range. Furthermore, given the relative rarity of SETI searches at these low frequencies, there’s always the possibility of discovering something unexpected. For SETI to be successful, radio searches must cover a wide range of frequencies to ensure we don’t miss that elusive signal.
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