Conventional SETI (Search For Extraterrestrial Intelligence) strategies have long been built on the idea that intelligent extraterrestrials (ETI) would aim to communicate with other intelligent civilizations along a very narrow band of the electromagnetic spectrum, preferably in the radio spectrum.

The hypothesis is that any putative technological civilizations out there would use electromagnetic signaling for virtual meetings at a so-called galactic watering hole. That is, a band of radio-quiet frequencies extending from 1420 MHz to 1662 MHz, encompassing the spectral lines of hydrogen (H) and hydroxyl (OH), both of which can combine to form water.

The idea of a cosmic electromagnetic watering hole makes for a powerful metaphor for potential galactic communication between advanced technological intelligences. If indeed such intelligence is out there.

But in a new paper just accepted for publication by *The Astrophysical Journal*, Ben Zuckerman, the paper’s sole author and a long-time UCLA professor of physics and astronomy, argues instead that we should be searching via what he terms broadband SETI.
That is, from the radio on up through the infrared and optical portions of the electromagnetic spectrum.

Our principal assumption is that a purposely communicative technological civilization will do its technological best to establish communication with other ETI, writes Zuckerman. This opens the possibility for the serendipitous detection of an alien transmitter in electromagnetic sky surveys undertaken for reasons that have nothing to do with SETI, he writes.

Thus, if a nearby extraterrestrial intelligence wants to communicate with other nearby terrestrial intelligence, then it can and will transmit signals that can be detected even by a civilization like ours, Zuckerman notes. That is, engaged in astronomical research that uses modest size telescopes, he writes.

The Bad News?

The totality of published astronomical surveys at radio and optical wavelengths are already sufficiently extensive to suggest that cosmically speaking there are very few, perhaps zero, communicative technological civilizations near us, Zuckerman told me via email.

But that doesn’t mean we shouldn’t continue searching. We just need to be smarter about it.

To that end, Zuckerman proposes an improved search technique that more closely corresponds to astronomical surveys that have been undertaken for reasons that have nothing to do with SETI. Published non-SETI radio and optical surveys are sufficiently extensive that they already supply meaningful constraints on the prevalence of nearby purposely communicative alien civilizations, he writes.

Most of the stars covered in such programs are located well beyond the 650-light-year distance we have considered here, Zuckerman writes. In total, radio SETI surveys have observed only a modest percentage of the few 100,000 relevant nearby stars that should be observed, he writes.

In contrast, non-SETI radio surveys have arguably covered more of the position and wavelength space in a hypothetical 650-light-year sphere around Earth than dedicated radio SETI search programs, Zuckerman notes.

What Does Zuckerman Propose?

Use much wider channels and try to cover the entire radio/microwave band from 1 Ghz to 100 Ghz, Zuckerman told me. Cosmically nearby extraterrestrials who possess large space telescopes will know that Earth is special and will beam strong signals toward Earth, he says.

*The NRAO’s Very Large Array in New Mexico. Credit: NRAO via Wikipedia*

According to a recent all-sky survey in a volume of radius of about 650 light years, there are about 500,000 single, solar-type stars, Zuckerman writes. So, we will assume that 200,000 of these are sufficiently old (greater than 4.5 billion years) will be of interest for hosting a technological civilization, he writes. Yet a targeted SETI search program may have to point its telescopes toward some 300,000 nearby stars to be sure that all old ones are included, he notes.

That’s in part because determining the age of an isolated star is not easy.

For a complete survey of “old” stars one should look also at some with poorly determined ages that might be younger than 4.5 billion years, says Zuckerman.

NASA’s Kepler satellite data suggests that about 30% of 200,000 planetary systems will include a potentially habitable rocky planet, or about 60,000 potentially habitable planets, Zuckerman writes. And Kepler projects that some 30% of sunlike stars will be orbited by an approximately earth-size rocky planet in the habitable zone, he notes in his paper.

But observations in the infrared spectrum will likely be key to finding any nearby ETI.

Nearby ETI are probably not transmitting at optical wavelengths because if they were, then their signal would have been detected by accident in one (or more) of the many published optical surveys of the sky, says Zuckerman.

Even so, SETI searchers would be wise to conduct a careful quantitative study of the ensemble of optical observations dating back over a hundred years. That would be painstaking but would be prudent for a comprehensive search.

ETI could well be transmitting at infrared wavelengths, but very little of relevance has been observed/published at IR wavelengths, says Zuckerman. For SETI, the infrared is still a big unknown, he says.

When should humanity have a handle on whether ETIs exist within 650 light years of Earth?

For a ‘good handle,’ infrared wavelengths will have to be well surveyed with a space antenna — because much of the IR region of the electromagnetic spectrum can’t be accessed from below the atmosphere, says Zuckerman. And I don’t know when an appropriate satellite will be in orbit, he says.

Sources:

California unveiled a plan Tuesday to bring at least 7.5 million acres of land and coastal waters under the care of Indigenous tribes.

That number represents roughly 7% of the state’s land and waters. It also corresponds with the amount of land the federal government promised it would hold as reservations for Indigenous tribes after California joined the union in 1850. Congress ultimately rejected these treaties in a secret meeting — after pressure from the state — and failed to notify tribes, many of whom upheld their end of the agreement to relocate.

The new policy, set by the California Natural Resources Agency, aims to start healing the harm caused by the state’s actions to bar tribes from their homelands and criminalize their cultural and land management practices. These actions not only harmed Native communities, whose cultures and ways of life are intimately tied to the plants, animals and landscape of their homelands, but also caused well-documented harm to ecosystems through the loss of biodiversity, takeover of invasive species, degradation of water quality and increase in wildfire risk.

“Tribal stewardship is so critical for all of us … the natural resources and everything that we rely on to live healthy, happy lives,” said Geneva E.B. Thompson, deputy secretary for tribal affairs at the Natural Resources Agency. “Getting Native people out into nature is going to bring that tribal stewardship with it. The basket weaver, she can’t help herself; she’s going to care for those basket weaving materials.”

Chuckwalla National Monument, a protected area in Southern California, was established in January 2025 by then-President Biden and spans nearly 700,000 acres.

(Tecpatl Kuauhtzin / For The Times)

Indigenous advocates applauded the policy announcement, but noted much more work needs to be done.

“The California Natural Resources Agency is taking important steps forward” to acknowledge and address the unratified treaties, Morning Star Gali, executive director and founder of Indigenous Justice and a member of the Ajumawi band of the Pit River Tribe, said in a statement. At the same time, “until there is a true and sustained commitment to land return, co-management, and meaningful investment for all California tribes, repairing these historic injustices will remain a long-standing effort that will take decades to fully address.”

The policy outlines three types of land-use agreements: access agreements that allow tribal members onto the land to reincorporate it into their communities and cultures, collaborative agreements in which land owners work with tribes to care for the land, and land return agreements in which land owners transfer ownership of the land to tribes.

The Natural Resources Agency estimates over 1.7 million acres are already under the stewardship of tribes, including over 100,000 through state land return programs, over 700,000 held as reservations and trust lands for federally recognized tribes, and over 900,000 acres through partnerships with California State Parks.

The agency did not set a date in which it hopes to reach its 7.5-million-acre goal. Some estimates also place the acreage in the unratified treaties closer to 8.5 million.

Angela Mooney D’Arcy, founder of the Sacred Places Institute for Indigenous Peoples, is photographed at Lewis MacAdams Riverfront Park in Los Angeles in May 2023.

(Jason Armond / Los Angeles Times)

“It’s really exciting to see what has been lifelong work for so many California Indigenous folks that have been my mentors … come to fruition,” said Angela Mooney D’Arcy, executive director and founder of the Sacred Places Institute for Indigenous Peoples. “As a California Indigenous advocate for land return for the past 30 years, what occurred to me in reading this document was how useful it could have been in so many different instances over the past 30 years.”

Access and collaborative agreements — and sometimes even land return agreements — come with requirements specifying what tribes can and cannot do with the land. Many require navigating sometimes tricky relationships with land managers who may have different priorities. It’s a ways off from tribes outright holding their homelands as sovereign nations, with the freedom to take care of the land as they see fit; however, these agreements can also help support tribes that do not yet have the capacity to single-handedly manage hundreds or thousands of acres.

Mooney D’Arcy, who is Acjachemen, hopes that when the rubber meets the road, the Natural Resources Agency will step in and champion these kinds of stewardship agreements when local organizations and agencies are resistant.

“We can have these great goals, but if the state is serious about these goals and vision, then it should also make sure to be present and … be prepared to advocate for tribes,” she said.

California’s Indigenous history following European contact is dark and violent.

Many tribal leaders were coerced into signing the original treaties, with limited to no translation support to help them understand what they were signing. The state’s first governor proclaimed that California must expect that confrontations between white settlers and Indigenous communities would give settlers the resolve for a “war of extermination” lasting until “the Indian race becomes extinct.” The state’s first legislative session outlawed the Indigenous practice of setting careful intentional fires to manage the land.

Tyler Mata, a member of the yak titʸu titʸu yak tilhini Northern Chumash Tribe, participates in a planned cultural burn at Johnson Ranch in San Luis Obispo on Dec. 11.

(Ruby Wallau / For The Times)

“We’ve seen really devastating effects. We’re seeing these algae blooms that are now overtaking our lakes and affecting our streams and our rivers,” Gali said. Meanwhile, some state parks are “just this huge tinderbox because it’s not being properly managed under tribal stewardship.”

Recent examples of tribes returning to care for their homelands, sometimes for the first time in well over a century, gives Thompson — the Natural Resources Agency’s first deputy secretary for tribal affairs — hope for the future.

She recalled the first land return she witnessed in the role: 46 acres of coastal wetlands to the Wiyot Tribe. During tours of the newly returned land, tribal culture experts kept breaking off to take care of the various native plants that they noticed needed some love.

Tribes participate in a friendly race after building traditional tule boats at the American River in Folsom, Calif.

(Kori Cordero)

More recently, she attended an intertribal boat race with Wilton Rancheria, Shingle Springs Band of Miwok Indians, and United Auburn Indian Community, thanks to an access agreement with California State Parks. Tribal youth worked with elders to harvest tule — a stalky plant native to California’s wetlands — and use it to build traditional boats. (State Parks provided the life jackets, lifeguards and food.)

The Natural Resources Agency’s new policy is an attempt to capture these moments not as one-off stories of healing, but as the state’s official practice moving forward, Thompson said.

“I’m so proud of this policy, but I’m so excited to see what the ripple effect is going to be,” she said. “It’s so much more beautiful seeing it in practice than it is writing it out of paper.”