Advancing Space Technology and Preparing for Contact with Extraterrestrial Intelligence through Multilateralism

Is it possible that we can account for the Fermi paradox by looking to our own behavior as a species? Some science fiction of the 1950s pointed in that direction, as witness The Day the Earth Stood Still (1951). Dr Kelvin F Long addresses the question in terms of the 'zoo hypothesis' in the essay below, asking what our culture could do to make itself less threatening to any outsider. Long is an aerospace engineer, astrophysicist and author. He leads the Interstellar Research Centre, a division of Stellar Engines, which conducts research on the science and technology associated with deep space exploration. He is a Chartered Member of the Institute of Physics and a Fellow of the British Interplanetary Society. He tells me he wrote this article as a means of fundamental protest at the current conflicts engulfing humanity and as a plea to any observing ETI not to judge our species by the immorality of those who hold power over the potential of humankind. Also available on his site are...

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The Long Afternoon of Earth

Every time I mention a Brian Aldiss novel, I have to be careful to check the original title against the one published in the US. The terrific novel Non-Stop (1958) became Starship in the States, rather reducing the suspense of decoding its strange setting. Hothouse (1962) became The Long Afternoon of Earth when abridged in the US following serialization in The Magazine of Fantasy & Science Fiction. I much prefer the poetic US title with its air of brooding fin de siècle decline as Aldiss imagines our deep, deep future. Imagine an Earth orbiting a Sun far hotter than it is today, a world where our planet is now tidally locked to that Sun, which Aldiss describes as “paralyzing half the heaven.” The planet is choked with vegetation so dense and rapidly evolving that humans are on the edge of extinction, living within a continent-spanning tree. The memory of reading all this always stays with me when I think about distant futures, which by most accounts involve an ever-hotter Sun and the...

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Green Mars: A Nanotech Beginning

I want to return to Mars this morning because an emerging idea on how to terraform it is in the news. The idea is to block infrared radiation from escaping into space by releasing engineered dust particles about half as long as the wavelength of this radiation, which is centered around wavelengths of 22 and 10 μm, into the atmosphere. Block those escape routes and the possibility of warming Mars in a far more efficient way than has previously been suggested emerges. The paper on this work even suggests a SETI implication (!), but more about that in a moment. Grad student Samaneh Ansari (Northwestern University) is lead author of the paper, working with among others Ramses Ramirez (University of Central Florida), whose investigations into planetary habitability and the nature of the habitable zone have appeared frequently in these pages (see, for example, Revising the Classical ‘Habitable Zone’). The engineered ‘nanorods’ at the heart of the concept could raise the surface temperature...

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The ‘Freakish Radio Writings’ of 1924

Mars was a lively destination in early science fiction because of its proximity. When H. G. Wells needed a danger from outer space, The War of the Worlds naturally looked toward Mars, as a place close to Earth and one with the ability to provoke curiosity. Closely studied at opposition in 1877, Mars provoked in Giovanni Schiaparelli the prospect of a network of canals, surely feeding a civilization that might still be alive. No wonder new technologies turned toward the Red Planet as they became available to move beyond visible light and even attempt to make contact with its inhabitants. All this comes to mind this morning because of an intriguing story sent along by my friend Al Jackson, whose work on interstellar propulsion is well known in these pages, as is his deep involvement with the Apollo program. Al had never heard of the incident described in the story. It occurred in 1924, when at another Martian opposition (an orbital alignment bringing Earth and Mars as close as they’ll...

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Our Earliest Ancestor Appeared Soon After Earth Formed

Until we learn whether or not life exists on other planets, we extrapolate on the basis of our single living world. Just how long it took life to develop is a vital question, with implications that extend to other planetary systems. In today's essay, Alex Tolley brings his formidable background in the biological sciences to bear on the matter of Earth's first living things, which may well have emerged far earlier than was once thought. In particular, what was the last universal common ancestor -- LUCA -- from which bacteria, archaea, and eukarya subsequently diverged? Without the evidence future landers and space telescopes will give us, we remain ignorant of so fundamental a question as whether life itself -- not to mention intelligence -- is a rarity in the cosmos. But we're piecing together a framework that reveals Earth's surprising ability to spring into early life. by Alex Tolley Once upon a time, the history of life on Earth seemed so much simpler. Darwin had shown how natural...

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Are Interstellar Quantum Communications Possible?

A favorite editor of mine long ago told me never to begin an article with a question, but do I ever listen to her? Sometimes. Today’s lead question, then, is this: Can we expand communications over interstellar distances to include quantum methods? A 2020 paper by Arjun Berera (University of Edinburgh) makes the case for quantum coherence over distances that have only recently been suggested for communications: …We have been able to deduce that quantum teleportation and more generally quantum coherence can be sustained in space out to vast interstellar distances within the Galaxy. The main sources of decoherence in the Earth based experiments, atmospheric turbulence and other environmental effects like fog, rain, smoke, are not present in space. This leaves only the elementary particle interactions between the transmitted photons and particles present in the interstellar medium. Quantum coherence is an important matter; it refers to the integrity of the quantum state involved, and is...

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The Odds on an Empty Cosmos

When Arthur C. Clarke tells me that something is terrifying, he’s got my attention. After all, since boyhood I’ve not only had my imagination greatly expanded by Clarke’s work but have learned a great deal about scientific methodology and detachment. So where does terror fit in? Clarke is said to have used the term in a famous quote: “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” But let’s ponder this: Would we prefer to live in a universe with other intelligent beings, or one in which we are alone? Are they really equally terrifying? Curiosity favors the former, as does innate human sociability. But the actual situation may be far more stark, which is why David Kipping deploys the Clarke quote in a new paper probing the probabilities. Working with the University of Sydney’s Geraint Lewis, Kipping (Columbia University) has applied a thought experiment first conceived by Edwin Jaynes to dig into the matter. Jaynes (1922-1998)...

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The Search for Things that Matter

Overpopulation has spawned so many dystopian futures in science fiction that it would be a lengthy though interesting exercise to collect them all. Among novels, my preference for John Brunner’s Stand on Zanzibar goes back to my utter absorption in its world when first published in book form in 1968. Kornbluth’s “The Marching Morons” (1951) fits in here, and so does J.G. Ballard’s Billenium (1969), and of course Harry Harrison’s Make Room! Make Room! from 1966, which emerged in much changed form in the film Soylent Green in 1973. You might want to check Science Fiction and Other Suspect Ruminations for a detailed list, and for that matter on much else in the realm of vintage science fiction as perceived by the pseudonymous Joachim Boaz (be careful, you might spend more time in this site than you had planned). In any case, so strongly has the idea of a clogged, choking Earth been fixed in the popular imagination that I still see references to going off-planet as a way of relieving...

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Finding a Terraforming Civilization

Searching for biosignatures in the atmospheres of nearby exoplanets invariably opens up the prospect of folding in a search for technosignatures. Biosignatures seem much more likely given the prospect of detecting even the simplest forms of life elsewhere – no technological civilization needed – but ‘piggybacking’ a technosignature search makes sense. We already use this commensal method to do radio astronomy, where a primary task such as observation of a natural radio source produces a range of data that can be investigated for secondary purposes not related to the original search. So technosignature investigations can be inexpensive, which also means we can stretch our imaginations in figuring out what kind of signatures a prospective civilization might produce. The odds may be long but we do have one thing going for us. Whereas a potential biosignature will have to be screened against all the abiotic ways it could be produced (and this is going to be a long process), I suspect a...

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The Ambiguity of Exoplanet Biosignatures

The search for life on planets beyond our Solar System is too often depicted as a binary process. One day, so the thinking goes, we'll be able to directly image an Earth-mass exoplanet whose atmosphere we can then analyze for biosignatures. Then we'll know if there is life there or not. If only the situation were that simple! As Alex Tolley explains in his latest essay, we're far more likely to run into results that are so ambiguous that the question of life will take decades to resolve. Read on as Alex delves into the intricacies of life detection in the absence of instruments on a planetary surface. by Alex Tolley "People tend to believe that their perceptions are veridical representations of the world, but also commonly report perceiving what they want to see or hear." [17] Evolution has likely selected us to see dangerous things whether they are there or not. Survival favors avoiding a rustling bush that may hide a saber-toothed cat. We see what we are told to see, from gods in...

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And Then There Were Four (or Maybe Not)

I’m delighted to see the high level of interest in Dysonian SETI shown not only by reader comments here but in the scientific community at large. I wouldn’t normally return to the topic this quickly but for the need to add a quick addendum to our discussions of Project Hephaistos, the effort (based at Uppsala University, Sweden) to do a deep dive into data from different observatories looking for evidence of Dyson spheres in the form of quirks in the infrared data suggesting strong waste heat. Swiftly after the latest Hephaistos paper comes a significant re-examination of the seven Dyson sphere candidates that made it through that project’s filters. You’ll recall that all seven were M-dwarfs, which struck me at the time as unusual. Only seven candidates emerged from over five million stars sampled, interesting especially because the possibility of a warm debris disk seemed to be ruled out. But Tongtian Ren (Jodrell Bank Centre for Astrophysics), working with Michael Garrett and...

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Seven Dyson Sphere Candidates

I’m enjoying the conversation about Project Hephaistos engendered by the article on Dyson spheres. In particular, Al Jackson and Alex Tolley have been kicking around the notion of Dyson sphere alternatives, ways of preserving a civilization that are, in Alex’s words, less ‘grabby’ and more accepting of their resource limitations. Or as Al puts it: One would think that a civilization that can build a ‘Dyson Swarm’ for energy and natural resources would have a very advanced technology. Why then does that civilization not deploy an instrumentality more sly? Solving its energy needs in very subtle ways… As pointed out in the article, a number of Dyson sphere searches have been mounted, but we are only now coming around to serious candidates, and at that only seven out of a vast search field. Two of these are shown in the figure below. We’re a long way from knowing what these infrared signatures actually represent, but let’s dig into the Project Hephaistos work from its latest paper in...

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Project Hephaistos and the Hunt for Astroengineering

For a project looking for the signature of an advanced extraterrestrial civilization, the name Hephaistos is an unusually apt choice. And indeed the leaders of Project Hephaistos, based at Uppsala University in Sweden, are quick to point out that the Greek god (known as Vulcan in Roman times) was a sort of preternatural blacksmith, thrown off Mt. Olympus for variously recounted transgressions and lame from the fall, a weapons maker and craftsman known for his artifice. Consider him the gods’ technologist. Who better to choose for a project that pushes SETI not just throughout the Milky Way but to myriads of galaxies beyond? Going deep and far is a sensible move considering that we have absolutely no information about how common life is beyond our own Earth, if it exists at all. If the number of extraterrestrial civilizations in any given galaxy is scant, then a survey looking for evidence of Hephaistos-style engineering writ large will comb through existing observational data from...

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SETI and Gravitational Lensing

Radio and optical SETI look for evidence of extraterrestrial civilizations even though we have no evidence that such exist. The search is eminently worthwhile and opens up the ancillary question: How would a transmitting civilization produce a signal strong enough for us to detect it at interstellar distances? Beacons of various kinds have been considered and search strategies honed to find them. But we've also begun to consider new approaches to SETI, such as detecting technosignatures in our astronomical data (Dyson spheres, etc.). To this mix we can now add a consideration of gravitational lensing, and the magnifications possible when electromagnetic radiation is focused by a star’s mass. For a star like our Sun, this focal effect becomes useful at distances beginning around 550 AU. Theoretical work and actual mission design for using this phenomenon began in the 1990s and continues, although most work has centered on observing exoplanets. Here the possibilities are remarkable,...

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Close Stellar Encounters and Earth’s Orbit

Galaxies look fixed in astronomical photos, but of course they’re dynamic systems ever in motion. The closest stars to Earth at Alpha Centauri will eventually close to within about 3 light years if we wait thirty thousand years or so. After that, as the system moves away again, Ross 248 will emerge as the closest interstellar target, closing to about the same distance before moving off into the night. But that will require waiting a bit longer, on the order of another 6000 years. We might also keep an eye on Gliese 445, which in 46,000 years or so will close to less than 4 light years of the Sun. So everything is moving all the time, and we can say something more about future encounters. The REsearch Consortium On Nearby Stars (RECONS) has found that within the local 10-parsec volume, 81 percent of the 357 main sequence stars in its stellar census are less than half as massive as the Sun. That’s about the current estimate for the percentage of stars in the galaxy that are M-dwarfs,...

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Alone in the Cosmos?

We live in a world that is increasingly at ease with the concept of intelligent extraterrestrial life. The evidence for this is all around us, but I’ll cite what Louis Friedman says in his new book Alone But Not Lonely: Exploring for Extraterrestrial Life (University of Arizona Press, 2023). When it polled in the United States on the question in 2020, CBS News found that fully two-thirds of the citizenry believe not only that life exists on other planets, but that it is intelligent. That this number is surging is shown by the fact that in polling 10 years ago, the result was below 50 percent. Friedman travels enough that I’ll take him at his word that this sentiment is shared globally, although the poll was US-only. I’ll also agree that there is a certain optimism that influences this belief. In my experience, people want a universe filled with civilizations. They do not want to contemplate the loneliness of a cosmos where there is no one else to talk to, much less one where valuable...

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Open Cluster SETI

Globular clusters, those vast ‘cities of stars’ that orbit our galaxy, get a certain amount of traction in SETI circles because of their age, dating back as they do to the earliest days of the Milky Way. But as Henry Cordova explains below, they’re a less promising target in many ways than the younger, looser open clusters which are often home to star formation. Because it turns out that there are a number of open clusters that likewise show considerable age. A Centauri Dreams regular, Henry is a retired map maker and geographer now living in southeastern Florida and an active amateur astronomer. Here he surveys the landscape and points to reasons why older open clusters are possible homes to life and technologies. Yet they’ve received relatively short shrift in the literature exploring SETI possibilities. Is it time for a new look at open clusters? by Henry Cordova If you're looking for signs of extra-terrestrial intelligence in the cosmos, whether it be radio signals or optical...

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Alien Life or Chemistry? A New Approach

Working in the field has its limitations, as Alex Tolley reminds us in the essay that follows, but at least biologists have historically been on the same planet with their specimens. Today’s hottest news would be the discovery of life on another world, as we saw in the brief flurries over the Viking results in 1976 or the Martian meteorite ALH84001. We rely, of course, on remote testing and will increasingly count on computer routines that can make the fine distinctions needed to choose between biotic and abiotic reactions. A new technique recently put forward by Robert Hazen and James Cleaves holds great promise. Alex gives it a thorough examination including running tests of his own to point to the validity of the approach. One day using such methods on Mars or an ice giant moon may confirm that abiogenesis is not restricted to Earth, a finding that would have huge ramifications not just for our science but also our philosophy. by Alex Tolley Perseverance rover on Mars - composite...

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Galactic ‘Nature Preserves’ over Deep Time

Speculating about the diffusion of intelligent species through the galaxy, as we've been doing these past few posts, is always jarring. I go back to the concept of ‘deep time,’ which is forced on us when we confront years in their billions. I can’t speak for anyone else, but for me thinking on this level is closer to mathematics than philosophy. I can accept a number like 13.4 × 10⁹ years (the estimate for the age of globular cluster NGC 6397 and a pointer to the Milky Way’s age) without truly comprehending how vast it is. As biological beings, a century pushes us to the limit. What exactly is an aeon? NGC 6397 and other globular clusters are relevant because these ancient stellar metropolises are the oldest large-scale populations in the Milky Way. But I’m reminded that even talking about the Milky Way can peg me as insufferably parochial. David Kipping takes me entirely out of this comparatively ‘short-term’ mindset by pushing the limits of chronological speculation into a future...

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Can the ‘Zoo Hypothesis’ Be Saved?

If we were to find life other than Earth’s somewhere else in the Solar System, the aftershock would be substantial. After all, a so-called ‘second genesis’ would confirm the common assumption that life forms often, and in environments that range widely. The implications for exoplanets are obvious, as would be the conclusion that the Milky Way contains billions of living worlds. The caveat, of course, is that we would have to be able to rule out the transfer of life between planets, which could make Mars, say, controversial. But find living organisms on Titan and the case is definitively made. Ian Crawford and Dirk Schulze-Makuch point out in their new paper on the Fermi question and the ‘zoo hypothesis’ that this issue of abiogenesis could be settled relatively soon as our planetary probes gain in sophistication. We could settle it within decades if we found definitive biosignatures in an exoplanet atmosphere, but here my skepticism kicks in. My...

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Charter

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).

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If you'd like to submit a comment for possible publication on Centauri Dreams, I will be glad to consider it. The primary criterion is that comments contribute meaningfully to the debate. Among other criteria for selection: Comments must be on topic, directly related to the post in question, must use appropriate language, and must not be abusive to others. Civility counts. In addition, a valid email address is required for a comment to be considered. Centauri Dreams is emphatically not a soapbox for political or religious views submitted by individuals or organizations. A long form of the policy can be viewed on the Administrative page. The short form is this: If your comment is not on topic and respectful to others, I'm probably not going to run it.

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