I hardly need to run through the math to point out how utterly absurd it would be to have two civilizations develop within a few light years of each other at roughly the same time. The notion that we might pick up a SETI signal from a culture more or less like our own fails on almost every level, but especially on the idea of time. A glance at how briefly we have had a technological society makes the point eloquently. We can contrast it to how many aeons Earth has seen since its formation 4.6 billion years ago.
Brian Lacki (UC-Berkeley) looked into the matter in detail at a Breakthrough Discuss meeting in 2021. Lacki points out that our use of radio takes up 100,000,000th of the lifespan of the Sun. We must think, he believes, in terms of temporal coincidence, as the graph he presented at the meeting shows. Note the arbitrary placement of a civilization at Centauri B, and others at Centauri A and C, along with our own timeline. The thin line representing our civilization actually corresponds to a lifetime of 10 million years. What are the odds that the lines of any two stars coincide? Faint indeed, unless societies can persist for not just millions but even billions of years. We don’t know if they can, but we need to think about it in terms of what we might receive.
Image: Brian Lacki’s slide illustrating temporal coincidence. Credit: Brian Lacki.
But there is another point. Should we assume that stars near the Sun are roughly the same age as ours? You might think so at first glance, given the likely formation of our star in a stellar cluster, but in fact clusters separate and diverge over time, so that finding the Sun’s birthplace and its siblings is challenging in itself (though some astronomers are trying). As we’re also learning, slowly but surely, stars around us in the Milky Way’s so-called ‘thin disk’ – within which the Sun moves – actually show a wider range of ages than we first thought.
A planet-hosting star a billion years older than ours might be a more interesting SETI target than one considerably younger, simply because life has had more time to start emerging on its planets. But untangling all the factors that help us understand stellar age and movement is not easy. What is now happening is that we are developing what are known as chrono-chemo-kinematical maps, which track these factors along with the chemical composition of the stars under study. Here we’re combining spectroscopic analysis with models of stellar evolution and radial velocity analysis.
This multi-dimensional approach is greatly aided by ESA’s Gaia mission and its extensive datasets on stars within a few thousand light years of the Sun. Gaia is remarkably helpful at using astrometry to pin down stellar motion and distance. Then we can factor in metallicity, for the oldest stars in the galaxy were formed at a time when hydrogen and helium were about the only ingredients the cosmos had to work with. A chrono-chemo-kinematical map can interrelate these factors, and with the help of neural networks tease out some conclusions that have surprised astronomers.
Thus a new paper out of the Leibniz-Institut für Astrophysik Potsdam. Here Samir Nepal and colleagues have been using machine learning (with what they call a ‘hybrid convolutional neural network’) to attack one million spectra from the Radial Velocity Spectrometer (RVS) in Gaia’s Data Release 3. Altogether, they are working with a sample of 565,606 stars to determine their parameters. Here the metallicity of stars is significant because the thin disk, which extends in the plane of the galaxy out to its edges, has been thought to consist primarily of younger Population I stars. Thus we should find higher metallicity, as we do, in a region of ongoing star formation.
But the Gaia mission is helping us understand that there is a surprising portion of the thin disk that consists of ancient stars on orbits that are similar to the Sun. And while the thin disk has largely been thought to have begun forming some 8 to 10 billion years ago, the maps that are emerging from the Potsdam work show that the majority of ancient stars in the Gaia sample (within 3200 light years) are far older than this. Most are metal-poor, but some have higher metal content than our Sun, which implies that early in the Milky Way’s development metal enrichment could already take place.
Let me quote Samir Nepal directly on this:
“These ancient stars in the disc suggest that the formation of the Milky Way’s thin disc began much earlier than previously believed, by about 4-5 billion years. This study also highlights that our galaxy had an intense star formation at early epochs leading to very fast metal enrichment in the inner regions and the formation of the disc. This discovery aligns the Milky Way’s disc formation timeline with those of high-redshift galaxies observed by the James Webb Space Telescope (JWST) and Atacama Large Millimeter Array (ALMA) Radio Telescope. It indicates that cold discs can form and stabilize very early in the universe’s history, providing new insights into the evolution of galaxies.“
Image: An artist’s impression of our Milky Way galaxy, a roughly 13 billon-year-old ‘barred spiral galaxy’ that is home to a few hundred billion stars. On the left, a face-on view shows the spiral structure of the Galactic Disc, where the majority of stars are located, interspersed with a diffuse mixture of gas and cosmic dust. The disc measures about 100 000 light-years across, and the Sun sits about half way between its centre and periphery. On the right, an edge-on view reveals the flattened shape of the disc. Observations point to a substructure: a thin disc some 700 light-years high embedded in a thick disc, about 3000 light-years high and populated with older stars. Credit: Left: NASA/JPL-Caltech; right: ESA; layout: ESA/ATG medialab.
Here is an image showing the movement of stars near the Sun around galactic center, as informed by the Potsdam work:
Image: Rotational motion of young (blue) and old (red) stars similar to the Sun (orange). Credit: Background image by NASA/JPL-Caltech/R. Hurt (SSC/Caltech).
A few thoughts: Combining data from different sources using the neural networks deployed in this study, and empowered by the Gaia DR3 RVS results, the authors are able to cover a wide range of stellar parameters, from gravity, temperature and metal content to distances, kinematics and stellar age. It’s going to take that kind of depth to begin to untangle the interacting structures of the Milky Way and place them into the context of their early formation.
Secondly, these results really seem surprising given that while the majority of the metal-poor stars in thin-disk orbits are older than 10 billion years, fully 50 percent are older than 13 billion years. The thin disk began forming less than a billion years after the Big Bang – that’s 4 billion years earlier than previous estimates. We also learn that while metallicity is a key factor, it varies considerably throughout this older population. In other words, intense star formation made metal enrichment possible, working swiftly from the inner regions of the galaxy and pushing outwards.
So our Solar System is moving through regions containing a higher proportion of ancient stars than we knew, and upcoming work extending these machine learning techniques, now in the planning stages and using data from the 4-metre Multi-Object Spectroscopic Telescope (4MOST) should refine the results of the Potsdam team in 2025. I return to what this may tell us from a SETI perspective. Ancient stars, especially those with higher than expected metallicity, should be interesting targets given the opportunities for life and technology to develop on their planets.
Maybe we’re making the Fermi question even tougher to answer. Because many such stars in the nearby cosmic environment are older — far older — than we had realized.
The paper is Nepal et al., “Discovery of the local counterpart of disc galaxies at z > 4: The oldest thin disc of the Milky Way using Gaia-RVS,” accepted for publication in Astronomy & Astrophysics (preprint).
Fascinating Article!
For the sake of interest let’s assume some civilizations do persist for billions of years (which might give them a very long-term perspective) and let’s assume FTL travel is either impossible or very expensive so even old advanced civilizations don’t travel or communicate many light years from home. Then such a civilization might look ahead for temporarily-near neighbors in their trip around the galaxy. Depending on circumstances this might have significant effects on any civilization on their incoming neighbors.
It might initiate a blossoming of knowledge and understanding if the two exchange messages and maybe even visits.
It might result in the more technologically advanced civilization establishing a colony in or near the other, with the result tbd as the stars draw apart.
It might be that the more advanced civilization fears aliens and sterilizes planets ahead of them.
On the other hand they might try to make barren candidate planets they pass more conducive to life.
There is a lot to think about here and I think a lot of SF to be written.¡
While species can exist for 10 my, H. Spaiens has only existed for much less than 100 ky, and technological-industrial civilization for less than half of a millennium. The problem for longevity is the need to extract material resources that are finite. For example, metals on Earth are finite. We can extend their lifetimes to shift from mining ever less rich ores to recycling. However, as recycling is not perfect, eventually this approach fails. We blithely talk about KII civilizations harvesting the sun’s energy output, but if we are forced to use technology not that dissimilar to the current PV panels, their lifetimes are in mere decades and we’ll need to be replaced. even with highly efficient recycling, they will eventually use up the resources we have, with the critical ones as the limiting factor. Even if we hope to become a KII civilization, at even very modest rates of growth, we reach the limit of solar output in less than 10 millennia. Then what? Expanding throughout the galaxy, replicating the model of capturing every star’s full output, we would become a KIII civilization in about 1 my. Then stasis.
Life on earth has existed for at least 3.5 by, with biology allowing very high, but not perfect, recycling of necessary elements. But important elements like phosphorus are limiting, so that Earth’s active geological processes have to resupply the P that has been lost and inaccessible.
For [post-]humans to exist on Earth and remain technological, we would need to find some way to utilize biological materials to substitute for those we use now. I very much doubt that is possible.
So we end up taking one of 2 paths. A technological one that peters out within a few million years, or a non-technological one that allows our species to evolve and extend our “civilization/culture” for much longer.
However, unless there are many more similarly transient technological civilizations in the galaxy, the coincidence of at least one other seems very unlikley and probably needs FTL transmissions for any meaningful communication. If we maintain the technological path and eventually explore the galaxy, we are more likely to find ourselves coincident with intelligent, but non-technological, cultures simply because of their longevity. Which brings us back to the Fermi Question.
If life and intelligence do arise almost everywhere, then those technological civilization might be represented as brief transients that appear through deep time, with occasional overlapping transients, but mostly isolated.
I agree with the first part. Who cares if a star can last a trillion years if the supply of materials to maintain K2 collection rates only last 1 billion years.
You lose me on the second. Biology and technology both employ mechanics and electrons to do work. If biology and technology can both only achieve imperfect recycling rates then the longevity of a planet’s biomass cannot be linked to recycling efficiency. Earth’s biomass is tiny compared to it resource pool, Earth’s mass. Increasing the biomass to K1 or K2 proportions duplicates the problems faced by K1 or K2 technological civilizations. The longevity of Earth’s biomass is due to its small relative scale.
Constant, compounding growth aren’t necessary to achieve a galactic footprint. Technological progress only requires a minimum number of minds with free time to spend on science. A growing population accelerates technological progress but I don’t see why any knowable truth could hide from a small, never-growing population. Once universal construction and the mechanics of consciousness are unlocked, a people could enjoy any lifestyle they choose till the end of the universe. As long as consumption is low enough, of course.
If consumption rates are linked to longevity and space faring people are widely separated in time, we shouldn’t expect to see any peoples addicted to constant, compounding growth.
Imho, looking for K2 or K3 peoples is equivalent to looking for perfectly spherical dairy cows. Not finding them should be expected or, at the very least, their absence can’t be evidence against practical dairy cows.
Yes, biomass is restricted to carrying capacity and recycling efficiency. Recall that during the carboniferous there was no biology to recycle lignin, which is why we have such large Carboniferous coal seams. Without recycling, life would have had to rely on the carbon and other elements being generated by geologic processes. But we can certainly extend the biomass via various means too, at the cost of potentially shortening the longevity. However, life uses very common elements for the most part, and recycling is inherent in the self-replication of life. Technology, at least our type, is not self-replicating and needs active replacement. This creates a burden – the larger the scale of technology, the greater the requirements of maintenance and replacement. Technology is not cell-based, with the means to replicate. The difficulty of recycling is therefore more difficult – just consider the issue of different plastics alone – we are at the lignin stage of recycling in the Carboniferous. It will improve, but technology is so complex that the effort to recycle is far more energy-intensive than for life. IMO, this makes our technological civilization inherently shorter-lived than a biosphere.
I think there is more than an either-or choice here. We know, for instance, that waste heat from increasing computation will lead to boiling the oceans by the 24th century unless we move computation and industry offworld. Signal latency from LEO to the surface is in most locals, better than latency to regional datacenters over cable. So once Starlink network and competitors are in space and operating, expect the next phase to be orbiting datacenters launched by Starship, running on solar power and radiating their waste heat to space.
Earth’s surface will remain a preserve for non-technological life, while humanity bifurcates between primitivists on the surface that live in harmony with nature and trans/post-humanists who live in harmony with technology, alongside terraformed Mars.
Making simplistic extrapolations of expansion across the galaxy always fails to consider the economic costs of expansion vs the limited benefits in the absence of FTL communications and transportation. There really is no economic benefit to any world to send out colony ships to other star systems, so you can’t expect government structures to finance any of this other than possibly robot exploration. So colonization efforts will be financed by the colonists themselves. Private enterprises will only find profit in providing colonization transit services in exchange for surrender of all passenger assets remaining on the originating world.
So to assume that once you reach one world that the colonists will automatically start building new starships to go to another is very economically ignorant.
You would need to grow a planets population from a small set of colonists to the order of hundreds of millions to billions to support the industrial infrastructure to be able to build, and its people to afford, new starships to new planets.
It is highly likely that colonists will suffer roadblocks that will stagnate their development in adapting to new planetary environments (like terraforming) that will eat up all their economic surplus output for generations or more, with a good chance of a return to barbarism and fall of civilization, leaving the colonists distant descendants to rebuild their own civilization from scratch or just picking up the pieces after a dark age or two or three.
A planet with a higher incidence of natural disaster than Earth would keep setting a colony civilization back at much more regular intervals.
Your assumption that colonists would have to take time [ millennia? ] to build their economy before sending on the next ships may be too pessimistic. The idea that populations must rebuild is not necessarily true. The population of people may remain low, but self-replicating robots may take on the task far more rapidly. Think of Asimov’s Solaria as a model. As long as a colony has something to trade to pay for transport – then starships could be bought and sold to ensure the original owners can continue to build starships, and the colonies can maintain the “Outward Urge”. Then again, a robot civilization may not need to stop at all, just dropping off “starter kits” for each world to kickstart its own robotic economy if desired. Galactic exploration would then be as fast as flight can be achieved.
If we discount meat intelligence as the colony payloads and think purely in terms of microbes (prokaryotes and eukaryotes) with sufficient robustness that a colony could seed a suitable planet, tiny payloads fired off from a home world could seed the galaxy with life within a million years, possibly as short as 50,000 years. A mere eyeblink. With exponential growth, these microbes could replicate to carrying capacity within a few years. [ On Earth, phage viruses keep bacterial numbers in check. Recall that without checks and restraints on houseflies, we would be knee-deep in them in a year! Exponential growth is serious. ]
If we wanted to, we could do directed panspermia this way within the next century. I would make each payload time-release capsules of different organisms to create a “basic starter ecosystem” of single-cell and multicellular organisms that could eventually evolve into a rich biosphere recapitulating terrestrial life [ but not necessarily phenotypes ] over a few hundred million years. It would be an altruistic program, obviously. However, if any ETI thought similarly, we might find that life with common biology was ubiquitous. Given the age of the universe, we just might be one of those directed panspermia operations.
For meat intelligence like us, somewhat larger seed ships could put humanity on all the suitable planets, using self-replicating robots to build the needed infrastructure for humanity to thrive and bootstrap a new civilization on similar timetables for sending, but drastically collapsed times needed for the new civilizations to emerge and replicate the process.
People have thought along similar lines…
In under a century of trying we have been able to achieve elementary fusion and fission. Seems reasonable that more advanced civilizations than ours – even only marginally more advanced – might be able to configure any metals or other elements needed.
Although stellar age and metallicity are correlated, I believe it would be misleading to think of them as synonymous. In the early universe, low metallicity stars may have been the rule, rather than the exception, but some of those stars were very massive and quickly sped through their evolution into the supernova or planetary nebula stage in an extremely ‘short’ time. Most of the early galaxy may have been dominated by hydrogen and helium, but there would have been pockets of other elements, and even metallic, carbon and silicate dust grains. Even globular clusters may have high-metallicity stars and rocky planets. perhaps not as many, but there will be exceptions.
And how do we determine the metallicity of a star? We look at its spectrum. But an extremely old star born during a time when the interstellar medium was deficient in medals (its planets would be predominantly H/He gas giants) might exhibit many metallic lines in its spectrum, from nucleogenesis in its core throughout its long lifetime. These heavy elements would be cycled up by convection to the surface layers where we can observe them. Convection is an important factor in radiative transfer and is common in old, main sequence stars. Then there is orbital mixing, past galactic collisions and other processes which currently stir up the stellar population.
When we consider further how the stellar populations may have been mixed and seeded with stars of various ages, many of them are second and third generation stars, it is difficult to justify their metallicity with their age, or even their location. Another factor to be considered is that many, if not most, stars were born in open clusters and have since been dispersed or ejected into the disk population as those clusters evaporated due to tidal stresses.
Yes, the oldest stars do not have rocky planets, and the younger ones born in an interstellar medium enriched by metals do tend to be more likely to be friendly to life. But this gradient only exists in the statistical sense, it tells you little about a particular star’s chances to support a planetary biosphere.
The best place to look for life is a light, small, faint, old star of late spectral type (F-M). It is most likely to have “metallic” planets and enough of a stable old age for life to have established and evolved there. The alleged effects of other factors (lack of a satellite, magnetosphere, tidal locking, flares, binary companions, etc) can be assessed later.
Perhaps this is like giving toasts at a table…
For arm chair astronomers and astronauts, a delight of this pursuit is examining colorful analytical charts constructed with or adapted to the newest data. E.g., drawing new colored lines and bounds on an H-R diagram representing a new stellar path; or a link between blue to red stars and brown dwarfs.
In this instance we’ve got a revised set of near neighbors and it should have some impact on the search for life and receiving communications from the articulate members of such a cosmic family. And based on the precedent of our modeling, we have use as a road guide in this inquiry the Drake equation, plus standing by for radio signals from beyond the solar system.
To frame the latter effort, using our own geological and biological history we have made Project Ozma a pivotal point. And as we recount it to ourselves it makes sense of a sort. But at the same time, it is easy to imagine that sentience could have taken a much different route to reach a point where it would knock on our door.
Our solar system history of 4.5 billion years until project Ozma is representative, of course. But we don’t know how or with what sort of variation. It could be, for example, that some creature on Jupiter had invented a radio transmitter a long time ago and it was well received by its neighbors in the Belt or Zone, but the ionospheric interference there was prohibitive for deep space transmission or reception.
A science fiction story there, perhaps. But when we consider all the other differences about Jupiter vs. Earth, we would not expect to see a biped sitting at a desk in a chair with rollers and a reclining back typing at a keyboard. Both Jupiter and Earth could be considered representative or illustrative of exoplanets with rich chemistries, however. And some jovian or neptunian exoplanets could be considered habitable – for something.
So that is kind of a lead in to another idea. Milestones in terrestrial biological and geological history could be altered considerably for either terrestrial or jovian exoplanets. To take one case, the jump from prokaryotic to eukaryotic cells and the cooperative merger and specialization in collective operation of the latter. If life on Earth extends back as far as to when it cooled off enough to survive, the wait for eukaryotic cell development is somewhat discouraging. Let someone correct me, but before a billion years ago, how much was there? Any? The trouble is there is no specific time requirement for this ascent.
Then, in addition, if eukaryotic life arrives on Earth: After it cooled off it formed? Or it survived in-fall from somewhere else? While the latter evades the local origin issue, is one arrival any more “miraculous” than the other? At least the second allows nature more time and lab space to perfect the packaging and process.
Pre-biotic or “nearly biotic” chemistry arguably existed in cooling circumstellar or protoplanetary disks. It would appear that there is room for saying that pre-planetary formation chemistry of such nature would argue favorably for giving life a good send off on a newly formed planet. Were there survivable viruses at the boundary of life and non-life, life in a sense would seem more universal. And perhaps these systems are alive in a spontaneous sense. Viruses though complex are simple enough that they can re-emerge, not only in time on Earth but across space. If there are no living hosts, then perhaps other viruses…
But on the other hand, we are forced to believe that life got started here with a very local event, then ascended to eukaryotic cells, and eventually to us after running an incredible gauntlet, evading thunder lizards, volcanoes, tidal waves and successive extinction events ( pictured in Fantasia with Stravinsky’s “Rites of Spring” musical accompaniment. If that is what it takes to find cognitive awareness in this galaxy or beyond, then it would seem life beyond prokaryotic would be unlikely in any large local sample.
Clues pro or con on this matter are likely located within the solar system: Mars, Enceladus and some other sites. If we include pristine comets, I think they would give some indications about these other star systems in our neighborhood in their C-H-N-O based chemistry.
The Oort Cloud is a solar inheritance, but since the sun formed in a larger cloud shared with other coalescing stars, that medium could have introduced the same life seasoning into those star systems too. Which brings us back to the populations of stars discussed above. For the common stellar forming cloud, the output would be stars and circumstellar disks of varying mass, resulting in varying evolutionary histories from there. Mixing of the stars into the galactic medium would mean neighbors of varying age. The earlier generation clouds would be less enriched with supernova or planetary nebulae products, but likely not bereft of biological building blocks.
In most of these discussions it is easier to argue for considerable variation. But, in sober summary to suggest I have not lost all my marbles, the most critical argument is whether our situation is unique or repeatable enough to expect detection of other life, perhaps even contact it.
Estimates are sloppy, but probably well over a 1 bya, and possibly 2 bya for the emergence of eukaryotes. It is the metazoa that are perhaps more important, and while there are hints that they existed well before the Cambrian, we are only sure about their emergence around 550 mya..
If we are trying to make estimates e.g. Drake Equation, I suspect temporal coincidence as a factor is a very small fraction indeed, indicating the opportunity (for briefly existing humanity) to meet another civilization is very small. I wonder if there is a way to detect expired civilizations at great distances?
Born in 1949, each year I experience an asymptote up to certainty for the probability of us being alone as an intelligent, communicating species in this galaxy. This is not at all how things seemed to be in the 1950s, and frankly it is a bit of a bummer.
We now know that life can begin very early. We now know about extremophiles. That there are more stars in our galaxy than we thought. That there are more exoplanets than we thought. That our galaxy is much older than we thought.
One might think that this little list would occasion optimism, but it has the reverse effect – that despite all these newly-perceived advantages, we still find nothing.
Three historians walk into a bar, an American, a Briton, and a Chinese.
They begin to discuss the influence of Napoleon Bonaparte on the history of the contemporary world.
The American asserts that Napoleon was an exceptional force of nature, an extraordinary individual who, for better or worse, fundamentally changed everything.
The Brit says that the social conditions and historical forces of the late 18th century were already in place and and the modern world would emerge pretty much as we know it today regardless of the presence or lack of any particular personality.
The Chinese scholar thinks about it for a while and says; “I think it is to early to tell yet.”
—
Its an old story, available in many variations and applicable to many topics, but that is the case for a reason.
Its been only a little more than a century that we’ve even known about the existence and nature of electromagnetic radiation (Maxwell) and somewhat less than that how to produce and detect them. The idea that it was technically feasible to escape the pull of planetary gravity and travel through the solar system was not even conceived of until about a century ago (Tsiolkovsky), and not seriously considered until after I was born (1947). How solar systems are born and the chemical nature of life and evolution was still a mystery for a good part of my lifetime.
We simply have not been playing this game anywhere near long enough to be impatient because we still have no answers. We haven’t found anything because we’ve barely started looking! Back around the middle of the last century we were just too optimistic. My apologies to Frank Drake and Carl Sagan.
I suspect that other intelligent civilizations are highly distant from us, in both space and time and that we may never find another one. There may be only a handful of intelligent (spaceships and telescopes) species at any one time in our galaxy, so it is not surprising we haven’t run into one after a mere century of half-hearted, inept searches. But its a bit premature to give up now. We’ve barely started.
H.C.,
Your observation sent me off in several directions! First, the version I had on that final retort years ago, was that it was Chou En-Lai, Premier of China and
Mao’s comrade who had responded to the query “What was the impact of the French Revolution.”
Possibly at a press conference. If so, whether he moved on to another point or left the room, I am still curious. This week the consequence would appear to be that the FR gave everyone something to sing at summer Olympic ceremonies. But one could imagine just as well, that in Earth’s remote future, amid desolation, archeologists finally cracking the code of a last remaining remnant of our civilization strike a gold vein: “Three guys went into a bar…”
Over two centuries ago (1818), Percy Bysshe Shelley wrote of the mysterious ancient Egyptian civilization in a manner nearly as cryptic as its monuments must have appeared to the non-Pharoahic public back then. It’s hard to decide what to provide as an excerpt; so here is the poem in entirety:
I met a traveller from an antique land
Who said: Two vast and trunkless legs of stone
Stand in the desart.[d] Near them, on the sand,
Half sunk, a shattered visage lies, whose frown,
And wrinkled lip, and sneer of cold command,
Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things,
The hand that mocked them and the heart that fed:
And on the pedestal these words appear:
“My name is Ozymandias, King of Kings:
Look on my works, ye Mighty, and despair!”
No thing beside remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.
Likely, Shelley was not fully briefed on the work of Napoleon’s
science team ( e.g., Jean-Francois Champollion and others decoding the Rosetta Stone) what publishing delays and the consequences of the decades of war could have wrought. But the expedition eventually published detailed archeological reports. In one form, I found a paperback copy of 750 pages, each page a color or black and white print of ancient Egyptian buildings, writings and artifacts. Commissioned by order of Napoleon in a manner in to which pharoahs could relate . (Description de L’Egypte – Taschen Books, 2007,
http://www.taschen.com).
So that might have been an immediate consequence of the French
Revolution.
Though the compendium was the result of the 1798-1801 expedition, I suspect that Shelley did not have access to all the eventual findings, what with his composition’s publication in 1818, Napoleon’s other overseas obligations – and that Champollion was still deciphering the Rosetta Stone into the 1820s.
But I’m still curious if Chou En-Lai had something else of more immediate concern he wanted to address or merely walked away.
The Green Bank meeting might have been influenced by motivated reasoning. If you want to get time to do a search for ETI, you want the answer for “How many extant, communicating ETIs are in our galaxy?” to be in the many 1000s for the probability of success to be reasonably high enough to justify the search.
Bracewell had suggested probes might be sent by ETI. There were suggestions of a “Galactic Club” of communicating ETI civilizations. Drake’s equation could produce many orders of N from 1 (us) to millions, depending on the probabilities and length of communicating technological civilizations. Even today, those probabilities and numbers get really speculative from f_l, f_i, f_c, and L. Even if we accept that f_l proves very high ( [HZ] planets with life ), we have no idea whether f_i is vanishingly small, or eventually likely. f_c could be high if any civilization acts as we do, or very low if they take a very different path. L could be short for many reasons, or very long. We have no idea.
Given the uncertainties, which included f_p, and f_e at the time, it isn’t hard to think that optimistic guesses could have driven the high value for N which led to an extended Project Ozma to Ozma II and later to SETI.
Our only example is us so far. The proliferation of metazoa was generally considered to have started less than 0.6 gya. H. Sapiens only emerged around 200 millennia ago, with archaeological and recorded history well within 15 millennia ago ( 0.0025 % of the time since the current metazoan phyla emerged ). Path dependency may make this a low-probability event. If we wreck our current civilization, how long before we recover as portrayed in “A Canticle for Leibowitz”?
Even if life proves transient, the overlap in time is far longer by many orders of magnitude, compared to technological, communicating, ETI, unless such civilizations have solved their longevity.
Intriguing. This means that when interstellar asteroids pass through the Sol system – or if they have been trapped in stable orbits e.g. in the Kuiper Belt – we could be looking at remnants of a metal-rich star system up to 13 billion years old. That implies a higher-than expected possibility of finding mine workings, space junk, disseminated messages, nanites, and so forth, right here in our own system.
Thank you, Henry. This is the same conclusion I’ve come to and it’s very well-stated here.
The Kuiper belt is a rather large volume to search. Assuming viable [propellantless?] propulsion, how long would it take to do close surveys of each body assuming a certain radius > X?
OTOH, if we are looking for microbial life, assume it is spread by being wafted off the exoplanet and some being captured by icy bodies. If these are ejected from the system and some enter our system, like ‘Oumuamua or Borisev, then samples taken while in transit, may just have microorganisms.
Similarly, the same could be said of our long-period comets. If they are pristine when perturbed, it is possible they might have ancient terrestrial bacteria on their surfaces.
These possibilities are long shots but just might reveal interesting biology, either from another system or reveal early examples of our terrestrial life with their frozen genome sequences.
It is hard to estimate how quickly history could move forward. Just getting a number of satellites launched is difficult, since it is less than the number currently in orbit and much more than the number of launches. SpaceX says it has launched over 6000, and the Russians and U.S. more, so to an order of magnitude, let’s say 100,000 in 67 years. If we force an exponential model onto that, and assume the same applies to the Kuiper Belt, and assume “hundreds of thousands”, let’s say a million, Kuiper Belt objects, and most implausibly, assume the survival of human civilization, then the progression that began in 2015 with New Horizons might lead to the survey of all these objects by 2095.
When we put on the wizard’s cap and try to prognosticate this way, the specifics are inevitably blurry. But I assume much could be done with the combination of a space catapult like SpinLaunch, an orbital tether far short of a true space elevator, and low-thrust optimal trajectories.
If a practical means of decelerating them can be worked out (and note that such probes would already need to survive high acceleration to work with SpinLaunch), the probes Earth sends would remain on the bodies (though inert), and if a former civilization thought the same way, our probe just needs to be able to find theirs to get the ball rolling.
@M.S.
Good to be reminded that exponential growth can deceive us about possibilities. However, there is a great difference between launching satellite swarms and vehicles of the New Horizons type that must not only reach the target within the 30-50 AU Kuiper belt but also decelerate and possibly land too. Maybe Starship-sized vehicles, carrying many probes to be dispersed on the outward journey are the way to go, but each must be able to decelerate to a near zero velocity by the time they reach their target. However small the probe, it needed to shed 10s of km/s velocity using some sort of propellant drive. The rocket equation is not very forgiving.
If you have any thoughts on how this may be achieved, propellant or propellantless, I would be interested.
This is only sci-fi guessery, but I wonder if the probe could melt out a flat spot on an asteroid with a laser as it approached, then smash into it with a carefully shaped projectile moving in advance of the probe, then use a shock-absorbing impact shield to smack into bits of material shot out toward it in a straight line, before it finally gets to the surface. If I use very, very wishful thinking, the probe ought to decelerate repeatedly by these collisions at some “slow” (x10000g or less?) pace, and crash onto the surface of the asteroid intact. :) I doubt this is the real solution, but if they’re alive in 2095 I bet they can do things I can’t imagine right now.
I don’t understand the need for a Big Ferry Rocket – couldn’t the SpinLaunch containers could act as “MIRVs” just as easily?
@M.S.
Spinlaunch or other approaches like magnetic launch would be best either on an airless body like the Moon, or coupled in pairs in orbit so that the payloads are launched in opposite directions to negate any momentum transfer to the launcher.
Deceleration at the target may prove very difficult. Another way is to harness the miniaturization of probes and have a swarm released at the target with a multitude of sensors whose data can be stitched together to provide an encompassing image and analysis of the target and sent back to Earth. If any of these swarms detected something interesting, then send a targeted probe and lander.
If what we are looking for is a Bracewell-type probe, then this presents another problem. We would need to do extensive space sweeps, possibly in a spherical volume around the sun as there is no a priori reason why it should remain near the ecliptic.
May exponential technology development and capabilities save the day.
Great article. Paul, are all ancient stars red or white dwarfs of some kind?
Some years ago I tried to visualize civilizations coming and going:
See https://vimeo.com/manage/videos/195239607
But I’ve become very very skeptical of the densities represented in the above animation and this article made me realize that if EM signals can cross the entire galaxy in ~100,000 years, and if civilizations are separated by millions of years, their residual signals are long gone unless beacons were set up that last eons — of which we have not seen or heard.
“…are all ancient stars red or white dwarfs of some kind?”
Interesting question, Scott. I don’t know how these stars break down but given the comparatively short lifetime of G-class stars, I would think the M-dwarfs would predominate in this population. Maybe someone can point us to a source for what the percentages are thought to be.
Red dwarfs can live a long, long time, but they aren’t necessarily old. There are probably many red dwarfs being born right now, but they will all live a long time.
White dwarfs are the end product of stellar evolution for most stars, but whether they are old or not depends on the mass of the star when it first formed, as well as WHEN it first formed. Massive stars go through their evolutionary stages very quickly, the really heavy ones (up to a hundred solar masses) last only a few million years before they evolve off the main sequence, go supernova, or lose most of their mass to the interstellar medium as planetary nebula. They wind up as white dwarfs. Or neutron stars, or black holes.
Red dwarfs are low mass stars, (0.1-0.7 solar masses) and they evolve very slowly. No one knows how they wind up because the universe isn’t old enough for any of them to have died yet.
In general, all stars undergo more or less the same evolution. They are born, they stay on the main sequence until they run out of fuel, then they become red giants for a short period of time. Those above above a certain mass go supernova. The others eventually become white dwarfs. However, the time it takes for a star to undergo this evolution is highly dependent on its initial mass. Massive stars die quickly, light ones can last forever. To make things even more complicated, the rate at which stars form has not been constant since the formation of the Galaxy. It is thought there was a burst of star formation during the early universe.
Our sun was born about 5 billion years ago, quickly reached its current size and luminosity (the main sequence, where its mass-luminosity position on the main sequence is determined by its initial mass) and will stay there for about another 5 billion years. After that, it will start running out of fuel and swell up to supergiant size and brightness for a short time, then fade into obscurity, probably as a white dwarf. Although our sun is currently brighter and more massive than most stars, it is nowhere near as bright or as massive as the brightest stars. The stars increase explosively in number as they become fainter and less massive. The mathematical curve (the Mass Function)that describes the number of stars (at birth) as a function of their initial mass is not well known, but it is probably pretty steep at the low end.
The picture is complicated because we only see a snapshot of this process, these events take millions, billions of years. Also the picture is complicated by binary stars (which can affect their companion’s evolution). The chemical composition of the birth nebula no doubt plays a major role, too. Observationally, unraveling all this is difficult because the vast majority of stars are old, small and faint, but the young, big, bright ones can be seen at immense distances, so you get selection effects.
As for the percentages and distributions, I don’t really know. I don’t think anyone really knows. Our lifetime is so short, we have to surmise how stellar evolution yields the stellar populations we see. Its like walking briefly through a climax forest and trying to make sense how the populations of different trees changed as the forest slowly evolved into a stable, final configuration–and this may not even be its final, stable configuration!
It is hard to tell how massive a star is, or how old it is, or even how bright it is. These factors all influence each other in complex ways, and the problem is complicated by the fact the commonest, faintest stars are the hardest to see unless they are really close to us. So untangling all these parameters, and determining how they change over time, is still an ongoing process. Stellar structure and evolution are not distinct disciplines, each intimately affects the other, and both influence the chemical evolution of the galaxy. They all play a role in the distribution of life and intelligence in the cosmos.
Our planetary system has done some celestial body tossing into the Milky Way galaxy of its own…
https://www.space.com/saturn-threw-comet-out-of-solar-system?utm_medium=social&utm_content=space.com&utm_campaign=socialflow&utm_source=facebook.com&fbclid=IwY2xjawEbTlBleHRuA2FlbQIxMQABHTKmTX0BOYD54ZGAirS-oBYKt9MhN9NHFrKKJ6RRmOlpxnBrZTKxMZdA9w_aem_nH3KGG4252BszEQN8GNIFw
If there are 400 billion stars in the Milky Way galaxy and most of them are presumed to have systems surrounding them, I am certain there are far more bits out there than we imagine. We should be seeing more such objects, statistically speaking.
I dunno, Larry. No doubt there are lots of fragments of other stellar systems flying around the galaxy, but the spaces between the stars are vast. Also, these splinters are hard to see, only when they fly near the sun do they reflect enough light to be detected, and at perihelion they are moving pretty fast, we don’t have too many survey programs designed to catch them. The recent passages of Yomama and Borisov will probably rectify that! The velocities of these objects as they approach the Sun from deep space will probably be roughly comparable to the high-velocity (halo) stars that crash through the galactic disk periodically. But near the sun, they won’t be noticeable for more than a few weeks at a time.
As for those who are captured by our solar system, we have to identify them first (peculiar orbits?).
I don’t doubt there are a lot of these interlopers out there, but catching them is not going to be easy, and by the time we find them in the mass of data collected by our automated survey systems, they will be long gone.
This new telescope will help with our finding more interstellar visitors:
https://www6.slac.stanford.edu/news/2023-08-10-rubin-observatory-will-detect-abundance-interstellar-objects-careening-through-our
If we’re ruling out reds, as I’m increasingly inclined these days, here’s what we got in our 10pc bubble: GJ 892 is 11 Gy. delta Pavonis is over 6.6 Gy. 61 Virginis is 6.1-.6 Gy.
GJ 892 will meet our criterion as a non-M ancient star at +0.11 Fe/H. (Too high and these stars start cooking up warm Neptunes which we exobiologists don’t want.)
But I’m still worried.
Tectonics will stop on Earth in the 5 Gy’s. Any Earthlikes on the stars I noted above are nontectonic. No tectonics means the planet goes more Venuslike in its activity: volcanoes and maybe the odd uplifted plateau; and even the volcanoes will likely peter out. Nutrients will run off into their oceans. Plants die. Desert worlds (maybe with ruins?).
I am afraid that the Ancient Ones might end up being us, after all.
Forgive me for going off-topic, but…
Are there any official first contact protocols?
If we ever do come across solid evidence of ETI, say by receiving a signal, recovery of hardware, telescopic observation, are we certain the news will
be released to the public without censorship? Can we be confident some government agency will not try to cover up the discovery in order to further its own sinister motives, or “for our own good”, or to “prevent public panic”?
I understand there are informal procedures among researchers to carefully verify and then publicly release a discovery using multiple, independent, observations, but is it possible (at least in some countries) the authorities will step in and clamp down on “national security” grounds.
Are there laws, generally agreed-upon standards, journalistic procedures etc in place? Is there anything official? Is any of this written down anywhere?
I’m not talking about any silly Area 51 conspiracy theories here, but too many people in power seem determined to control or exploit information these days. I would not be surprised if there is a Plan somewhere ready to be implemented on a moment’s notice.
Henry, let me quote myself from a while back:
“The First SETI Protocol was drawn up in the 1980s to address the issue, laying down procedures that begin with notifying the worldwide SETI community, verifying the potential alien signal, then announcing it to the public. No reply would be sent without first establishing a global consensus.
“That latter, of course, is the sticking point. As Grinspoon explains, a Second SETI Protocol should have tuned up our policy for sending messages from Earth, but arguments over whether it should only affect responses to received messages — or messages sent before any extraterrestrial signal was detected — have complicated the picture. Language calling for international consultations before we make further deliberate transmissions was deleted from Michaud’s draft of the Protocol when the Permanent Study Group of the SETI subcommittee of the IAA met last year in Valencia.
“Grinspoon’s article is a calm assessment of the current situation, and I recommend it to you.”
The reference to Grinspoon can be found in “Active SETI and the Public”:
https://www.centauri-dreams.org/2007/12/27/active-seti-and-the-public/
I am convinced that these protocols exist because they are part of the sociological development of the human species. It’s a bit like transposing our models of society into space. We need to anticipate in our technological societies because they may be too complex.
I do not think I am wrong in saying that the societies close to nature are more in the instant present even if there is a conceptualization rather in the religious or mythological sense of the word.
Conceptualizing these senarios with ETI is a psychological way to master the world in the broad sense of the term: if there is such an event; I will do such thing. We have thousands of senarios like this, you will notice that they come mainly from the military…
Did prehistoric man envisage senario as complex? I do not believe that he was endowed with a great intelligence. Why? because it had to essentially ensure its means of subsistence in the immediate therefore less leisure in a harsh environment; the relationship to time was different.
The unexpected event (f. example a tiger attack on the group) had to be managed “brutally”: the fight or death. Not too much time to conceptualize although he was able to learn and inventer hunting or defense techniques. Great subject…
The real question of contact protocols with an ETI makes me smile a little bit because we don’t know at all what we will have in front of us. I do not denigrate: because it is worth something that nothing at all but I believe it is mainly because the human species wants to dominate…or survive.
Evoking these protocols is one thing, but do we have resilience protocols if an ETI were to arrive?
these strategies envisage means of contacts and then bases of exchanges the whole in a progression that is either friendly exchange or fighting.
Do these senarios consider contact with an entity like in Solaris? Would they be credible and especially applicable in front of an ETI that would master all our data of all our evolutions and why not would have the power to extinguish our sun as we blow a candle…let’s be crazy!
would they be applicable to a contact not of one but of two or three ETI that would annoy our eyes at the same time? Not on…but the human needs to be reassured: space is so big !
…so why shave in the morning, would add W Allen :)
Stars, their history and characteristics are critical to the evolution of life, and also the direction it takes. Ants have been around for a hundred million years but we split from our common ancestor with the chimps six million years ago. Binocular vision, depth
perception, stereoscopic vision, and 3-axis shoulder movement (which made possible projection of weapons and killing at a distance) were dependent on a continuous overhead tropical forest canopy.
While there may be alternate pathways to the acquisition of these characteristics, absence of a forest canopy may exclude this pathway.
Even after stars and planets are formed there are many ways in which intelligent life may or may not arise.
“Binocular vision, depth perception, stereoscopic vision, and 3-axis shoulder movement (which made possible projection of weapons and killing at a distance) were dependent on a continuous overhead tropical forest canopy.”
True, but our most recent evolutionary history was not in the canopy, but the savanna. The characteristics useful for the rain forest turned out to be valuable, but not essential, for survival on the grasslands.
Adaptions for one environment can sometimes be valuable in another, totally different one. Not only that, but adaptions like “Binocular vision, depth
perception, stereoscopic vision, and 3-axis shoulder movement” may have only been necessary but not sufficient conditions for intelligent life, and only in OUR case. The hand, useful for grasping branches and tools could be replaced by cephalopod tentacles. Binocular vision might be useless to a sentient creature living in the deep, sunless sea. A sentient squid does not need a three axis shoulder, or a bipedal posture.
We can see how our lives in the trees and the plains helped form our technological culture, but its possible other organisms might achieve sentience in totally different environments. And many creatures evolved from arboreal to steppe environments never developed intelligence of any kind.
Its easy to associate our evolution with how we got smart, but there are other ways too. Other intelligences may come from totally different histories.
I’d be willing to put good money on a wager that if we ever do encounter ETI, they will not be apes like us. They won’t even be humanoid. They will be very different, and perhaps from an evolutionary lineage with terrestrial analogs but not our primate model. Or as one wit put it “like a cross between a tarantula and a jellyfish”.
A lot of other things went into the design. Pyrrole rings arrayed as porphyrins with a central ferrous atom to form heme – the oxygen carrying moiety of hemoglobin molecule. Hemoglobin packed into red blood cells to reduce viscosity from higher blood hemoglobin concentrations. A circulatory system to move the blood around to sustain a large brain. A respiratory system transferring oxygen at atmospheric partial pressures to the blood.
Binocular vision, stereoscopic vision and depth perception adding to the understanding of the environment. All of these were dependent on brachiation, as was 3-axis shoulder movement which permitted projection of objects in all directions, thereby increasing interaction with the environment.
An opposable thumb with a strong pinch and stereognosis contributed to toolmaking which in turn contributed to the control of fire, leading to cooking, softening of food, reduced mastication, shrinkage of teeth and alteration of the airway, contributing to the development of speech, a modulation of sound from the larynx. Upright stance altered the orientation of the oropharynx to the laryngopharynx, also contributing to the development of speech.
It is highly improbable that this sequence might be repeated elsewhere, and another intelligent species almost certainly would be quite different from us.
Yes, indeed, such may be the next intelligent creature we find, and its history would involve a different sequence of events. The end result of that sequence would be a creature aware of its surroundings, able to interact with its surroundings, and to communicate with like creatures.
I just love Brian Lacki’s diagram, as it show graphically what I’ve pointed out here earlier.
That even when one stellar system not only develop life, but also a civ.
There’s nothing to say that two civs will appear at the same time, or even that close in time that radio or any other emissions will be picked up – but instead have passed us unheard tens of hundreds of millions of years ago.
As for possible technosignatures, my favourite is still Przybylski’s Star, sometimes labelled Ap, with the ‘p’ for peculiar, but it’s actually not of spectral class A, but a slowly rotating F3 star which make it even more weird. Low in metals, but an abundance of elements not supposed to be there at all. Did it once have a Dyson swarm, sphere, ring used to produce exotic elements that since have collapsed?
Jokes aside, it is still so odd that Przybylski’s Star might be that sign in the sky we’re looking for.
@Andrei
Yes indeed, that is a remarkable object! I looked it up and its properties definitely suggest something very strange is going on there. Are you aware of any other stars with similar characteristics? That is certainly a strong candidate for technosignature status. Thanks for turning me on to this dude.
Hello Henry.
While Przybylski’s Star share some characteristics with Ap stars, including the slow rotation, it’s the only known star to have spectral lines of elements in the actinide series.
Reference: https://academic.oup.com/mnras/article/477/3/3791/4964763
Hi, Andrei
I’d heard before about the stars with Technetium in their spectra, and how for a while it was conjectured this might be a technosignature. But this system is really intriguing, particularly since “it’s the only known star to have spectral lines of elements in the actinide series”.
Lets hope that technetium is of the variety with a halflife of 4,2 million years. Else we got a civ obsessed with medical diagnosis on our hands.
Technetium can be produced naturally when Molybdenum capture neutrons.
The stars that show the technetium line are however often red giants, meaning they have gobbled up one or several terrestrial type planets when they expanded and such planets even might have had plenty of actinides in their cores, so the Technetium might be the decay product of thorium and uranium. So when found at a red giant type star, it’s not a rule breaker – but one where we instead could use to figure out the chemical make up of the cores of the previous planets.
And now that we’ve also noted some other stellar classes that have had a bite of their planetary family, stars with other chemical imbalances might also be explained.
And it’s here IMO where Przybylski’s Star stand out, if a terrestrial planet would have fallen in, it should have had an iron+nickel core. And we don’t see iron.
So to make my final post on this matter I link to a previous post on Przybylski’s Star here from 2017: https://www.centauri-dreams.org/2017/03/28/the-challenges-of-przybylskis-star/
“Technetium stars” are asymptotic-giant-branch (AGB) stars, which are low-to-intermediate-mass stars in the very late stages of evolution, which will evolve into planetary nebulae and white dwarfs.
The technetium is a clear signature of the combination of internal nuclear processes (in particular, slow-neutron-capture processes, which can produce Tc-99, with a half-life of 200,000 years) and occasional deep convection which reaches down into regions where nuclear reactions have been operating and “dredges” them up to the surface.
This process is sufficiently well-understood and modeled that we can attribute the presence of technetium to the result of a particular stage in the evolution of ABG stars (“third dredge-up”).
So the technetium we see in some stars is best understood as something made recently (i.e., within a few million years) in their interiors and brought to the surface by deep convection, not something accreted from outside.
Another phenomenon that “might be a tech signature” falls to a natural explanation…
Statistically, it is almost impossible that life in the universe is reformed, from the assembly of amino acids and other basic compounds, as we do, that is to say in the form of a vertical symmetry (2 eyes; 2 arms etc.) It would be an absolutely extraordinary coincidence. Even if there were a biological assembly quite similar, the simple fact that the gravities are different on the planets would automatically change the final form of this life.
The considerations developed here are as always interesting but remain centred on the question of technological development, that is to say, on the material aspect of things.
Could it be that there should be a distinction between several things to clarify the debate ?
a) the development of “simple” life in the sense solely biological = exobiology. As Henry says and his excellent story with Napoleon: we can not know what “the mixture” will give, only the time factor will count and that’s what we lack. In this sense I think we must think the search for life elsewhere not for ourselves and in the immediacy (would be nice) but by leaving our own trace or a signal (how? ) and why not “instructions” to our three distant descendants if that poses the question of our evolution…or replacement. Today, we are reduced to speculations on a few observed bases.
b) the technological development of what could be a “life” and here we have already evoked the autoreplication of machines whether our own or those of other ETI if they have evolved in this direction. This point brings us back to the question of the mastery of matter, energy and resources.
In a way it’s a reassuring vision that we like, because it reduces our uncertainty; we build objects which gives us a kind of power over things. It is reassuring, because if we discovered an extraterrestrial OBJECT we would feel that we would have the ability to disassemble it; to understand it and “communicate with it”.
Conversely, we are anxious at the idea of the unknown in the universe whose immensity of parameters we cannot control. We are unfortunately prisoners of our jar-universe like the goldfish in the aquarium. yes I know it’s frustrating;)
The question is to define protocols: what are we looking for? how? why? and to do well we would have to repéter the thing by conceptualizing other universes (multiver; multi-dimensions; different univeselles constants etc. It is a work of titan; we only begin to create some computer models that allow these modelling…
Why would an ETI systematically develop towards technology? if you look at a flower, it is a living organism “biological” that has perfectly adapted to its environment that develops, colonizes, competes with other species, uses energy, rather cleverly, all without any “technology”.
You will say: it is because we are all stardust as Hubert Reeve said. it is simply a medium in another medium. The question is: what is our field of research? The wider it is in the universe the more uncertainty increases, the harder it is the more time we need. (or maybe a little bit of fate, who knows?)
in this sense exobiology in search of simple organisms seems to me a good track but condemns us not to know the next step.
Conversely, a direct contact with an ETI would probably inform us by default about its evolution that we could deduce. (it should be done quickly in the case of the alien of Ridley Scott:D)
It is therefore also necessary to distinguish the development of life on its host planet and OUTSIDE its planet This second case, generally assumes a “technology” except to suppose a biological compound that can resist in the interstellar environment
(cryogenization to resist therefore inactive?) or a form of “life” capable of evolving without artifact in space ‘ that is perfectly adapted to this hostile environment according to our criteria: see SF heading?
Space seems to be only a kind of very dynamic matrix filled with matter and energy that allows to generate life from time to time, but which is NOT life.
One can therefore observe indefinitely the matter and the forces in presence – and it is very good – but time that we do not fully and perfectly understand the “mechanism” of life in all its forms we will be reduced only to speculate.
Will we understand this great and mysterious question one day? may be? will it be for the better or for the worse? It is up to each of us to make our own opinion. Personally, I believe in randomness ;)
Stellar oddball: Nearby star rotates unlike any other
By Robert Lea published 15 hours ago
V889 Herculis doesn’t rotate like any other star, defying stellar models.
https://www.space.com/oddball-star-rotation-v889-herculis
If Advanced Civilizations Using Quantum Communications, Is That Why We’ve Never Seen Them?
August 6, 2024
by Mark Thompson
Establishing communication with an alien intelligence is one of the news items I, and I’m sure many others, long to see. Since we have started the search for advanced civilisations we have tried numerous ways to detect their transmissions but to date, unsuccessfully. A new paper suggests quantum communication may be the ideal method for interstellar communication. It has many benefits but the challenge is that it would require a receiver over 100km across to pick up a signal. Alas they know we don’t have that tech yet!
The search for alien signals has been undertaken under the banner of the search for extraterrestrial intelligence or SETI for short. It began in 1960 when Frank Drake commenced the first search. It was of course not fruitful but since then, large radio telescopes have been used to undertake searches. There have been many projects but of particular interest has been Project Breakthrough. It has used advanced technology and international collaborations but still there has been no success.
Full article here:
https://www.universetoday.com/168040/if-advanced-civilizations-using-quantum-communications-is-that-why-weve-never-seen-them/
The paper is here:
https://arxiv.org/abs/2408.02445
On Interstellar Quantum Communication and the Fermi Paradox
Latham Boyle
Later SETI researchers have said that the famous Wow! signal of 1977 would probably have been rejected by more modern search programs, but here we are – and it does generate publicity for SETI efforts…
https://www.space.com/39251-on-this-day-in-space.html
This is an excellent documentary on the signal from 2022…
https://www.youtube.com/watch?v=TjQUucV83w4
What was done to Big Ear and why is a travesty, however…
http://www.bigear.org/
Was the Wow! signal a hydrogen maser? The title and essence of the of the article below certainly seems to think so:
https://www.universetoday.com/168176/the-wow-signal-deciphered-it-was-hydrogen-all-along/
The paper may be found here:
https://arxiv.org/abs/2408.08513
To quote:
“We hypothesize that the Wow! Signal was caused by sudden brightening from stimulated emission of the hydrogen line due to a strong transient radiation source, such as a magnetar flare or a soft gamma repeater (SGR),” the researchers write. Those events are rare and rely on precise conditions and alignments. They can cause clouds of hydrogen to brighten considerably for seconds or even minutes.
My comments:
What is so frustrating about the Wow! signal of 1977 is how limited the resources were when it was detected at the time. Thus, we are left with an endless mystery that cannot be determined exactly unless the signal ever returns.
My concern is that while many focus on this Wow! signal, I have read about much better candidates over the following decades which have been largely ignored and forgotten. Another factor in what makes past and modern SETI so limited and frustrating.
https://astrobiology.com/2024/08/seti-institute-starts-first-low-frequency-search-for-alien-technology-in-distant-galaxies.html