From Open Minds TV:
In the search for intelligent extraterrestrials, scientists listen for incoming radio signals and they hunt for Earth-like planets. Some scientists are also looking for megastructures constructed by aliens.
NASA’s Kepler space telescope searches for planets using the transit method–Kepler’s sensors detect dips in brightness caused when an alien planet passes in front of its star from Kepler’s perspective. And this same method is used by scientists searching the universe for alien megastructures.
Simple illustration of a Dyson Sphere. (Credit: Vedexent/Wikimedia Commons)
According to Universe Today, astronomer Geoff Marcy, who was recently appointed to the new Watson and Marilyn Alberts Chair for SETI (Search for Extraterrestrial Intelligence) at the University of California at Berkeley, was awarded a grant to hunt for evidence of Dyson spheres using Kepler data. A Dyson sphere is a theoretical megastructure envisioned by theoretical physicist Freeman Dyson consisting of a giant array of solar panels that would surround a star to harvest its energy.
Scientists hunting alien megastructures are also looking for theoretical structures known as ringworlds. Universe Today explains that ringworlds “would consist of a giant ring in orbit around a star, constructed comfortably inside the star’s habitable zone.”
Whether alien megastructures actually exist is unknown. But as Universe Today points out, “The possibility alone is exciting enough to make it worth continuing to look.”
Actually looking for Ring Worlds and Dyson Spheres would be relatively easy using Kepler data since the Kepler probe uses occluded starlight to detect transitioning alien planets.
The theory is that advanced alien tech would be larger constructions than normal planets and thus, the starlight would be blocked longer. That suggests super-alien cultures.
Sigh. What ever happened to old fashioned UFOs, lol?
From Centauri Dreams:
Astronautics pioneer Robert H. Goddard is usually thought of in connection with liquid fuel rockets. It was his test flight of such a rocket in March of 1926 that demonstrated a principle he had been working on since patenting two concepts for future engines, one a liquid fuel design, the other a staged rocket using solid fuels. “A Method of Reaching Extreme Altitudes,” published in 1920, was a treatise published by the Smithsonian that developed the mathematics behind rocket flight, a report that discussed the possibility of a rocket reaching the Moon.
While Goddard’s work could be said to have anticipated many technologies subsequently developed by later engineers, the man was not without a visionary streak that went well beyond the near-term, expressing itself on at least one occasion on the subject of interstellar flight. Written in January of 1918, “The Ultimate Migration” was not a scientific paper but merely a set of notes, one that Goddard carefully tucked away from view, as seen in this excerpt from his later document “Material for an Autobiography” (1927):
“A manuscript I wrote on January 14, 1918 … and deposited in a friend’s safe … speculated as to the last migration of the human race, as consisting of a number of expeditions sent out into the regions of thickly distributed stars, taking in a condensed form all the knowledge of the race, using either atomic energy or hydrogen, oxygen and solar energy… [It] was contained in an inner envelope which suggested that the writing inside should be read only by an optimist.”
Optimism is, of course, standard currency in these pages, so it seems natural to reconsider Goddard’s ideas here. As to his caution, we might remember that the idea of a lunar mission discussed in “A Method of Reaching Extreme Altitudes” not long after would bring him ridicule from some elements in the press, who lectured him on the infeasibility of a rocket engine functioning in space without air to push against. It was Goddard, of course, who was right, but he was ever a cautious man, and his dislike of the press was, I suspect, not so much born out of this incident but simply confirmed by it.
In the event, Goddard’s manuscript remained sealed and was not published until 1972. What I hadn’t realized was that Goddard, on the same day he wrote the original manuscript, also wrote a condensed version that David Baker recently published for the British Interplanetary Society. It’s an interesting distillation of the rocket scientist’s thoughts that speculates on how we might use an asteroid or a small moon as the vehicle for a journey to another star. The ideal propulsion method would, in Goddard’s view, be through the control of what he called ‘intra-atomic energy.’
Image: Rocket pioneer Robert H. Goddard, whose notes on an interstellar future discuss human migration to the stars.
Atomic propulsion would allow journeys to the stars lasting thousands of years with the passengers living inside a generation ship, one in which, he noted, “the characteristics and natures of the passengers might change, with the succeeding generations.” We’ve made the same speculation here, wondering whether a crew living and dying inside an artificial world wouldn’t so adapt to the environment that it would eventually choose not to live on a planetary surface, no matter what it found in the destination solar system.
And if atomic energy could not be harnessed? In that case, Goddard speculated that humans could be placed in what we today would think of as suspended animation, the crew awakened at intervals of 10,000 years for a passage to the nearest stars, and intervals of a million years for greater distances. Goddard speculates on how an accurate clock could be built to ensure awakening, which he thought would be necessary for human intervention to steer the spacecraft if it came to be off its course. Suspended animation would involve huge changes to the body:
…will it be possible to reduce the protoplasm in the human body to the granular state, so that it can withstand the intense cold of interstellar space? It would probably be necessary to dessicate the body, more or less, before this state could be produced. Awakening may have to be done very slowly. It might be necessary to have people evolve, through a number of generations, for this purpose.
As to destinations, Goddard saw the ideal as a star like the Sun or, interestingly, a binary system with two suns like ours — perhaps he was thinking of the Alpha Centauri stars here. But that was only the beginning, for Goddard thought in terms of migration, not just exploration. His notes tell us that expeditions should be sent to all parts of the Milky Way, wherever new stars are thickly clustered. Each expedition should include “…all the knowledge, literature, art (in a condensed form), and description of tools, appliances, and processes, in as condensed, light, and indestructible a form as possible, so that a new civilisation could begin where the old ended.”
The notes end with the thought that if neither of these scenarios develops, it might still be possible to spread our species to the stars by sending human protoplasm, “…this protoplasm being of such a nature as to produce human beings eventually, by evolution.” Given that Goddard locked his manuscript away, it could have had no influence on Konstantin Tsiolkovsky’s essay “The Future of Earth and Mankind,” which in 1928 speculated that humans might travel on millennial voyages to the stars aboard the future equivalent of a Noah’s Ark.
Interstellar voyages lasting thousands of years would become a familiar trope of science fiction in the ensuing decades, but it is interesting to see how, at the dawn of liquid fuel rocketry, rocket pioneers were already thinking ahead to far-future implications of the technology. Goddard was writing at a time when estimates of the Sun’s lifetime gave our species just millions of years before its demise — a cooling Sun was a reason for future migration. We would later learn the Sun’s lifetime was much longer, but the migration of humans to the stars would retain its fascination for those who contemplate not only worldships but much faster journeys.
Goddard was obviously influenced by his contemporary J.D. Bernal with his The World, the Flesh and the Devil which predicted Man’s spread out into the Solar System and interstellar space with artificial worlds and hollowed out asteroids.
These worlds are needed because such journeys will take hundreds or perhaps thousands of years.
Of course that brings in natural evolution and what these people inside these places will become when they eventually reach their destinations and if they’ll actually have need of them.
An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization, and emergence of novel functional niches associated with existing genes. Linear regression of genetic complexity on a log scale extrapolated back to just one base pair suggests the time of the origin of life 9.7 billion years ago. This cosmic time scale for the evolution of life has important consequences: life took ca. 5 billion years to reach the complexity of bacteria; the environments in which life originated and evolved to the prokaryote stage may have been quite different from those envisaged on Earth; there was no intelligent life in our universe prior to the origin of Earth, thus Earth could not have been deliberately seeded with life by intelligent aliens; Earth was seeded by panspermia; experimental replication of the origin of life from scratch may have to emulate many cumulative rare events; and the Drake equation for guesstimating the number of civilizations in the universe is likely wrong, as intelligent life has just begun appearing in our universe. Evolution of advanced organisms has accelerated via development of additional information-processing systems: epigenetic memory, primitive mind, multicellular brain, language, books, computers, and Internet. As a result the doubling time of complexity has reached ca. 20 years. Finally, we discuss the issue of the predicted technological singularity and give a biosemiotics perspective on the increase of complexity.
A very fine paper, except for one thing.
The authors only use one data-set to reach their conclusions.
And I believe they are wrong unless they can prove we live in a simulated universe.
From Centauri Dreams:
Jules Verne once had the notion of a comet grazing the Earth and carrying off a number of astounded people, whose adventures comprise the plot of the 1877 novel Off on a Comet. It’s a great yarn that was chosen by Hugo Gernsback to be reprinted as a serial in the first issues of his new magazine Amazing Stories back in 1926, but with a diameter of 2300 kilometers, Verne’s comet was much larger than anything we’ve actually observed. Comets tend to be small but they make up for it in volume, with an estimated 100 billion to several trillion thought to exist in the Oort Cloud. All that adds up to a total mass of several times the Earth’s.
Of course, coming up with mass estimates is, as with so much else about the Oort Cloud, a tricky business. Paul R. Weissman noted a probable error of about one order of magnitude when he produced the above estimate in 1983. What we are safe in saying is something that has caught Freeman Dyson’s attention: While most of the mass and volume in the galaxy is comprised of stars and planets, most of the area actually belongs to asteroids and comets. There’s a lot of real estate out there, and we’ll want to take advantage of it as we move into the outer Solar System and beyond.
Comets and Resources
Embedded with rock, dust and organic molecules, comets are composed of water ice as well as frozen gases like methane, carbon dioxide, carbon monoxide, ammonia and an assortment of compounds containing nitrogen, oxygen and sulfur. Porous and undifferentiated, these bodies are malleable enough to make them interesting from the standpoint of resource extraction. Richard P. Terra wrote about the possibilities in a 1991 article published in Analog:
This light fragile structure means that the resources present in the comet nuclei will be readily accessible to any human settlers. The porous mixture of dust and ice would offer little mechanical resistance, and the two components could easily be separated by the application of heat. Volatiles could be further refined through fractional distillation while the dust, which has a high content of iron and other ferrous metals, could easily be manipulated with magnetic fields.
Put a human infrastructure out in the realm of the comets, in other words, and resource extraction should be a workable proposition. Terra talks about colonies operating in the Oort Cloud but we can also consider it, as he does, a proving ground for even deeper space technologies aimed at crossing the gulf between the stars. Either way, as permanent settlements or as way stations offering resources on millennial journeys, comets should be plentiful given that the Oort Cloud may extend half the distance to Alpha Centauri. Terra goes on:
Little additional crushing or other mechanical processing of the dust would be necessary, and its fine, loose-grained structure would make it ideal for subsequent chemical processing and refining. Comet nuclei thus represent a vast reservoir of easily accessible materials: water, carbon dioxide, ammonia, methane, and a variety of metals and complex organics.
Energy by Starlight
Given that comets probably formed on the outer edges of the solar nebula, their early orbits would have been more or less in the same plane as the rest of the young system, but gravitational interactions with passing stars would have randomized their orbital inclinations, eventually producing a sphere of the kind Jan Oort first postulated back in 1950. Much of this is speculative, because we have little observational evidence to go on, but the major part of the cometary shell probably extends from 40,000 to 60,000 AU, while a projected inner Oort population extending from just beyond the Kuiper Belt out to 10,000 AU may have cometary orbits more or less in the plane of the ecliptic. Out past 10,000 AU the separation between comets is wide, perhaps about 20 AU, meaning that any communities that form out here will be incredibly isolated.
Image: An artist’s rendering of the Kuiper Belt and Oort Cloud. Credit: NASA/Donald K. Yeomans.
Whether humans can exploit cometary resources this far from home will depend on whether or not they can find sources of energy. In a paper called “Fastships and Nomads,” presented at the Conference on Interstellar Migration held at Los Alamos in 1983, Eric Jones and Ben Finney give a nod to non-renewable energy sources like deuterium, given that heavy elements like uranium will be hard to come by. Indeed, a typical comet, in Richard Terra’s figures, holds between 50,000 and 100,000 metric tons of deuterium, enough to power early settlement and mining.
But over the long haul, Jones and Finney are interested in keeping colonies alive through renewable resources, and that means starlight. The researchers talk about building vast mirrors using aluminum from comets, with each 1 MW mirror about the size of the continental United States. Now here’s a science fiction setting with punch, as the two describe it:
Although the mirrors would be tended by autonomous maintenance robots, the nomads would have to live nearby in case something went wrong… Although we could imagine that the several hundred people who could be supported by the resources of a single comet might live in a single habitat, the mirrors supporting that community would be spread across about 150,000 km. Trouble with a mirror or robot on the periphery of the mirror array would mean a long trip, several hours at least. It would make more sense if the community were dispersed in smaller groups so that trouble could be reached in a shorter time. There are also social reasons for expecting the nomad communities to be divided into smaller co-living groups.
Jones and Finney go on to point out that humans tend to work best in groups of about a dozen adults, whether in the form of hunter/gatherer bands, army platoons, bridge clubs or political cells. This observation of behavior leads them to speculate that bands of about 25 men, women and children would live together in a large habitat — think again of an O’Neill cylinder — built out of cometary materials, from which they would tend a mirror farm with the help of robots and computers. Each small group would tend a mirror farm perhaps 30,000 kilometers across.
The picture widens beyond this to include the need for larger communities that would occasionally come together, helping to avoid the genetic dangers of inbreeding and providing a larger social environment. Thus we might have about 500 individuals in clusters of 20 cometary bands which would stay in contact and periodically meet. Jones and Finney consider the band-tribe structure to be the smallest grouping that seems practical for any human community. Who would such a community attract — outcasts, dissidents, adventurers? And how would Oort Cloud settlers react to the possibility of going further still, to another star?
While by no means is this is a new theory, ( note the Jules Verne story ), it presents the scenario of the very slow spreading of intelligent biological life through-out the Galaxy ( see Slow Galactic Colonization, Zoo Hypothesis and the Fermi Paradox ).
Now here’s a thought; could a potential alien Oort Cloud civilization be the basis of the Ancient Astronaut Theory and the legends of the Sumerian Gods, the Anunnaki?
There’s no hard evidence of that of course, but there are Pluto-sized and larger objects in the Kuiper Belt glowing in the infrared, a sign that was said to represent a Dyson Sphere type civilisation.
Either these are natural objects such as Brown Dwarf stars, or potential alien civilisations whom don’t care whether they are detected in the infrared or not.
And that’s disturbing.
From Centauri Dreams:
What happens to us if our SETI efforts pay off? Numerous scenarios come to mind, all of them speculative, but the range of responses shown in Carl Sagan’s Contact may be something like the real outcome, with people of all descriptions reading into a distant message whatever they want to hear. Robert Lightfoot (South Georgia State College) decided to look at contact scenarios we know something more about, those that actually happened here on Earth. His presentation in Huntsville bore the title “Sorry, We Didn’t Mean to Break Your Culture.”
Known as ‘Sam’ to his friends, Lightfoot is a big, friendly man with an anthropologist’s eye for human nature. His talk made it clear that if we’re going to plan for a possible SETI reception, we should look at what happens when widely separated groups come into contact. Cultural diffusion can happen in two ways, the first being prompted by the exchange of material objects. In the SETI case, however, the non-material diffusion of ideas is the most likely outcome. Lightfoot refers to ‘objects of cultural destruction’ in both categories, noting the distorting effect these can have on a society as unexpected effects invariably appear.
Consider the introduction of Spam to the islands of the Pacific as a result of World War II. The level of obesity, cancer and diabetes soared as cultures that had relied largely on hunting, farming and fishing found themselves in the way of newfound supplies. Visitors to some of these islands still note with curiosity that Spam can be found on the menus of many restaurants. Today more than half of all Pacific islanders are obese, and one in four has diabetes. On the island nation of Tonga, fully 69 percent of the population is considered obese.
Lightfoot mentioned Tonga in his talk, but I drew the above figures from the World Diabetes Foundation. Can we relate the continuing health problems of the region to Spam? Surely it was one of the triggers, but we can also add that the large-scale industrialization of these islands didn’t begin until the 1970s. Imported food and the conversion of farmland to mining and other industries (Nauru is the classic example, with its land area almost entirely devoted to phosphate mining) meant a change in lifestyle that was sudden and has had enormous health consequences.
Objects of cultural destruction (OCDs) show their devastating effects around the globe. The Sami peoples of Finland had to deal with the introduction of snowmobiles, which you would have thought a blessing for these reindeer herders. But the result was the ability to collect far larger herds than ever before, which in turn has resulted in serious problems of over-grazing. Or consider nutmeg, once thought in Europe to be a cure for the plague, causing its value to soar higher than gold. Also considered an aphrodisiac, nutmeg led to violence against native growers in what is today Indonesia and played a role in the creation of the East India Company.
But because SETI’s effects are most likely going to be non-material, Lightfoot homed in on precedents like the ‘cargo cults’ of the Pacific that sprang up as some islanders tried to imitate what they had seen Westerners do, creating radios out of wood, building ‘runways’ and calling for supplies. In South Africa, a misunderstanding of missionary religious teachings led the Xhosa people to kill their cattle, even though their society was based on herding these animals. Waiting for a miracle after the killings, a hundred thousand people began to starve. Said Lightfoot:
Think about contact with an extraterrestrial civilization in this light. There will be new ideas galore, even the possibility of new objects — plants, animals, valuable jewels. Any or all of these could be destabilizing to our culture. And just as they may destabilize us, we may contaminate them.
I think the most powerful message of Lightfoot’s talk was that this kind of destabilization can come where you would least expect it, and have irrevocable results. Tobacco, once used as a part of ritual ceremonies in the cultures where it grew, has become an object of cultural and medical destruction in our far more affluent society. Even something as innocuous as a tulip once became the object of economic speculation so intense that it created an economic bubble in 17th Century Holland and an ensuing economic panic.
What to do? Lightfoot told the crowd to search history for the lessons it contains about cultures meeting for the first time. We need to see when and why things went wrong in hopes of avoiding similar situations. If contact with an extraterrestrial culture someday comes, we’ll need a multidisciplinary approach to identify the areas where trouble is most likely to occur. A successful SETI reception could be the beginning of a philosophical and scientific revolution, or it could be the herald of cultural decline as we try to re-position our thinking about the cosmos.
I don’t think the radio searches of SETI will produce anything; there’s a better chance that UFOs are ET spacecraft and eventually black ops corporations will reveal that they’ve been back engineering their hardware for years.
That being said, on the off chance that ET contact does happen, in any form, cultural cross contamination is bound to happen. Whether some cargo cults will form because of contact is moot, because in my opinion, that’s how the world’s religions were formed in the past.
From The Daily Galaxy:
The species that you and all other living human beings on this planet belong to is Homo sapiens. During a time of dramatic climate change 200,000 years ago,Homo sapiens (modern humans) evolved in Africa. Is the human species entering another evolutionary inflection point?
Paul Davies, a British-born theoretical physicist, cosmologist, astrobiologist and Director of the Beyond Center for Fundamental Concepts in Science and Co-Director of the Cosmology Initiative at Arizona State University, says in his new book The Eerie Silence that any aliens exploring the universe will be AI-empowered machines. Not only are machines better able to endure extended exposure to the conditions of space, but they have the potential to develop intelligence far beyond the capacity of the human brain.”I think it very likely – in fact inevitable – that biological intelligence is only a transitory phenomenon, a fleeting phase in the evolution of the universe,” Davies writes. “If we ever encounter extraterrestrial intelligence, I believe it is overwhelmingly likely to be post-biological in nature.”Before the year 2020, scientists are expected to launch intelligent space robots that will venture out to explore the universe for us.
“Robotic exploration probably will always be the trail blazer for human exploration of far space,” says Wolfgang Fink, physicist and researcher at Caltech. “We haven’t yet landed a human being on Mars but we have a robot there now. In that sense, it’s much easier to send a robotic explorer. When you can take the human out of the loop, that is becoming very exciting.”
As the growing global population continues to increase the burden on the Earth’s natural resources, senior curator at the Smithsonian National Air and Space Museum, Roger Launius, thinks that we’ll have to alter human biology to prepare to colonize space.
In the September issue of Endeavour, Launius takes a look at the historical debate surrounding human colonization of the solar system. Experiments have shown that certain life forms can survive in space. Recently, British scientists found that bacteria living on rocks taken from Britain’s Beer village were able to survive 553 days in space, on the exterior of the International Space Station (ISS). The microbes returned to Earth alive, proving they could withstand the harsh environment.
Humans, on the other hand, are unable to survive beyond about a minute and a half in space without significant technological assistance. Other than some quick trips to the moon and the ISS, astronauts haven’t spent too much time too far away from Earth. Scientists don’t know enough yet about the dangers of long-distance space travel on human biological systems. A one-way trip to Mars, for example, would take approximately six months. That means astronauts will be in deep space for more than a year with potentially life-threatening consequences.
Launius, who calls himself a cyborg for using medical equipment to enhance his own life, says the difficult question is knowing where to draw the line in transforming human biological systems to adapt to space. Credit: NASA/Brittany Green
“If it’s about exploration, we’re doing that very effectively with robots,” Launius said. “If it’s about humans going somewhere, then I think the only purpose for it is to get off this planet and become a multi-planetary species.”
Stephen Hawking agrees: “I believe that the long-term future of the human race must be in space,” Hawking told the Big Think website in August. “It will be difficult enough to avoid disaster on planet Earth in the next hundred years, let alone the next thousand, or million. The human race shouldn’t have all its eggs in one basket, or on one planet.”
If humans are to colonize other planets, Launius said it could well require the “next state of human evolution” to create a separate human presence where families will live and die on that planet. In other words, it wouldn’t really be Homo sapien sapiens that would be living in the colonies, it could be cyborgs—a living organism with a mixture of organic and electromechanical parts—or in simpler terms, part human, part machine.
“There are cyborgs walking about us,” Launius said. “There are individuals who have been technologically enhanced with things such as pacemakers and cochlea ear implants that allow those people to have fuller lives. I would not be alive without technological advances.”
The possibility of using cyborgs for space travel has been the subject of research for at least half a century. A seminal article published in 1960 by Manfred Clynes and Nathan Kline titled “Cyborgs and Space” changed the debate, saying that there was a better alternative to recreating the Earth’s environment in space, the predominant thinking during that time. The two scientists compared that approach to “a fish taking a small quantity of water along with him to live on land.” They felt that humans should be willing to partially adapt to the environment to which they would be traveling.
“Altering man’s bodily functions to meet the requirements of extraterrestrial environments would be more logical than providing an earthly environment for him in space,” Clynes and Kline wrote.
“It does raise profound ethical, moral and perhaps even religious questions that haven’t been seriously addressed,” Launius said. “We have a ways to go before that happens.”
Some experts such as medical ethicist Grant Gillett believe that the danger is that we might end up producing a psychopath because we don’t quite understand the nature of cyborgs.
NASA, writes Lauris, still isn’t focusing much research on how to improve human biological systems for space exploration. Instead, its Human Research Program is focused on risk reduction: risks of fatigue, inadequate nutrition, health problems and radiation. While financial and ethical concerns may have held back cyborg research, Launius believes that society may have to engage in the cyborg debate again when space programs get closer to launching long-term deep space exploration missions.
“If our objective is to become space-faring people, it’s probably going to force you to reconsider how to reengineer humans,’ Launius said.
In what is its most targeted search to date, the SETI Institute has scanned 86 potentially habitable solar systems for signs of radio signals. Needless to say, the search came up short (otherwise the headline of this article would have been dramatically different), but the initiative is finally offering some quantitative data about the rate at which we can expect to find radio-emitting intelligent life on Earth-like planets — a rate that’s proving to be disturbingly low.
Indeed, by the end of its survey, SETI calculated that less than one-percent of all potentially habitable exoplanets are likely to host intelligent life. That means less than one in a million stars in the Milky Way currently host radio-emitting civilizations that we can detect.
A narrow-band search
The SETI researchers, a team that included Jill Tarter and scientists at the University of California, Berkeley, reached this conclusion after scanning 86 different stars using the Green Bank Telescope in West Virginia. These stars were chosen because earlier Kepler data indicated they host potentially habitable planets — Earth-like planets that sit inside their sun’s habitable zone.
As for the radio bands searched, SETI looked for signals in the 1-2 GHz range, a band that’s used here on Earth for such things as cell phones and television transmissions. SETI also constrained the search to radio emissions less than 5Hz of the spectrum; nothing in nature is known to produce such narrow band signals.
Each of the 86 stars — the majority of which are more than 1,000 light-years away — were surveyed for five minutes. Because of the extreme distances involved, the only signals that could have been detected were ones that were intentionally aimed in our direction — which would be a deliberate effort by ETIs to signal their presence (what’s referred to as Active SETI, or METI (Messages to ETIs)).
“No signals of extraterrestrial origin were found.” noted the researchers in the study.”[I]n the simplest terms this result indicates that fewer than 1% of transiting exoplanet systems are radio loud in narrow-band emission between 1-2 GHz.”
Wanted: Alternative signatures
Despite the nul result, SETI remains hopeful for the future. Scanning potentially habitable solar systems is a fantastic idea, and it’s likely the first of many such targeted searches. At the same time, however, SETI will have to expand upon its list of candidate signatures.
It has been proposed, for example, that SETI look for signs of Kardashev scale civilizations, and take a more Dysonian approach to their searches. Others have suggested that SETI look for laser pulses.
Indeed, the current strategy — that of looking for radio-emitting civilizations — is exceedingly limited. Even assuming we could detect signals from a radio-capable civilization within a radius of 1,000 light-years, the odds that it would be contemporaneous with us is mind-bogglingly low (the time it takes for radio signals to reach us notwithstanding).
And as we are discovering by virtue of our own technological development, the window of opportunity to detect a radio-transmitting civilization is quite short. Looking to the future, it’s more than reasonable to suggest that alternative signatures — whether they be transmitted deliberately or not — be considered.
This is something SETI is very aware of, and the researchers said so much in their paper:
Ultimately, experiments such as the one described here seek to firmly determine the number of other intelligent, communicative civilizations outside of Earth. However, in placing limits on the presence of intelligent life in the galaxy, we must very carefully qualify our limits with respect to the limitations of our experiment. In particular, we can offer no argument that an advanced, intelligent civilization necessarily produces narrow-band radio emission, either intentional or otherwise. Thus we are probing only a potential subset of such civilizations, where the size of the subset is difficult to estimate. The search for extraterrestrial intelligence is still in its infancy, and there is much parameter space left to explore.
The paper is set to appear in the Astrophysical Journal and can be found here.
I suppose this is the natural outreach of the Kepler planetary searches; to see if there are radio signals coming from some of these planets. But as Terence McKenna once said, “To search expectantly for a radio signal from an extraterrestrial source is probably as culture-bound a presumption as to search the galaxy for a good Italian restaurant.“
Words of wisdom. I think it’s a mistake to believe that civilizations will use radio to broadcast out into the Universe. Convergent theories of evolution aside, it’s not a proven fact that other intelligences would follow the same evolutionary path as humans and thus invent similar communication techniques.
Of course, time will tell.
Hat tip to the Daily Grail.
From Aeon Magazine:
The Pont de Normandie bridge over the Seine estuary. Photo by Jean Gaumy/Magnum
Make a model of the world in your mind. Populate it, starting with the people you know. Build it up and furnish it. Draw in the lines that connect it all together, and the ones that divide it. Then roll it into the future. As you go forward, things disappear. Within a century or so, you and all the people around you have gone. As things go that are certain to go, they leave empty spaces. So do the uncertainties: the things that may not be things in the future, or may take different forms — vehicles, homes, ways of communicating, nations — that from here can be no more than a shimmer on the horizon. As one thing after another disappears, the scene fades to white. If you want a vision, you’ll have to project it yourself.
Occasionally, people take steps to counter the emptying by making things that will endure into the distant future. At a Hindu monastery in Hawaii, the Iraivan Temple is being built to last 1,000 years, using special concrete construction techniques. Carmelite monks plan to build a gothic monastery in the Rocky Mountains of Wyoming that will stand equally long. Norway’s National Library is expected to preserve documents for a 1,000-year span. The Long Now Foundation dwarfs these ambitions by an order of magnitude with its project to build a clock, inside a Nevada mountain, that will work for 10,000 years. And underground waste disposal plans for the Olkiluoto nuclear power plant in Finland have been reviewed for the next 250,000 years; the spent fuel will be held in copper canisters promised to last for millions of years.
An empty horizon matters. How can you care about something you can’t imagine?
A project can also reach out to the distant future even if it doesn’t have a figure placed on its lifespan. How many blueprints for great works, such as Gaudí’s Sagrada Família cathedral in Barcelona, or Haussmann’s Paris boulevards, or even Bazalgette’s London sewers, were drawn with the distant future in the corner of the architect’s or the engineer’s eye? The value of longevity is widely taken for granted: the 1,000-year targets for the Iraivan Temple, the new Mount Carmel monastery and the National Library of Norway are declared with little explanation as to why that particular round number has been chosen.
Instead, they play to intuition. A 1,000-year span has an intuitive symmetry for nations such as Norway that have a millennium of history behind them: it alludes to the depth of the nation’s heritage while suggesting that the country has at least as much history yet to come. For spiritual institutions, 1,000 years is short enough to be credible — England, for example, is dotted with Norman churches approaching their millennium — and long enough to refer to a timescale that extends beyond normal human capacities, thus pointing to the divine and the eternal.
People don’t generally reach out to the distant future for the future’s sake. Often what they chiefly want to reach is a contemporary audience. Going to extreme lengths to prevent vestigial nuclear hazards the other side of the next ice age is a demonstration of capacity, commitment to safety, and attention to detail. If this is what we’re doing for the distant future, it says to an uneasy public, you can be absolutely sure that we’ve got every possible near-term risk covered, too.
At the ultimate extreme, the Voyager space probes are carrying samplers of human culture, on golden disks, out of the solar system and on into infinite space. The notional beneficiaries are life forms that are not known to exist, from planets not yet detected, at distances the probes will not reach for millions of years. But the real beneficiaries were the people who reflected on our species and its place in the universe as they assembled the records and their content. The golden disks were mirrors of the culture that made them.
Any project with a distant time-horizon can be explained away as an exercise that invokes the future in the pursuit of immediate goals. But even if such a project is all about us, that doesn’t mean it’s not about the future too. The Long Now Foundation is an attempt to cultivate a consciousness that expands the horizons of the present. (Its name emerged from Brian Eno’s observation that in New York what people meant by ‘now’ was markedly shorter than what people meant by it in Europe.) By expanding ‘now’ to multi-millennial proportions, it makes us part of the future, and the future part of us.
The Great Cathedrals of the Middle Ages ( and of course, The Great Pyramids millenia earlier ) fit into this category also. Whole families were employed for generations constructing these great pieces of archecture and art.
It has been proposed that future interstellar missions to Alpha Centauri, Gliese and Tau Ceti could be considered long-term multi-generation projects also ( barring invention of a warp drive ). Such projects could only happen if Earth like worlds are confirmed by advanced telescopes inspecting these stars in order to justify the expense of these missions.
Either way, future projects of this magnitude aren’t strangers to Mankind. Maybe the horizon isn’t quite so empty?
I couldn’t resist posting this today after reading it at Centauri Dreams. It’s extremely mainstream, by which the papers Paul Gilster discusses uses geological travel times for interstellar travel and the effects on the Fermi Paradox.
But he talks about the “zoo” hypothesis for our supposed lack of contact with ETIs ( no discussion of UFOs what-so-ever of course ) and I find that fascinating:
Many explanations for the Fermi paradox exist, but Hair and Hedman want to look at the possibility that starflight is so long and difficult that it takes vast amounts of time (measured in geologic epochs) to colonize on the galactic scale. Given that scenario, large voids within the colonized regions may still persist and remain uninhabited. If the Earth were located inside one of these voids we would not be aware of the extraterrestrial expansion. A second possibility is that starflight is so hard to achieve that other civilizations have simply not had time to reach us despite having, by some calculations, as much as 5 billion years to have done so (the latter figure comes from Charles Lineweaver, and I’ll have more to say about it in a moment).
Image: A detailed view of part of the disc of the spiral galaxy NGC 4565. Have technological civilizations had time enough to spread through an entire galaxy, and if so, would they be detectable? Credit: ESA/NASA.
The authors work with an algorithm that allows modeling of the expansion from the original star, running through iterations that allow emigration patterns to be analyzed in light of these prospects. It turns out that in 250 iterations, covering 250,000 years, a civilization most likely to emigrate will travel about 500 light years, for a rate of expansion that is approximately one-fourth of the maximum travel speed of one percent of the speed of light, the conservative figure chosen for this investigation. A civilization would spread through the galaxy in less than 50 million years.
These are striking numbers. Given five billion years to work with, the first civilization to develop starfaring capabilities could have colonized the Milky Way not one but 100 times. The idea that it takes billions of years to accomplish a galaxy-wide expansion fails the test of this modeling. Moreover, the idea of voids inside colonized space fails to explain the Fermi paradox as well:
…while interior voids exist at lower values of c initially, most large interior voids become colonized after long periods regardless of the cardinal value chosen, leaving behind only relatively small voids. In an examination of several 250 Kyr models with a wide range of parameters, the largest interior void encountered was roughly 30 light years in diameter. Since humans have been broadcasting radio since the early 20th century and actively listening to radio signals from space since 1960 (Time 1960), it is highly unlikely that the Earth is located in a void large enough to remain undiscovered to the present day. It follows that the second explanation of Fermi’s Paradox (Landis 1998) is not supported by the model presented.
There are mitigating factors that can slow down what the authors call the ‘explosively exponential nature’ of expansion, in which a parent colony produces daughter colonies and the daughters continue to do the same ad infinitum. The paper’s model suggests that intense competition for new worlds can spring up in the expanding wavefront of colonization. At the same time, moving into interior voids to fill them with colonies slows the outward expansion. But even models set up to reduce competition between colonies present the same result: Fermi’s lunchtime calculations seem to be valid, and the fact that we do not see evidence of other civilizations suggests that this kind of galactic expansion has not yet taken place.
Temporal Dispersion into the Galaxy
I can’t discuss Hair and Hedman’s work without reference to Hair’s earlier paper on the expansion of extraterrestrial civilizations over time. Tom had sent me this one in 2011 and I worked it into the Centauri Dreams queue before getting sidetracked by preparations for the 100 Year Starship symposium in Orlando. If I had been on the ball, I would have run an analysis of Tom’s paper at the time, but the delay gives me the opportunity to consider the two papers together, which turns out to work because they are a natural fit.
For you can see that Hair’s spatial analysis goes hand in glove with the question of why an extraterrestrial intelligence might avoid making its presence known. Given that models of expansion point to a galaxy that can be colonized many times over before humans ever emerged on our planet, let’s take up a classic answer to the Fermi paradox, that the ‘zoo hypothesis’ is in effect, a policy of non-interference in local affairs for whatever reason. Initially compelling, the idea seems to break down under close examination, given that it only takes one civilization to act contrary to it.
But there is one plausible scenario that allows the zoo hypothesis to work: The influence of a particularly distinguished civilization. Call it the first civilization. What sort of temporal head start would this first civilization have over later arrivals?
Hair uses Monte Carlo simulations, drawing on the work of Charles Lineweaver and the latter’s estimate that planets began forming approximately 9.3 billion years ago. Using Earth as a model and assuming that life emerged here about 600 million years after formation, we get an estimate of 8.7 billion years ago for the appearance of the first life in the Milky Way. Factoring in how long it took for complex land-dwelling organisms to evolve (3.7 billion years), Lineweaver concludes that the conditions necessary to support intelligent life in the universe could have been present for at least 5.0 billion years. At some point in that 5 billion years, if other intelligent species exist, the first civilization arose. Hair’s modeling goes to work on how long this civilization would have had to itself before other intelligence emerged. The question thus has Fermi implications:
…even if this ﬁrst grand civilization is long gone . . . could their initial legacy live on in the form of a passed down tradition? Beyond this, it does not even have to be the ﬁrst civilization, but simply the ﬁrst to spread its doctrine and control over a large volume of the galaxy. If just one civilization gained this hegemony in the distant past, it could form an unbroken chain of taboo against rapacious colonization in favour of non-interference in those civilizations that follow. The uniformity of motive concept previously mentioned would become moot in such a situation.
Thus the Zoo Hypothesis begins to look a bit more plausible if we have each subsequent civilization emerging into a galaxy monitored by a vastly more ancient predecessor who has established the basic rules for interaction between intelligent species. The details of Hair’s modeling are found in the paper, but the conclusions are startling, at least to me:
The time between the emergence of the ﬁrst civilization within the Milky Way and all subsequent civilizations could be enormous. The Monte Carlo data show that even using a crowded galaxy scenario the ﬁrst few inter-arrival times are similar in length to geologic epochs on Earth. Just what could a civilization do with a ten million, one hundred million, or half billion year head start (Kardashev 1964)? If, for example, civilizations uniformly arise within the Galactic Habitable Zone, then on these timescales the ﬁrst civilization would be able to reach the solar system of the second civilization long before it evolved even travelling at a very modest fraction of light speed (Bracewell 1974, 1982; Freitas 1980). What impact would the arrival of the ﬁrst civilization have on the future evolution of the second civilization? Would the second civilization even be allowed to evolve? Attempting to answer these questions leads to one of two basic conclusions, the ﬁrst is that we are alone in the Galaxy and thus no one has passed this way, and the second is that we are not alone in the Galaxy and someone has passed this way and then deliberately left us alone.
The zoo hypothesis indeed. A galactic model of non-interference is a tough sell because of the assumed diversity between cultures emerging on a vast array of worlds over time. But Hair’s ‘modified zoo hypothesis’ has great appeal. It assumes that the oldest civilization in the galaxy has a 100 million year head start, allowing it to become hugely influential in monitoring or perhaps controlling emerging civilizations. We would thus be talking about the possibility of evolving similar cultural standards with regard to contact as civilizations follow the lead of this assumed first intelligence when expanding into the galaxy. It’s an answer to Fermi that holds out hope we are not alone, and I’ll count that as still another encouraging thought on the day the world didn’t end.
I have a problem with this simply because of the economics involved; what is the motivation for ETIs to expand into the Universe to begin with?
Like, are they like humans in the sense that we go because “it’s there?”
Or are there more practical impulses involved like “can we make money” on these endeavors?
A commentor to this particular post wrote that before we colonize ( if we ever do ) the Moon, Mars and other planets in this Solar System ( and perhaps the closer stars ) that it’ll be cheaper to shoot small probes with micro cameras to these places ( NASA is already proposing sending tele-operated probes to the Lunar surface instead of astronauts ) and sell virtual reality tours. Expanded versions of Google Earth and Google Mars!
In other words, it’s cheaper to build Universes that have Star Trek and upload your mind into it than actually building such things as star-ships!
Could this be an answer to the Fermi Paradox?