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:
Stretch out your time horizons and interstellar travel gets a bit easier. If 4.3 light years seems too immense a distance to reach Alpha Centauri, we can wait about 28,000 years, when the distance between us will have closed to 3.2 light years. As it turns out, Alpha Centauri is moving in a galactic orbit far different from the Sun’s. As we weave through the Milky Way in coming millennia, we’re in the midst of a close pass from a stellar system that will never be this close again. A few million years ago Alpha Centauri would not have been visible to the naked eye.
The great galactic pinball machine is in constant motion. Epsilon Indi, a slightly orange star about an eighth as luminous as the Sun and orbited by a pair of brown dwarfs, is currently 11.8 light years out, but it’s moving 90 kilometers per second relative to the Sun. In about 17,000 years, it will close to 10.6 light years before beginning to recede. Project Ozma target Tau Ceti, now 11.9 light years from our system, has a highly eccentric galactic orbit that, on its current inbound leg, will take it to within the same 10.6 light years if we can wait the necessary 43,000 years.
And here’s an interesting one I almost forgot to list, though its close pass may be the most intriguing of all. Gliese 710 is currently 64 light years away in the constellation Serpens. We have to wait a bit on this one, but the orange star, now at magnitude 9.7, will in 1.4 million years move within 50,000 AU of the Sun. That puts it close enough that it should interact with the Oort Cloud, perhaps perturbing comets there or sending comets from its own cometary cloud into our system. In any case, what a close-in target for future interstellar explorers!
I’m pulling all this from Erik Anderson’s new book Vistas of Many Worlds, whose subtitle — ‘A Journey Through Space and Time’ — is a bit deceptive, for the book actually contains four journeys. The first takes us on a tour of ten stars within 20 light years of the Sun, with full-page artwork on every other page and finder charts that diagram the stars in each illustration. The second tour moves through time and traces the stars of an evolving Earth through text and images. Itinerary three is a montage of scenes from known exoplanets, while the fourth tour takes us through a sequence of young Earth-like worlds as they develop.
Anderson’s text is absorbing — he’s a good writer with a knack for hitting the right note — but the artwork steals the show on many of these pages, for he’s been meticulous at recreating the sky as it would appear from other star systems. It becomes easy to track the Sun against the background of alien constellations. Thus a spectacular view of the pulsar planet PSR B1257+12 C shows our Sun lost among the brighter stars Canopus and Spica, with Rigel and Betelgeuse also prominent. The gorgeous sky above an icy ocean on a planet circling Delta Pavonis shows the Sun between Alpha Centauri and Eta Cassiopeiae. Stellar motion over time and the perspectives thus created from worlds much like our own are a major theme of this book.
From Epsilon Eridani, as seen in the image below, the Sun is a bright orb seen through the protoplanetary disk at about the 4 o’clock position below the bright central star.
Image: The nearby orange dwarf star Epsilon Eridani reveals its circumstellar debris disks in this close-up perspective. Epsilon Eridani is only several hundred million years old and perhaps resembles the state of our own solar system during its early, formative years. Credit: Erik Anderson.
Vistas of Many Worlds assumes a basic background in astronomical concepts, but I think even younger readers will be caught up in the wonder of imagined scenes around planets we’re now discovering, which is why I’m buying a copy for my star-crazed grandson for Christmas. He’ll enjoy the movement through time as well as space. In one memorable scene, Anderson depicts a flock of ancient birds flying through a mountain pass 4.8 million years ago. At that time, the star Theta Columbae, today 720 light years away, was just seven light years out, outshining Venus and dominating the sunset skies of Anderson’s imagined landscape.
And what mysteries does the future hold? The end of the interglacial period is depicted in a scene Anderson sets 50,000 years from now, showing a futuristic observation station on the west coast of an ice-choked Canada. The frigid landscape and starfield above set the author speculating on how our descendants will see their options:
Will the inhabitants of a re-glaciating Earth seek refuge elsewhere? Alpha Centauri, our nearest celestial neighbor, has in all this time migrated out of the southern skies to the celestial equator, where it can be sighted from locations throughout the entire globe. It seems to beckon humanity to the stars.
And there, tagged by the star-finder chart and brightly shining on the facing image, is the Alpha Centauri system, now moving inexorably farther from our Sun but still a major marker in the night sky. Planet hunter Greg Laughlin has often commented on how satisfying it is that we have this intriguing stellar duo with accompanying red dwarf so relatively near to us as we begin the great exoplanet detection effort. We’re beginning to answer the question of planets around Alpha Centauri, though much work lies ahead. Perhaps some of that work will be accomplished by scientists who, in their younger years, were energized by the text and images of books like this one.
What I find facinating is a comment by a reader ( kzb ) of this post concerning the Fermi Paradox:
One frequently-seen explanation of the Fermi paradox is that interstellar travel is just too difficult: the distances are so great that no intelligent species has ever cracked the problem.
This article highlights an argument against this outlook. One scale-length towards the galactic centre, and the space density of stellar systems is 2.7 times what it is around here. Two scale lengths in and the density is 7.4 times greater. The scale-length of our galaxy is around only 2.1-3kpc according to recent literature.
Intelligent species that evolve in the inner galactic disk will not have the same problem that we have. Over galactic timescales, encounters between stellar systems within 1 light-year will not be uncommon.
I think you can see what I am saying, and I think this is one aspect of the FP discussion that is poorly represented currently.
And Erik Anderson’s response:
@ kzb: I give an overview of the Fermi Paradox on page 110 and I didn’t miss your point. It was definitely articulated by Edward Teller, whom I explicitly quote: “…as far as our Galaxy is concerned, we are living somewhere in the sticks, far removed from the metropolitan area of the Galactic center.”
Of course this precludes the explanations that there is no such thing as speedy interstellar travel ( be they anti-matter or warp drives ) and UFOs are really just mass hallucinations.
However Anderson’s book is novel in its’ treatment of interstellar exploration over vast timescales and that closer to the Galactic Center, possible advanced civilizations could have stellar cultures due to faster stellar movements and much shorter distances between stars. And I find that novel in an Olaf Stapledon kind of way!
That and the fact as we are discovering using the Kepler and HARP interstellar telescopes multiple star systems that have their own solar systems and many of them could have intelligent life lends credence to Mr. Anderson’s themes.
So I might treat myself to an early Christmas present by purchasing Anderson’s book!
For some reason, 60 years seems to be enough time for SETI to scan the local star neighborhood for radio signals, a sign mainstream science believes will be the way we’ll prove there’s ET intelligence in the Universe.
And as Mankind hasn’t received any radio signals from Out There yet, the famous “Fermi Paradox” is invoked.
The following abstract gives yet another possible explanation of the “silence” and one I have heard of before, but it’s the first time I’ve seen it tossed out into the mainstream:
The emerging science of evolutionary developmental (“evo devo”) biology can aid us in thinking about our universe as both an evolutionary system, where most processes are unpredictable and creative, and a developmental system, where a special few processes are predictable and constrained to produce far-future-specific emergent order, just as we see in the common developmental processes in two stars of an identical population type, or in two genetically identical twins in biology. The transcension hypothesis proposes that a universal process of evolutionary development guides all sufficiently advanced civilizations into what may be called “inner space,” a computationally optimal domain of increasingly dense, productive, miniaturized, and efficient scales of space, time, energy, and matter, and eventually, to a black-hole-like destination. Transcension as a developmental destiny might also contribute to the solution to the Fermi paradox, the question of why we have not seen evidence of or received beacons from intelligent civilizations. A few potential evolutionary, developmental, and information theoretic reasons, mechanisms, and models for constrained transcension of advanced intelligence are briefly considered. In particular, we introduce arguments that black holes may be a developmental destiny and standard attractor for all higher intelligence, as they appear to some to be ideal computing, learning, forward time travel, energy harvesting, civilization merger, natural selection, and universe replication devices. In the transcension hypothesis, simpler civilizations that succeed in resisting transcension by staying in outer (normal) space would be developmental failures, which are statistically very rare late in the life cycle of any biological developing system. If transcension is a developmental process, we may expect brief broadcasts or subtle forms of galactic engineering to occur in small portions of a few galaxies, the handiwork of young and immature civilizations, but constrained transcension should be by far the norm for all mature civilizations.
The transcension hypothesis has significant and testable implications for our current and future METI and SETI agendas. If all universal intelligence eventually transcends to black-hole-like environments, after which some form of merger and selection occurs, and if two-way messaging (a send–receive cycle) is severely limited by the great distances between neighboring and rapidly transcending civilizations, then sending one-way METI or probes prior to transcension becomes the only real communication option. But one-way messaging or probes may provably reduce the evolutionary diversity in all civilizations receiving the message, as they would then arrive at their local transcensions in a much more homogenous fashion. If true, an ethical injunction against one-way messaging or probes might emerge in the morality and sustainability systems of all sufficiently advanced civilizations, an argument known as the Zoo hypothesis in Fermi paradox literature, if all higher intelligences are subject to an evolutionary attractor to maximize their local diversity, and a developmental attractor to merge and advance universal intelligence. In any such environment, the evolutionary value of sending any interstellar message or probe may simply not be worth the cost, if transcension is an inevitable, accelerative, and testable developmental process, one that eventually will be discovered and quantitatively described by future physics. Fortunately, transcension processes may be measurable today even without good physical theory, and radio and optical SETI may each provide empirical tests. If transcension is a universal developmental constraint, then without exception all early and low-power electromagnetic leakage signals (radar, radio, television), and later, optical evidence of the exoplanets and their atmospheres should reliably cease as each civilization enters its own technological singularities (emergence of postbiological intelligence and life forms) and recognizes that they are on an optimal and accelerating path to a black-hole-like environment. Furthermore, optical SETI may soon allow us to map an expanding area of the galactic habitable zone we may call the galactic transcension zone, an inner ring that contains older transcended civilizations, and a missing planets problem as we discover that planets with life signatures occur at a much lower frequencies in this inner ring than in the remainder of the habitable zone.
The mention of inner rings or zones smacks of the Anthropic Principle, so I’m not too impressed with this abstract, but it looks like it’s a very well written hypothesis.
But my question is this; “Why does the mainstream consider 60 years enough search time for ET activity to be detected?”
Are we really that convinced we’re on top of the local Galactic food-chain?
And where does that leave the issue of UFOs? Are they possible manifestations of civilizations who have attained Technological Singularity status?
Hat tip to the Daily Grail.
As this blog enters its sixth anniversary this month, I have never given much thought of it lasting this long. In fact, it almost ended last year when I took a long hiatus due to health issues; both for myself and my wife.
But as time went on and both my wife and I slowly recovered, I discovered I still had some things to say. And I realized the world never stopped turning in the meanwhile.
As I started to post again, the personal site Facebook became a semi-intelligent force unto itself. I say ‘semi-intelligent’ because it is spreading exponentially due to its posting of its games and constant proliferation of personal info unannounced and unapproved by individuals. And people, especially young folks don’t care this happens.
Distributed networks, mainly Facebook, Google and the World Wide Web in general are forms of distributed Artificial Intelligence. Does that mean we are in the early throes of the Technological Singularity?
I think we are IMO.
And if we are in the early upward curve of the Technological Singularity, how would that affect our theories of ancient intelligence in the Universe?
Well, I think we should seriously rethink our theories and consider how the Fermi Paradox might figure into this. Thinkers such as George Dyvorsky have written a few treatises on the subject and I believe they should be given due consideration by mainstream science. (The Fermi Paradox: Back With a Vengeance).
Speaking of mainstream science, it is slowly, but surely accepting the fact the Universe is filled with ancient stars and worlds. And if there’s a possibility the Universe has ancient worlds, there’s a chance there might be anicent Intelligences inhabiting these worlds:
The announcement of a pair of planets orbiting a 12.5 billion-year old star flies in the face of conventional wisdom that the earliest stars to be born in the Universe shouldn’t possess planets at all.
12.5 billion years ago, the primeval universe was just beginning to make heavier elements beyond hydrogen and helium, in the fusion furnace cores of the first stars. It follows that there was very little if any material for fabricating terrestrial worlds or the rocky seed cores of gas giant planets.
This argument has been used to automatically rule out the ancient and majestic globular star clusters that orbit our galaxy as intriguing homes for extraterrestrials.
The star that was announced to have two planets is not in a globular cluster (it lives inside the Milky Way, although it was most likely a part of a globular cluster that was cannibalized by our galaxy), but it is similarly anemic as the globular cluster stars because it is so old.
This discovery dovetails nicely with last year’s announcement of carbon found in a distant, ancient radio galaxy. These findings both suggest that there were enough heavy elements in the early universe to make planets around stars, and therefore life.
However, a Hubble Space Telescope search for planets in the globular star cluster 47 Tucanae in 1999 came up empty-handed. Hubble astronomers monitored 34,000 stars over a period of eight days. The prediction was that some fraction of these stars should have “hot Jupiters” that whirl around their star over a period of days (pictured here in an artist’s rendition). They would be detected if their orbits were tilted edge-on to Earth so the stars would briefly grow dimmer during each transit of a planet.
A similar survey of the galactic center by Hubble in 2006 came up with 16 hot Jupiter planet candidates. This discovery was proof of concept and helped pave the way for the Kepler space telescope planet-hunting mission.
Why no planets in a globular cluster? For a start, globular clusters are more crowded with stars than our Milky Way — as is evident in the observation of the dwarf galaxy M9 below. “It may be that the environment in a globular was too harsh for planets to form,” said Harvey Richer of the University of British Columbia. “Planetary disks are pretty fragile things and could be easily disrupted in such an environment with a high stellar density.”
However, in 2007 Hubble found a 2.7 Jupiter mass planet inside the globular cluster M4. The planet is in a very distant orbit around a pulsar and a white dwarf. This could really be a post-apocalypse planet that formed much later in a disk of debris that followed the collapse of the companion star into a white dwarf, or the supernova explosion itself.
Hubble is now being used to look for the infrared glow of protoplanetary disks in 47 Tucanae. The disks would be so faint that the infrared sensitivity of the planned James Webb Space Telescope would be needed to carry out a more robust survey.
If planets did form in the very early in the universe, life would have made use of carbon and other common elements as it did on Earth billions of years ago. Life around a solar-type star, or better yet a red dwarf, would have a huge jump-start on Earth’s biological evolution. The earliest life forms would have had the opportunity to evolve for billions of years longer than us.
This inevitably leads to speculation that there should be super-aliens who are vastly more evolved than us. So… where are they? My guess is that if they existed, they evolved to the point where they abandoned bodies of flesh and blood and transformed themselves into something else — be it a machine or something wildly unimaginable.
However, it’s clear that despite (or, because of) their super-intelligence, they have not done anything to draw attention to themselves. The absence of evidence may set an upper limit on just how far advanced a technological civilization may progress — even over billions of years.
Keep in mind that most of the universe would be hidden from beings living inside of a globular star cluster. The sky would be ablaze with so many stars that it would take a long time for alien astronomers to simply stumble across the universe of external galaxies — including our Milky Way.
There will be other searches for planets in globular clusters. But our present understanding makes the question of a Methuselah civilization even more perplexing. If the universe made carbon so early, then ancient minds should be out there, somewhere.
Methuselah civilizations eh?
Sure. If there are such civilizations out there, it is because they wish to remain in the physical realm and not cross over to the inner places of shear mental and god-like powers.
As with all things ‘Future’, the answer could come crashing down upon us faster than we are prepared for.
As usual, thanks to the Daily Grail.