≡ Menu

Dyson Spheres: Hoping to Be Surprised

“Were the chemicals here on Earth at the time when life began unique to us? We used to think so. But the most recent evidence is different. Within the last few years there have been found in the interstellar spaces the spectral traces of molecules which we never thought could be formed out in those frigid regions: hydrogen cyanide, cyano acetylene, formaldehyde. These are molecules which we had not supposed to exist elsewhere than on Earth. It may turn out that life had more varied beginnings and has more varied forms. And it does not at all follow that the evolutionary path which life (if we discover it) took elsewhere must resemble ours. It does not even follow that we shall recognise it as life — or that it will recognise us.”

— Jacob Bronowski, from The Ascent of Man

How accurate do you think we are in projecting what extraterrestrial civilizations might do? The question is prompted by recent speculation on Dyson spheres and the supposition that advanced cultures will invariably build them. After all, a Dyson sphere would seem to be a natural for beings who wanted to extract as much usable power as possible from their sun. Such a civilization, which Nikolai Kardashev thought of as ‘Type II,’ using all the power of its star, would doubtless think breaking up a local gas giant and using it to enclose that star made sense.

Diagram of a Dyson sphere

So let’s assume for a moment that extraterrestrial beings follow a game plan we humans have devised. And let’s take it to the next logical level. Going from Type II to Kardashev’s Type III, cultures that exploit the resources of entire galaxies, we would have to admit the possibility of creating Dyson spheres around every star in a galaxy, an interesting thought when you ask what methods are best for detecting signs of intelligent life elsewhere in the universe.

Image: A Dyson sphere allows a civilization to exploit maximal energy from its star. Excess infrared could conceivably mark its location to SETI-oriented astronomers. Credit: Guillermo A. Lemarchand.

Hunting for Dyson Spheres

For instead of listening for radio broadcasts or looking for optical beacons, finding Dyson spheres, either by themselves or in a wavefront spreading through a galaxy, is an observational SETI that could be successful even if its targets have no interest in trying to contact us. Thus Bruce Dorminey’s recent essay on SETI’s new wave, the idea of searching for distinctive signatures of Dyson spheres and their derivatives. Dorminey, author of the fine Distant Wanderers: The Search for Planets Beyond the Solar System (2001), tracked down people who have begun looking for such objects. People like Dan Wertheimer (UC-Berkeley), who analyzed a thousand solar-type stars (having culled those at least a billion years old), looking for excess infrared. 32 stars made the final cut and were examined for radio or optical transmissions, with no sign of alien intelligence.

Dick Carrigan (retired from Fermilab) has spent five years on 11,124 sources identified by the Infrared Astronomical Satellite (IRAS). It’s all in Dorminey’s essay, how Carrigan went after objects with an infrared temperature of 200-600 K, looking for the radiation of waste heat, again finding no signs of intelligent activity when scanning several contenders for anomalous radio signals. Or consider James Annis (Fermilab), who analyzes not single stars but entire galaxies looking for signs of engineering.

Here’s Annis on the possibilities, looking for a galaxy that might emit only 100th of one percent of the light expected from it, the possible signature of astroengineering at work:

“If you were to see obvious dust clouds around a candidate galaxy in the infrared, then it could be a dusty starburst galaxy where the dust is very clumpy and you can see ongoing star formation. But if you got an infrared galactic image that was completely smooth with no lumpiness, that’s an interesting object.”

Dorminey notes that to achieve this level of dimming on a galactic scale, a Type III civilization would need to have gone to work on just about every star in its galaxy. Which cannot, of course, be ruled out when you’re dealing with technologies at this level. Even here, though, we have to avoid being too doctrinaire. One argument against intelligent life in the nearby cosmos is the lack of Type III engineering, the assumption being that any culture that could harness an entire galaxy’s power would already be blindingly obvious to us. “My guess,” says Dan Wertheimer, “is that just from the astronomical data on file we would have discovered such a civilization by accident.”

Alien Technologies, Human Assumptions

Would we? That would bring us back to Type II as the only kind of advanced civilization to look for, but I disagree with Wertheimer. Here’s one reason why: In trying to understand hypothetical alien cultures, we’re assuming we can extrapolate forward from our own technology to what we would do if we had the necessary tools. Thus Dyson’s sphere, maybe 150 million kilometers in radius, a meters-thick shell rotating around its star. We can see this as a desirable outcome, so we assume aliens would as well. But would they? Perhaps a Type II society would have made breakthroughs in energy management that would render a Dyson sphere a historical curiosity, like some early 19th Century idea of a flying machine powered by flapping wings and a steam engine.

No, I can’t imagine what those breakthroughs would be, but then, that’s the point. How accurate can we be about predicting what science will find down the road? As Brian Wang has recently noted, projecting technology on our own planet out even fifty to a hundred years is all but impossible. For that matter, how can we be sure advanced engineering works would even be detectable, much less understood? My border collies are supremely intelligent dogs (one of them, anyway), but do they understand the difference between artifact and natural object? Do they know what a technology is? Yet the gap between border collie and human could be minor compared to the gap between human and extraterrestrial, especially if the latter has been developing its own technology for millions of years, if not billions.

None of which is to downplay what Wertheimer, Carrigan and Annis have done. Although the odds are daunting, I’m all for keeping our eyes open, and if a search for anomalous stars with excess infrared emission turns up interesting objects, let’s by all means investigate them. If we find galaxies with high infrared and low optical luminosity, let’s subject them to detailed scrutiny. But let’s not make any more assumptions than we have to. A negative result in a search for Dyson spheres or anomalous galaxies may only point to the limitations of our ability to project where technologies go as societies enter higher Kardashev levels.

Anomalous Galaxies and Their Uses

NGC 5907

If you want to find something anomalous about galaxies, consider the case of NGC 5907, a spiral galaxy 39 million light years away. Observations of this galaxy in 1998 by Michael Liu (UC-Berkeley) and an international team of astronomers showed an odd mix of stars. Expecting to see hundreds of bright stars in their field of view, the researchers found only a few. Evidently twenty times more light comes from dwarfs than giant stars in the halo of this galaxy. Liu, lead author of the paper on this work, described the finding this way:

“Our results force us to turn to more esoteric descriptions of the stellar content of NGC 5907’s halo. In particular, our data combined with the measured colors of the halo suggest a very metal-poor stellar population with an enormous excess of faint dwarfs. This is the first direct evidence of a substantial population of stars which is essentially all dwarf stars. Such a population has been invoked in the past as a constituent of the dark matter making up galaxy halos.”

Image: NGC 5907. Can an entire galaxy become the subject of advanced engineering? If so, would we recognize the result? Credit: Brad Ehrhorn, Dan Azari, and Chris Lasley/Kitt Peak Advanced Observing Program.

Larry Klaes recently noted this as an example of anomalies that could be related to engineering on the galactic scale. His point was not that NGC 5907 demonstrates such, but that given the vast number of galaxies we have to observe, our attempts to examine them in the context of SETI are in their infancy. And if I am right that a Type III civilization is going to be extremely difficult to recognize, then hunting for galactic anomalies makes sense in the context of a broader search, rather than one focused on a particular, perhaps overly narrow range of emissions.

There is no question that we are re-examining the nature of the SETI search as we grapple with such issues. In radio frequencies, we are most likely to be able to receive a directed signal, which means that here — or in the optical range as well — our best bet is to find extraterrestrials who already have an interest in communicating with us. Again, we have no reason to assume that alien cultures will feel such a need. Extending SETI into the realm of deep-sky observation (optical SETI is already doing this), using parameters that are both carefully selected yet open to anomalous result, seems a natural and logical development.

LOFAR and the Quest for Synergy

Which brings us to LOFAR, the Low Frequency Array that is now planning to link radio detectors across Britain, France, Holland, Sweden and Germany. LOFAR studies a wide range of frequencies between 20 MHz and 80 MHz, and again between 120 MHz and 240 MHz. Its primary function is scientific, notes Robert Nichol of Portsmouth University in The Guardian:

“We will be looking for all sorts of different things with Lofar,” added Nichol. “We will make surveys of the skies to look for unexpected events; for things that go bump in the night, as it were. We will also be able to study the universe’s childhood years. We know a lot about the Big Bang, when the universe was created 13 billion years ago, and a lot about it now. But its early childhood years, around 500 million years after the Big Bang, remain a mystery.”

But Nichol adds that extraterrestrial broadcasts could potentially be found by LOFAR’s detectors. LOFAR, in other words, is a project dedicated to basic research that could have SETI ramifications on the periphery, and I think that’s about the right mix. Those of us who doubt SETI will produce a confirmed extraterrestrial civilization any time soon would still like to see synergy between ongoing science and the attempt to make such discoveries. And we’d like to be proven wrong in our SETI pessimism. Whichever wavelengths we’re studying, whatever objects in the heavens, let’s keep our minds open and hope to be surprised.

Comments on this entry are closed.

  • ljk April 4, 2008, 14:50

    I wonder how many of these objects are actually Dyson Shells?

    The incidence of mid-infrared excesses in G and K giants

    http://arxiv.org/abs/0804.0521

  • David April 4, 2008, 15:53

    Interesting paper, when the authors refer to the stars with mid-IR excess
    as candidates for having a debris disk, I think they mean disks which are relatively close to the star (under a few AU), analogous to the asteroid belt around the sun. This is because the dust in a Edgeworth-Kuiper belt would be much cooler and have IR emission that only becomes obvious as longer wavelengths than the ones discussed in the paper.

  • dad2059 April 4, 2008, 18:13

    In light of the possibility of Vinge’s Singularity, perhaps the Kardashev Scale should be reassessed, given its human technology bias?

    Of course any study of possible ETI ‘civilizations’ will be biased because of our limited sample, us.

    Despite my cynicism, the Universe is a huge place and there is plenty of room for ETI who construct Dyson Shells in the classical sense. As astronomical instruments become more sensitive, maybe galaxies like NGC 5907 can be scrutinized more accurately.

    Perhaps we will get our pleasant surprise!

  • ljk April 4, 2008, 19:02

    I was at the birth of that Dyson Shell diagram shown in this
    thread when it was created for the first issue of SETIQuest
    magazine, which I was editor and co-producer of way back
    in 1994.

    I actually talked with the artist they had there on how the
    Dyson Shell should look. Apparently it is a bit dated now,
    according to Robert Bradbury – if a Dyson Shell concept
    can be considered old at this point:

    http://www.aeiveos.com:8080/~bradbury/ETI/Authors/Dyson-FJ/DysonShells.html

    It is always fun to see how many times the drawing has been
    reproduced as the representation of the ultimate ball.

    You can see the original article and the drawing here:

    http://www.coseti.org/lemarch1.htm

  • James M. Essig April 4, 2008, 19:44

    Hi ljk, David, and other Folks;

    Dyson spheres are really cool, I mean literally.

    Just imagine a Dyson Sphere built around the Sun that would collect solar energy and then very effeciently reconvert it back into hydrogen or othr heavier elements by energy conversion to baryonic matter such as by some future exotically effecient particle accellerators. The Dyson Sphere could have levels of dewar type electromagnetic shielding that would prevent the leakage of almost all thermal energy into space through the Dyson Sphere. Superconducting material would be of benefit here in order to prevent even long wave radiofrequency radiation from leaking into the interstellar void regardless of whether that radiation was a result of thermal blackbody interior emmissions and/or the result of electrodynamic machinery and technical implementations as a result of current flux changes, magnetic flux changes, or electric field flux changes including electromagnetic communication systems operating from within the Dyson Sphere.

    If we could develope some increadably high mass-specific energy storage density capacitors, the solar energy from the Sun could be converted to electrical potential energy and stored within the capacitors wherein it could be gradually used to power the civilization located within the Dyson Sphere. The same dewar type electromagnetic insulating features in the above paragraph could be utilized here as well. Given that the time averaged energy output of our entire civilization is about 10 EXP 13 Watts and that the Sun’s current output is about 4 x (10 EXP 26) Watts, the energy produced by a billion years worth of current solar output could power a current human scale civilization for 4 x (10 EXP 13) x 3 x (10 EXP 7) x (10 EXP 9) years or about 1.2 x 10 EXP 30 years.

    I will have more to post on this concept tomorrow.

    Thanks;

    Jim

  • djlactin April 5, 2008, 1:03

    hmmm. just did an energy balance calculation of the temperature inside a dyson sphere. Assuming that energy is lost only by blackbody radiation, and that inner (absorbing) and outer (emitting) surface areas are the same, a dyson sphere at 1 AU from the sun would equilibrate to a temperature of 396K = 123C. Clearly, this is unacceptable.

    To achieve stable temperature of 33 C (still a bit warm if you ask this canadian), the sphere would have to be at about 1.7 AU or have an effective radiating area (fins?) about 3 times the inner absorbing area.

    I’m sure this would be attainable by a technology competent to construct a dyson sphere, but there are other questions. For example, I’d think the location of the sphere around the star (equivalently, the position of the star within the sphere) would be unstable: due gravitation, any movement of the star off-centre would be amplified.

  • Wirehead April 5, 2008, 1:25

    Theory:

    If we don’t find dyson spheres, it is more likely that convenient interstellar transportation exists than if we do find dyson spheres.

  • Karl Schroeder April 5, 2008, 4:28

    Milan Cirkovic and I have been discussing related ideas for a while. A while ago I sent him an analysis of the “visibility problem” if you’d like to call it that; I’ve posted it on my site if anybody’s interested in. Briefly, the keywords here are “ecosystem services” and “partial programs” as the keys to unlock why an advanced civilization would probably not be building Dyson spheres, and in any case why it would not be visible.

    Of course, I’d be delighted to be proven wrong, so I hope they keep looking…

  • Bob Shaw April 5, 2008, 5:48

    If you consider the matter of SETI on a proper statistical basis, then the chances of a local detection of any form of ET are quite small. The key to detection of intelligence – NOT merely ‘life’, which may well be practically everywhere – is time. Local searches provide us with just one snapshot of time in our close neighbourhood. By examining ever-more-distant galaxies we can look for IR and other anomalies providing evidence of galaxy-spanning astroengineering (whether by a civilisation or by self-replicating probes), and we can do this over a wide range of timescales within a Galaxy’s development. We can’t hope for communication, obviously, but there’s every chance we can demonstrate that a galaxy has been modified in some way. Combine deep time and the oft-quoted ‘galaxies like grains of sand’ and there’s a real opportunity to find at least the industrial detritus of past intelligences.

    Bob Shaw

  • dad2059 April 5, 2008, 7:09

    The main beefs the scientific community has had with Dyson shells is that the extraordinary structural materials that would have to be employed to hold the object together. Also it couldn’t be spun up for gravity, it would require some sort of gravity generator to provide that necessity. Another conundrum is which way would you have your population settle the damn thing, inside the sphere or outside? Either way you would have to have gravity generators.

    Of course it is assumed that a K-type II civilization would have the technical chops to overcome those issues. And it also assumes that the population is still organic/biological in nature. The original organic race(s) could have uplifted themselves via Singularity and are no longer biological entities. Such beings could build a Shell of computronium around their sun, perhaps even converting the matter of the sun into building material and useful energy to run their simulations. That’s Matrioshka Brain territory there and possibilities of ‘black body’ objects.

    Dyson himself was surprised about the rigid ‘shell’ idea that sprung up . Originally, his shell was massive amounts of satellites and habitats in Earth’s orbit packed close together to make optimal use of the solar energy. Then breaking the other planets up to make even more orbital habs and sats.

    He also admitted taking the idea from J.D. Bernal’s ‘The World, The Flesh and The Devil’.

    The idea has a long and distinguished history.

  • Adam April 5, 2008, 7:29

    Hi Jim

    I seriously doubt anything could store that much energy. A Dyson shell has to radiate eventually because the thermodynamic gradients that power everything need a heat-sink. If we dump heat as microwaves just a bit shorter than the CMB, at a radiator temperature of 3.25 K, then the radiator surface has to be ~ 20,768 AU in radius to handle the Sun’s output. A lower output temperature means a much larger radiator. I seriously doubt anything can be made that big except for very tenuous gas.

    So what’s to be done? A civilization needs thermodynamic gradients and so at some temperature it must radiate. Perhaps the old SF idea of “cooling lasers” might be feasible? By dumping heat as a coherent beam pointing into the intergalactic void, advertising one’s presence to the galaxy might be avoided. In that case I suspect a real Dyson sphere will be needed to manage the Sun’s light, instead of the Dyson Swarm that Dyson himself imagined.

  • Administrator April 5, 2008, 8:00

    For readers looking for Karl Schroeder’s further thoughts on all this, go to:

    http://www.kschroeder.com/weblog/archive/2008/04/05/the-invisibility-of-advanced-civilizations

    Note this from Karl’s post:

    “…a civilization that offloads as much of its data processing as possible into natural processes in the physical world, through partial programs, is more energy-efficient than one that builds “computronium” to do its thinking, and probably calculates faster (because the energy required by an algorithmic process and the speed with which it’s executed are related). The more such processes are substituted by integration with the natural world, the harder it will be for us to see the operations of that civilization from interstellar distances. In fact, I would argue that a civilization that integrates efficiently with its environment on these two levels will be invisible by definition.”

    Karl and Milan Cirkovic has been looking at these matters for some time; I’m hoping to be reviewing Milan’s new paper here on the site as soon as it’s ready for publication.

  • george scaglione April 5, 2008, 9:19

    jim,ljk,everybody, so help me you should all know by now that i would be the last one to “throw cold water”! but having said that my friends…sure i can take a dyson sphere very seriously! but now!? when apollo on steroids is proving to be enough of an engineering challange i think we had better all just wait and see! sincerely and respectfully,your friend george

  • kurt9 April 5, 2008, 12:47

    I think the most likely place to find alien super civilizations is the Virgo Supercluster of galaxies, which is about 60 million light years away. Virgo is the nearest place that has many times more stars than our own galaxy. All of the other galaxies near ours tend to be much smaller or less dense (Andromeda) than ours. This means that statistically speaking, we did emerge in the most likely galaxy in our neighborhood and that we are alone in our neighborhood.

    If there are Dyson spheres and the like, they are most likely to be found in the Virgo Supercluster. Are their any observational anomalies associated with the Virgo? If so, perhaps that is the artifact of intelligent E.T.

    Maybe the dark matter, if it is real, is computronium or some other artifact of E.T.I.

    Any of these scenarios are far more likely than humanoid aliens cruising around in starships with a technology level equal or little more advanced than our own (e.g. Star Trek).

  • Adam April 5, 2008, 23:14

    Hi All

    Sidereal engineering seems excessive, doesn’t it? Dyson’s Swarm, Bradbury’s Brain, and similar UltraMegaEngineering projects seem like efforts by a civilization still controlled by its evolutionary past – exponential growth at all cost! Yet how rapidly does the expansion run out of resources and room? Even at Kardashev’s 1% growth we’d be using every last erg of the Sun’s output in just 3,088 years, and the Galaxy’s in just 2,413 years after that (assuming a Galactic luminosity of 30 billion Solar.) So in the year ~ 7,508 AD we’d eyeing off the rest of the Universe for another ~ 2,763 years of exponential growth, assuming a trillion galaxies. Then what?

    The above assumes FTL, or measuring calendar time via a relativistic clock and nearly-as-fast-as-light speeds. Of course we could try for an asymptotic approach to steady-state, though I’ve no idea how we’d manage that process. Seems we need a different approach to measuring a civilization’s success than “economic growth.”

  • James M. Essig April 6, 2008, 0:15

    Hi Adam;

    Thanks for the clarification on the need to have a heat sink.

    One option involving the heat sink laser beams is to shine the beams to distant proximate storage media wherein they would be used to power mass producing accellerators that produce protons, and/or to charge capacitive storage mechanisms for photon conversion to electrical energy. The energy could then be beamed back to the Dyson Sphere in concentrated mode for recycling thus permitting the Dyson Sphere to operate essentially forever.

    In the event that the Dyson Sphere somehow cooled to the point where normal room temperature technologies could not operate, perhaps we could have then figured out a way to move about that requires little or no energy. One such method might be to somehow skew the quantum mechanical wave-function of a person or a transport within such a Dyson Sphere so that the wavefunction probability amplitude for location is greatly squeezed ahead of the bulk of the mass of the person or transport thus causing the object to tunnel over macroscopic distances within the Dyson Sphere. Now this tunneling might be induced by setting up an energy barrier or energy state discontinuity in front of the object to be transported of just the right exact shape and energy level. This might be possible without the existence of any hidden quantum variables, however, if it turns out that there are hidden variables, then perhaps the whole process is made a little easier.

    Hi George;

    You make a good point. We are now only just finishing up the ISS in a couple of years. I look forward to the fun of more ambitious projects, but it will be a long time before we construct Dyson Spheres.

    Thanks;

    Your Friend Jim

  • J. Cuttance April 6, 2008, 5:01

    Another possibility is an advanced civilisation building orbiting energy collectors, at a distance of about mercury’s or closer.

    These collectors may be the diameter of a planet, and produce a dip in a star’s intensity characteristic of a planet of such a size as it passes in front of the star.

    But the energy collectors will be of low mass compared to such a planet and will not make the star “wobble”, a characteristic picked up by modern doppler techniques.

    If we find a “dip” without its expected “wobble”, we might have found a civilisation.

  • Ronald April 6, 2008, 9:46

    Fascinating topic.
    I have been wondering, at a fundamental level, why would an advanced civilization build a Dyson sphere (or something similar), if they could?

    What I mean is, there has to be some sensible rationale for it. As I argued before, not everything that can technically be done, will be done, because sometimes there are better alternatives to achieve the same (‘better’ defined as more energy efficient, cheaper, etc.). So it all depends on the objectives: living space, energy capture, …

    A shortcoming, I think, of the Kardashev scale in strict sense, is the assumption that any advanced civilization will have as a prime and logical objective the full utilization of all the energy of its star, and so on. Whereas, if a priority objective would be to disperse across its galaxy, it would require only a very small fraction of its stellar output, and of each next star, to advance further. Therefore I have once, on this site, suggested to subdivide the Kardashev scale further, to distinguish civilizations capable of interstellar travel and colonization, without the requirement of ‘full utilization’ of its own star.

    Recently, I have made some estimates of future energy needs of humankind, assuming that it will keep growing at 3% per year. I was inspired by a post on Adam’s interesting site (crowlspace, 10 Feb., comment 17 Feb.) stating that, at this growth rate, we would need to strip the giant planets for Helium-3 within 1200 years. I could hardly imagine that, given the huge energy content of the He-3 of those planets’ atmospheres.

    So I did some calculating and the results were quite astounding. I should have known better than to doubt Adam’s expertise ;-) ;
    If indeed our energy consumption keeps growing at 3% per year, from a present base of some 15 TeraWattYear (TWY), humankind’s cumulative energy consumption will have used up all of the He-2 of Uranus (7.3 * 10^12 TWY) by the year 2800, the He-3 of all four gas giants (2 * 10^14 TWY) by 2900 and we will need the entire output of our sun (3.8 * 10^14 TW) on a continuous basis by 3050 (reducing our erngy consumption growth rate to 2.5% or 2% per year will only buy us a couple of centuries), even a 1% growth rate a few millennia. That is what exponential growth does over time, even if the growth rate itself is very modest!

    So, an objective for a civilization to build a Dyson sphere around its star, could be, indeed, to utilize its full energy potential. This, however, could be achieved much more easily and safely (and incrementally) by means of a large and increasing fleet of solar panels and relay stations. No need for such a risky (see further) ‘all or nothing’ structure. To build a Dyson sphere just to collect solar energy is unneccesarily cumbersome, like building a palace as a support for the solar panels :-) .

    Leaves the need for more living space. The main rational purpose that I can think of, for a civilization to go through the humongous effort and risk (gravitational and rotational imbalances, meteorite impacts, stellar evolution and fluctuations, etc.) to build a Dyson sphere around its star, would be just that, a lot of living space.
    This renders the discussion more philosophical; why would a civilization want so more living space? For instance, would population growth per se, a rather primitive survival-driven goal, remain an objective for any advanced civilization? And even if so, what would be a more effective, efficient and low-risk way of achieving this: building a Dyson sphere, or going to the stars to colonize and terraform other planetary systems. Concretely: a Dyson sphere with an area of roughly 1 billion Earths, or colonizing and terraforming a billion earthlike planets. I bet the latter. A civilization that can construct a Dyson sphere can also terraform a small planet. And if 10% of the solartype stars of our Milky Way galaxy (i.e. about 7% or 30 billion) have a terraformable earthlike planet, that leaves some 3 billion candidates. And it can be done incrementally, learning as one proceeds, spreading the risk to a maximum.

    I love the idea of Dyson spheres, but I suspect they are the galactic equivalent of the Great Wall of China :-) .

    That is why I particularly like Wirehead’s theory, suggesting interstellar travel as an alternative to Dyson spheres (although he does not elaborate what exactly they would be alternatives *for* (what goals), so I assume that living space is meant as a primary goal, possibly combines with other goals, such as energy, risk spreading, philosophical/religious goals,…).

    Comment to Kurt9: not too pessimistic: the Andromeda galaxy contains a lot more stars then even our own galaxy and it seems that it contains a higher proportion of main sequence and solar type stars. And the Andromeda galaxy is a somewhat safer place too, with a significantly lower rate of supernovae (about 1 per year, compared with 3-4 in our MW galaxy).

    Just some Sunday afternoon intergalactic meanderings.

  • george scaglione April 6, 2008, 11:04

    kurt very well thought out and i kind of hope that you are correct. boy oh boy,if we are alone in this galaxy!?wow.you know correct me if i’m wrong,but i once read that the point of 2001 a space odyssey was that an intelligent alien race upon finding itself alone in the galaxy then started out to seed intelligence into the galaxy so that they would no longer be alone. “they” might then be us!!!!!!!! do you know what always astonded me?the sheer time that they where willing to wait! my god just the time it would take to fly around and search the galaxy! but anyway kurt thanks for some really cool comments,your friend george

  • philw1776 April 6, 2008, 11:58

    Wouldn’t it be a hoot if all this Dark Matter hypothethis explaining galactic rotation was BS with the REAL explanation for the extra hidden mass of galaxies being a proliferation of ‘invisible’ well-shielded Dyson Spheres?

  • James M. Essig April 6, 2008, 13:43

    Hi Folks;

    Thanks for the active dialogue. This is another really good thread as we can see in the large number of postings thus far.

    Ronald;

    Thanks very much for doing the math. Your analysis is very insightful. It just shows we need to go green even on a cosmic scale.

    I am not sure if I believe that a continuous increase in energy usage growth of 3% per year is any more realistic than the growth of the human population wherein each family has four kids which survive on average to twice the mean onset of the most fertile productive years of human females. Even three kids as such on average would lead to, in well under a few thousand years, the complete conversion of the baryonic mass of the observable universe to human living flesh. Somewhen, the universe is going to have to go green and sustainable and do more for less. Such would be the ultimate objective by organizations like Green Peace etc.

    Thanks;

    Jim

  • Athena April 6, 2008, 16:25

    I like both these as alternatives: Karl’s concept of a zero footprint and Wirehead’s theory that absence of Dyson spheres may imply feasible interstellar travel. They foster optimism not only about the existence of other civilizations but also about (pardon the pun) their intelligence and hence longevity. They also serve as a reminder against anthropocentric thinking.

  • James M. Essig April 6, 2008, 18:13

    Hi Folks;

    Another exotic method in which to store mattergy in very long cosmic duraton energy reserves is to construct huge rotating toriodal rings made of neutronium wherein the diameter of the rings would be on the order of 600,000 LY and their mass would approach 10 EXP 18 solar masses with a mass just below that which would produce a blackhole with the same radius. The Schwarzschild radius for black-holes is RH= [2GM]/(C EXP 2). The radius of a Solar massed blackhole is 2.9 km.

    These huge rotating rings might be constructed having a lower diametric specific density in order to prevent infalling matter from causing the formation of a blackhole. Both the mass of the blackhole and its relativistic kinetic energy could be gradually bled off to power the Dyson Spheres wherein the Dyson Spheres would be shielded from electromagnetic energy losses and wherein the thermodynamic gradiant to keep the Dyson Spheres operational could be provided by a system of laser beam external heat dumps wherein the emmitted lasers light would be converted to mass or electrical potential energy and then sent back to the Dyson Spheres for recycling and for restocking the thermodynamic gradient to power the Dyson Spheres hopefully somehow without future limit. The temporarilly dumped mattergy could be stored in safe, armoured storage vessels such as those utilizing neutronium armour and other automatic defense systems in order to prevent terrorist tamporing or othe manevolant actions by unscrupulous individuals or organizations.

    The rings would have to be spun up to relativistic rotational velocities in order to prevent gravitational collapse as they are constucted. Give humanity a trillion years of evolution and population growth, and it just might be possible.

    Thanks;

    Jim

  • Mark April 6, 2008, 18:52

    What if an intelligent civilization, instead of using the natural solar radiation output of its star, simply siphoned off all the star’s mass and converted that directly into energy? Then they wouldn’t have to worry about building any spheres. Just park some sort of siphoning device in low orbit, and take advantage of E=mc^2 to get more bang for the buck than even a Dyson sphere could. I’m not talking about fusion or any other such natural star-powering process, I’m talking about converting the entire mass of the star into back-to-back gamma rays, as would be the case if you annihilated it particle-for-particle with an equivalent mass of antimatter. Wouldn’t this be a more efficient means of obtaining all the energy output of the star? This way you wouldn’t have to wait billions of years for the star to shine out, you could convert the whole thing to energy on whatever timescale you needed. You’d also avoid having your precious and expensive Dyson sphere blown to bits when the star went nova or supernova.

    So for concrete proof of the existence of advanced star-consuming civilizations, what we should be looking for are places in the universe that are:
    1) Empty (because there’s no star there anymore, its matter having been entirely consumed), and
    2) Dark (because the civilization advanced enough to convert an entire star into energy would be also capable of trapping 100% of the gamma ray output produced, leaving no residue.

    Hmmm… “Empty” and “Dark.” Do we know of any such places in the cosmos?

  • Chris Petersen April 6, 2008, 22:31

    I don’t see how Wirehead’s theory that absence of Dyson spheres may imply feasible interstellar travel. It doesn’t follow from an observed absence of astroengineering. Energy from somewhere would still be needed to run computations (i.e. of a mind-uploaded society; the more energy you have, the more interesting diversity could be supported).

  • Adam April 7, 2008, 2:21

    Hi Ron

    Exponential growth is surprising, isn’t it? Growth in energy demand is hard to keep track of – some sources say 2.6%, some say 2.2% – but the difference is mere decades on centennial timescales. Even Kardashev’s analysis assumed a mere 1% growth and yet that means we’re using power equivalent to the Sun’s output by ~ 5096 AD, 3411 AD @ 2.2%, and 3,195 AD @ 2.6%. Incredible.

  • Ronald April 7, 2008, 4:22

    What is by now a clear result of the entire above (and fascinating) discussion to me is that: a truly advanced civilization, and particularly a galactic one, can and will only survive if it manages to control its primitive aggressive, consumptive and exploitative tendencies.
    In other words: advanced civilization is not so much an extremely advanced level of energy harnessing (although that may and will probably be a part of it as well) and growth as an objective per se, but rather these technilogical achievements merely to serve other ‘higher’ purposes, such as exploration, creativity, study, the seeding of life and intelligence, etc.
    It is an extremely delicate balance between necessary degrees of aggressiveness and exploitation, required to get (also literally) forward, and the necessary degrees of meekness and self-restraint.
    Which may, for a part, explain why truly advanced civilization might be such an exceeding rarity. We haven’t reached it yet. Sobering in a way.

  • Ronald April 7, 2008, 8:40

    Adam,

    yes astounding indeed, I came to AD 3050 at 3% annual growth, very similar result.
    However, I suspect that human energy consumption would not keep growing like this indefinitely, even if it were completely free, though probably to a very high level, say a couple of hundred times present US citizens’ consumption per capita. Until the point, where energy is simply no longer a limiting factor in achieving human ambitions (such as colonizing Mars and making it to the nearest stars). Like we are not using more and more air (or rather oxygen), just because it is free.
    Human energy requirements might as well level off at something like several hundred (or a few thousand) times present consumption.
    A lot, but no problem for Deuterium/He-3 fusion.

  • andy April 7, 2008, 12:02

    Assuming the growth in energy demand keeps growing exponentially, and we supply this energy by building Dyson spheres around all stars in a region of space of radius R, how long before the rate of change of R is equal to the speed of light?

    The power consumption in 2004 was 15 terawatts (from Wikipedia and a growth rate of 2.4% (estimates further up the thread).

    I’m going to take the amount of power available in a volume by assuming a number density of stars as 0.0005 per cubic light year (from SolStation – I’m neglecting M dwarfs as the larger stars produce far more energy), and for simplicity I am going to assume those stars each have the same luminosity as the Sun.

    Assuming I’m doing the calculation right (and that rounding errors aren’t causing problems), it seems that by about the year 3700 we are going to have to be expanding human-controlled space faster than the speed of light to keep up with energy demands.

  • hiro April 7, 2008, 17:17

    That’s why we need to create some new methods like collecting Casimir (vacuum) energy from space-time itself or energy from “mini-black hole” (r=1mm, is it possible to make such one?). If we have fusion generators around 2100s, I really doubt we still use that kind of technology in 3000 AD. Therefore, I guess the exponential growth theory doesn’t work in this situation.

  • James M. Essig April 7, 2008, 21:38

    Hi Folks;

    This is a really great thread!

    Another possible energy supply might be the discovery of additional nuclear forces which can liberate much more energy than current nuclear fusion or fission processes, perhaps wherein if the latent energy available is normally decoupled from release within our real particle mattergy universe, even perhaps much more energy than is available from direct and complete conversion of mass to energy. Perhaps there are even finer sub-nuclear structures closer to the would be ultimate irreducable physical material commonly referred to by theologians as prime matter wherein the latent energy available would be far greater than the latent energy of the zero point fields. Recall that calculations of the latent energy available within the zero point fields is as high as 120 orders of magnitude greater than the average within our oberservable universe. A volume of space equal to one 10 EXP – 41 cubic meters of vacuum would accordingly have as much latent energy as the entire observable universe commensurate with the 120 orders of magniture value. This spatial volume is 100 times less than a cube of space with a edge length of one 10 trillionth of an inch.

    We might need to develope a new lexocography to describe such dynamic sources of effect in terms other than E = M(C exp 2). We might need a whole new scientific epistemology to describe physical powers that are much more intense than E = M(C exp 2) and label them with phrases such as dynamic potentiality. The possibility always exist that a super intense particle interaction involving relatively miniscule quantities of energy could cause a phase change in the whole multiverse itself as a result of causing the multiverse to tunnel out of the allegded metastable minimum in which it may rest within the socalled scalar fields in accordance with the multiverse theory of Chaotic Inflation.

    A best, we might need an explainative paradymn that literally involves anthropocentric creation of energy in violation of current thermodynamic laws of conservation of matter and energy.

    Thanks;

    Jim

  • Adam April 8, 2008, 0:10

    Hi andy

    Clever approach to the question. Of course if we develop matter annihilation – reverse baryogenesis – then to keep up we just throw more stuff in the reactors ;-)

    That, of course, runs into severe limits eventually too. There do seem to be problems with the whole exercise, but just what the answer would be I’m unsure.

  • Ronald April 8, 2008, 4:50

    @hiro:

    no, strongly disagree (with first part of your post): apart from the fact that vacuum- or zero-point energy is most likely pure speculation, a figment, the main conclusion from the whole above discussion (see also andy’s latest post above yours) is: exponential growth is per definition non-sustainable. Any advanced civilization must find its way to sustainability, in order to survive, even at a galactic level.

    Growth and energy consumption are no goals by themselves, but merely means to an end. A true goal for a civilization, such as ours, could be galactic habitation and long-term survival.

  • Karl Schroeder April 8, 2008, 7:40

    This is a really good discussion! I’d just like to throw one more monkey wrench into the apparatus, while ducking the accusation that I’m advertising my latest series (hard to talk about this without doing so): one of my problems with the Dyson sphere, as with the classic Ringworld, is that they don’t exploit the principle of surface to volume ratio to maximize living space. The useable living area of a Dyson sphere, even with magical gravity generators, is far less than the useable *volume* of many smaller spheres built with the same mass budget to sizes equal to the Jeans radius for the gas mixture they contain. Selecting energy use over living space as the measure of a civilization’s success is arbitrary, if not extremely last-century in its logic.

    Beware of exponential curves. Don’t forget that two houseflies, if allowed to breed unchecked, will result in their descendents outweighing the Earth after a year. Heck, why hasn’t that happened? (Mind you, I’m currently in Western Australia–maybe it *has.*)

  • george scaglione April 8, 2008, 8:15

    hello everybody,throughout this thread i have seen mention made of gravity generators! lol does anybody have the slightest idea ?how? that might be done! would be a handy little device to have so naturally mention of it piques my interest. i know it is only sf at the moment but still i thought i’d ask the question.what do i lose? a minute of typing? anyhow thank you one and all .and again…no offense to anyone but dyson spheres? pretty big enginering project for a species that is currently at a stage where we are making a big hullabaloo out of “just” going back to the moon! thanks all,your friend george ps as always i look forward to seeing everybodies ideas! g

  • Ronald April 8, 2008, 8:32

    James,

    as always, I am impressed by your numbers ;-)

    But as stated above, and repeated by Karl, a very interesting outcome of this discussion appears to be that energy utilization, beyond a certain level, does not seem to be limiting nor decisive for a civilization’s success.

    We could probably (more than) do with solar for maintenance of society and fusion where great energy density is required, such as space travel. Matter-antimatter annihilation would be even more than sufficient, maybe interesting for interstellar travel. Zero point/vacuum etc. is highly speculative anyway (and highly risky in disturbing this or another universe if it existed?).

    Leaves ‘living area’ as a criteria and measure of a civilization’s success and rationale for galactic colonization (in combination with terraforming).

    I find Karl’s observation on the volume/living area ratio of Dyson spheres quite interesting! If combined with my previous argumentation of risk versus risk spreading, it would strongly plead for interstellar colonization instead of ‘Dysoning’ your own system.

    I mean, if I were a policy maker with supreme decision-making responsibility and I could and had to choose between a certain (large!) investment to create a highly risk-concentrated living space of a billion earth surfaces near my own star, or a more or less similar (but spread out over time) investment to create a similar living area with maximum risk-spreading by colonizing and/or terraforming a billion planets, I would certainly choose the latter!

    Apart from the added ‘philosophical benefits’ of exploration and dissemination of life and intelligence. To the stars!

  • george scaglione April 8, 2008, 13:16

    hiro,just caught up with your comment above about how we should try to get and use in some way vacuum energy.well,RIGHT ON!! i agree and have spent time hocking about that very subject myself.don’t know if you ever saw any of the things i had said on the subject.but good to see you mention it too. the very best to you my friend! george

  • andy April 8, 2008, 14:09

    Something to note here is that a Dyson sphere would be hotter than a planet at the same distance from the star, since the ratio of the area over which the sphere is absorbing energy to the area over which the sphere is radiating is 1 (since any radiation emitted inwards is reabsorbed by the sphere), as opposed to 1/4 for a spherical planet with constant temperature over its surface. This implies that a Dyson sphere at 1 AU from the Sun would have an equilibrium temperature of about 120 degrees C, which is not particularly pleasant. To get a Dyson sphere at the same equilibrium temperature as the Earth, we’d have to build it at 2 AU.

    Assuming we make a 2 AU radius sphere out of rock (density=3000 kg/m^3) and assuming magic transmutation technology to convert matter of any kind into rock, the total mass of all the planets would give you a sphere 80 cm thick.

    Taking the gravitational binding energy of a planet to be the same as a uniform sphere of its mass and radius (actually, since the planetary density increases towards the core, this value will be too low, so the situation will be worse than I’m making it out to be), the total energy expended in dismantling the planetary system is 2.3E36 joules (neglecting the energy you need to move the vast quantities of mass into the right orbit, which will make things far worse than I’m making it out to be), which if you already had a Dyson sphere to harvest all of the Sun’s energy would take you about 200 years to collect.

    If you covered the entirety of a terrestrial planet in solar panels with 100% energy storage efficiency, it turns out the best one to choose is Venus (Jupiter is better, but the lack of a solid surface might make it tricky to put the solar panels there). This would take you about 200 billion years, by which time the Sun would presumably be a black dwarf.

    So the construction of a Dyson sphere would seem to be a catch-22 situation: the only way to harvest enough energy to obtain the building materials on a reasonable timescale is if you already have a Dyson sphere.

    I would thus be very surprised if any civilisation actually builds one.

  • Dave Moore April 8, 2008, 15:07

    I don’t think Dyson spheres in the classical sense are either likely or practical, but I came up with a scenario showing how our civilization could grown steadily inside the solar system to reach Kardeshev II levels of energy consumption without the need for exotic technologies.

    I’ve excerpted the relevant parts of the paper to I presented so I apologize if you feel you are coming in the middle of things.

    The Kuipier belt has an estimated two million bodies over 1 km size c.f. the asteroid belts 40,000 and estimates of the number of comets in the Oort cloud vary from 100 billion to 10 trillion with an estimated total mass of between 8 and 30 times that of Earth. There may be more comets in our Oort cloud than there are stars in our galaxy. Since, in terms of numbers and accessible material, this would constitutes the bulk of the bodies of our solar system, I suspect that is where the bulk of our civilization will end up there. A hydrogen fusion powered society would spread out first through the Kuipier belt then through the Oort cloud. Since the outer reaches of the Oort cloud are nearly a light year out a trip to a nearby stars would only be an order of magnitude greater than trips across Oort cloud itself, and these trips would be made by a society well versed in long voyages. (Average separation of each comet is an AU from its Neighbor)

    If each of a 100 billion comets in the Oort cloud were colonized and each one used 1000 MW of power (a small cities worth) then the total power consumption would be 10^20 watt. If we push this scenario a bit and assume there are 10 trillion comets colonized and 10,000 MW/per comet the total power output is 10^23 watt: that of a red dwarf star.

    The paper’s conclusion was that i) technological civilizations could easily have been around for geological scale lengths of time, and ii) it is quite feasible in a much shorter time than that to reach Kardeshev II to III levels of energy use and spread throughout the galaxy so advanced technological civilizations (the type you are most likely to encounter) are highly visible in the infrared from their waste heat production.

    Dave Moore

  • hiro April 8, 2008, 16:41

    I found an interesting article:

    CASIMIR EFFECT FOR TACHYONIC FIELDS by Marcin Ostrowski, Foundations of physics letters, Jun2005, Vol. 18 Issue 3, p227-242, 16p.

    I think building Dyson sphere is a waste of energy, resource and time, because the yielding is very low. Hence, an advanced extraterrestrial civilization might build a 1 AU particle collider (I feel sorry for LHC) to produce either antimatter or a mini black hole draw energy from it by dumping civilization wastes into the event horizon.

    If physical bodies can be transformed into holograms, then the exponential growth problem can be delayed at least several million years.

  • James M. Essig April 8, 2008, 16:58

    Hi Ronald;

    Thanks for the comments and the critical review of my latest posting on this thread.

    It would be wise as you stated to colonize the universe instead putting all of humanity around a Dyson Sphere around the Sun. Given the tendancy of humans to bear offspring, we are going to need lots of realestate to handle the ever growing human population. If our universe does extend forever is space, then there exist an infinite amount of energy available in the limit that our race lives onward forever, namely the infinite supply of hydrogen, helium, and other fusionable elements and isotopes: at least in so far as such isotopes would last indefinately. Perhaps there is some steady state type of mechanism that allows for the very gradual creation of baryonic mass even if the Big Bang Model is correct and I assume it is indeed correct.

    There is something elegant to the phrase, mankind has harnessed the power of the cosmos with the development of the hydrogen bomb. Now we just need to put nuclear fusion to good work in expanding the human race out into the cosmos, as well as meeting and setting up diplomatic relations with our ETI brethren.

    Thanks;

    Jim

  • Adam April 8, 2008, 18:30

    Hi All

    Nice to see you over here in Oz, Karl – I saw your blog post on the flies and I can only sympathise. We used to have some land in rural Queensland and the flies were so adhesive that just hand-swatting one would catch about ten at once.

    Neat observation on Jeans mass gas-spheres versus Dyson Shells. Making a whole bunch of Virgas makes more sense, especially since you can tailor spin-gravity to whatever level suits inside a Virga – though I would like to see how a Virga style habitat could be made solar-powered. I guess they’d need to be small spheres to avoid attenuation, though someone will think of light-pipes or channels or something if they want really big Virgas.

    Dave Moore, years ago there was a study on colonizing the Oort Cloud using giant light-collectors to power small colonies via starlight. Such a societal habitat niche would last for 100 trillion years because the Galaxy’s luminosity function will decline only very, very slowly. Low mass stars will evolve to higher luminosities and be present in greater numbers as the Galaxy ages, so the total light output over time is very nearly constant. Things only go dark after the last Main Sequence stars form ~ 100 trillion years from now.

    Also Greg Matloff has opined, in an online essay, that the Oort/EK Belts will be where ETIs might currently exist, quietly living life away from prying eyes.

    Another thought is just how long Life might get energy from gravitational collapse. Current neutron stars are produced via impulsive means, and so only form very violently. But imagine a degenerate dwarf made of iron – its collapse will actually go through a series of heavier element steps towards neutron degeneracy, and might be manageable. If a 2 solar mass star-corpse was collapsed to 16 km radius then about ~ 3.26 trillion years at Solar luminosity can be extracted as energy – with some fraction as neutrinos. Collapse to a black hole would extract 9 – 29 trillion (GR makes the sums tricky), but it also imposes a strict limit on how much can be extracted.

    Thus there might be a niche for life for many trillions of years yet. That’s the timescale that Dyson shell, Virga Cloud making civilzations might be planning for, so I wonder what they might do towards that end and just how slowly they might manage things. David Criswell posited extracting mass from the poles of higher mass stars, to provide materials for constructing UltraMegaStructures, to extend the Main Sequence and to propel stars into new orbits. Perhaps we should be looking for enhanced polar outflows around larger Main Sequence stars?

  • Adam April 8, 2008, 19:33

    BTW andy, as always, right on the money.

    One version of the Dyson Shell construction sequence (in Adrian Berry’s “The Next Ten Thousand Years”) was the disassembly of Mercury to provide shielding for the other planets against the transmuting of Jupiter into heavier elements – as we now know that only needs to fuse hydrogen/helium into carbon, as iron is hopelessly outclassed structurally by carbon allotropes.

    Seems needlessly messy and wasteful. About 90 million years of energy dumping at Solar Luminosity would be needed to fuse the lot. But the Sun is ~ 2% heavier elements and star-lifting would provide all the mass we’d ever need for UltraMegaStructures.

    My personal dream would be the terraforming of the Gas Giants – Jupiter and Saturn need a lot more carbon/oxygen, while Uranus and Neptune are pretty close to being Ocean Planets already. If we coat their molecular/metallic hydrogen cores in carbon, then we can place an ocean over that – shouldn’t need much more than a tiny fraction of their masses to enshell them.

    In the end it seems like an aesthetic choice – do we keep planets and remake them? Do we stay human, or become Artilects? Should brute matter be remade into computronium and the Sun enshelled as in a Matrioshka Brain? Or should we be more subtle? Darwinnowed gene-brain hybrids, like us, are motivated towards exponential growth, but Transformed Humans and/or Artilects will be able to bypass all that and reach for a whole different motivation set.

    Ezekiel wrote 2600 years ago “Turn from evil, and do good.” So much of society, its moral-systems and educational systems focus on the first, but there’s no clear road for what the second half is all about. What is good for us, as evolved creatures, may seem flawed and limited to beings able to reflect upon all levels of their programming. They will have all our recorded history to see the fruits of our attitudes and philosophies and there’s no telling what that might lead them to conclude.

    ETIs – if They persist for billennia – will have faced the same end-point of Darwinian evolution, and will have passed Judgement on themselves as a species. Speculating on Their choice and its consequences may well help us make our own, before that choice is taken away by circumstances. At some stage we will run into the limits of social organization driven by Darwinian mechanisms, and the end of it might be catastrophic.

  • Tox April 8, 2008, 21:38

    Hello, first visit here, nice article on the Dyson sphere and lots of good comments. However , it won’t work , obviously it’s thought provoking but encapsule the sun, and you will disconnect it from the network, ergo it will fizzle out. Therefore i’m sure aliens won’t have bothered, thats not to say that smaller scale spheres with artificial lightning wouldn’t be around.

  • Ron S April 8, 2008, 23:01

    Not sure if anyone commented on this yet, but there is the issue of the solar wind — it stays within the Dyson sphere. Assuming I didn’t grossly miscalculate, if evenly distributed within a 1 AU sphere it accumulates at about 8E-17 g/m^3/year (or 7E-20 atmospheres/year). It’s a plasma, and a hazard, though I suppose if left to itself it will slowly degrade to hydrogen gas, but not before causing some ‘entertaining’ fireworks.

    If you’re going to live within the exhaust from your power plant you need good ventilation or other safety measures. Possibly if you let the sphere first fill with a thin hydrogen atmosphere that will itself provide some protection from the solar wind. For maintenance you just need a group of chimneys with pressure valves. This is laughably primitive but you get the idea.

  • James M. Essig April 8, 2008, 23:24

    Hi Folks;

    We have all heard of the notion of the multiverse, and presumably the concept of innumerable multiverses, as proposed in theories and varients thereof such as Chaotic Inflation. We also have been exposed to the concept of spiritual realms such as Heaven, the abode of the angels etc. It occurred to me that there might be innumerable multiverse analogues for any spiritual or non-material realms. I am not trying to convert anyone here but am merely offering this concept as just a consideration of just how existentially and ontologically big creation might be.

    Now regardless of whether we adhere to any religious creeds or not or believe in a higher providential power or not, we all believe and chiefly feel confident with the concept that the universe around us and even all of the multiverses is atleast part of creation. Now what if there exist realms that are of the same class as creation wherein creation is defined as a realm where cause and effect are operable, but wherein these realms for lack of a better word are entirely distinct from creation yet some how are produced for lack of a better word by God or any other higher power or for those of you who do not believe in such, which some how are real for lack of a better word. Suppose further that there are an limitless number of such non-creation non-God realms where each one is entirely seperate and distinct from all of the others and for which different existential and ontological principles apply. Furthermore, suppose there are an infinite number of such classes wherein each class is entirely separate in terms of overarching existential and ontological principles from all of the others. I bring this notion up not to try to impress anyone since I am in no way a trained theologian, but as a deeply heartfelt imaginative conjecture on what we might somehow discover if we as the human race last essentially forever. However, part of the fun of arriving at ever more exotic destinations in the progress, exploratory, pioneering, and intellectual and spiritual achievement sense is taking the first steps. And so, in the spirit of this Dyson Sphere thread, I say first onward to the stars and hopefully to meet some of our ETI brethren and then onward further out into space and time and then to whatever lies beyond.

    Thanks;

    Jim

  • Ronald April 9, 2008, 3:44

    @andy: thanks for your interesting energetic calculation (> 2.3E36 joules required for a Dyson shell), confirming the impracticality of the same.

    The upside of all this to me is that it suddenly seems to make the challenge of interstellar travel and colonization look like peanuts :-)

    @Dave: with all due respect for your interesting scenario (I haven’t read the whole paper), but Oort/Kuiper Belt settling and conversion again seems to me less practical and efficient, than going to the nearest stars and settling (and if necessary terraforming) their planetary systems, in terms of energy requirements, timescale and risk. I mean, if you manage to get to the outer belts at about a lightyear, you can probably also make it to Alpha Centauri, etc. Then why go for the belts, if you can get the real thing? Like building some platforms in the Atlantic instead of crossing the ocean to a new continent, by the early colonists.

    @Adam: shouldn’t “the last Main Sequence stars form” be rather 100 billion instead of 100 trillion? (Still a long time, about 7 times the present age of the universe).

  • Ronald April 9, 2008, 4:27

    A little addition: I read about terraforming Mars and other terrestrial planets and moons (Zubrin, Fogg, Ahrens, among others), and its requirements, including energy reguirements, seemed quite realistic, even modest in comparison with some other scenarios described above (Dyson sphere, Oort/Kuiper belt settling). Terraforming Mars would require hundreds to some thousands of TWY (3000 TWY is about 10^23 J) of ‘human’ energy input to get the process going (the sun would provide the bulk of the rest). Peanuts for a whole planet.

    Sending a (laser-pushed) space ship of 1000 tonnes with a small crew in suspended animation to a nearby stellar system would cost on the order of tens to a few hundred TWY of energy. Say 300 TWY, which is about 10^22 J.
    I dare say the logical development of humankind in space will first see a colonization and gradual terraforming of Mars, then the leap to the nearest (sunlike) stars.