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Searching for Dyson Spheres

A Dyson Sphere makes an extraordinary setting for science fiction. In fact, my first knowledge of the concept came from reading Larry Niven’s 1970 novel Ringworld, a book that left such an impression that I still recall reading half of it at a sitting in the drafty little parlor of a house I was renting in Grinnell, Iowa. Ringworld had just come out as a Ballantine paperback with the lovely cover you see below. I was hooked after about three pages and read deep into a night filled with wind and snow.

It could be argued, of course, that a ring made out of planetary material, a habitat so vast that it completely encircles its star, is actually one of the smaller Dyson concepts. It was in 1960 that Freeman Dyson suggested how a civilization advanced to the point of such astro-engineering might use everything it found in its solar system to create a cloud of objects, a swarm that would make the most efficient use of its primary’s light. And as you keep adding objects, you point to the ultimate outcome, a Dyson Sphere that completely envelopes the star from which it draws its energy.

A Dyson Sphere Search with IRAS

Last April I looked at Dyson spheres in the context of an article by Bruce Dorminey that considered new SETI strategies. Now I see that Richard Carrigan, a retired physicist from Fermilab, has added a new paper to the arXiv site, one that discusses the work reviewed in that earlier story. Carrigan has been examining sources identified by the Infrared Astronomical Satellite (IRAS), the idea being to look for objects that seem to be radiating waste heat in such a way that they might be Dyson Spheres of one kind or another. A fully enveloped star won’t be visible to the eye, but Carrigan’s infrared search covers the blackbody temperature region from 100 to 600 degrees Kelvin for full or partial Spheres.

The data come from an IRAS database that covers 96 percent of the sky and includes some 250,000 sources. Exciting stuff on the face of it, because unlike a conventional SETI search, a hunt for Dyson Spheres involves no necessary intent to communicate on the part of the civilization in question. And when you’re dealing with SETI, the fewer preconceptions you bring to the dance, the better. Here’s the thinking behind Carrigan’s attempt:

For a Dyson Sphere the stellar energy from the star would be reradiated at a lower temperature. If the visible light was totally absorbed by a thin “shell” a pure Dyson Sphere signature would be an infrared object with luminosity equivalent to the invisible star and a Planck or blackbody distribution with a temperature corresponding to the radius of the spherical shell formed by the cloud of objects. For a sun-like star with the shell at the radius of the Earth the temperature would be approximately 300º K.

Sorting the Evidence

A distinct signature? You would hope so, and if that is the case, we can dig through our data practicing what Carrigan delightfully calls ‘cosmic archaeology,’ using data that cover the 8 to 100 micron infrared range needed to study a Dyson Sphere’s emissions under these assumptions. Yet an identification runs into immediate problems, not the least of which is the need to differentiate any candidate from natural sources that show much the same signature. A cocoon of gas and dust around a young star, for example, might mimic an artificial source.

Carrigan goes through the possibilities — protostars, planetary nebulae, dying stars — and weighs their telltale infrared identity against a true Dyson Sphere, with notes on how to tell the natural from the potentially artificial. Here he considers the methods (italics mine):

A Dyson Sphere candidate with a blackbody distribution can have several characteristics such as a blackbody temperature, the distance from our Sun, magnitude in the infrared, and variability. It may also have a stellar signature in the visible or infrared. Slysh (1985) notes, “The confusion between red giants with thick circumstellar envelopes and possible Dyson Spheres in the IRAS survey is a serious problem, and to differentiate the two we need additional data.” …[S]ome of the source types discussed above populate the same region of an infrared color-color plot as a Dyson sphere candidate would. Non-Dyson Sphere objects can be eliminated using discriminants like spectral lines in the infrared or radio regime, implausible blackbody temperatures, established classifications, and statistical departures from a blackbody distribution.

A Dwindling List

So we still have a chance to find a true Dyson Sphere, assuming one or more are out there. If I had more money to burn, I would ring up Tibor Pacher with an offer to make another bet, this one saying that no Dyson Sphere will be found in this century. Tibor is bound to take that one, but I’ve lost several other bets recently and had better put down my cards (our other bet, on the date of the first true interstellar mission, is viewable at the Long Bets site; feel free to comment on either side of that one).

Image: A Dyson Sphere as envisioned by the producers of Star Trek: The Next Generation, from the episode “Relics.” Credit: Paramount Pictures.

Bet or no, the process of working through the database is fascinating, but the list of candidates quickly dwindles in Carrigan’s discussion. We wind up with a scant seventeen possibilities, none of them particularly promising, though worthy of further study. Carrigan comments:

This search has shown that at best there are only a few quasi-plausible Dyson Sphere signatures out of the IRAS LRS sample in the 100 < T < 600 ºK temperature region. This limit includes both pure and partial Dyson Spheres. With several possible exceptions all the “good” sources identified in this search have some more conventional explanation other than as a Dyson Sphere candidate. In spite of the fact that there are many mimics such as stars in a late dusty phase of their evolution good Dyson Sphere candidates are quite rare!

Next Steps

Where do we go from here? Compiling more on the list of seventeen Dyson candidates would be the logical next step (Carrigan discusses how). And we can search further using the more powerful Spitzer Space Telescope, an instrument with greater angular resolution than IRAS and three orders of magnitude better sensitivity in the infrared ranges needed for this work. This would extend the survey out past the center of the galaxy, but we’ll lose some of the IRAS sources, which are too bright for Spitzer’s camera to avoid saturation. And only one of the seventeen candidates Carrigan finds would be covered by such a Spitzer study.

This intriguing work reminds us how early we are in the study of Dyson Spheres, and the broader attempt to identify astro-engineering on this vast scale. The Low Resolution Spectrometer aboard the IRAS satellite was only sensitive enough to track solar-sized Dyson Spheres out to a range of some 300 parsecs, which includes a million solar-type stars. Extending that reach, and finding ways to either rule out or strengthen the case for some of Carrigan’s seventeen candidates, is work that extends our existing radio and optical SETI methods. Beefing up our infrared tools will help us determine whether a concept once considered outrageous might conceivably flag an extraterrestrial presence.

The paper is Carrigan, “IRAS-based Whole-Sky Upper Limit on Dyson Spheres,” available online.

Comments on this entry are closed.

  • Adam November 19, 2008, 18:38

    Wow! Seventeen candidates is pretty cool. Unlikely any will be Dyson Shells, but it’s worth dreaming.

    Robert Bradbury’s Matrioshka Brains are the most likely Dyson-sized structure we’ll see if the whole post-biological paradigm obtains in this Galaxy, but he posits much lower “exhaust” temperatures, since each Shell uses the thermal radiation from the next Shell inwards, and so long as there’s a thermal gradient, net power can be generated.

    He and Milan Cirkovic then postulate that ETIs will migrate to the Galactic fringe in search of a better heat sink gradient – should we be investigating large dark spheroids Out There? If They’re dumping heat from a star at 25 K then the outer shell is over 3900 AU across.

  • Dave Moore November 19, 2008, 19:38

    Three Points:

    i) I think IR searches for advanced technological exocivilization are the way to go as they make no assumptions about the civilization except that the second law of thermodynamics applies.

    ii) I don’t expect to find Dyson spheres as a space faring civilization in the transition from a Stage I Kardashev level of energy consumption to a Stage II Kardashev level of energy consumption would find it easier to colonize the Kuipier belt and Oort cloud rather than construct a Dyson sphere. Constructing a Dyson sphere would require breaking up a planet, which requires a lot more energy (and hence is more expensive) than using the in situ Hydrogen for power of the Kuipier belt and Oort cloud where you already have several Earth masses of material already broken up and ready for use. A star system with a colonized cometary belt should be lit up like a Christmas tree in the IR.

    iii) Given the immense amount of time available for planetary formation before the Earth was formed (2-5 billion years) then our nearest technological neighbor is likely on average to be a very old (100s of millions to billions of years ). And given that even fairly generous galactic colonization scenarios can occur in a short time relative to this (10-50 million years), then I suspect there are no other advanced technological exocivilizations in our galaxy. Even if they left us alone, the sheer size of their waste heat output would be obvious to us. However, galaxy-wide civilizations may be detectable by looking at other galaxies for their IR excess left by old, advanced civilizations.

    I would like to see an examination of this possibility. The signal may be very difficult to detect though as the IR excess from the civilization may be only a fraction of a percent of the Galaxy’s light output.

  • Adam November 19, 2008, 21:49

    Hi Dave

    David Criswell pointed out years ago that advanced civilizations would get most of their materials from the star not the planets, by “star-lifting”, thus breaking up planets isn’t necessary. Robert Bradbury’s Matrioshka Brain analysis assumes that the ETIs might do both, but conservative ETIs might retain natural planets for any number of reasons.


    The 25 K radius is only about ~250 AU out NOT the 3900 AU I posted.

  • taoist November 20, 2008, 0:23

    As Adam points out, a matroshka brain seems far more likely than any Dyson sphere. Accelerando, by Charles Stross, actually features a Matroshka Brain around Sol, happening in about a century, just following some of Ray Kurzweil’s trends, and Moore’s law and such.

    The reason a Matroshka brain seems so much more likely than a Dyson Sphere is that it is so much more directly useful. As humans become more and more integrated with our computers, computational power becomes increasingly useful. At some point, it seems incredibly likely that several factors will combine to give us a matroshka brain: 1. mini-sat computers with a free energy source (the sun or planet they orbit around) would be able to offer immense parallel computational power. 2. Given the power that could be obtained even from deconstructing the asteroid belt to make such a system would offer the computational power to simulate everything on the earth several times over. 3. As people become increasingly merged with computers, they will become increasingly comfortable spending time in virtual worlds.

  • Ronald November 20, 2008, 5:29

    I thought we went through this whole discussion about the (im)practicality and risks of Dyson spheres in this very interesting thread in April (https://centauri-dreams.org/?p=1806, also mentioned above by Paul)?

    And that we came tot the collective conclusion (or was it mainly me?) that, summarizing, Dyson spheres are quite risky and impractical (in terms of energy investment), other than incremental Dyson swarms of objects for solar/stellar energy collection.

    And the same holds true, to a lesser degree, for the Oort Cloud and Kuiper Belt (I know Dave is a great fan of colonizing those ;-) ): for much less energy investment it would be possible to terraform and colonize a terrestrial planet near a sunlike star (see various estimates in mentioned thread). And particularly with much more risk-spreading. Investing so much in your own stellar system is like putting all your eggs (and a lot of them!) in one basket. And it assumes maximum energy capture as a civilization’s ulimate goal, instead of, for instance, spreading out, spreading life, intelligence and civilization, and colonize its galaxy.

    I do agree with Daves point iii though.

  • Tibor November 20, 2008, 8:52

    There are two fine bets on the Long Bets site related to the discovery of extraterrestrial intelligence, but I feel there is still place for the bet suggested by Paul – is anybody out there ready to make a prediction about this? :-)

    Here the links to the bets:

    “The first discovery of extraterrestrial life will be someplace other than on a planet or on a satellite of a planet.”

    “Evidence of extraterrestrial intelligence within the solar system will be confirmed before evidence from several light-years away.”

  • James Davis Nicoll November 20, 2008, 11:55

    A culture that has harnessed the entire output of a star seems like it would be in a better position to afford the cost of sending colonists out to other stars. Also, the toolkit used to create a Dyson swarm would be more generally useful when settling other systems than one focused on terraforming planets and the gratification timescale seems like it would be much short for space structures than for terraformed planets.

    I suspect that if we are talking humans, the necessary timescale for terraforming is going to make it impossible for all but a very small fraction of organizations.

    One thing I noticed while playing around with broadcast power as a means of powering interstellar rockets is that phased arrays the size of a Dyson swarm have an impressively long reach. The downside (from our point of view) is that an advanced species that has a G type star/Dyson Swarm/emitter combo and which either takes a dislike to or shows a callous disregard for our well being while coveting the materials in the Earth could dismantle our planet over the course of about a week (Effective loss of habitability would occur sooner obviously) at galactic scale distances.

  • dad2059 November 20, 2008, 14:02

    A Dyson swarm is certainly a possibility, in our own species’ future and the galaxy at large, Bradbury’s Matrioshka Brain concept while the most likely outcome, isn’t necessarily carved in stone.

    ‘Ringworld’ and its sequels are some of my most favorite Niven works too Paul.

  • ljk November 20, 2008, 14:09

    I was recently checking the updates page of the Orion’s Arm
    Web site and I came across this concept, the Nicoll-Dyson Beam:


    Apparently a Dyson Swarm’s outer layers can be turned into a
    very powerful phased array laser beam. This beam could be
    used to send solar sail craft at relativistic speeds across the
    galaxy. It could also be used to destroy planet-sized targets
    many light years from the Dyson Swarm.

    Assuming such megastructures exist and that the beings who
    inhabit them (organic or Artilect) might be inclined to use them
    either as a means of galactic exploration, destruction, or both,
    what does it say that we have yet to see either solar sail craft
    coming our way, or an incredibly power beam coming to fry us?


  • kurt9 November 20, 2008, 15:23

    A solid Dyson sphere seems unlikely. What seems more likely is that more and more artifacts would be constructed in orbit around a star (space colonies, factories, computronium clouds, space craft, junk, party poppers, etc.) such that you end up with an effective cloud of objects we could call a Dyson cloud. Most likely, all of this stuff would be along the ecliptic along with the planets and belts (since that is where the resources are and transportation is easier). So, what you have is not a ring world, but a ring cloud that might not look much different than a natural asteroid or Kuiper belt, but maybe more dense. Such an artificial ring cloud is what we should be looking for. Such a ring cloud would look like a natural belt except that it would be denser.

    I have always thought that the proper strategy to find ETI is not to find their radio signals (maybe they don’t use the electromagnetic radiation for communication anymore), but to look for artifacts. Of course, I think we are alone in the Milkyway, so we have to look for ring clouds and the like in other galaxies, like the Virgo group. Given how far away that is, it is unlikely we will spot anything less than galactic-level engineering.

  • Dave Moore November 20, 2008, 15:48

    “The downside (from our point of view) is that an advanced species that has a G type star/Dyson Swarm/emitter combo and which either takes a dislike to or shows a callous disregard for our well being while coveting the materials in the Earth could dismantle our planet over the course of about a week.”

    This sounds interesting. Could I get more details. I’m particularly interested in how you can dismantle a planet within a week by means other than a black hole.

  • James Davis Nicoll November 20, 2008, 17:17

    Basically, you heat it with your interstellar beam until the planet evaporates. I will admit losses in the process will make the process last longer than output of a star/total binding energy of a planet indicates. You will lose most of the volatiles in the process and a certain fraction of the debris to effects like Poynting-Robertson drag but a considerable portion of the planet will remain in orbit around its star ready to be put to more useful purpose.

    It does take the entire output of a sunlike star to do it in just a week.

  • James Davis Nicoll November 20, 2008, 17:19

    We don’t see the beam coming to get us because it’s moving at C so the first we will know about it is that first brief moment as the oceans boil.

  • Ronald November 20, 2008, 17:30

    James Davis Nicoll Says:

    “A culture that has harnessed the entire output of a star seems like it would be in a better position to afford the cost of sending colonists out to other stars. Also, the toolkit used to create a Dyson swarm would be more generally useful when settling other systems than one focused on terraforming planets.”

    I see them as complementary rather than competing, for the very reason you mention: the energy provided by a star would enable such a civilization to travel to the stars ánd terraform planets.

    “and the gratification timescale seems like it would be much shorter for space structures than for terraformed planets.”

    I sincerely doubt that: the timeframes mentioned for terraforming of Mars that I have read ranged from about 300 to 1000 years, at least until the first unprotected inhabitants.

    “I suspect that if we are talking humans, the necessary timescale for terraforming is going to make it impossible for all but a very small fraction of organizations.”

    The returns would also be huge: a whole new planet.

  • Sean Welton November 20, 2008, 18:23

    The gamer in me can’t help but realize we’re looking for Halos! ;)

    Although I guess I never actually thought about the possibility of such a thing being real.


  • ljk November 20, 2008, 21:07

    Dave, this Web site discusses how long it might take to take
    apart a solar system to build a Matrioshka Brain:


    Assuming it does not fry the recipients, a Nicoll-Dyson beam
    might also make an excellent Optical METI device.

    NGC 5907 has a larger amount of supposedly red dwarfs than
    a spiral galaxy of its age should have, according to astronomers.
    We should be investingating that star island more closely.

  • James Davis Nicoll November 21, 2008, 0:47


    “A two-stage terraforming scenario is outlined for Mars. The approach adopted differs from past methodology in two ways. It adopts a more conservative and plausible Martian volatile inventory. Possible planetary engineering solutions, including possible synergic use of terraforming techniques, are examined in detail. In the first stage, the Martian environment is modified to a state where it can support microbial and hardy plant life in approximately 200 years. While this step is conceptually similar to past scenarios, it differs greatly in detail. The second stage deals with the creation of conditions tolerable for human beings over a period of approximately 21,000 years. It is concluded that terraforming Mars is possible but not by the passive, or near-spontaneous, methods favored by some workers. A powerful industrial effort is required both on the planet’s surface and in space as will be continuing technological intervention to stabilize the postterraformed regime. “

  • Adam November 21, 2008, 4:14

    Hi All

    A Dyson Shell as an energy collector could happen long before it becomes a Habitat or a diffuse habitat halo. Gerald Nordley pointed out about 9 years ago in an “Analog” piece that self-replicating solar collectors could easily tap a large fraction of the Sun’s output within ~50 years, all without using a lot of mass (in relative terms.) He proposed using the output for propelling starships – which is fine – but it could easily do a lot more. A multi-terawatt relativistic mass-beam can devolatise regolith on Mars to make an atmosphere, move asteroids, cause fusion reactions in a Jovian and so on. And Gerald just wanted to push 30,000 kiloton starships to 0.87c per year!

    Of course a terawatt beam is also a “terror”watt beam, but let’s hope security is at least as good as nuclear security is at present.

  • ljk November 21, 2008, 11:20

    Mr. Nicoll, nice to have you aboard.

    Could you point us to where you wrote about the Nicoll-Dyson
    Beam concept? I am a bit skeptical about the brief information
    on the idea in Wikipedia, which says the beam could destroy from
    a distance of millions of light years.

    Should we be really concerned about the beam from Messier 87?

  • Ronald November 21, 2008, 11:38

    “approximately 21,000 years”

    Oops! A bit more than the 300-1000 years I suggested, apparently that was just for the unprotected “hardy plant life”, JDN refers to.

    Indeed, that would require an entirely different kind of civilization with a truly long-term vision. Still worthwhile as a long-term investment.

    @Adam: “self-replicating solar collectors could easily tap a large fraction of the Sun’s output within ~50 years” (..) “A multi-terawatt relativistic mass-beam can devolatise regolith on Mars to make an atmosphere”

    Could that possibly speed up the Martian terraforming a bit?

  • James Davis Nicoll November 21, 2008, 11:53

    If I recall Dyson’s original paper, it was mostly about the energy collection.

    I do wish he’d not used the word “shell”, which a lot of people interpret as one solid thing, rather than some other choice of words that would make it clear we’re talking about a diffuse collection of orbiting facitilities.
    As Dyson put it in his discussion with Poul Anderson in Science, Vol. 132

    In reply to Maddox, Anderson, and Sloane, I would like only to add the
    following points, which were omitted from my earlier communication.

    1) A solid shell or ring surrounding a star is mechanically
    impossible. The form of “biosphere” which I envisaged consists of a
    loose collection or swarm of objects traveling on independent orbits
    around the star.

    From which we may deduce that Larry Niven never read this set of letters.

  • dad2059 November 21, 2008, 20:51

    Should we be really concerned about the beam from Messier 87?

    I know this question wasn’t meant for me, but it’s fascinating nonetheless.

    Would we be able to discern astroengineering from nature if we see it?

    A METI Optical Beam makes sense on many levels, an intergalactic beam from Messier 87 is akin to the Alexandrian Pharos Lighthouse, a definite “Here I am, come hither!”

    Just don’t get in the beam’s path.

  • James Davis Nicoll November 22, 2008, 12:25

    If the beam is high density, you can use it to power your emissarial space craft (Unfortunately the ISM in the path of the beam will be hot and diffuse so reaction mass may be scarce). Don’t think of it as a ravening beam of intergalactic destruction, think of it as an express highway to our alien buddies.

    Anyway, intergalactic invasions don’t use beams. They use the A is for Andromeda scenario, to get the low tech types at the far end to do all the heavy lifting.

  • taoist November 22, 2008, 18:14


    The paper that you reference fails to take into account exponential growth. Because of the massive amount of work involved, terraforming a planet is largely impractical unless it is done involving some sort of grey goo/self replication process. A self replicating process would be significantly faster, although still likely dependent on the energy situation of the planet being targeted, i.e. terraforming inner planets would be significantly easier than terraforming outer planets, as inner planets have more solar energy available for self replicating machines to take advantage of.

  • Adam November 23, 2008, 4:20

    Hi All

    Paul Birch sprouted a few terraforming ideas in the early 1990s that deserve more attention in such discussions IMHO.

    He has an unpublished paper online which discusses some very interesting technologies for terraforming Mars and Venus. He estimates that both planets could be given breathable atmospheres in ~20 years – Venus could be cooled sufficiently to cause its atmosphere to condense in about a decade using a clever cooling technique he describes.

    But, as he notes, three planets in one system isn’t much for a growing civilization. He proposes some very elaborate and clever ultra-structures one of which is germane to the current discussion: a SupraSelf. The object is a multi-layered structure 1.2 lightyears across which has one-gee surface gravity from its own mass. In my mind it’s physically the ultimate artificial habitat until we learn how to make pocket Universes – for that idea check out Greg Egan’s story Borderguards.

    A habitable object 1.2 light-years across would mass 2 trillion solar masses – twice the Milky Way. Such an object would be visible via its waste heat, but the red-shift would make it almost invisible – thus making for a hefty “Dark Matter” Galaxy. Birch says the inner layers (it is composed of 30 million nested shells) could have a red-shift/time-distortion factor of 2,500 making for some very curious possibilities indeed. Total area is ~200 billion trillion Earths – all of it inhabitable, unlike most of Earth. A population of 10^35 would be feasible. Surely a worthy effort for a Kardashev Type III to create over a few billennia.

    Perhaps Dyson Clouds/Shells are insufficiently ambitious for our SETA efforts?

  • Steve Bowers November 27, 2008, 4:34

    I’m quite glad that there are apparently no Dyson swarms near this location- the idea of a Nicoll-Dyson beam is a little unsettling (I’m the one who made the image for OA , by the way: yes, it is supposed to be a swarm, not a shell).

    I note that Mr Nicoll calculates that these things could be effective at very long distances- so perhaps my relief is ill-founded.

  • ljk December 1, 2008, 14:27

    Hi Steve – Nice job on bringing the Nicoll-Dyson Beam concept to
    public attention.

    I know Orion’s Arm is as much about creating stories which will
    naturally require conflict as depicting a possible future for the
    galaxy, but would you also be able to add more text on this aspect
    of the Dyson Swarm’s ability to launch solar sail craft and perform
    Optical METI?

    I think some very interesting stories could come out of those ideas
    in the process as well, without always having to resort to the need
    for war and destruction. I think that just being able to build a Dyson
    Swarm alone would make most other beings think twice before
    attempting to bother such a society/being.

    That being said, just how far could a Nicoll-Dyson Beam reach to
    inflict damage? The short Wikipedia entry the OA article links to
    says millions of light years, but I have questions about that. Plus
    my earlier queries here on more information about the device and
    its abilities have yet to be answered, thank you.

  • ljk December 3, 2008, 14:10

    The blog Cosmic Variance recently gave its own take on the
    search for Dyson Swarms here:


    As can be seen, the author like many others is still stuck in the
    mode of a Dyson Swarm only being built by and a habitat for
    organic beings. Thankfully a poster updated the author early
    on in the comments section with the Matrioshka Brain concept
    by Robert Bradbury.

    I say again, while I am certain there are plenty of organic type
    intelligences in the Universe along our lines, it is the artificial ones
    who will be able to and will be conducting most of the cosmic
    activities that we will be able to one day recognize.

    Unless all intelligences become navel-gazers and/or get lost in
    virtual worlds of their own making.

    And we may not be thinking widely enough in terms of the trees
    (beings living on worlds around stars) keeping us from seeing the
    forest (whole galaxies as living beings).

  • Steve Bowers January 17, 2009, 10:11

    …but would you also be able to add more text on this aspect
    of the Dyson Swarm’s ability to launch solar sail craft and perform
    Optical METI?…

    Sure; no problem.

  • ljk January 19, 2009, 23:14

    January 19, 2009

    Russia Proposes Mission to Search for Evidence of Astroengineering

    Written by Ian O’Neill

    It is probably the most seductive urge for mankind: search for extraterrestrial life. There are many ways to look for life; from digging into the Martian dirt with robotic landers looking for pre-biotic compounds, to building vast radio antennae to “listen” out for distant communications either leaked or transmitted deliberately from a distant star system from a developed, intelligent civilization. However, despite our best efforts, we appear to be the only form of life for hundreds of lightyears around. It is eerily quiet out there…

    Although we appear to be drawing blanks so far, it doesn’t stop us from trying to work out what we should be looking for. In the quest to find a vastly advanced alien civilization, a forthcoming Russian space telescope hopes to bridge the gap between science fiction and science fact, attempting to find evidence (or lack thereof) of observable attempts of astroengineering by an alien race…


  • ljk April 23, 2011, 23:43


    Remembering Robert Bradbury

    by George Dvorsky

    Sentient Developments

    Posted: Mar 6, 2011

    Robert Bradbury passed away suddenly and unexpectedly last weekend of a massive hemorrhagic stroke. His passing was the kind of thing that barely registered anywhere except among his immediate group of family and friends—and among a group of dedicated and niche scientists, futurists and technologists. For them, Bradbury’s premature passing represented a monumental blow to inspired and imaginative scientific inquiry.

    While Robert Bradbury, who died at the age of 54, may not have had the most recognizable name in the various scientific communities he was involved in, his impact to future studies, and in particular its relation to the search for extraterrestrial intelligence, cannot be overstated. Bradbury was a giant in this area, a creative and unconventional personality who paved the way for other like-minded thinkers and enthusiasts.

    To say that the scientific community lost its foremost thinker on SETI studies (the search for extraterrestrial intelligence) and the problem that is the Great Silence (also known as the Fermi Paradox) is hardly an exaggeration. Bradbury was a voracious collector of any and all articles, papers and studies conducted on the subject. From my conversations with him, I can tell you that his ability to recollect and reference these works was uncanny to the point of absurdity. He was an authority in the truest sense.

    Nobody more than Robert insisted on the simple fact that the correct resolution of Fermi’s Paradox—the fact that we do not observe any presence of Galactic extraterrestrial intelligence—will provide us with crucial insights into humanity’s future. It was this particular notion that has personally driven me to pursue SETI studies as a means to predict humanity’s potential developmental trajectories. Simply put, if you can predict, or even observe, how advanced extraterrestrials operate, we stand a better chance of understanding our own future.

    Despite the eeriness that is the Great Silence, Bradbury applied a natural optimism to his work. He sought to construct and develop hypotheses to the Fermi problem that did not jeopardize the potential for human possibilities. This included a grandiose “cosmic vision” of humanity’s future, and in this sense he was an heir apparent to Olaf Stapledon, H. G. Wells, and Freeman Dyson.

    To this end, Bradbury put forth a number of intriguing theories—theories that have since become foundational concepts amongst serious futurists, transhumanists and those concerned about the potential for a technological singularity. In particular, Bradbury was intrigued by megascale engineering concepts such as Dyson Spheres and Jupiter Brains. He even came up with one of his own, the the so-called Matrioshka Brain—a megascale computer that could exploit nearly the entire energy output of a star. Bradbury could never be accused of thinking small. Such concepts would go on to influence such thinkers as Anders Sandberg, Nick Bostrom, Robin Hanson and Ray Kurzweil.

    One of his most important works came in 2006 in his collaboration with Milan Ćirković, “Galactic gradients, postbiological evolution and the apparent failure of SETI” (New Astronomy 11, 628-639). In this paper, he argued that the most likely trajectory of a postbiological (i.e. digital) community would involve the quest for computational efficiency and optimization. Such a society, he argued, would likely involve spatially compact civilizations that would be extremely hard to detect, especially if located in outer regions of the Milky Way. This conclusion has served as an elegant and rather optimistic answer that contrasts to the more doom-and-gloom suggestions that are typically put out.

    The paper also criticized the orthodox approach to SETI projects, which Bradbury found irritatingly old-fashioned and conservative in the extreme. Instead of listening for intentional (or intercepted) radio messages, he thought it would be far more promising to search for artifacts and traces of astroengineering of advanced technological civilizations, like Dyson shells or Matrioshka brains. Such searches, he thought, would have to be conducted in the infrared part of the electromagnetic spectrum. A natural extension of this concept was the project of setting up new directions and expanded range of techniques for SETI observations, something which was consistently hinted at during the half-centennial jubilee of the OZMA Project in 2010. This study was, sadly, the last one Bradbury worked on and will be published posthumously. Clearly, his departure will be a great loss for the astrobiological and SETI communities.

    At a personal level, Robert Bradbury was known as a generous, driven and often outspoken individual. His unorthodox beliefs, a hallmark of the transhumanist and Extropian communities of which he was a big part, often translated to personal opinions that made others uncomfortable. Bradbury never shied away from saying things that might offend others, but this largely came from his powerful sense of outrage towards certain issues, including the problem of death. A radical life extension crusader, Bradbury railed against the needless deaths of people the world over and and how society spent so relatively few resources to address the issue.

    Along these lines, Bradbury also made a considerable impact on early efforts to re-conceptualize and pathologize the aging process. Back in 1991 he was already framing the problem of aging as something that could be solved. To that end he devised a theory of aging that involved insights into genetic defects, poor biological programming and insufficient repair mechanisms; the work has served as a precursor to Aubrey de Grey’s Strategies for Engineered Negligible Senescence (SENS).

    Not content to merely wax philosophical on heady issues, Bradbury made a number of attempts at various tech ventures, but often to poor results. He desperately wanted to succeed at being a technology entrepreneur, and at the time of his passing, may have felt deep frustration at not being more successful in this regard. He also wanted to marry and have children, but seemed to have doubts about having a successful and lasting relationship.

    It may take a few years before Bradbury’s contributions properly hit the radar. He leaves behind a rather remarkable body of work that I predict will eventually get the respect it deserves in the various scientific circles he was involved in.

    Thanks to Milan Ćirković and John Grigg for helping me write this piece.

  • Tom Kalbfus December 1, 2011, 20:18

    Ever consider a Dyson Sphere that is a Matrioshka Brain? The two are not mutually exclusive you know. Now I like the concept of a solid continuous shell 150,000,000 km in radius around a Sunlike star. Most of the interior of the Dyson shell is designed to absorb the maximum amount of radiation from the star, with the exception of the equatorial band. The equatorial band, in this case is a ringworld, but the ringworld is also part of the Dyson Sphere. The sphere is almost entirely enclosed except for 1,000 km wide circular openings at the sphere’s north and south poles. The equatorial band is about 1,500,000 km wide, there are no walls to retain atmosphere, the atmosphere just naturally bunches up around the equator, as one moves further from the equator the air gets thinner and thinner until it can no longer support life. The equatorial region is landscaped, has rivers mountains and vast equatorial oceans in the middle, with the land of course on the periphery. To provide gravity, the Sphere or perhaps just the equatorial band rotates once every 9 days. To provide night and day, an inner ring of shadow squares 50,000,000 km in radius alternately shades or lets light through to hit the equatorial band, everywhere else along the Dyson sphere’s inner surface reflects little light, and it appears black to the inhabitants of the equatorial band at night. There are either 10 or 8 shadow squares in the inner ring, 10 if they are orbiting in the direction of the sphere’s spin, 8 if they are orbiting in the opposite direction. In the former circumstance, the shadow square ring makes one tenth of a rotation for every complete rotation of the Dyson Sphere, in the later case the Shadow square ring makes one eigth of a rotation for every rotation of the Dyson Sphere.
    Now what’s the rest of the Dyson Sphere for? For the Matrioshka Brain of course, but I don’t want to give the wrong impression, the Matrioshka Brain doen’t have to consist of one entity thinking incomprehensible thoughts, it is rather a simulator of one billion worlds. The Worlds could be a virtual galaxy allowing “FTL travel” between them, and to the ring, or it could represent a “time machine” of sorts that recreates the past of one particular world at one billion points in time of the World’s past. We could be residing in a Matrioshka Brain Dyson Sphere right now and not even know it.

  • Tom Kalbfus December 4, 2011, 18:13

    One possible way to make a Dyson Sphere is to do it out of materials in the Alpha Centauri system. From my understanding Alpha Centauri A has 1.1 solar masses and Alpha Centauri B has 0.85 solar masses. Now if we were to take apart Alpha Centauri B and starlift 0.1 Solar masses of material out of Alpha Centauri A, we’d have a sunlike primary of 1.0 solar masses and 0.95 solar masses of material to build the Dyson Sphere out of. Central to the Dyson Sphere is the Dyson Ring of Ringworld, this one rotates once every 9 days to create 9.81 meters per second squared of centripedal acceleration, so we have the weight of one Jupiter mass under the equivalent of one gravity pulling outward, to counterbalance this, we have the weight of 0.95 solar masses of material being pulled toward the primary under the combined Solar gravity + 0.95 solar masses of gravity in the nonrotating ring outside the rotating ring on the inside, the rest of the sphere utilizes another Jupiter’s mass to create a 1 meter thick shell to intercept most of Alpha Centuari A’s radiation, with 1,000 km wide circular openings at the north and south poles of this sphere. Now 0.95 solar masses of material is going to have some weight under Solar gravity at 1 AU, so the question is, what kind of solid habitable Dyson ring can it support under inward centripedal acceleration. If I have time, I’ll try to figure this out later, but the idea is, instead of using some super impossible material with the bonding strength of an atomic nucleous, what sort of engineering work arounds can we come up with using known forms of matter. We balance outward centrifugal force with inward weight due to mass and gravity, and when the two balance, we have a short term stable megastructure.

  • ljk December 28, 2011, 17:20

    Type III Dyson Sphere of Highly Advanced Civilizations around a Super Massive Black Hole

    Makoto Inoue, Hiromitsu Yokoo

    (Submitted on 23 Dec 2011)

    We describe a new system for a society of highly advanced civilizations around a super massive black hole (SMBH), as an advanced Type III “Dyson Sphere”, pointing out an efficient usage of energy for the advanced civilizations. SMBH also works as a sink for waste materials.

    Here we assume that Type III civilisations of Kardashev classification [1] form a galactic club [2] in a galaxy, and the energy from the SMBH will be delivered to the club members, forming an energy control system similar to power grids in our present society. The energy is probably transmitted by a sharp beam with coherent electro-magnetic waves, which provide a new concept for the search for extraterrestrial intelligence (SETI) via detection of such energy transmission signals. This expands the search window for other intelligences within the Universe.


    4 pages, 1 color page


    General Physics (physics.gen-ph)

    Journal reference:

    Journal of British Interplanetary Society, Vol. 64, pp.58-62, 2011

    Cite as:

    arXiv:1112.5519v1 [physics.gen-ph]

    Submission history

    From: Makoto Inoue [view email]

    [v1] Fri, 23 Dec 2011 06:09:53 GMT (5350kb)


  • ljk July 29, 2012, 16:12


    Do Dyson Spheres and Von Neumann Probes make the Fermi Paradox Worse?

    Lincoln Cannon

    Lincoln Metacannon

    Posted: Jul 24, 2012

    Are we ourselves perhaps the self-replicating probes (panspermia?) of another civilization that has already begun colonizing the universe?

    Scientists Anders Sandberg and Stuart Armstrong are working on a paper that explores the relation between theoretical engineering capacities and colonization of the universe. Of course, this is not a new topic. For decades, scientists and philosophers have analyzed what has come to be known as the “Fermi paradox”, named after physicist Enrico Fermi, who called attention to two apparently conflicting observations: on the one hand, the universe appears old and large enough to have produced many Earth-like planets capable of supporting intelligent life; yet on the other hand, we have no objective evidence for the existence of intelligent life beyond humanity on Earth. Many have argued that if intelligent life existed elsewhere then it should have been able to colonize the universe many times over by now, but perhaps “many times” grossly underestimates just how many times it could have happened by now.

    In the video, Stuart provides an enjoyable and thought-provoking presentation of the analysis that he and Anders have been working on. He reasons, based on our improving understanding of theoretical engineering capacities, that an intelligent civilization not much more advanced than us could start and complete within 10,000 years (and perhaps orders of magnitude faster) a project of launching a sufficient number of replicators for universal colonization. Basically, the civilization could build a Dyson sphere around its star and harness that energy to build and launch trillions of von Neumann self-replicating probes toward all the galaxies in the observable universe.

    Stuart then observes that this makes the Fermi paradox “worse” because 10,000 years (or less) on cosmological scales is almost no time at all, suggesting that the critical path would be travel time (rather than any earlier stage in the project), and there’s clearly been more than enough travel time available to the probes of any intelligent inhabitants of stars and galaxies older than our own. He concludes that one of following explanations must be true:

    1) The technology is impossible.

    2) His calculations or assumptions are wrong.

    3) We are already colonized, but don’t know it.

    4) Technological civilizations are far rarer than most imagined.

    Near this point in Stuart’s presentation, the audience engaged him in some interesting conversation. Everyone allowed #1 and #2 to be rejected, at least for sake of argument. However, when Stuart expressed his inclination toward #4 rather than #3, some members of the audience questioned his reasoning, suggesting that we ourselves are perhaps the self-replicating probes (panspermia?) of another civilization that has already begun colonizing the universe. Stuart responded that he considers this unlikely because it doesn’t seem to make sense that the colonizing civilization would use a mechanism that forgets its origin.

    I don’t share his assessment for a few reasons: first, if evolution is sufficiently predictable then we may not have forgotten our origins in the most pertinent sense; second, forgetting in some senses may be valuable to the robustness of a replicator or the interestingness of its results; and third, we have practical and moral reasons to trust that technological civilizations are not rare, as outlined in the New God Argument.

    In case you didn’t actually watch the video, I’ll add in closing that Mormons make an appearance in Stuart’s presentation. He uses us as an example of persons that would want to colonize the universe for ideological reasons. I wonder if he knows anything about Mormon Transhumanists?

    Lincoln Cannon is a philosopher and professional software engineer. In his spare time, he serves as president of the Mormon Transhumanist Association.

  • ljk October 9, 2012, 9:22


    First warp drives, and now we’re searching for Dyson Spheres. Awesome.

    October 5, 2012 6:50 PM

    Tom Cheredar

    First warp drives, and now we’re searching for Dyson Spheres. Awesome.

    If NASA’s recent efforts to build a warp drive engine wasn’t enough to convince you that Star Trek will eventually mirror our own reality, then perhaps the latest research project from Penn State’s Astrophysics department will.

    A team of Penn State researchers were recently awarded a sizable grant to search the universe for intelligently created spheres large enough to fit a planetary system inside — and to do so without ever setting foot on a galaxy-class Federation spaceship like the Enterprise-D.

    The enormous objects are officially called Dyson Spheres, named after a 1960 theory by physicist Freeman Dyson about looking for extraterrestrial life. And as the theory goes, a Dyson Sphere is a dark object roughly the size of Earth’s orbit that is constructed around the entirety of a star. The object would also harness the star’s energy for the purpose of sustaining lifeforms inside the sphere almost indefinitely.

    Dyson himself thought the theory was ridiculous, in part due to the insane amount of raw materials necessary to build such a mega-device, which would also require ultra-advanced technology capable of maintaining the correct temperature to support life. Even in the fictional Star Trek universe, record of a Dyson Sphere’s existence was only discovered once (in The Next Generation episode Relics).

    But that’s not stopping assistant professor Jason Wright of Penn State’s Department of Astronomy & Astrophysics and his team of researchers from looking. Using NASA’s Wide-field Infrared Survey Explorer (WISE) satellite, the team will conduct searches based on Dyson’s theory that such structures would be detectable by giving off the same amount of infrared radiation as the star contained inside of it.

    Wright told The Atlantic that such a sphere probably wouldn’t be a solid shell (such as the one from the Trek episode), but rather a collection or swarm of devices banded together.

    The Penn State team’s grant was funded by the John Templeton Foundation’s New Frontiers program, which is “intended to foster research that, because of its non-mainstream nature or breadth of questions asked, would not usually be funded by conventional funding sources.” Academic researchers were asked to submit grant proposals that answered big questions, such as “Are we alone in the universe? Or, are there other life and intelligence beyond the solar system?”

    If Wright and his team are able to find evidence of an actual Dyson Sphere, I’d say it’s safe to assume we’re most definitely not the only ones in the universe.

    Read more at http://venturebeat.com/2012/10/05/dyson-spheres-research/#zB9RY3JXup1WCxBj.99