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No Sign of Galactic Super-Civilizations

‘Dysonian SETI’ is all about studying astronomical data in search of evidence of advanced civilizations. As such, it significantly extends the SETI paradigm both backwards and forwards in time. It moves forward because it offers entirely new search space in not just our own galaxy but galaxies throughout the visible universe. But it also moves backward in the sense that we can use vast amounts of stored observational data from telescopes both ground- and space-based to do the work. We don’t always need new instruments to do SETI, or even new observations. With Dysonian SETI, we can do a deep dive into our increasingly abundant digital holdings.

At Penn State, Jason Wright and colleagues Matthew Povich and Steinn Sigurðsson have been conducting the Glimpsing Heat from Alien Technologies (G-HAT) project, which scans data in the infrared from the Wide-field Infrared Survey Explorer (WISE) mission and the Spitzer Space Telescope. This is ground-breaking work that I’ve written about here on several occasions — see G-HAT: Searching For Kardashev Type III and SETI and Stellar Drift for recent articles. Jason Wright himself explained G-HAT in the Centauri Dreams article Glimpsing Heat from Alien Technologies.

Last April, G-HAT produced a paper that found only a small number of galaxies out of the 100,000 studied that showed higher levels of mid-infrared than would be expected, with the significant caveat that there are natural processes at work that could mimic what might conceivably be the waste heat of an advanced civilization, a Kardashev Type III culture deploying the energies of its entire galaxy. This is a finding that shows us, in Wright’s words, that “…out of the 100,000 galaxies that WISE could see in sufficient detail, none of them is widely populated by an alien civilization using most of the starlight in its galaxy for its own purposes.”

A fascinating finding in its own right, because we’re dealing with a large sample of galaxies that are billions of years old. The Kardashev model moves from Type II, a technology capable of using the entire energy output of its star, to Type III, a technology capable of using an entire galaxy’s luminous energies. If we assume a progression toward ever more capable energy harvesting like this, then abundant time has been available for Type III cultures to arise. Those interesting galaxies with a mid-infrared signature larger than expected will receive more study, to be sure, but the result at this point seems stark. None of the galaxies studied show signs of civilizations that are reprocessing 85 percent or more of their starlight into the mid-infrared.


Image: The Sombrero galaxy (M104), a bright nearby spiral galaxy. The prominent dust lane and halo of stars and globular clusters give this galaxy its name. If a Kardashev Type III civilization were engaged here, shouldn’t we be able to detect it? Credit: NASA/ESA and The Hubble Heritage Team (STScI/AURA).

But we keep looking, and those few anomalous galaxies from G-HAT still need explanation. Michael Garrett is general and scientific director for ASTRON (Netherlands Institute for Radio Astronomy). Garrett has been working with data on 93 candidate galaxies found in the most recent paper from G-HAT (citation below). These were the galaxies with mid-infrared values enough out of the ordinary to elicit attention. The G-HAT paper (lead author Roger Griffith) calls them “…the best candidates in the Local Universe for Type III Kardashev civilizations.”

The stellar energy supply of a galaxy as examined in the Kardashev taxonomy is roughly 1038 watts, with waste heat energy expected to be radiated in the mid-infrared (MIR) wavelengths, which means temperatures between 100 and 600 K. Garrett’s new paper notes that the 93 sources G-HAT has found would — if the radiation measured here were interpreted as waste heat — include galaxies reprocessing more than 25 percent of their starlight. But can we make that interpretation? Garrett is quick to add that there are many ways that emissions in the mid-infrared can develop through entirely natural astrophysical processes.

To make a determination about what is actually happening, Garrett relies on a relation known as the infrared radio correlation, which the paper calls a ‘fundamental relation’ for galaxies that holds over a wide range of different redshifts and covers at least five orders of magnitude in luminosity. It extends, as the paper notes, well into the FIR/Mid-Infrared and sub-millimetre domains. The tight correlation between infrared and radio emissions was originally uncovered with data from the IRAS (Infrared Astronomical Satellite) mission, launched in 1983. And it takes us into interesting territory as a diagnostic tool, as the paper notes:

The physical explanation for the tightness of the correlation is that both the non-thermal radio emission and the thermal IR emission are related to mechanisms driven by massive star formation. For galaxies in which the bulk of the Mid-IR emission is associated with waste heat processes, there is no obvious reason why artificial radio emission would be similarly enhanced. While the continuum radio emission level might increase through the use of advanced communication systems, the amount of waste energy deposited in the radio domain is likely to be many orders of magnitude less than that expected at Mid-IR wavelengths.

The Garrett paper, then, looks at the 93 G-HAT sources in terms of the mid-infrared radio correlation, with the assumption that galaxies associated with Type III civilizations should appear as outliers. The result: The correlation holds as expected. The likely interpretation is that the excesses of radiation in mid-infrared wavelengths are due to natural heat sources rather than the heat of a titanic civilization going about its business. Garrett puts the point bluntly: “The original research at Penn State has already told us that such systems are very rare but the new analysis suggests that this is probably an understatement, and that advanced Kardashev Type III civilisations basically don’t exist in the local Universe.”

In an email this morning, I ran today’s post by Jason Wright, who said that Garrett’s study was the kind of thing the G-HAT team had hoped for, an investigation into what might have caused the galactic anomalies by other methods. He also noted that even with this information, we can’t absolutely rule out a K-III:

“Kardashev’s original line of research was to estimate the power available to a KIII to transmit radio waves that we would detect at Earth. Determining that these galaxies are radio bright in a way correlated with their MIR is a good bit of information to have, but it doesn’t rule anything out (they do seem to be consistent with starbursts, as expected, but they’re not inconsistent with KIII’s). On the other hand, there’s no reason I can think of that bright radio emissions from leaked communications would follow the MIR-radio correlation for starbursts (what a coincidence that would be!).”

Or is a Kardashev Type III civilization advanced enough that it produces low waste heat emissions in ways that are beyond our understanding? Whatever the case, the paper adds that the correlation method can be extended into the search for possible Kardashev Type II civilizations within our own or nearby galaxies:

…it should be noted that the IR-radio correlation is also known to hold on sub-galactic scales (e.g. Murphy (2006). A comparison of resolved Mid-IR and radio images of nearby galaxies on kpc scales can also be useful in identifying artificial mid-IR emission from advanced civilisations that lie between the Type II and Type III types. While Wright et al. (2014a) venture that Type III civilisations should emerge rapidly from Type IIs, it might be that some specific galactic localities are preferred – see for example Cirkovic & Bradbury (2006) or are to be best avoided e.g. the galactic centre. A comparison of the resolved radio and mid-IR structures can therefore also be relevant to future searches of waste heat associated with advanced civilisations.

The paper is Garrett, “The application of the Mid-IR radio correlation to the G^ sample and the search for advanced extraterrestrial civilisations,” accepted at Astronomy & Astrophysics (abstract). The Griffith paper on recent G-HAT results is Griffith et al., “The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. III. The Reddest Extended Sources in WISE,” Astrophysical Journal Supplement Series Vol. 217, No. 2, published 15 April 2015 (abstract / preprint).


Comments on this entry are closed.

  • John September 22, 2015, 10:37

    What I get from this is that we can rule out the most massive of massively industrialised scenarios for alien civilisations. That’s interesting in itself but doesn’t add up to ‘we’re alone’.

  • Joseph Voros September 22, 2015, 10:44

    I would think that a serious look at PGC54559 Hoag’s Object is prima facie warranted, as a possible candidate for Kardashev Type III Dysonian macro-engineering. The rationale is given at: http://arxiv.org/abs/1412.4011


  • Eric Hughes September 22, 2015, 11:52

    > Or is a Kardashev Type III civilization advanced enough
    > that it produces low waste heat emissions in ways that are
    > beyond our understanding?

    This is the single most salient sentence in the whole piece. The experimental work knocks out one single scenario for the nature of intentional energy use at such a scale. It says that such structure does not emit waste heat in this band.

    On the other hand, I find this result completely unsurprising. Any Type III structure would be harnessing truly massive amounts of energy, enough so that the waste heat at 100K is still very large, enough for it to be worthwhile to figure out how to exploit it. Just because we don’t know how to run a heat engine between 100K and 3K is no evidence at all that such a thing is impossible or infeasible. (Or, rather more speculatively, that such use of energy is governed by the analysis of heat engines.)

    Another scenario not excluded is that the energy use is hiding itself, removing any signal that points to its existence. This could be by, say, minimizing the magnitude of any signal or mimicking other signals (such as pretending to be a brown dwarf. Terran ecological systems exhibit plenty of camouflage strategies, for example.

  • Harold Daughety September 22, 2015, 11:52

    I believe it is a certainty that there are no human – populated planets “out there” and whatever intelligent beings there are have their own philosophies. Dyson spheres are a product of human imagination and an extrapolation of human history. There is no reason to believe Dyson spheres are within the reach of any civilization or that they are more desirable that simpler alternatives. We might as well look for “warp drive signatures” or any other science fiction phenomena.

  • Alex Tolley September 22, 2015, 12:17

    I think there is a problem for teh assumption for KIII civs. KI-KII is of the order of 10^9 fold energy increase, and from KII-KIII about 10^9. However slow your assumed growth rate is, the transition from KII-KIII occurs in the blink of cosmic time. Even filling the known universe would be s9imilar. After that, everything must be static in energy consumption and therefore industrial growth. That may be difficult to achieve for an expanding civilization to remain static in growth.

    This suggests to me that KIII civs are not going to be around for long enough for us to observe. What we will see instead is various fractions of KII civs in a galaxy.

    I suspect it is far more likely that advanced civs will somehow transcend the need for physical growth, even physicality, and therefore disappear from observation. This might very well be in the Clarke or Stapledon sense.

    [ What powers these civs have would be like magic, and moving stars around might be trivial. ;) ]

    I’m therefore not surprised that G-HAT hasn’t found any KIII civs, simply because the required static nature of such a civ may be unstable.

  • R Kelley September 22, 2015, 12:25

    Perhaps super-civilizations are able to obtain most/all of their energy from sources which are not currently known to us. For example, perhaps they can tap directly into the quantum vacuum and get all the energy they want from that. I would like to think that there are still many scientific advances mankind will make in the future and we can still become an inter-steller (if not inter-galactic) civilization.

  • ljk September 22, 2015, 13:22

    NCG 5907. Check NGC 5907. Astronomers say it has a preponderance of red dwarf suns for a spiral galaxy, but we know the place is just covered with Dyson Shells and Matrioshka Brains.



  • Digbijoy Nath September 22, 2015, 13:54

    Species that are technologically advanced enough to be capable of building Dyson spheres, do NOT need to build Dyson spheres for energy harvesting and heat management.

  • Alex Tolley September 22, 2015, 14:06

    Since we are in the mood for wild speculation what about this:

    1. The appearence of dark energy is not a natural phenomenon but rather the omnidirectional-beaming of energy for civilizations.

    2. Gravitation is decreasing because matter is being lost from the universe.

    3. Dark energy is being produced by conversion of matter to dark matter rather than known energy conversion methods like fusion, as the net efficiency is higher.

    4. That is why we don’t see manifestations of Dyson spheres/swarms. It is like looking for multitudes of open fires in cities, when energy is produced by internal combustion, nuclear fission and direct conversion of sunlight to electricity. Capturing the radiative energy of stars is far too primitive. Stars are moved to places where they can be dismantled and converted to dark matter and the energy radiated as dark energy that is used to power civilizations throughout the universe.


  • RobFlores September 22, 2015, 14:41

    Really I expect Type III civs to be from our POV
    very close to Omniscient even transcendental in comparison to
    our own. I also don’t understand the need for so much raw energy
    Unless they are creating pocket universes I don’t see the need in a Type III.

  • tchernik September 22, 2015, 15:12

    This only says our expectation of seeing civilizations develop in some direction and under some assumptions is most likely wrong.

    Planet-bound civilizations with very abstemious power requirements would be completely invisible, possibly after existing for millions of years.

    We believe that civilizations would be expansionist in the physical realm, modifying their planetary systems and others like some kind of devouring swarm, but it’s not too hard to imagine most of them eventually outgrowing that phase, becoming wise lotus eaters instead, focused on other more subtle endeavors, like the exploration of virtual or abstract spaces.

    Or they could also evolve if very different, orthogonal ways to ours, going more into what people like Stanislaw Lem described in his novels: truly alien aliens, that wouldn’t (or couldn’t) ever attempt space travel.

    Of course, it is simpler by Occam’s to assume there is no one out there. Either because they never emerged (the best option for our own sake IMO), or because the died off for some mysterious reason.

  • Hiro September 22, 2015, 15:44

    Or type III civilizations can mass produce large scale quantum computers for quantum simulations or testing several different variations of vacuum and stay within some star clusters instead of colonizing the entire galaxy for no reason. Empires rise and fall, the expansionists always disappear after a long period of time. The ultimate goal of every advanced civilizations is getting out of this universe, failing to do so will disappear.

  • Andrew Palfreyman September 22, 2015, 15:48

    10^36 Watts suitably manipulated likely allows for the sculpting of spacetime. Bespoke metrics. Interesting and doubtless useful for speeding up travel and communications.

  • Sam Foster September 22, 2015, 15:54

    I find the Kardashev classification to be way over simplified and narrow., being way too human/geo-centric to encompass the vast time scales and diversity of life forms that potentially exist. It seems based on the assumption that an advanced civilization that exists now or existed in the past would follow a trajectory very close to our own. All the great leaps in scientific and astronomical knowledge are based on the opposite assumption.

  • Ashley Baldwin September 22, 2015, 16:08

    I would agree that there are many other ways such a civilisation would utilise energy and how crude interest as a waste product seems. Such life could have even evolved/transcended into energy itself. Quantum mechanics is so bizarre that anything and everything can happen as the usual physical laws of the galaxy disappear . Who knows how many dimensions there are to occupy /utilise assuming string theory is correct. On a lower level , gravitational energy could be harnessed direct. Black holes are so utterly esoteric and alien that they could be unnatural phenomena and we would never know. The laws of physics at any level don’t exist at the singularity . Even neutron stars pack a hefty gravitational and magnetic punch . I agree that until we have even a clue as to what accounts for dark energy and mass ( not sure what the difference is and have regularly seen to two terms used interchangeably ) then I don’t think we can comment meaningfully , which also applies to the quantum level and all the separate forces existing there . Sci-fi or not , if a wormhole did open near Saturn as in “Interstellar” we wouldn’t know it was there as we still haven’t managed to observe gravitational waves let alone quantum disturbances . Kardashev III is so far ahead of us that I don’t think we could remotely comprehend such a civilisation. But it’s good to try and we have to start somewhere. Personally I would rather spend money on a big enough telescope and coronagraph to start looking for microbes on Alpha Centauri . Putting things into perspective even that would be mans greatest ever discovery !

  • Larry Kennedy September 22, 2015, 17:50

    Good comments above. I feel I should tip my hat though to the authors of the papers who provide information and analysis to provide some anchor for our ramblings.
    While like many I have faint hope for results I still find these studies worthwhile. I’m glad this stuff isn’t quite as fringe as it once was.

  • Dave Moore September 22, 2015, 19:05

    I have a feeling that the waste heat signal of a galaxy-spanning civilization will be well hidden by natural signals, mainly because galaxy-wide civilizations will never approach Kardashev III levels of power.

    Imagine a civilization on a continent with 10 million people. It may well produce a capital city of a million people. It may produce dams, aqueducts, fortifications, pyramids. Now, imagine that same 10 million people spread out over a vast ocean of coral atolls. The level of technology is never going to rise above thatched huts, dugout canoes and small villages. This second scenario is much closer to colonizing a galaxy with sub-light spacecraft than the first.

    Our civilization will stop well short of a power level equivalent to all the sunlight falling on the Earth just to prevent runaway global warming.

    And I suspect the same thing will happen with our Solar System civilization. It may well stabilize at well short of Kardashev II levels, especially if the bulk of it resides in the Oort cloud using Hydrogen fusion.

    A Dyson Sphere would be the sign of a desperate civilization that has maxed out its resources.

    Therefor, your galaxy spanning civilizations may be Kardashev 1.5 level civilizations endlessly repeated throughout the galaxy, which means that the total waste heat radiated is but a small fraction of the galactic total.

  • Joe September 22, 2015, 21:06

    The idea of a Kardashev Type III civilization is pure fantasy comparable to Middle Earth or Harry Potter. For such an idea to be taken even half seriously there needs to be some plausible concept of how the energy of 100 billion stars distributed over millions of cubic light years could possibly be harnessed.

  • Joe September 22, 2015, 21:15

    Uh Oh. I forgot about the black holes. A type III civilization would have to harness all the black holes in a galaxy too, not just the stars.

  • Rangel September 22, 2015, 22:39

    I always tought of Kardashev concept of civilization energy usage as not real, of course it is just my personal opinion, but i believe an advance civilization just use energy in a way we cannot understand right now or the ‘electronics’ they build requires minimal even close to zero energy through some unknown scientific breakthough, meaning they never do need to use such vast ammounts of energy for any purpose.

  • Harold Daughety September 22, 2015, 23:41

    @Joe – Well said! Or as an engineer boss was prone to say, Quit jawing and show me your numbers. . .
    I really liked science fiction when it was expected to be fiction.

  • DCM September 23, 2015, 4:32

    Some excellent observations above.
    And, like it or not, many may have to accept it that we may be the first.

  • Brett Bellmore September 23, 2015, 6:49

    The thing is, just because you’ve got the capacity to exploit the entire energy potential of a galaxy, doesn’t mean you want to. Given such control, you might instead aim to husband that energy against the dark eons ahead, instead of squandering it in the now.

    K III civilizations might be going around putting stars out, not using their energy.

  • Zanstel September 23, 2015, 8:37

    The paper assume that they emit infrared because we assume that they
    1- Consume growing numbers of energy
    2- They use energy by degrading itself.

    It’s a principle obtained from Second Law of Thermodynamics. But…
    We are really sure that Second Law is so absolute? If time travel is possible, then reverts thermodynamics too, so there is no need to emit heat. If someone could create a space where time travel backwards, entropy would go backwards too, so you could make real perpetual machines.

    Second, the perspective of perpetual growing could be completely wrong, and the seed of selfdestruction. As minimal growing will reach soon needed of growing resources of a space that grows faster than light, any civilization that can not control their growing it could ensure their dooming.
    So, a KIII civilization not only should grow, but regulate their grow to not need grow, but desire it, so they only grow when they could without collapse their resources. You only could grow successfully when you don’t need to grow to live. Near a paradox.
    Very complex position that probably derives in to stagnation of a civilization.

  • Cambias September 23, 2015, 8:56

    The notion that Type II/Type III civilizations are camouflaging themselves to avoid detection is pretty alarming: what could they be afraid of?

  • ljk September 23, 2015, 10:18

    Cambias said on September 23, 2015 at 8:56:

    “The notion that Type II/Type III civilizations are camouflaging themselves to avoid detection is pretty alarming: what could they be afraid of?”

    These perhaps:


    Or maybe this (see the Leviathan section):


  • James Stilwell September 23, 2015, 11:22

    Observers of M-104 should keep in mind that what they are seeing is 29.35 million years ago…Every conversation is therefore pure speculation…I like the idea that KIII civs would be akin to a God in human eyes…Clarke said to expect magical powers from them…

  • Steve Bowers September 23, 2015, 11:45

    Civilisations as big as a galaxy would be divided by light-speed delays into innumerable factions each of which are unable to contact each other in real time. It take two hundred thousand years to get a message from one end of the galaxy to the other and back, making it impossible to ever get a consensus.
    (So that’s ten quintillion coffees with sugar, and fourteen quintillion with milk and sugar, and seventeen quintillion teas – how many want sugar again?)

  • DCM September 23, 2015, 11:52

    “Cambias September 23, 2015 at 8:56

    The notion that Type II/Type III civilizations are camouflaging themselves to avoid detection is pretty alarming: what could they be afraid of?”

    Maybe we’ll soon find out.

  • RobFlores September 23, 2015, 11:52

    “The notion that Type II/Type III civilizations are camouflaging themselves to avoid detection is pretty alarming: what could they be afraid of?”

    They are not afraid. Think anti-insect netting for your sleeping
    tent, as analogy. Most insects can’t really hurt you, but they are
    a nuisance. However some can potentially make you ill.

    Hopefully they wont use bug zappers as a form of entertainment.

  • Ashley Baldwin September 23, 2015, 12:57

    I think that it is easy to fall into the “rare Earth” fallacy/trap here by assuming negative results from a relatively crude search for advanced are informative . Creating life in our own image and mistaking measurement for understanding .How can we know what we don’t know ? Dear old Donald Rumsfeldt’s unknown unknowns . It’s almost like returning to the old geocentric pre Copicernicum universe , which was really about humans being at the centre of everything. Some people have gone even further and are proposing calling this time the “Anthropocene ” . I find this dumbfounding and utterly unhelpful though it is well intentioned and designed to show how we can effect are own evolution ( or bring about our extinction ) . How long has human civilisation been about, ten thousand years or so and as a species at best for a few million . We may only even have been speaking for just 50000 years ( the time that evidence of tool making and rudimentary art first appeared ) . The dinosaurs got nigh on 200 million years and are lucky to get a street or two named after them ! But the key is that ,egocentricity apart, civilisations will only last at the infrared signature waste heat level for a short time during their evolution before going extinct ( which Earth’s own history illustrates all too clearly Bruce Willis with hydrogen bombs not withstanding ) or moving on to levels distanced far greater than a cave man to modern day. Such civilisations’ technology might just as well be magic such is its superiority to us .Reviewing the astrobiology literature shows a constant tug o war between the suitability of other star/planet types for life or not with argument against and for in equal amounts based around a small amount of observational data and a lot of simulation. We really haven’t a clue but starting to look is the right way, it’s only by doing this that will allow the development of instruments that can look in detail starting with simple life around neighbouring stars. Even that will be a monstrous breakthrough whether it is like or unlike us. Arthur C Clarke famously said that there are only two answers to the question is there life elsewhere ? Yes or no, both of which terrified him . And me though I think that so many of the elements and molecules essential to life are readily available in the universe , ready to act as building blocks of a myriad forms of unknowable life forms in all manner of environments.We may not be anything like evolved or equipped enough to look for Kardashev civilisations yet but we certainly have the will to start by looking for simple life . If only we had the money. I say money because we are within five years of having the technology to search planets spectroscopically within 50 light years or . Only money stands in the way. Even the searchers who authored the article above would have begged and borrowed to scrimp the funds for such a visionary project .
    The imminent rebirth of the manned space programme will stretch Nasa’s coffers along with the massively overspent JWST when it finally launches . On top of that Congress are very keen for a Europa mission which I sure we would all welcome as a realistic way of looking for life , but which will drain funds even further. Space telescopes are treated with suspicion post JWST which is a real shame as the maturing and mass production of much of their technology in combination with a welcome Space X driven launcher cost war have made such devices potentially cheaper than ever. In real terms the Hubble telescope costs around JWST prices , but the equally as large and well equipped WFIRST comes in at less than a third of the costs. Use a big and strong but proven ground designed mirror ( that should work perfectly well in space) and you could now build a JWST sized telescope , with more functions than Hubble or JWST, with “off the peg ” components for less than half the price and launch it for just $100 million dollars . Pennies compared to a space shuttle launch.
    Quite frankly it will be a disgrace if we don’t look for Life elsewhere and in doing so understand ourselves better in order to step onto that first rung of looking for and becoming a Kardashev Civilisation.

  • Hiro September 23, 2015, 15:02

    Another interesting classification:

    Type I: individual creature in the civilization can think at the rate 10^20 computations/second for 1kg of the brain or matter.

    Type II: the bar is 10^30 cps per kg.

    Type III: the requirement is 10^40 cps per kg.

    It seems like we are still too dumb to out guess what type III civilizations (if any) are doing.

  • justsomeguy September 23, 2015, 15:11

    Would a follower of Kardashev (for whom the Kardashev Scale is named) be referred to as a Kardashian? And their followers — what do you call someone who is just keeping up with the Kardashians?

  • Eric Hughes September 23, 2015, 15:18

    > For such an idea to be taken even half seriously there
    > needs to be some plausible concept of how the energy
    > of 100 billion stars distributed over millions of cubic
    > light years could possibly be harnessed.

    In other words,”if I can’t imagine it, it can’t exist”. I trust I don’t need to argue how idiocentric and even anthropocentric this statement is.

    > The notion that Type II/Type III civilizations are
    > camouflaging themselves to avoid detection is pretty
    > alarming: what could they be afraid of?

    To continue the biological analogy: predation. Or if you would rather impute more intention, use the civilized term, warfare.

    As others have said above, the biggest step is assuming that the first one exists. Once you’re in a scenario where one can exist, assuming more than one is a much smaller step, and assuming that their interests are not aligned an even smaller one.

  • Brian September 23, 2015, 18:46

    Should this really be so surprising? On Earth we see this all the time, once a nation reaches the certain standard of living its population growth evens out or even becomes negative. Any successful advanced Civilization would have to stop expanding at some point otherwise it would use up the entire universe or simply reach a point where its growth needs exceed its ability to expand. This simply gives some more weight to the idea that point is far below KIII. Could that be wrong? sure! Their is no reason an Alien Civilization is anything like us. However when talking about plausible intelligent civilization we have to use the samples we know exist or could exist and right now thats only us.

  • Alex Tolley September 23, 2015, 20:31

    @Hiro, what if that just means that the size of brains decreases, keeping the organism’s brainpower fairly constant?

    What is perhaps more important the “meta-mind” built from all those connected brains.

  • Hiro September 24, 2015, 1:35

    “….Any successful advanced Civilization would have to stop expanding at some point otherwise it would use up the entire universe or simply reach a point where its growth needs exceed its ability to expand…”

    Even though the laws of physics allow it, but no one has ever built a building with an area 1000000 square mile.

    @ Alex Tolley: why constant brain power? PS4 is much more powerful than PS3 but their sizes are almost the same. The same argument can be used in the case of USB and SD card.

  • Alex Tolley September 24, 2015, 13:08

    @Hiro – I am simply suggesting that your assumption may be wrong. There is an argument that human brains have peaked in size and cannot get any larger. (We may even be getting smaller brains since we started civilization). It is possible we can enhance our brains with prosthetics rather than external tools, but probably not by many orders of magnitude.

    I am sure we will continue to both evolve and improve our technology, although culture may be far more important in terms of what we think about and what we can think about. But I think individuals will be no more intelligent that we are today, just enhanced with better education, tools and communication. In that sense I think if any one of use was transported to the future when there is a KII civilization in our solar system, if biological humans are still around, then I think we could understand and adapt to that environment successfully.

  • JoeP September 25, 2015, 17:44

    There are a lot of good points in this comment thread, of particular enjoyment for me were the doubts cast upon the presumed needs of advanced civilization energy requirements.

    Higher technology often results in lower power and more efficient devices. Compare a modern cell phone to a massive vacuum tube based system of the early 20th century. Compare powerful radio stations to modern fiber optic networks and laser communication. Compare massive travel to a huge business conference involving hundreds of cars, people, and a dozen jet planes, to a simple virtual web meeting streamed on the Internet.

    So, why should a “civilization” require vast resources? This assumes that civilizations are built upon ever increasing numbers of discrete individuals that have massive power needs. For all we know, an advanced ET might have evolved to just a single entity or a small collection.

    I think it is worthwhile to look for super massive structures and signatures in the EM spectra, but we are in some sense via this Kardashev model is just projecting our own vision out there and trying to detect it after the fact.

  • Sam Foster September 26, 2015, 17:15

    a lot of good replies but that last one nails it. the whole kardashev theory seems built on the premise that more advanced civilizations = larger scale technologies = bigger waste byproducts, and so on. but what about moore’s law? what about quantum computing? and what about a million other things we haven’t even imagined yet? i definitely support the continued search for life in the universe, but even in that quest the definition of “life” has recently shifted to include not just complex life forms, but bio-signatures, microbial life and their building blocks (vis-a-vis astrobiology). and we’re not even sure yet that our own home system could be considered “alive” in this sense. while any process or paradigm for discovering life elsewhere that is scientific and critical is admirable, does the kardashev theory even really meet such a condition? in my view, it’s a perspective that’s too colored by anthropomorphic principles to be fully useful.

    my 2 cents.


  • Larry Kennedy September 27, 2015, 0:42

    @ Sam Foster
    I look at it from the opposite direction. To me it is precisely our inability to reason out these things with any confidence that makes any actual observations valuable.

  • Michael September 27, 2015, 11:22

    We may not detect them because of their infrared signature around stars, instead of colonising star systems they could just be wandering between the stars bringing their own light power sources with them, much more space to expand there.