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Colossus and SETI: Searching for Heat Signatures

Yesterday we looked at the PLANETS telescope, now under construction on the Haleakala volcano on the island of Maui. What will become the world’s largest off-axis telescope is considered a pathfinder, part of the progression of instruments that will take us through the array of sixteen 5-meter mirrors that will be called ExoLife Finder, itself to be followed by Colossus, an instrument comprised of 58 independent off-axis telescopes. Colossus will use ultra-thin mirror technologies and interferometric methods to achieve an effective resolution of 74 meters. And it will be optimized for detecting extrasolar life and extraterrestrial civilizations.


Image: Artist’s rendering of the Colossus telescope. Credit: Colossus/Dynamic Structures Ltd.

How to build something on such a scale? The design work is being handled by a consortium led by Jeff Kuhn (University of Hawaii), Svetlana V. Berdyugina (University of Hawaii/Kiepenheuer Institut für Sonnenphysik), David Halliday (Dynamic Structures) and businessman Caisey Harlingten, backed by an international team of astronomers associated with the PLANETS Foundation, as we saw yesterday. Building an instrument of this scale calls for innovation across the board, especially in terms of reducing weight and heightening resolution.

Thus Colossus relies upon extremely lightweight mirrors that deploy electromechanical force actuators that control the mirror’s shape and provide its stiffness. These mirrors are not separated from their electromechanical backing structure after manufacturing, depending on a network control system to fix their shape. In this overview of the Colossus design, they are described as ‘live mirrors,’ unlike normal telescope optics because they have much less mass and can be created without conventional grinding.

Civilization and Heat

An instrument like this has sufficient aperture and scattered light suppression to detect exoplanet biomarkers and, if they exist, the markers of extraterrestrial civilizations. It’s on this latter issue that I want to focus today. Over the past few years, we’ve delved into what is being called ‘Dysonian SETI,’ the search for other civilizations not through dedicated beacons but astronomical evidence of their activities. The reference to Freeman Dyson goes back to his description of spherical structures for gathering the total luminosity of a host star, the so-called Dyson sphere, or as it is also imagined, the Dyson ‘swarm’ of energy-gathering technology.

Richard Carrigan, a scientist emeritus in the Accelerator Division at the Fermi National Accel­era­tor Laboratory, has run searches for such objects using data from the Infrared Astronomical Satellite (IRAS) mission (1983), which he believes sensitive enough to find Dyson spheres out to about 300 parsecs. But he is hardly the only one to mount such searches. The Russian radio astronomer Vyacheslav Ivanovich Slysh likewise surveyed infrared data for Dyson signatures, as did M. Y. Timofeev, collaborating with Nikolai Kardashev, in an attempt to scan the same IRAS data.

Carl Sagan, working with Russell Walker, was analyzing “The Infrared Detectability of Dyson Civilizations” (a paper in The Astrophysical Journal) back in the 1960s, noting the problems of distinguishing a Dyson sphere signature from natural phenomena. I won’t go deeper in this direction, though if you’re interested, the archives here cover the various search attempts as well as the ongoing work of the Glimpsing Heat from Alien Technologies group at Ohio State (see Archaeology on an Interstellar Scale and G-HAT: Searching for Kardashev Type III for more references on recent work). The point is that we have yet to find something that can be identified as a Dyson sphere or swarm despite repeated attempts.

The building of Colossus would allow us to move beyond the enormous Dyson constructs (spherical structures with planetary-like radii) to examine much weaker, but surely more likely, heat signatures from an active extraterrestrial civilization. Running a civilization takes power, and we know that by virtue of the laws of thermodynamics, power produces heat. Notice that in both Dysonian searches and these attempts to find heat as a byproduct of a civilization’s ongoing activities, we are not assuming any intent to communicate on the part of the extraterrestrial culture. We are simply trying to observe the unavoidable consequence of being a tool-using civilization that has reached a certain level of development.

In a paper looking at Colossus and its application to this search, Jeff Kuhn and Svetlana Berdyugina explain the point this way:

Waste heat is a nearly unavoidable indicator of biological activity, just as the energy that civilization consumes is eventually reintroduced into the planetary environment as heat. On planetary scales, biologically produced heat tends to be spatially clustered, just as an ET civilizations’ technological heat is difficult to distribute uniformly. Planetary surface topography and the efficient tendency for population to cluster in agrarian and urban domains leads to heat ‘islands’ (cf. Rizwan et al. 2008).The temporal and spatial distribution of this heat can be an observable ‘fingerprint’ for remote sensing of civilizations. Here we argue that we may soon be in a position to detect this thermodynamic signal from Type I, nearly Earth-like civilizations.


Image: The Earth at night seen from space (NASA). Colossus will be able to detect similar patterns of advanced civilization heat islands. Credit: Colossus consortium.

A search for Dyson spheres assumes a Kardashev Type II civilization, one capable of using the total energy output of its system’s star, according to the scale Nikolai Kardashev devised in 1964. But Kuhn and Berdyugina argue that an instrument like Colossus is capable of looking for Kardashev Type I, those civilizations capable of using all the energy available to their planet from its star. The argument here is that Type I civilizations (we are sometimes said to be at about Kardashev level .07) will inevitably evolve toward greater power consumption.

The correlation between power consumption and accumulated information content is a strong one in our society. In fact, we humans collect information with a doubling time on the order of two to three years, while our power consumption increases at a pace that outstrips population growth (global power consumption grows by about 2.5 percent per year, while the world’s population grows at something less than half this rate). The assumption, then, is that even a very efficient advanced civilization will still have high power requirements because of the cost to build and use its base of information. As cultures mature, information content grows.

But as we’ll see tomorrow, there are limits on the power a civilization can consume at the planetary level. And waste heat radiation can become a powerful signature for detection with the right equipment. A tool like Colossus, operating not with a wide field of view like most of the giant telescopes in the pipeline but observing only a few arcseconds of the sky at a time, would be capable of studying nearby planets in the habitable zone of their stars to detect such waste heat. A survey of stars within roughly 60 light years of the Sun could thus help us identify an extraterrestrial civilization or, just as important, demonstrate the lack of same.

More on Colossus tomorrow as we look at its methods, and address the question of whether technological civilizations survive. We can’t know the answer to this yet, but beginning a statistical survey of nearby stars is one way to get a glimpse of our own possible destiny. We also need to think about giant telescopes and their capabilities at detecting photosynthetic organisms in extrasolar systems. We may not find civilizations, but we can still find life.

The Colossus description paper is Kuhn et al., “Looking Beyond 30m-class Telescopes: The Colossus Project,” SPIE Astronomical Telescopes and Instrumentation (2014). Full text. The paper on Colossus and waste heat is Kuhn & Berdyugina, “Global warming as a detectable thermodynamic marker of Earth-like extrasolar civilizations: the case for a telescope like Colossus,” International Journal of Astrobiology 14 (3): 401-410 (2015). Full text. For the overview on Colossus, see the project’s home page.


Comments on this entry are closed.

  • Tom Mazanec May 16, 2017, 13:35

    (we are sometimes said to be at about Kardashev level .07)

    We are currently 0.73 on the Kardashev scale.

  • Jeff Kuhn May 16, 2017, 14:06

    Sklovskii and Sagan (1966) tried to put a formula to Kardeshav’s idea…with P the total power a civilization uses (in Watts), the the Kardashev “type” (now not an integer) is K = log(P)/10 – 0.6 so Earth is now about K=0.7

  • Mauro Cavalcanti May 16, 2017, 16:03

    Great article, as usual. Centauri Dreams rocks!

    Just in case, the article by Sagan & Walker cited in the text is freely available from NASA ADS: http://adsabs.harvard.edu/doi/10.1086/148718

  • Harry R Ray May 16, 2017, 17:02

    On the subject of Kardashev levels: A SHOCKING NEW REPORT on the dinosaur extinction event has just surfaced. For those not up to date, the asteroid itself could not have killed the dinosaurs. It had to be in COMBINATION with a series of devastating plagues AND the CONCURRENT Deccan Traps supervolcano eruptions. NOW, this new report stated that EVEN THIS would not have been enough UNLESS the asteroid struck IN JUST THE RIGHT TIME!!! If the asteroid that created Chixalub Crater had struck 30 seconds(or more)EARLIER or 30 seconds(or more)LATER, OR, had struck at the time it did, BUT JUST A FEW DEGREES TO THE NORTH OR SOUTH, we would NOT be here and, as a result of the known geological history of Earth trom then to the present, dinosaurs would STILL be the alpha species! This is due to the UNUSUALLY HIGH SULPHER CONTENT of the gypsom-rich regolith in the area(CASE IN POINT: The famous “Chrystal Caves” are just a few hundred miles away from the impact site)! Now, I will go BEYOND THIS NEW REPORT and state that if the asteroid had been just a little bit BIGGER or just a little bit SMALLER, the sulpher levels in the atmosphere would have either killed ALL LAND-BASED multi-cellular life or would have not have been sufficient to kill the dinosuars! When you take into account ALL OF THESE FACTORS, with ANY ONE resultong in a DIFFERENT OUTCOME, the odds become AOS(which stands for Astronomical On Steroids)! I hate it when a TERRIBLE, REDICULOUS movie like “Jupiter Rising” MAY ACTUALLY BE RIGHT IN ITS PREMISE! To any of you out there who may know what KS designation ETI would have the capability to direct an asteroid or comet with just the right mass and composition(especially if it were a COMET, because it must NOT BREAK APART BEFORE IMPACT) to just the right location on Earth AT JUST THE RIGHT TIME, please post it in a comment on this blog on this website. THANK YOU!

    • Alexander Tolley May 16, 2017, 18:58

      Let’s be clear. The BBC Documentary is a speculation, not a proof. There are many theories about the extinction of the dinosaurs, including that they were already dying out and the KT event was just the final if large, nail in their evolutionary coffin.

      Let’s not forget that one dinosaurian offshoot, the birds, survived the KT event and did extremely well. They even recapitulated the theropod design with the Phorusrhacids, or “terror birds”.

      Any theory that requires some highly unlikely probabilities should be a suspect. We have had 5 major extinction events, of which the Permian was the most devastating. The theories that explain them should not rely on very low probability events otherwise we end up with an extremely improbable outcome without a lot of other failed events to explain.

      • Mauro Cavalcanti May 16, 2017, 20:56

        With all due respect, this seems to me (a former paleontologist who dedicated some time studying a much larger mass extinction, the Permo-Triassic event) the same kind of nonsense of the old ‘Rare Earth’ hypothesis of Ward & Brownlee, or the ‘Anthropic Principle’ cherished by Frank Tipler (himself a well-known opponent to SETI). Even if hypothetical ETI (or a god?) had ‘designed’ the K-T extiction, what to make of the Permo-Triassic event which wiped out 96% of Earth’s biota? Or the earlier Silurian-Ordovician event, which had a strong impact on the marine biota? Maybe among zillions of habitable planets, such ETI would find some strange pleasure in monitoring our little Earth for hundreds of millions of years, periodically directing the impact of asteroids or meddling with volcanoes (or both) for extingushing a part of the biota, opening space for other groups? Perhaps they got tired of big and ugly and stupid dinosaurs and decided to wipe them out so that the lovely small mammale had a better chance of evolving intelligence? Frankly, this is not even reasonably good science fiction!

        • David Herne May 17, 2017, 2:44

          Alexander and Mauro, thank you for bringing balance to the force! My brother is a practicing palaeontologist (who is about to take up a new curatorship in Queensland, home to many exciting recent discoveries). I look forward to quizzing him on this.

          • ljk May 17, 2017, 10:25

            We also know that some of the dinosaurs escaped the KT event and made it all the way to the Delta Quadrant:


            Dinosaurs lasted on Earth for over 160 million years (not counting the birds). It is said we have found the fossilized remains of perhaps just 10 percent of all known dinosaur species. By comparison, humans have only been on Earth for about 7 million years, if you include our most distant ancestors which were barely different from other primates then or now. Yet look at us typing away on this blog and sending probes to the stars.

            If by chance some dinosaurs species did evolve enough to develop a technological civilization and some of the remains of their society survived to be found by human paleontologists, would such a find be accepted by science? Would a professional dinosaur hunter want to risk being labeled a crank and ruin his career?

            • Alexander Tolley May 17, 2017, 12:28

              In the Whovian universe there are the Silurians. Dinosaurs also seem to turn up out of their time, often in London, rather than DC, and on the odd spaceship. You can never keep a reptile/dinosaur down. ;)

              It is so interesting to see how the depiction of dinosaurs has changed, especially since the famous painting at the Smithsonian. They got slimmer, then more colorful, then partially feathered. I’ve even read suggestions that young theropods were covered in downy feathers. New discoveries and analytic techniques are increasing our knowledge of these animals in most interesting ways. However, I expect them to stay in their time unless we ever find a way to recreate them in our present.

              • ljk May 17, 2017, 14:49

                I recently watched Jurassic Park again, which premiered in 1993. In the beginning of the film the main dinosaur guy mentions to a group at one of his digs that birds came from dinosaurs. This brought a round of laughter from those around him, to which our hero had to explain and show why the idea was not so absurd.

                Recall at the very end of the film, the idea is reinforced when our surviving heroes are flying away from the island and a flock of pelicans are seen nearby flapping their way over the ocean, with our hero giving them a knowing smile.

                I think a lot of the general public learned from JP first that dinosaurs were not the big, lumbering, universally gray, cold-blooded, and not-too-bright creatures they had historically been portrayed as. Never underestimate the power of entertainment media to mass educate, for both good and bad.

                • Mauro Cavalcanti May 17, 2017, 16:26

                  But the issue is: neither ‘dinosaurs’ nor humans could ever have evolved in other planets. Intelligent life we should surely expect to find, but nothing to be confounded with a human or dinosaur (except, as Sir Arthur C. Clarke wrote in the novelization of 2001 , “in a very dark night”). Although evolutionary convergences (themselves driven by physical laws) can have an important role in the shape of things out there, we should not expect to find them to be identical to dinosaurs, humans, dolphins, or any Earthly lifeform. As a historical process, evolution does not repeat itself.

                  • ljk May 18, 2017, 8:52

                    But could something like creatures similar to what we have had and do have on Earth evolve elsewhere if environmental conditions are similar?

                    For example, we may be the only planet in the entire Universe with actual cetaceans, but might something similar in form and function appear in the waters of another world based on the fact that organisms evolving in a liquid medium will develop in certain similar ways even if the eventual outcome is not a duplicate.

                    • ljk May 18, 2017, 8:53

                      To clarify: I know you already addressed that their physical forms may be similar due to the environment they developed in, but could that same environment also shape a creature’s thinking and behavior to fall into similar patterns as their terrestrial equivalents?

                    • Alex Tolley May 18, 2017, 12:54

                      That is a good question. We just don’t know what the possible space for life can be. Even with our biology, we don’t know what fraction of the possible space has been explored. What we do know is that chordates are just one phyla that proved successful on earth. Whether this phyla (or a very close version) would appear again on a rerun is unknown. Opinions differ on this question. That is why finding different geneses for life in the galaxy (or even our solar system) would be so interesting and valuable. Even protists would tell us a lot about the possible space of biology from metabolism to replication.

            • Mauro Cavalcanti May 17, 2017, 15:29

              Sure, I had forgotten that ST Voyager episode. Sci-fi writer Robert Sawyer explored a similar theme in his Quantaglio Ascension trilogy.

          • Mauro Cavalcanti May 17, 2017, 15:24

            David, I’m glad to contribute. I’m getting older and easily run out of patience with nonsense, so I apologize for being so grumpy. But I am of the opinion that good science should stick to hard facts, and to theories themselves supported by such facts. Nothing against a little bit of speculation, but there are adequate places for it, as the good science-fiction literature (such as that written by Clarke, Asimov, Benford, Baxter, among others). BTW, I highly recommend the novel “Evolution” by Stephen Baxter, which depicts the development of humans on Earth from small scavenger mammals to a Kardashev-type II civilization miilion of years in the future. And it has one of the greatest description of the K-T event to ever appear in the sci-fi literature!

            • David Herne May 17, 2017, 19:27

              I am quite a fan of Stephen Baxter’s writing. I’ll look for the novel, thanks.

  • Ron S. May 16, 2017, 17:05

    I’d like to know where this energy is coming from. Aside from the developing world the per capita energy consumption here on Earth is flat to declining. Will a more advanced civilization increase energy consumption? Will their population grow exponentially? These seems unlikely.

    The Kardashev scale, if of any value at all, is about capability not actuality. All the waste heat this paper expects to form a detectable signal is unlikely, and therefore is a poor basis for conducting an astronomical survey.

    [Note: CD seems to have lost its cookie so I had to reenter my name and email.]

    • Paul Gilster May 16, 2017, 18:10

      Ron, haven’t seen any problems re login for anyone else, though I did just set up SSL for security on the site. Sorry about any problems.

      What’s your source on the energy curve? From the US Energy Information Administration, I get this:

      “The International Energy Outlook 2016 (IEO2016) Reference case projects significant growth in worldwide energy demand over the 28-year period from 2012 to 2040. Total world consumption of marketed energy expands from 549 quadrillion British thermal units (Btu) in 2012 to 629 quadrillion Btu in 2020 and to 815 quadrillion Btu in 2040—a 48% increase from 2012 to 2040.”

      • Ron S. May 16, 2017, 19:37


        There are other sources and analyses since the data are public. About halfway down is a useful chart that breaks down the per capita usage over decades among the US, Europe, China and some others. Putting all the data in one world bin is misleading, just as it is for population growth and other indicators.

        • Ron S. May 16, 2017, 19:42

          Oops. Not halfway down. It’s Figure 7.

          • ljk May 17, 2017, 10:38

            There are now over 7.5 billion humans on Earth, up from 3 billion just half a century ago. And it took until the year 1800 for the human population to reach 1 billion. The numbers will be over 10 billion by 2050 and there is no plateau as the so-called experts once predicted.

            How much longer can our finite little planet sustain so many people before something really gives? Nature and governments under martial law from all the stress will not be humane in their solutions to overpopulation.

            Tuesday is Soylent Green Day….

            • Ron S. May 17, 2017, 15:17

              Yet you answer your own question: follow the trend line and the population will reach a ‘natural’ maximum. So why the hand wringing?

              But I utterly reject this scenario, and I base it in our history. As a society becomes affluent population growth drops and often reverses. People choose this style of family planning because in a developed society it is in their own best interests. No compulsion or disaster required. Falling into the one-world-bin trap is where you go wrong.

              • ljk May 18, 2017, 9:03

                Ron S., would you please clarify about this “trend line” and how a population will reach a “natural maximum”?

                Human numbers may be dropping in the developed nations, but in other parts of this planet they have not.

                Checking this excellent site on world numbers, I see was mistaken about one thing…


                There will be 10 billion humans on Earth by the year 2100, not 2050 as I said previously. Nevertheless, that still does not indicate a plateau or natural maximum to me.

                Overpopulation is already a problem: We are seeing its signs in multiple ways, but most people do not wish to address it because they feel helpless about it, or they fear what may have to be done, or as usual they think the government will fix things.

                My concern still is that either nature or governments under pressure will do it for us, and it will not be pretty. Nature is always looking for a balance and we humans have way overtipped the scales.

                Perhaps if we ever get a really serious SETI program that will one day find other intelligences in the galaxy, they might give us clues as to how other species survived their cultural adolescence, assuming their evolution applies to ours in any significant way. If we learn that most other advanced beings are not like us, that may tell us something quite critical about our chances of surviving and thriving in the Cosmos.

            • Antonio May 18, 2017, 8:00

              “The numbers will be over 10 billion by 2050 and there is no plateau as the so-called experts once predicted.”

              Totally wrong.



              • ljk May 18, 2017, 12:09

                I corrected my error here already.

    • Jeff Kuhn May 16, 2017, 23:54

      Sure but…Since we can’t even define what “life” is we will be hard pressed to find a true universal biomarker for “advanced civilization.” Nevertheless its worth trying to find physics-based, non-sociological remote sensing signals. Sure. The per capita energy consumption shows brief historical plateaus, but hasn’t the total human power usage increased monotonically? Interestingly we’re not yet using as much power as all the plants on Earth now use for photosynthesis. Its also interesting to notice that one quantity that does seem to follow an exponential growth curve is “human manipulatable information content (say in bytes)”. This seems to be true as far back as the printing press. If advanced life (even beyond “the singularity”) is all about information storage and manipulation then there are hard thermodynamic limits that force increasing power consumption (although none of our data systems are close to those limits now). Life seems to depend on departures from statistical/thermal equilibria and by universal physical principles I think this means there will always be a heat signal to life. The fact that it seems to increase with “advancement” could be our own problem, but to the extent that life is a competitive phenomenon it could be that we’ll always be hungry for more…

    • Ronald May 17, 2017, 9:46

      I agree that, as I have proposed on this website a few times, an alternative kind of Kardashev scale should be invented (in fact, I think such things already exist), not based on energy consumption, but on extent of cosmic expansion, since this is what ultimately makes a species and civilization (or its offshoots) long-term survivable.
      The scale would still look similar to the present Kardashev scale, e.g.:
      – Less than planetary-wide.
      – Planetary-wide.
      – Multi-planet within own planetary system.
      – Multi-system (i.e. more than one planetary system).
      – Galactic.
      – Multi-galactic.
      – …

      I also think there should be more levels between multi-system and galactic, for instance distinguishing a civilization’s ability to settle different stellar types, or varying degrees of ability to adapt (terraform) a planet and planetary system (Dyson swarms etc.), possibly even modify a star.

      • hiro May 17, 2017, 15:39

        A species in theory can colonize the galaxy and be stupid at the same time, being stupid means never reaching the level of computing higher than 10^20 cps/kg. Thus one could classify level 1,2,3 as 10^20 cps/kg, 10^30 cps/kg and 10^40 cps/kg respectively and it doesn’t matter whether it’s natural or artificial intelligence. We probably are the smartest one on this planet but not the top dog in this galaxy.

        Also, the classification can be modified as:
        1) No tech, no electricity
        2) Classical devices & using electricity
        3) Universal quantum devices + other exotic stuff
        4) Quantum CTC

        The problem of some advanced civilizations that hide inside some star clusters and do illegal scientific researches is very hard to detect, there is no way to differentiate natural vs artificial novae inside the star clusters.

  • James Stilwell May 16, 2017, 17:59

    These instruments must be built…just in case breaking the light speed barrier isn’t in the cards for humanity for a 1000 years to come…this might be one reason why no one to our knowledge has visited earth just out of sheer curiosity…

  • Ashley Baldwin May 16, 2017, 18:20

    The whole filled aperture/interferometry concept is very exciting and I’m sure the only way forward to the kind of 75m plus aperture “telescopes” with the angular resolution necessary to operate sufficient stray star light suppression from the ground . It may be that a contrast of even 1e7 could even be reached with suitable adaptive optics which would be more than enough to image Exo Earths within 50 light years or so in the thermal infrared.

    Regardless of looking for signs of civilisation creating thermal emission the 5 and 10 micron infrared bands would offer good emissive atmospheric spectra . One thing the Colossus descriptions don’t mention however, which is vital to imaging in these long wavelengths , is the effect of background sky and more importantly the need to subtract its extensive thermal signature from any image . This can be done but is much easier in optimal viewing sites . I.e cold and free from excess water vapour , the perennial enemy of ground based imaging .

    Cold and dry essentially means above 5000m ( at which atmospheric water vapour content drops off precipitously ) which effectively limits sites to the high areas of the already climatically dry Atacama desert in either Chile ( where some supporting infrastructure is already in place ) or Argentina. I know the designers of the ELT 2.2-5 micron METIS infrared imaging system where bitterly disappointed that the relatively low ( sub 3000m) Cerro-Amazones site ( just 20kms from the infrastructure of the VLT) was picked ahead of a supra 5000m site at Cerro Pachon in nearby but more remote Argentina. Infrastructure ( road links, power, water , living quarters , internet links etc ) is important however and building it from scratch would add a significant fraction to the overall cost of any observatory on top of the already substantial bulk telescope cost. Altitude is a must for any Colossus though .

    The high Antarctic domes C and F are much better again still ( with the added bonus of months of uninterrupted darkness in winter) but extremely remote ( and environmentally hostile – though still much , much better and easier than space it has to be said ) with little or no infrastructure ( admittedly a little with Concordia base at dome C) so thus unlikely options in the near or even medium term.

    • Ronald May 17, 2017, 3:28

      Thank you for the additional interesting information, I was just going to ask where Colossus would be built.
      My additional question (maybe I missed it) is: what, if any foreseen, is the timeframe for Colossus?

      • Jeff Kuhn May 17, 2017, 9:33

        The PLANETS group is now building a single segment prototype. It should be onsky in a year. The ProxB Observer (ELF) could be onsky in 4 years and a Colossus in another 4 years. The 25m ELF takes $50-100M. Colossus $500M.

  • Richard BW May 17, 2017, 4:31

    Interesting article, as always. Thank you Paul.

    I think detecting civilisations through waste heat is worth a shot, but I’m not convinced we’ll get any clear result. One hallmark of our own civilisation is increasing energy efficiency. There are more and more of us, so overall energy consumption is likely to continue rising – but as technology improves, how much of that energy will go to waste? We are becoming increasingly adept at minimising the energy needs of our devices, and also at converting waste heat into useful energy.

    Whilst the quantity of waste heat we generate is currently still rising (at least, I assume it is), because of population growth and third world development, the efficiency with which we use energy also rises, so waste heat _per head_ of Earth’s population is likely to fall.

    The logical extreme is energy consumption that generates waste heat at identical levels to the background: all energy gradients are exploited, creating close to 100% efficiency.

    Of course, this perfect equilibrium may never be reached, by us or by ETI. New energy technologies may create a post-scarcity culture where profligate energy use is standard. But it’s reasonable to assume that even after an explosion of wasteful energy use, ‘better’ technologies will once again begin to create less waste heat; waste heat is a form of pollution: it is intrinsically undesirable to a planet-bound global civilisation.

    I’d suggest that there may be ‘pulses’ of waste energy as new energy technologies are developed and used profligately – fossil fuels (or equivalent), clean nuclear, solar, vacuum energy, whatever – but that there would follow a period of renormalisation where the waste heat signature sinks slowly back to background levels.

    We’d be extraordinarily lucky if Colossus catches an alien civilisation during one of those pulses. But it’s definitely worth a shot, and the telescope will produce great science regardless.

    • Jeff Kuhn May 17, 2017, 9:24

      Perhaps the best way to use the most power without over-heating the planet would be to cover the surface with 100% efficiency photovoltaics. Use that power to do useful work and then “wasteheat” the planet to it’s expected water bearing temperature. Such a planet would appear optically dark because of the low optical albedo of photovoltaics but would be IR emissive. Colossus could “easily” pick out such an exoplanet as a possible highly civilized world. Then we look for atmosheric biomarkers like oxygen….

  • ljk May 17, 2017, 10:14

    Those light flashes Carl Sagan noted during the 1990 flyby of the Galileo probe have not only been explained, they might also be a way for us to find life on exoplanets:


  • Mauro Cavalcanti May 17, 2017, 15:43

    But should not these scales be statistically correlated? That is, really, a question. Should cosmic expansion be related to energy consumption?

  • Mauro Cavalcanti May 18, 2017, 9:44

    I am sure you will like “Evolution: A novel”. It is one of the best novels by Baxter I have read. Evolutionary biologists and paleontologists should love it, given the large variety of species (all of them known from fossils – I checked) he mentions along the narrative.

  • Mauro Cavalcanti May 18, 2017, 16:18

    Sure, that’s what we call evolutionary convergences. They are to be expected indeed. We know of cases even here on Earth – a classical example is that of ichtyosaurs (marine reptiles of the Mesozoic) and present-day dolphins. Although not closely related, these groups developed more or less similar forms to adapt to the similar challenges posed by the environment. Physical laws matter. Maybe *really* strange alien lifeforms are outside the realms of possibility posed by such laws.

  • Mauro Cavalcanti May 18, 2017, 16:30

    Nice question! Really a pleasure to debate with you, sir. Well, according to the great Prof. Marvin Minsky (pioneer of artificial intelligence research and inventor of what may be the most beautiful programming language ever, Lisp), probably there may indeed be limits to the thinking and behavioral patterns of alien lifeforms, ultimately determined by physical laws as well. See his article “Communication with Alien Intelligence” ( http://web.media.mit.edu/~minsky/papers/AlienIntelligence.html). But since behavioral patterns are much more elastic than morphological ones (at least among Earthly organisms with more developed neural systems), we should expect to find out some really strange, even incomprehensible, patterns in this context. Sci-fi literature (both the good and the bad one) has plenty of examples.

    • ljk May 19, 2017, 9:11

      Maybe this is the ultimate reason SETI has yet to succeed – in addition to the sporadic support, limited budgets and telescope time, ignorant politicians and related types cutting SETI efforts down before they can even begin, skittish and narrow-range thinking professionals, and a general public more focused on UFOs, alien abductions, and bad science fiction than the actual scientific method – that ETI are, in fact, often more like us than not.

      If they also view and react to the concept of intelligent life beyond their worlds as humanity has done for the majority of its relatively short existence, then it is little wonder we have yet to find them, or they us.

  • Mauro Cavalcanti May 18, 2017, 16:42

    Alex, I beg to respectfully disagree, in part, from your statement that “Even with our biology, we don’t know what fraction of the possible space has been explored.”. Indeed, we have some clues: in a paper entitled “The Skeleton Space: A Finite Set of Organic Designs”, Thomas & Reif (Evolution, vol. 46, no. 2, pp. 341=360, 1993) provide what seems to me convincing evidence that the morphospace explored by Earthly lifeforms can indeed by known, and it has even not been entirely occupied. They conclude that “These results strongly support the hypothesis that the essential elements of organic design are inherent in the material properties of the universe.” This is one most fascinating paper, which regrettably has been overlooked even by those few biological scientists bold enough to publish anything related to exobiology (a term which I still prefer to “astrobiology”).

    • Alex Tolley May 18, 2017, 22:49

      Interesting paper. What the authors seem to be saying is that skeleton types and components have limited (~ 180 possibilities) and that these are mostly filled. So if you limit morphological space to the building blocks, then indeed that space has been largely filled. If however, you regard the space as the arrangement and form of these components, then obviously that space is vast by comparison. I would make the comparison with architecture. There are basic architectural forms, but the range of buildings is vast by comparison. If one’s view is that a tent, yurt, and tipi are all examples of a single type, then architectural forms are very limited. If you regard them as different, then the space of architecture is clearly wider. Both views are possible.

      Sean Carroll has a Nature review article on evolutionary forms and complexity, which cites Thomas and Reif’s paper.
      “Chance and necessity: the evolution of morphological complexity and diversity” SB Carroll – Nature, 2001 – nature.com

  • Jeff Kuhn May 18, 2017, 20:41

    Loose threads… Kardashev index is “dimensionful” (based on TerraWatts power consumption and logarithmic, omega is linear and scaled to the local available stellar “free energy” on the exoplanet. So these “indices” won’t match up.

    Another interesting civilization advancement index could be something like the “free information ‘energy”” of a civilization… that we could compute if we knew how many total bytes of information it stores and/or manipulates. Unfortunately this probably doesn’t make for a useful remote sensing signal except possibly for tell-tale radiated power/heat used to administer this information. It does mean that any civilization that has language (and not necessarily printed or recorded) could fit on this scale.

    A rousing conversation. Thanks all for content and references. For future questions or specifics of PLANETS/ELF/Colossus send your thoughts to those websites.

  • Mauro Cavalcanti May 19, 2017, 9:54

    Yet another interesting thread, sir! I do agree that your comparison of evolutionary and human architectural designs is a very appropriate one. As of the morphospaces (both realized and theoretical) proposed by Thomas & Reif, even if they have a threshold determined by physical laws, the number of possible combinations is indeed quite large and therefore some strange, although functional and recognizable, alien lifeforms maybe expected. Thanks for pointing out the paper by Carroll, I knew it already, it is another useful reference for sure.

  • Robert May 19, 2017, 14:56

    Recent work on the Second Law has shown evidence that heat can be recycled in contradiction to the usual statements of the law. The work of Sheehan et. al. show high ambient temperature but more recent work shows some effect at room temperatures. The paper is “Experimental Test of a Thermodynamic Paradox”


    This relates to the discussion since we might then assume a sufficiently advanced civilization may be able to recycle its energy to a near perfect degree and either leave no signature or disguise the heat signature to blend in any thermal background.

  • ljk May 25, 2017, 13:09

    Listening to starlight: Our ongoing search for alien intelligence

    If ET is out there, he’s doing a great job hiding from us.

    Andrew Tarantola, May 25, 2017

    Full article here:


    To quote:

    As for the SETI Institute, its technological roadblocks are being resolved with upgrades — and lots of them. The research group is looking to expand the number of dishes in the Allen Array from 42 to at least 128 in the near term before eventually growing it to more than 300 dishes. The Institute is also improving the sensitivity of its feeds — the antennas that take the collected radio signals from the dishes and convert them into digital signals — as well as their frequency response and converting the whole feed system to run cryogenically. “That improves the signal-to-noise ratio,” Diamond explained “since heat generates radio noise.” Finally, the Institute is looking to upgrade the antennas’ backend to enable them to sample more parts of the night sky — expanding from current 3-beam system up to 12.

    “But even those enhancements probably don’t get us to the point of being able to detect Earth-like leakage,” Diamond lamented.

    That’s why the SETI Institute is teaming with IBM to apply the company’s advanced machine learning algorithms to the Institute’s massive data archive. The Institute is already the only SETI group that performs real-time analysis of its collected signals, using fast Fourier transform to look for narrow-band carrier signals that would indicate a non-natural source. The Apache Spark cluster computing tools, however, “have the ability to extract, if it exists, from patterns that, to us, would otherwise look like radio noise,” Diamond said. “It’s given us the ability to actually do experiments that we’ve never been able to do before, including possibly detecting an Earth-like planet that’s just emitting leakage.”

    Essentially, the Institute can point the ATA at a known exoplanet (or system like TRAPPIST-1), measure the star system’s radio signature, then wait for the planet to transit behind the sun and measure the system’s radio signature again. If there’s a significant difference in the readings, that could mean there’s something afoot on that exoplanet. The Institute wouldn’t necessarily be able to understand what’s encoded in the transmission but it would provide strong impetus for other astronomical research groups to follow up with their own observations. This is actually very close to what the Breakthrough Listen Initiative team is doing, albeit with a less sensitive piece of equipment.

  • Douglas F Dwyer May 26, 2017, 2:35

    The improved signal processing could also be used to extract “radar returns” from local stellar systems likeTrappist.
    Fast Radar Bursts will have provided natures “chirped” signal source. Compression and correlation using previous FRB measurement can be used to raise the signal to noise so that we dont have to wait generations to get information direct from the stellar and planetry surface.

  • ljk May 30, 2017, 13:58

    Is the Rio Scale pointless when it comes to determining the merits of a SETI candidate?


    I think Frank White’s 1987 book The SETI Factor does a very good job of categorizing the various possible means we may detect alien life and how humanity may react to them in relation. For example, humanity will probably have very different reactions to the discovery of Martian microbes compared to a transmission from another star system, or an alien vessel landing on the White House lawn, pardon the cliché on that last one:


    FYI, White is also the author of The Overview Effect, basically what happens when you leave Earth and look back upon our world:


  • ljk June 1, 2017, 10:05

    Breakthrough Initiatives and Jodrell Bank Center for Astrophysics announce a SETI partnership:


    To quote from the above link:

    “Manchester, UK – May 31 – Breakthrough Initiatives and The Jodrell Bank Centre for Astrophysics at The University of Manchester announced a new partnership to search for evidence of intelligent life beyond Earth.

    “Breakthrough Listen, the most comprehensive scientific search for intelligent life ever launched, will share information with Jodrell Bank’s team, who wish to conduct an independent SETI search via its 76-m radio telescope and e-MERLIN array.

    “As part of a growing international collaboration of astronomers and observing facilities focused on SETI, the collaboration will openly exchange observing plans, search methods and data, including the rapid sharing of any promising new signal made by either party for additional observation and analysis by the other. The two teams are planning a series of meetings and conferences to refine search strategies, data analyses and results.”

    It is ironic in one sense that Jodrell Bank is doing SETI now, because when two legendary SETI pioneers approached the facility back in 1959 to see if they could use the institution’s huge radio telescope to search for alien signals, the response was a negative one. See here:


    The relevant quote:

    “Shortly after discussing his interstellar communication idea with Morrison, Cocconi realized that a 250-foot wide radio telescope constructed at Jodrell Bank in England just two years earlier would be able to send a detectable signal to the Solar System’s nearest stellar neighbor, Alpha Centauri. Conversely, such a giant dish antenna should also be able to pick up strong electromagnetic transmissions from any technological beings living around the nearest suns. Cocconi wrote to the astronomer in charge of Jodrell Bank, Sir Bernard Lovell, to ask if the steerable instrument that would later bear the English astronomer’s name could be used to search for any intelligent beings in the Milky Way galaxy. Sir Bernard did not share Cocconi’s enthusiasm about the potential for the radio telescope to open up a whole new vista in our understanding of the cosmos and turned Cocconi down.

    “Undeterred, Cocconi and Morrison put their research findings and ideas into a two-page paper titled “Searching for Interstellar Communications,” which was published in the September 19, 1959 edition of the periodical Nature (available online here: http://www.coseti.org/morris_0.htm ).”

  • ljk June 2, 2017, 9:22

    Are Aliens Communicating with Neutrino Beams?

    Article Updated: 1 June 2017

    by Matt Williams


    So are the folks in charge of neutrino detection facilities looking for intelligent patterns in their data? Prove me wrong here but I don’t think SETI is high on their list of priorities.

    Paul Gilster has been asking this very question about neutrino SETI for years in this blog. Just type in the word “neutrino” in the search text box to see for yourself. So far as I know no one in charge has even bothered to say boo on the subject, officially or otherwise. Again, please prove me wrong here.

    It is not hard to imagine at all that all sorts of advanced conversations and activities are going on out there while most of humanity wonders which celebrity is doing who and if their favorite sports team composed of multimillionaires is going to make the playoffs.

  • Mauro Cavalcanti June 2, 2017, 11:13

    Or porn (as in that disturbing novel by Mary Doria Russell, “The Sparrow”)…

    • ljk June 6, 2017, 10:09

      To quote from Solaris by Stanislaw Lem:

      “We have no need of other worlds. We need mirrors. We don’t know what to do with other worlds. A single world, our own, suffices us; but we can’t accept it for what it is.”

      “We take off into the cosmos, ready for anything: for solitude, for hardship, for exhaustion, death. Modesty forbids us to say so, but there are times when we think pretty well of ourselves. And yet, if we examine it more closely, our enthusiasm turns out to be all a sham. We don’t want to conquer the cosmos, we simply want to extend the boundaries of Earth to the frontiers of the cosmos. For us, such and such a planet is as arid as the Sahara, another as frozen as the North Pole, yet another as lush as the Amazon basin. We are humanitarian and chivalrous; we don’t want to enslave other races, we simply want to bequeath them our values and take over their heritage in exchange. We think of ourselves as the Knights of the Holy Contact. This is another lie. We are only seeking Man. We have no need of other worlds. A single world, our own, suffices us; but we can’t accept it for what it is. We are searching for an ideal image of our own world: we go in quest of a planet, a civilization superior to our own but developed on the basis of a prototype of our primeval past. At the same time, there is something inside us which we don’t like to face up to, from which we try to protect ourselves, but which nevertheless remains, since we don’t leave Earth in a state of primal innocence. We arrive here as we are in reality, and when the page is turned and that reality is revealed to us – that part of our reality which we would prefer to pass over in silence – then we don’t like it anymore.”

      Also this:


      The Jesuits went to the Native Americans to convert them based on a logic by Thomas Aquinas and others that everyone would eventually come to the conclusion about God the way they have. They learned something quite different upon arrival. See here:


      A valuable lesson before we head out into the Universe with our own preconceived notions. It may be unavoidable as we are limited creatures, after all, but we should be both aware and honest about our limitations and true motives, if we want to even half-succeed.

  • ljk June 10, 2017, 13:31

    How Social Media Users Decoded a Simulated Message from Extraterrestrials

    Humanity won’t share a language with an alien civilization, so how can we decode a message from ET if we receive one? One astrophysicist says: crowdsource it.

    by Emerging Technology from the arXiv

    June 8, 2017


    To quote:

    On May 6, Heller received the largest number responses after the Daily Mail and the Huffington Post reported the challenge. At this, a group on Reddit posted the answer, which probably distorted the result Heller got after this. In total he received, 66 correct solutions, two of which were from high school students.

    That’s interesting work that has clear implications for the way humanity should deal with a message from the stars. The astronomical community is already committed to publicly releasing any message it receives from extraterrestrials.

    But Heller’s work shows that this is not just lip service to the people who pay for astronomy. It shows that the global community is capable of decoding such a message and should be given the chance. “Distribution in the social media would not only offer an efficient means of decryption but also offer an unprecedented opportunity to unite humans all over the globe in a common scientific and cultural effort,” he concludes.

    The participants of the first SETI meeting at Green Bank in 1961 would surely agree.

    Ref: http://arxiv.org/abs/1706.00653: Decryption of Messages from Extraterrestrial Intelligence Using the Power of Social Media—The SETI Decrypt Challenge

    • Alexander Tolley June 10, 2017, 16:21

      Thanks for posting the paper. It seems I got more right than I thought.

      • ljk June 12, 2017, 9:25

        You are welcome, Alexander. Now let us hope a real ETI message will be as accommodating in decipherment. However, I have the feeling a real transmission from out there will probably be more like the one found in Stanislaw Lem’s His Master’s Voice:


        Remember the Martian “microfossils” of 1996? That is physical evidence we have right in our hands and twenty years later we are still debating what was found in that meteorite:


  • ljk June 12, 2017, 9:16

    Astronomers are picking apart the recent claim of comets causing the Wow! Signal of 1977, and with good reasons:


    To quote:

    “Regarding the criticisms of his theory, the unflappable Paris is not concerned. “I suspect that SETI, who have used the Wow! signal as a source of revenue, are nervous,” he says. However, this is disputed by the fact that Shostak and his fellow scientists in the SETI community have frequently talked down the importance of the Wow! signal, pointing out that their experiments find signals like the Wow! signal, in that they are transient and never seen to repeat, all the time.”

    As usual, everyone has more than one agenda when it comes to aliens, especially if they want to take them out of the equation. Not only are Paris’ credentials rather suspect, he is or was apparently part of some UFO group. They tend to prefer their aliens coming right to our doorstep, rather than sending us long-distance messages.

    Humans either want their aliens to save us or they make convenient boogeymen. This is likely just more projections of our own ignorance and fears upon the Cosmos, which definitely could not care less about what humans want or think. And as with creationists, the cloak of science is ironically being used to make the idea look legit. Sadly the science-ignorant mainstream media is eating it up.

    The one good thing out of this is that most of the general public will forget this matter in due course, if they even bother to read about it at all with all the other nonsense going on across this planet right now. The real scientists will hopefully continue to do what they do best, which this Paris person seems to be having more than a little trouble with, further shedding light on the strong possibility he has an agenda that has squat to do with real science. Whenever someone starts claiming persecution and such by the science community, you can be pretty sure what we have going on here is pseudoscience cult behavior.

    An excellent scientific tearing apart of this comet issue here:


    I am surprised I have not seen or heard anything on this from Robert Gray of The Elusive Wow:


    Keep this handy:


    • ljk June 13, 2017, 9:05

      The comet theory pusher continues to get lessons in how the science process really works. However all his responses show that he has his own agenda and no amount of science or facts will change his mind – thus, religion:


      To quote:

      Paris said he had even received a phone call from a technician who helped build the Big Ear telescope who was excited that “the mystery has been solved.” But Paris’ research is still in the firing line.

      [Well, an anonymous claim. That’s good enough for science – NOT.]

      “The claimed detection—even if it’s real—is much, much weaker than the Wow signal, and lasts for longer. So at best the paper shows that comets are detectable in the radio—not that they’re capable of the kind of burst that produced the Wow signal,” Lintott told Motherboard. “Saying ‘The Wow signal might be a comet if comets do something we haven’t seen them doing’ seems not very exciting.”

      A Reddit user, also claiming to be a radio astronomer, posted a lengthy takedown of Paris’ paper over the weekend, arguing, “This paper was also just really, really, really short on details that a radio astronomer would want, to the point where it likely wouldn’t have passed a referee at a ‘regular’ journal.”

      But Paris has kicked back against what he calls an “emotional” response. “I am not in the business of responding to emotions,” he told Motherboard. “There are too many people ‘excited’ or ‘upset’ about this project. Emotions should not have any part in science.”

      [If his last comment doesn’t make you laugh out loud, then you do not get the irony here.]

      It is not that the comet idea itself is a wrong possibility, it is how Paris is going about the process. Science is not determined by a popular vote or who has the coolest sounding idea, at least not in its properly handled form.

      There are plenty of astronomers who would love the Wow! Signal not to be aliens for a variety of reasons. Instead Paris sounds like way too many UFO cultists.

    • ljk June 13, 2017, 9:48

      In 2015 (those idyllic pre-comet days) a number of experts were interviewed about the Wow! Signal:


      One of them was Gerry Harp of The SETI Institute. He had this to say about the Wow! Signal, which does not sound like he was making too much money off it:

      Harp: The “Wow!” signal was almost certainly radio frequency interference. The signal failed to pass even the simplest tests to exclude interfering signals from that observation campaign. From another perspective, at the Allen Telescope Array (ATA), we see dozens of signals comparable to “Wow!” every day. This is simply because we have much more computational power than they did back when “Wow!” was seen. If the “Wow!” signal were seen today, it would be a yawn. However, there is a silver lining to the “Wow!” signal. “Wow!” has inspired a lot of public interest in SETI. Despite being a not very scientific result, public awareness of “Wow”! has been beneficial to SETI. So I generally think of “Wow!” as being a good thing from that perspective.


      Harp: It isn’t at all special or different from signals that we observe every day at the ATA. I hope you’re not disappointed that I’m not so impressed by the “Wow!” signal. I think you will find that many professional scientists in the field do not find the “Wow!” signal very convincing. But that doesn’t mean that SETI isn’t a good thing to do. There is still a 50% chance, by my estimates, that our first discovery of life off of our planet will be a discovery of a transmitting civilization.

      • ljk June 14, 2017, 9:12

        More weighing in on the subject, this one from Seth Shostak of The SETI Institute:


        To quote:

        Additionally, there are the comments of Robert Dixon, the radio astronomer who was director of the Ohio State Radio Observatory when the WOW signal was found. He too makes the point that intense hydrogen signals from comets are basically unknown. But an even stronger argument from Dixon is that the comets were nowhere near the telescope’s sight lines when the signal was found. And that’s a show stopper.

        Recently, Chicagoan Bob Gray, who has spearheaded much of the follow-up attempts to recover the WOW signal, has joined with the SETI Institute to make further observational efforts using the Allen Telescope Array. You never know; maybe the bit will flip, and an extraterrestrial broadcast will come blasting in.

        • ljk June 15, 2017, 8:53

          Another article critiquing the comet theory:


          • ljk July 7, 2017, 9:16

            Alan Hale of Comet Hale-Bopp fame (that was 20 years ago this year when the comet “visited” Earth) weighs in on the Wow! Signal and the comet “explanation” and then discusses SETI and the Drake Equation:


            To quote:

            To this author, one possible solution to the Fermi Paradox results from the fact that, regardless of how common or uncommon the evolution of intelligent life might be, we assume that that intelligent life will behave more or less as we do, i.e., it will ask these questions, try to explore space, and so on.

            Indeed, this assumption is implicit in arguments both for and against SETI efforts. But there is no reason whatsoever to believe that such an assumption might be true; indeed, to make such an assumption is to be anthropomorphic almost to the point of arrogance. It may very well be that intelligence is commonplace in the galaxy, but that the intelligences involved have no interest in expanding outward into space, or have concluded that, because the distances involved are so great, the energy expenditures are too extreme to be justifiable, and/or they have achieved some kind of fulfillment at home.

            We simply have no way of knowing how any kind of alien psychology – developed under conditions that we cannot even begin to speculate about – might behave.

            Hale has picked up on the main flaw of SETI, that it is looking for the equivalent of us. Of course as I have stated multiple times based on the 2009 document SETI A Critical History, those in charge on SETI in the early decades picked one particular device – radio astronomy – and parameters for the aliens that did not stray too far from humans and stuck with it, with only other options like Optical SETI being taken seriously in the late 1990s and even wider ideas like Dyson Shells coming in much later.

  • ljk June 12, 2017, 13:04

    A new brief overview of METI:


    To quote:

    Future efforts will try to update this system, using either the more sophisticated radio signals we possess today, or turning to lasers to beam ourselves to other planets. METI will begin their search by beaming to Proxima Centauri, the nearest star to our sun.

    Douglas Vakoch, the former director of Interstellar Message Composition at the SETI Institute and president of METI, said to Forbes, “It’s too late to conceal ourselves in the universe, so we should decide how we want to represent ourselves.” But how can we know how what we choose to represent is what will be received when we have no comprehension of the technology aliens may be using, or of their specific culture?

    The central debate over what we send to aliens stems from what they would think if they received a signal. Opinion is split among scientific heavyweights over whether aliens would be benevolent or malevolent. Carl Sagan believes that any contact would be benign because, as he stated in his novel Contact, written in 1985, “In the long run, the aggressive civilizations destroy themselves, almost always.” On the other hand, Stephen Hawking believes that “if aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans.”

    Other specialists such as Seth Shostak, an astronomer at SETI, think that if we truly believed in a threat, we would be more careful about all radio use; he told phys.org, “We cannot pretend that our present level of activity with respect to broadcasting or radar usage is ‘safe.’ If danger exists, we’re already vulnerable.”

  • ljk June 13, 2017, 10:03

    Seven of the more prominent historical METI, though the 1962 Soviet one is usually not as well known:


    To quote (from METI Number 7):

    On October 10, 2016, the ESA’s Cebreros station in Spain beamed the message to Polaris, the North Star, 434 light years away. Though the Polaris star system isn’t likely well-suited for life, it was chosen for its symbolic value as a guiding object. It’s unlikely that any alien civilization would be around to detect it, and even if one did it would be nearly 900 years before we would hear back from them, but the initiative’s primary goal is to get people to look at the Earth from a cosmic viewpoint and recognize just how small, fragile, and, possibly, alone we are in the cosmos.

  • ljk June 20, 2017, 13:15

    Interstellar communication using microbial data storage: implications for SETI (part 1)

    Most have assumed the best way to search for signs of extraterrestrial intelligence is to look for radio or optical communications. However, in the first of a two-part paper, Robert Zubrin argues that other formats may be more effective, with implications both for SETI and astrobiology in general.

    Monday, June 19, 2017


  • ljk June 28, 2017, 9:09

    Is it time to rethink the search for alien life? It has been time to rethink this for decades now.


    To quote:

    Alien A.I.?

    All of these parameters offer scientists a reasonable range of variables for discovering life — but only as long as that life is “the soft, squishy kind, like us,” Shostak said. However, a sophisticated extraterrestrial civilization could theoretically have advanced far beyond that, creating forms of artificial intelligence housed in machinery, which simply don’t have the same requirements as organic life.

    “Machines live forever, and they can go anywhere — they don’t care about oceans and atmospheres,” Shostak said.

    With that view, many of the factors that are currently thought to be indicators of life on other worlds, such as liquid water and a breathable atmosphere, are rendered irrelevant. As such, researchers would need to identify other signals to pinpoint which planets might harbor aliens, Shostak said.

    But Shostak also offered reassurances, telling the Future Con attendees that at least they won’t need to worry about scientists or the government concealing the news when alien life finally does appear — the story would be too big for them to hide it for long, he said.

    “Will we all start singing ‘Kumbaya’ and just get along when that happens? I don’t think so,” Shostak said at Future Con. “But it’ll change things. Forever after, you will know — as amazing as you are — that you’re not the only miracle, you’re not the only kid on the block. And I think that’ll be very interesting to learn.”

  • ljk June 29, 2017, 10:38

    Astrobiology: Hunting aliens

    Ramin Skibba

    Nature 546, 596–597 (29 June 2017)


    Published online 28 June 2017

    Ramin Skibba enjoys a profile of the woman heading the search for life off Earth.

    Making Contact: Jill Tarter and the Search for Extraterrestrial Intelligence

    Sarah Scoles Pegasus: 2017.

    ISBN: 9781681774411

    Full review here:


    To quote:

    That it could take centuries to find alien intelligence created another problem for Tarter and her colleagues: funding. Scoles describes how they repeatedly scrambled for federal support for the SETI Institute and their telescope array at the Hat Creek Radio Observatory northeast of San Francisco, California; in the mid-1990s, they lost it at the hands of resistant Congress members, especially Democratic Senator Richard Bryan of Nevada.

    This only strengthened Tarter’s resolve as she pitched to the heads of private companies, including Microsoft, Intel and Hewlett-Packard. Funding from commercial entities presents its own ethical questions, including potential conflicts of interest, a lack of oversight and a dependence on benefactors’ caprices [No worse than depending on the government, as we have seen time and time again. NASA’s SETI program only lasted one year as just one example; they even tried to hide its purpose by calling it HRMS instead of SETI. Sad.]. These resonate even more today, with the likes of SpaceX, Blue Origin, Planetary Resources and many other for-profit organizations getting involved in space exploration.

    Tarter has faced a further challenge: gender. She was regularly the only woman in the room, and senior men often dismissed her or took credit for her ideas. Science and engineering colleagues “told Jill she wasn’t going to make it because she was a woman”, astronomer Dan Werthimer once said.

    Probably she has also had to contend with ‘unconscious bias’, in which both men and women tend to hire and promote male scientists rather than women with the same qualifications. Scoles only touches on these persistent hurdles, which are now being addressed, belatedly, by the astronomy community (see M. Urry Nature 528, 471–473; 2015).

    • ljk June 29, 2017, 10:43

      Speaking of gender issues in science and Jill Tarter, she recently called out some sexist comments made at Starmus by a Nobel Prize winning scientist and admonished Neil deGrasse Tyson for not addressing his remarks on the panel, which I guess he was heading:


      • ljk July 6, 2017, 8:55


        The Biography of SETI Pioneer Jill Tarter, Making Contact: Jill Tarter and the Search for Extraterrestrial Intelligence, is Released

        Wednesday, July 05 2017 – 12:11 pm, PDT

        July 5, 2017, Mountain View, CA — Jill Tarter is the subject of a new book by Sarah Scoles, Making Contact: Jill Tarter and the Search for Extraterrestrial Intelligence, which was released yesterday. Jill is a pioneer in SETI research and currently holds the Bernard M. Oliver Chair at the SETI Institute. Making Contact is not just for scientists and SETI enthusiasts, but truly is the story of Jill’s life and her life’s work.

        “This is one woman’s view of the roller coaster history of SETI explorations,” said Jill. “Sarah has told it with a fresh voice that makes me grin.”

        In Making Contact, Scoles examines the science behind the work that tries to answer the question, “Are we alone?” Jill was the inspiration for the character of Ellie Arroway in Carl Sagan’s Contact, a role played by Jodie Foster in the film, which celebrates its 20th anniversary this month. Scoles tells Jill’s story, and also begins to wonder how a new generation of SETI research will look.

        “A fictional story about SETI, partly inspired by Tarter, has spurred so many people’s interests in astronomy and life in the universe,” said Scoles. “I hope the nonfictional tale of the actual search and the actual Tarter can do something similar.”

        Scoles suggests that without Jill, SETI programs, including the SETI Institute’s Allen Telescope Array (ATA) and Breakthrough Listen might not exist. Additionally, funding for SETI research has always been a challenge to obtain. Indeed, the SETI Institute’s own SETI program is funded entirely through private donations and receives no government support. Jill’s ongoing efforts continue to make groundbreaking SETI research possible.

        “Jill is not only a SETI pioneer, and world-class astronomer, her life and work have served as inspiration for an entire new generation of women in science, including many here at the SETI Institute” said Institute CEO, Bill Diamond. “Her toughness, tenacity and perseverance in a male-dominated field of enquiry are fully explored in this captivating biography of a scientist possessed by what is perhaps humankind’s greatest quest – answering that singular question – Are we alone?”

        Jill and Sarah will appear together on July 12 at the Cubberley Community Center in Mountain View, CA to discuss the book and new directions in SETI research. The presentation is part of the SETI Institute’s SETI Talks series and will also feature SETI Institute scientists Elliot Gillum and Seth Shostak. Tickets are available here.

        • ljk July 6, 2017, 9:03

          An excerpt from the Tarter biography here:


          The idea for the ATA came from a series of workshops held from 1998 to 2000. These posh gatherings, collectively called SETI 2020, plotted the route of SETI research for the next 20 years. While scientists and their university salaries don’t expect overly cushy conferences, Tarter and her SETI colleagues didn’t want those usual invitees: They wanted Silicon Valley technologists—specifically, Greg Papadopoulos of Sun Microsystems, David Liddle of Interval Research Corporation, and Nathan Myhrvold of Microsoft—on board. And Silicon Valley technologists, with their dreamy entrepreneurial visions, require minibars and rooms of their own, with views.

          At the conference, the attendees’ main conclusion was “SETI needs its own telescope,” closely followed by “And perhaps we should figure out how to build it.” Though piggybacking had worked well in SETI’s early decades, to gather and handle the stream of data they expected, they would need their own setup and computers hundreds of times faster than those that existed. The tech moguls, used to thinking about the big thing after the next big thing, suggested the SETI scientists “make a bet on technology,” specifically on a concept called Moore’s law. This law, which is just an observation of what happens in the real world, states that computers double in power every two years. It has held true since the first gigantic Macintosh. Even if you haven’t heard of this modern-day math, you know how slow your two-year-old laptop now seems compared to shiny new ones on the shelves of Best Buy. Papadopoulos and Liddle felt sure they could count on Moore’s law: The computing power doesn’t exist today, but it will be there tomorrow, when you need it. And it will be cheap(ish).

          It was a Silicon Valley idea, new to the scientists, and it felt radical back then, when everyone still had dial-up AOL and videos didn’t go viral because they took too long to load.

          • ljk July 9, 2017, 15:10


            Astronomer gives insights into SETI film ‘Contact’

            Mike Chapman, Record Searchlight

            Published 7:08 p.m. PT July 8, 2017 | Updated 7:14 p.m. PT July 8, 2017

            Astronomer Jill Tarter admires the movie “Contact,” whose main character was inspired by the 73-year-old scientist, but she told an audience at the Redding Library on Saturday that the movie took a few cinematic liberties.

            “It was a really good movie, but it wasn’t perfect,” Tarter told an audience of nearly 100 people attending the library’s summer film program.

            The 1997 film stars Jodie Foster and is based on the novel by Carl Sagan. Tarter is a former director of the Center for SETI Research and her passion is the search for extraterrestrial intelligence, just like Foster’s movie character.

            Tarter has a connection with Shasta County because over her career she’s listened for electromagnetic signals from outer space at various satellite installations around the globe, including the Allen Telescope Array at the Hat Creek Radio Observatory in the eastern part of the county.

            One of the film’s scientific errors is when Foster, right before a huge kissing scene, describes an equation giving the probability of intelligent civilizations in our galaxy. Foster says there’s the likelihood of millions of species waiting to be discovered.

            Not so fast, says Tarter. “Wrong by seven factors of 10,” she said while providing running commentary during the movie.

            Another thing that annoys Tarter is a scene where scientists at a satellite station hear some sort of chatter coming from the vicinity of the star Vega. Foster excitedly yells into a walkie-talkie, but Tarter says a real scientist wouldn’t do that because it would disrupt the very signal you’re trying to hear.

            “You don’t shout into a walkie-talkie,” she said.

            Tarter likened the effect of a walkie-talkie to having a cellphone on the moon, whose call would be the second strongest signal in the sky, easily interfering with stellar frequencies.

            She also said the movie character Kent wasn’t in Sagan’s book, but there actually was a blind physicist and astronomer that the moviemakers met in Australia and they wrote him into the film.

            Tarter has another beef with a champagne scene. “No one ever drank champagne,” she said, and if the scientists ever did, it would be because they’d be celebrating hearing signs of an ET.

            Fellow scientists use the radio telescopes in the SETI project to listen for “someone else’s technology,” Tarter said.

            A couple of times, she thought she had a transmission breakthrough that later proved unfounded.

            “I’ve had a couple of false positives that were amazing highs,” she said.

            Several audience members waited until after the movie to meet Tarter in person. One fan was Sofia Hansen, 17, of Redding, who five years ago was an intern at the Allen array during a summer camp.

            Tarter autographed the book, “Looking for Life in the Universe,” that depicts Tarter on the cover.

            “It was very exciting to have her (Tarter) give live commentary (during the movie), Hansen said.

            • ljk July 13, 2017, 8:56

              Jill Tarter, Feminist Cosmic Icon

              A new book about the astronomer describes the struggles she faced while trying to answer one question: Are we alone in the universe?

              SETI astronomer Jill Tarter, wearing her trademark turtle earrings, shows a model of the Allen Telescope Array in California.

              Marina Koren

              July 12, 2017


              To quote:

              Koren: The work seemed to involve constant attempts to find funding, and Tarter spent most of her time flying around the world trying to raise money. Why was it difficult to fund SETI research?

              Scoles: First, I think it’s difficult because many people don’t take the subject seriously. Imagine going to a rich person and saying, “Hey, I’d like to use your investments to see if E.T. is phoning.” Some would probably say, and have said, “Great! Thank you for your interest in the cosmos.” Others would probably say, and have said, “Definitely, definitely not.” Second, I think people understandably see a lot of problems on our own planet, with our own species, and want to help fix those. SETI doesn’t provide clean drinking water, you know? And, third, there’s no guarantee SETI scientists will ever find intelligent life, and no timeline on the possibility that they do. Could happen tomorrow. Could happen in 1,000 years. It’s not a particularly time-sensitive investment for someone to make.

              Koren: How did Tarter make the public, politicians, and other astronomers care?

              Scoles: To convince people that SETI was viable, Tarter had to go both big-picture and small-detail. She had to frame SETI as this fundamentally human enterprise, one that investigates the core questions that linger at the back of our collective consciousness: Why are we here? How did we get here? Where do we fit into the universe? Are there others out there who wonder the same things? She had to give the TED-style version of SETI before TED Talks existed. And then she had to show that scientists had the technical wherewithal to investigate those questions, getting into the nittiest, grittiest details of radio-telescope receivers and antenna arrays. She laid out the philosophical groundwork, and then broke out, essentially, the engineering blueprints.


              Koren: So let’s jump to what we, humanity, have sent out there, for someone else to hear. Tarter thought the message that Voyager 1 [and 2] carried back in 1977 wasn’t representative of Earth, that “we had lied through our teeth.” What should we be shouting into the void?

              Scoles: For Tarter’s part, she doesn’t necessarily think we should be shouting into the void—not because she’s afraid that will draw malevolent interstellar marauders to us, but because she doesn’t think we’re ready to do it right. And “right,” here, means broadcasting continuously for a long time with a message that people all around the globe can agree on.

              But when she said we had lied through our teeth in the Voyager message, she meant that we had left out the bad parts of Earth-life, like all that fighting we do. She thinks a portrait of humanity should include our flaws.

              Very smart people have spent a lot of time thinking about how to send a representative message that could be understood by beings that, you know, might not even have eyes and definitely do not speak any of Earth’s languages. But, for my part, I’d be happy to receive a content-free ping that only conveys, “Hey, we’re out here, too!” It’s hard to misread that. And so, in my opinion, that would be a great thing to say ourselves sometime.

              • ljk July 21, 2017, 9:23


                To quote:

                When did you first find out about Jill Tarter and her work with SETI?

                Well I guess let’s start with the fake Jill Tarter, because that was all I knew from the film. All I knew was fake Jill Tarter for a really long time. My family rented the movie Contact probably as soon as it came out on video. Yes, VHS. We watched it and I’d never seen a movie that I cared about so much and was just like, “wow.” I’d never heard of radio astronomy because I was 12. I didn’t know that searching for extraterrestrials was this scientific pursuit that was more than science fiction. I was very enamored of this character, Ellie Arroway, who had dedicated so much of her life, her fake life to the search.

                Then I studied astronomy in college and did an internship in Green Bank, West Virginia, where the first SETI search took place. It turned out all the other interns were similarly obsessed with Contact because [we] were the same age. So we watched it one night and my friend said, “Hey, you know that is based on a real person.” I was like, “What? What are you saying right now? That’s not true. That’s crazy.” But it was not crazy and it was true.

  • ljk July 7, 2017, 12:17

    Solving the Mystery of Whose Laughter Is On the Golden Record

    Adrienne LaFrance

    June 30, 2017

    Forty years ago, the sound of a human cackle was blasted out into the cosmos—but who is the person laughing? And why did the track disappear from official recordings?

    Full article here:


    To quote:

    “Laughter is ancient,” says Robert Provine, the author of Laughter: A Scientific Investigation. “Laughing, like crying, is a human instinct. It’s not under conscious control. Whereas crying is a solicitation of caregiving, laughter is the signal of play. It is the sound of play, literally.”

    Laughter is one of humanity’s most joyful peculiarities. Infants typically laugh long before they can speak. Laughter transcends differences in language entirely, yet remains a deeply important element of cultural and social interaction. Humans aren’t the only creatures that laugh—a chimpanzee’s laugh sounds like a dog panting; a rat laughs in ultrasonic chirps—but the rhythm and cadence of human laughter is unique to us. Humans also know, without really realizing, exactly what laughter sounds like. It’s a signal of play that we know immediately when we hear it, characterized by short bursts of sounds that last about one-fifteenth of a second and repeat in intervals each fifth of a second, Provine told me.

    Selecting the right laughter for the Golden Record would have been less fraught, presumably, than selecting which language to feature on the record. Indeed, the language question created all sorts of difficulties. Sagan had suggested a day or two of recording at the United Nations headquarters in New York City, where delegates from each member nation might record a “hello” in their native language. “I had hoped that something like half of the voices could be male and half female, in order to reflect the distribution of sexes on the planet Earth,” he wrote in Murmurs of Earth, a book about the project published in 1978. “I was told that this was quite difficult on entirely other grounds. Virtually all the chiefs of delegations were male, and it was unlikely that they would delegate the privilege of saying ‘hello’ to the stars to anyone else.”

    And so laughter, for all its complexities on Earth, was simpler to represent than language on the Golden Record. Except, when you listen to the “Footsteps, Heartbeat, Laughter” track of the “Sounds of Earth” audio that’s on the Voyager website—or to the version uploaded by NASA to Soundcloud—you won’t actually hear any laughter. What happened to it? And whose voice is supposed to be there? I started to ask around.

  • ljk July 10, 2017, 21:16

    Inside China’s Supermassive Alien-Searching Radar Dish


    To quote:

    A 46-year-old tourist who introduced himself to me in FAST’s astronomical museum as Mr Yu was more resolute.

    “I think the dish will find them,” he said, standing near a cheery display depicting grinning grey aliens. “FAST is a breakthrough for exploration of the universe. I’d give aliens my greetings, then discuss the origin of human life and evolution with them. I want to know where we are from, and where we are going.”

  • ljk July 13, 2017, 8:49


    Exoplanet Transits as the Foundation of an Interstellar Communications Network

    Press Release – Source: astro-ph.IM

    Posted July 12, 2017 10:14 PM

    Two fundamental problems for extraterrestrial intelligences (ETIs) attempting to establish interstellar communication are timing and energy consumption.

    Humanity’s study of exoplanets via their transit across the host star highlights a means of solving both problems. An ETI ‘A’ can communicate with ETI ‘B’ if B is observing transiting planets in A’s star system, either by building structures to produce artificial transits observable by B, or by emitting signals at B during transit, at significantly lower energy consumption than typical electromagnetic transmission schemes.

    This can produce a network of interconnected civilisations, establishing contact via observing each other’s transits. Assuming that civilisations reside in a Galactic Habitable Zone (GHZ), I conduct Monte Carlo Realisation simulations of the establishment and growth of this network, and analyse its properties in the context of graph theory.

    I find that at any instant, only a few civilisations are correctly aligned to communicate via transits. However, we should expect the true network to be cumulative, where a “handshake” connection at any time guarantees connection in the future via e.g. electromagnetic signals.

    In all our simulations, the cumulative network connects all civilisations together in a complete network. If civilisations share knowledge of their network connections, the network can be fully complete on timescales of order a hundred thousand years. Once established, this network can connect any two civilisations either directly, or via intermediate civilisations, with a path much less than the dimensions of the GHZ.

    Duncan H Forgan

    (Submitted on 6 Jul 2017)

    Comments: 17 pages, 21 figures, accepted for publication in the International Journal of Astrobiology

    Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)

    Cite as: arXiv:1707.03730 [astro-ph.IM] (or arXiv:1707.03730v1 [astro-ph.IM] for this version)

    Submission history

    From: Duncan Forgan Dr

    [v1] Thu, 6 Jul 2017 09:02:27 GMT (1795kb,D)