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SETI: An Alternate Strategy

How would an advanced society communicate its history and values to the stars? Bill St. Arnaud argues that just as we can uncover our own history through careful analysis of archaeological sites, so SETI might uncover traces of ETI cultures in the form of signals that take advantage of natural astrophysical processes. Read on for more on an idea Bill first broached in a Centauri Dreams post called Virtual Von Neumann Probes. A consultant and research engineer, Bill’s work has involved everything from charging methods for electric vehicles to next generation Internet networks. But his interest in SETI continues to mesh with his expertise in networking in this examination of a novel way to speak from the deep past.

by Bill St. Arnaud

To date most SETI research has focused on the assumption that an advanced extra- terrestrial society will want to “communicate” with similar beings throughout the universe. But it is my belief that given the vast distances and time that communication via a “communications channel” even if it is one way, such as optical or radio frequency transmissions will be impractical.

Current SETI searches assume that an advanced civilization will use extremely powerful omni-directional transmitters or highly directional and focused signals targeted at our solar system. The challenge with either approach is the fact that successful one-way communication between intelligent species is the dependency on the “L” term in the Drake equation. L represents the length of time for which such civilizations release detectable signals into space. If L is relatively short then possibility of two separate intelligent civilizations being coincident in time to send and receive a signal is very small. So even though there may have been many intelligent civilizations we will probably never be aware of their existence.

Given these constraints I suggest instead that we look for extra-terrestrial intelligence in a similar way we searched for signs of intelligence on earth prior to the modern age. We cannot hope to communicate to prehistoric man, but we know that intelligent beings existed on earth thousands of years ago through archaeological evidence such as cave paintings, pyramids, monuments, etc.

More recently societies have been burying time capsules for future generations to discover and hopefully marvel at our accomplishments and perspectives of the future. Indeed several spacecraft have included time capsules to be hopefully discovered by humans or extra-terrestrial intelligent beings in the far future. Part of the Apollo 11 Lunar Module, still on the moon, includes a plaque showing the arrangement of the Earth’s continents in 1969. The LAGEOS satellite (which will re-enter the atmosphere in 8.4 million years) contains a plaque showing the arrangement of the Earth’s continents in the past, present, and future. Pioneer 10 and Pioneer 11 both contain plaques that give pictorial information about their time and place of origin. The two Voyager spacecraft each contain a golden record that contains pictures and sounds of Earth, along with symbolic directions for playing the record and data detailing the location of Earth.

The understandable challenge of physical time capsules is the probability of locating and/or discovering these time capsules by future generations or aliens. Given the vast distances of space it is highly improbable that these time capsules will ever be discovered by any kind of intelligent being.

So rather than deploying physical time capsules can we think of a way of deploying electromagnetic time capsules made from self amplifying or self re-generating optical and RF signals that propagate forever and are easily discoverable and locatable? SETI researchers, in the past, have often speculated on self replicating robots that could travel to distant planets and recreate themselves by using local materials, but the complexity of such a device boggles the mind. Self amplifying and regenerating electromagnetic signals on the other hand would conceivably be much easier to deploy and possibly be achievable with current technology.

Self amplification and regenerating signals could use natural physical process such as gravitational lensing, stellar corona pump amplification, orbital angular momentum and other techniques to propagate electromagnetic signals indefinitely. But rather than being a straight line propagation in the direction of the original signal, self amplification and regenerated signals may propagate in all sorts of random directions depending on the physical properties of the amplification and regeneration process itself. As such the signals may be bouncing around the galaxy from one star to another in no particular predetermined direction.

Image: An example of one kind of naturally occuring gravitational lensing, in this case involving galactic clusters. Lensing clusters are clusters of elliptical galaxies whose gravity is so strong that they bend the light from the galaxies behind them. This produces distorted, and often multiple images of the background galaxy. But despite this distortion, gravitational lenses allow for greatly improved observations as the gravity bends the lights path towards Hubble, amplifying the light and making otherwise invisible objects observable. Credit: JPL.

Given that they depend on natural physical processes for amplification and regeneration the originating transmission does not to be that powerful or directional. It is conceivable that low power transmissions are that all is required to launch a self amplifying and regenerating electromagnetic signal. The signals may also be in a part of the spectrum that is not usually commonly assumed for interstellar transmission but rather exist in parts of the spectrum associated with the physical amplification and regeneration process.

There are a host of problems with current interstellar electromagnetic signaling such as attenuation, dispersion, group delay, etc etc. Given these limitations how could we hope to deploy a self replicating optical signal that will maintain its integrity over the vast distances and time of space?

One intriguing possible solution is using gravitational lenses to refocus and amplify a interstellar electromagnetic signal. In an interesting post called The Gravitational Lens and Communications, Paul Gilster quotes the work of Italian physicist Claudio Maccone, who explains that a ‘Sun-Alpha Centauri direct radio bridge exploiting both the two gravitational lenses, this minimum transmitted power is incredibly… small! Actually it just equals less than 10-4 watts, i.e. one tenth of a milliwatt is enough to have perfect communication between the Sun and Alpha Cen through two 12-meter FOCAL spacecraft antennas.`

One should also note that a gravitational lens acts like a lens with a gradient refractive index which also collimate and reduce electromagnetic dispersion.

Other possible mechanisms for self replicating signals include RF Orbital Angular Momentum (OAM), quantum entanglement and using stellar corona as pump amplifiers. As an example see the recent post about solar corona masering. I am sure there are other possible candidates. I challenge the reader of this missive to think of other ways of creating self replicating electromagnetic time capsules.

If we can come up with a plausible mechanism for deploying self replicating optical/rf time capsules the next obvious step would be to see if we can detect any such phenomena in our local interstellar region.

Instead of searching for communications signal from an extraterrestrial intelligent civilization we should perhaps instead look for “archaeological” evidence of their existence with the most likely candidate being a easily discoverable self replicating electromagnetic time capsule.

If you have any suggestions or comments, or think I am completely nuts please feel free to contact me at Bill.st.arnaud@gmail.com


Comments on this entry are closed.

  • Michael May 14, 2018, 15:07

    Imagine techaliens transmitting from within a globular cluster with all those close stars and with quite a few neutron stars and blackholes. They could see and communicate all over the Universe, they would be quite a foe if they chose to be as well !

  • Gary Wilson May 14, 2018, 15:19

    A series of brilliant articles lately. Thanks to Paul and Centauri Dreams.

    • Paul Gilster May 14, 2018, 15:55

      You are very welcome, sir!

  • DCM May 14, 2018, 15:59

    Makes sense.
    And it’s entirely possible that other intelligent beings might not be interested in communicating, and not necessarily from fear. We don’t know what they are or would be like. We’re vastly different from spiders and octopi yet we share much of the same DNA and have always occupied the same world. What about creatures from a different world with a totally different history?
    Beings like us may exist in a few places, far apart and even isolated in small nearby galaxies.
    So the cheapest, safest way of searching for them is best while we use our own nearby planets and build space habitats. Since we know nothing about others we need to concentrate on expanding and preserving ourselves before meeting them. Secure your base.

  • Gary Wilson May 14, 2018, 16:30

    It’s a wonderful idea Bill. A self-replicating beacon seems like a brilliant idea to me. Many of the other detection methods will often turn into detections of long defunct technological civilizations as well. A deserted, decaying Dyson sphere for example. No civilization will be immortal. There are far too many ways to make disastrous mistakes along the way.

  • John Freeman May 14, 2018, 17:59

    A very interesting idea and article. And, if it were realised….

  • hiro May 14, 2018, 18:52

    1) Sending information through Einstein-Rosen Bridge (whose radius is around several nanometers).
    2) Communication by using quantum entanglement at the speed of light between several nodes in the vast network.

    Both cases are silent and impossible to detect signatures from far away.

  • Harold Shaw May 14, 2018, 20:16

    The choice of reference coding isn’t obvious. A civilization could increase the likelihood that the message could be deciphered by sending multiple signals, each using a different reference coding. This assumes the multiple signals don’t interfere each other.

  • Dmitry Novoseltsev May 14, 2018, 23:10

    Respected Mr. Bill St. Arnaud,
    I would like to draw attention to several new types of potential objects for SETI. Read more here:
    https://i4is.org/wp-content/uploads/2017/05/Principium17%201705170945.opt.pdf , pp. 30-35.
    https://i4is.org/wp-content/uploads/2017/08/Principium18%20Aug2017%20opt.pdf , pp. 31-41.
    https://i4is.org/wp-content/uploads/2017/12/Principium19.pdf , pp. 27-35.
    By the way, Professor Claudio Maccone is aware of the issue.
    Another material has not yet been published.
    But if the passableness of the Kerr black holes at least in some cases will be confirmed, so in our Universe, from the earliest stages of its fairly cold existence, may already be artificial collapsors by “travelers” from other universes of the Multiverse with similar properties. In this case, it is also possible to record the signals from their “beacons”.
    In connection with the specifics of one-way transmission of “beacons” to very remote fast moving objects through the gravitational lens of the artificial collapsor, I believe it is possible to try to identify them among the so-called Fast Radio Bursts as soon as enough data is collected.

  • Curious May 14, 2018, 23:17

    Really some thought provoking articles recently – well done. I am always struck by the innate simplicity of a rock cairn. Simply pile some rocks up in a mound and anyone can immediately see that it isn’t natural. So question might be what harmless yet unnatural thing can we create that will last millions of years and yet isn’t as impossible to find like a space probe? Maybe our Moon (or other moons) which has no atmosphere or very active geology might be the best for such a thing. A large geometric trench seems achievable and easily spotted from a passing alien ship a million years hence

    • ljk May 15, 2018, 10:36

      We must be careful about such assumptions. Recall when the Canals of Mars were considered obvious evidence of intelligent life on the Red Planet.


      • Harold Shaw May 15, 2018, 12:41

        If the canals of Mars were artificial, they would have been revealed as artificial. It is not that difficult to design something to appear extraordinary to a wide range of consciousness and qualia.

        • ljk May 16, 2018, 10:01

          We only know the canals were not real because we could visit Mars in person via our space probes. We do not yet have the luxury with other star systems. So we may end up thinking we see some kind of artificial activity and come to similar conclusions as Percival Lowell and others did about Mars without enough evidence. Think Tabby’s Star.

          Percival Lowell was no ignoramus from the “primitive” 19th Century. You should read his books on Mars: Substitute the Red Planet in his texts and he sounds very similar to the current state of knowledge we have about ETI dwelling elsewhere in the galaxy.

          • Harold Shaw May 16, 2018, 13:35

            Natural phenomenon can be misinterpreted as artificial and artificial phenomenon can be misinterpreted as natural. However, if a civilization intends to signal other civilizations, they must construct something that looks out of the ordinary, something that encourages a closer look. The closer you look at a genuinely artificial message, the more artificial it will appear.

            The lesson we should learn from Lowell is to not jump to premature conclusions. We should not use Lowell’s confusion as a lesson that extraordinary messages can not be constructed. A moon sized pictograph would be extraordinary.

    • Harold Shaw May 15, 2018, 11:43

      I think this is a very polite way to METI. It establishes a threshold for how technically advanced a civilization must be to see the message and it would be difficult to consider it as an invasion of another civilization’s privacy. For staunch critics of METI, it also offers a way METI could increase our survival chance. If an ETI could see this image, they could also see our city lights, it doesn’t increase our visibility. Instead it demonstrates that we are aware we can be seen and that we assume there are other civilizations. It would demonstrates that we are less likely to be unawares.

    • J. Jason Wentworth May 15, 2018, 15:20

      Indeed–and in places shielded from meteoric erosion, such as in caves and lava tubes (especially on airless planets and moons, including our own), even messages scratched (or “lasered”) into the walls, or just drawn in dirt on the floor using any old object, would last practically forever. If the body in question orbited far enough from the Sun, it and any such messages on it could outlast the Sun. Hopefully such everlasting messages will be more intellectually fascinating than “Jerry loves Susie” or “Kilroy was here”… :-)

  • Ivan Vuletich May 15, 2018, 2:10

    “using stellar corona as pump amplifiers.”

    Nooooooooo!!!!! The Alpha Centaurians are just waiting for us to come out hiding so they can launch their invasion fleet! :-)

  • J. Jason Wentworth May 15, 2018, 2:26

    PART 1 of a Two-Part Reply:

    I like this idea. We might even be able to “heterodyne” a relatively low-power radio–and/or perhaps even laser–transmitter against the Sun’s radio and/or light emissions, in order to produce “beat” signals that we could control in order to use them as, say, a two-tone code (like that used for the 1974 Arecibo message). It might work like this:

    If you’re in a room with a device that generates a steady tone or hum (the sound need not have a narrow bandwidth), such as a refrigerator, freezer, air conditioner, boiler, or furnace, use your voice to hum at the same frequency as the loudest portion of the device’s hum. Then, slowly raise and lower the pitch of your hum, and you will hear over-tones and under-tones that are created by the interactions (either mutually-reinforcing or mutually-attenuating) of the device’s steady hum and your variable-frequency (literally, “audio FM”) hum. If you control the variations in your hum pitch, you can generate “dot-and-dash” over-tones and under-tones that are quite loud, even if the device’s audio output is much louder than that of your own voice—other people can easily hear the over-tones and under-tones. Also:

    The Sun, as was discovered during the radar research conducted in World War II, transmits radio waves having a wavelength of 1 meter, which corresponds to a frequency of 300 MHz (the Sun emits radio waves at other wavelengths, of course, but the strongest emission they detected was at 1 m). From what I’ve heard in audio recordings made at several radio wavelengths, the natural radio emissions of the Milky Way and—usually—our Sun are pretty steady, a “whisper” or “hiss” that isn’t very different from the “spread-out (frequency-wise) hum” of the above-mentioned devices. So:

    If a radio telescope equipped with a transmitter broadcast a continuous, audio-modulated carrier signal at the same wavelength as the Sun’s peak radio emission (and using an audio frequency the same as the loudest portion of the Sun’s “hiss”), then the radio telescope’s transmitter could create “dot-and-dash” over-tones and under-tones in the Sun’s radio emissions—as an alien radio telecope would “hear” them—by varying its radio frequency up and down in a controlled and timed manner, with respect to the Sun’s radio frequency. (If necessary—depending on the orientation of the Earth’s orbital plane with respect to the target exoplanetary system—the transmitter’s frequency changes could be calculated to take into account Doppler-shift effects caused by the Earth’s rotation and its orbital motion about the Sun.) Plus:

    This method need not be restricted to a single wavelength of the Sun’s electromagnetic emissions. It could also be used at other desired wavelengths, and at harmonics of such wavelengths (including the 21 cm hydrogen wavelength). As an alternative, the background galactic radio “hiss” (at 21 cm, or at the water wavelength [the “watering hole”]) might be used as the “to-be-modulated” loud natural radio emission, and:

    This technique—utilizing either solar or galactic electromagnetic emissions, interacting with artificial emissions from a variable-frequency transmitter—should work at optical wavelengths as well as at radio ones, making it possible to, in effect, greatly increase the output power and range of interstellar laser communication systems. (Such laser—and/or radio—communication improvements could also be useful for interstellar probes as well as for civilization-to-civilization [Earth-to-exoplanet] direct contacts, by reducing the probes’ required onboard radio or laser output power levels.) I know of a quick way to test this idea, which would cost nothing! I’ll describe it below, but first:

    I’m almost 100% certain that it would work with radio and light waves as it does with sound waves, and here is why (Leonard de Vries also mentioned this in “The Second Book of Experiments” [see: http://www.abebooks.com/servlet/SearchResults?sts=t&an=de+Vries%2C+Leonard&tn=The+Second+Book+of+Experiments&kn=&isbn = and http://www.google.com/#q=The+Second+Book+of+Experiments+by+Leonard+de+Vries ]). One of his experiments with sound involved tuning two tea kettles (or other common sound sources, such as cheap children’s flutes) so that their sounds—while they were both of the same frequency—were out-of-phase such that the two sounds cancelled each other out, resulting in silence! He pointed out that the same mutual-cancellation effect had also been demonstrated with two light sources; plus:

    My late friend Gary Moore, who was a photographer and an electronics technician, told me that the tiny black dot that is sometimes seen at the very center of an optical “pinhole ‘lens’” is a minute area where the light waves cancel each other out, producing darkness. Since radio waves, like light waves, are also electromagnetic radiation, this mutual-cancellation effect also works with RF, as *this* webpage explains (see: http://www.quora.com/Is-it-possible-to-cancel-out-a-radio-wave-by-sending-in-a-wave-with-the-same-amplitude-and-frequency-that-is-antiphased ). Now ((CONTINUED IN PART 2)

    • Bill St. Arnaud May 23, 2018, 10:06

      Interesting idea. But I see 2 problems with this approach:

      1. Electromagnetic waves do not interfere with each other. Its only when they hit a detector do you get interference patterns as you would see with waves in a medium like waves on water.

      2. The angular separation between the beat source (earth) and the carrier generator (the sun) of 1 AU would quickly result in 2 divergent signals at interstellar distance. Unless it is an omni-directional signal, or one with a broad wavefront you may completely miss the beat. Also the beat signal would be oscillating through space as the earth rotates around its own axis and orbits the sun


  • J. Jason Wentworth May 15, 2018, 2:26

    PART 2 of a Two-Part Reply:

    The posters on this webpage explained that achieving total radio wave cancellation, as perceived from “all points of view,” is difficult if not impossible (although 20 dB – 30 dB attenuation is quite doable, especially with Amplitude Modulation [AM]), *but* my idea doesn’t involve total mutual cancellation. Instead, it involves (which is easier to do than total cancellation) the selective creation of louder overtones and/or undertones—the “dots-and-dashes”—by varying the radio (or laser) transmitter’s frequency slightly above and below the Sun’s (or the galaxy’s) background radio (or optical) “hiss” frequency, while modulating the radio (or laser) carrier wave with the same audio frequencies (the “hiss”) that the Sun or the galaxy is producing. As well:

    Although the audio would be impressed onto the radio or laser carrier wave using AM (Amplitude Modulation), the radio or laser frequency would be varied above and below that of the Sun or the galaxy; the signal would still be an AM radio or AM laser signal (FM, of course, uses audio modulation that varies the radio frequency as the audio frequency varies), just an AM signal whose frequency is varied up and down to produce overtones and undertones that “beat with” the Sun’s (or the galaxy’s) steady radio (or optical) “hiss” in order to produce “dots-and-dashes” using the Sun’s (or the galaxy’s) radio output power. Because of the much greater transmitter power that is used in this method (that of the Sun or the galaxy), the extremely narrow bandwidths that are usually needed in interstellar signals might not be necessary. Plus:

    The overall effect—as heard on the receiving end of the signal, light-years away—would be that of CW (Continuous Wave, having a constant amplitude and frequency) transmissions that are used for Morse Code; CW transmitters put out a continuous sine wave, which produces a fixed audio tone in the receiver (which requires a BFO [Beat Frequency Oscillator, see: https://en.wikipedia.org/wiki/Beat_frequency_oscillator ] in order to create the audio—my set-up would not require the receiver to have a BFO in it, since the signal would be AM), and tapping the code key (or paddles) produces the (short) dots and (long) dashes. In my set-up, the Amplitude Modulated audio “beats”—created with the help of the Sun’s (or the galaxy’s) radio or optical “hiss”—would be the dots and dashes. In addition:

    Because the transmission distances are so great in this case, total or near-total mutual cancellation (to create intervals of silence or near-silence) may in fact be easy to accomplish, since both transmitters—the Sun (or the “slice of the galaxy” behind the Sun) and the radio (or laser) transmitter on Earth—would be along the same line-of-sight, as “viewed” from another star light-years away. Now, regarding the quick and free way of testing this idea, to see how it works at radio frequencies:

    Amateur radio operators (ham radio operators) often own more than one transmitter (they use multiple modulation systems, including AM). One ham could transmit to another using two AM transmitters on the same frequency, and slightly vary one transmitter’s frequency in order to produce the overtone and undertone “beats.” If one transmitter—the fixed-frequency one, which would simulate the Sun or the galaxy (audio recordings of the solar or galactic “hiss” could even be played through it)—had an output power considerably higher than that of the varying-frequency transmitter (say, 1,500 watts and 1 watt, respectively), such an arrangement could be used to test how a radio telescope could produce audio “beats” by varying its frequency above and below that of the Sun. And:

    It’s also possible that hams could do “live” tests—utilizing the Sun’s radio emissions, that is—between each other, as I’m pretty sure that they have radio band allocations that are at those frequencies where the Sun “broadcasts” with significant RF output power. They might even find such “Sun-bands” Morse Code radio to be another useful modulation method that they would like to use. (That wouldn’t “spoil it” for METI transmissions using my method, however, since interstellar radio transmissions—which are sent from highly-directional antennas or antenna arrays using powerful transmitters—have ERP [Effective Radiated Power] levels of millions of watts, while ham radio transmissions [whose maximum allowed transmitter power is 1,500 watts in the U.S., if memory serves] are far too feeble to cross interstellar space even as detectable RF noise.)

  • AlexT May 15, 2018, 3:25

    Even from the first sight I can see that proposed ideas much more problematic than building swarm “replicable robot”…
    Now step-by-step:
    1. Quantum entanglement – present time we can only use this effect in the way that has no any difference from regular laser comunication, there is not exists any quantum entanglement FTL communication devices, and I suppose will never be such devices…
    2. Gravitational lenses, yes may be it can sound attarctive on the first sight, but …
    2.1 To het some gain from such lense observer and observed object should be somehow focused one ralively to other, and when wetalking about focusing we talk about distances mesured by light years units…
    2.2 When we talk about gravitational lenses , we should take in account that depending of the gravitational lens size and focus distance the time shift beteew signals carried by photons can have order of hundreds/thousands light years – this will limits maximal datarate accordingly , so supposed observer and civilisation should have very long life and too much patience , let say typycal message transmission (like “Hello world”) can take 10000-100000 even more years :-)
    Wandering what Drake’s L we should put in equation in this case…
    I suppose this proposition is based mostly on emotions (wish so hardly METI) than on science.

    • hiro May 15, 2018, 18:27

      The big different in quantum entanglement vs laser comm is factoring some 10^10^10000… digits of primes.

      • AlexT May 16, 2018, 2:39

        Is this number was taken from your dreams?
        How well you understand results and outcomes of multiple QM experiments with quantum entanglement and experimentator’s conclusion about possibility of FTL communication using this effect?

        • hiro May 16, 2018, 19:34

          This is good old (either full or “semi”) quantum communication with very mean encryption to stop eavesdropping from outsiders. There is no FTL or whatsoever. I’ve learnt enough QM to understand an elementary amount of stuff; yeah just barely enough to know the very basics.

          • AlexT May 17, 2018, 14:10

            Even light speed communication that uses quantum entanglement is not in “old good” state , there is couple of lab experiments that try to use entanglement for secure communication, no more. There is no any evidience of FTL communication meanwhile and there is not any sciencifice theory that allows this possibility even in theory, oposite modern science prohibits FTL information transfer… End multiple experiments prove this theory.

  • AlexT May 15, 2018, 3:55

    «self re-generating optical and RF signals that propagate forever»
    – this is the New incarnation of Perpetuum Mobile…
    As well as I know even our Univers exists for limited time, so wandering is those RF signals supposed to last till the next Big Bang and even will continue to spread after it?

  • Andrew Palfreyman May 15, 2018, 3:59

    It’s probably a poor idea to blast petawatts omnidirectionally out from Earth until we at least have a plan A,B and C in case Bad Things Happened. But we might as well get started with tight beaming METI to upcoming destinations like the Alpha Centauri system. I assume the solar gravlens would help in this regard, but it’s going to take a while to get out to >550 AU with a decent power supply. The 0.1 mW trick only works with a gravlens-assisted receiver at the destination, so we’ll need something fairly decent that has good longevity.

    • AlexT May 15, 2018, 11:58

      The Sun gravitational lens has diameter more than 1.2Milion meters, it takes about 4s for the electromagnetic wave to travel from one side of the Sun “lens” to another, I suppose this 4s delay will plague maximal achievable data transfer rate i.e maximal signal bandwidth will be less than 1/4 Hz.
      550AU travel to focus point it self not easy implement task + fact that 550AU orbit will have dramatically long rotation period…
      Sumary it is nice fantasy for fantasy, not more.

      • AlexT May 16, 2018, 2:30

        Sorry misprint Sun diameter is approximately 1.2 Milion kilometers :-), not meters.

  • ljk May 15, 2018, 9:19

    These human ancestors may not have left us a deliberate message, but we can still learn things from and about them from their physical evidence:


  • Alex Tolley May 15, 2018, 11:09

    The BBC’s “Sky at Night” program’s current episode is about early discoveries from the Gaia data. Good episode for the non-astronomers among us. Looks like Gaia data analysis will be the source of some fascinating posts on CD.

    Now that Gaia data has been released, I am interested to know whether it lends support or can falsify Greg Matloff’s “conscious star” hypothesis. IIRC, he was waiting for this data.

  • Alex Tolley May 15, 2018, 11:13

    If I understand Bill’s argument correctly, it implies that signals should be coming from all over the sky, rather than from target stars. But weak signals lensed by stars should also mean that to detect them, the sensors need to be at our sun’s gravitational “focus”, starting out at around 550 AU. Doesn’t that mean we need detectors spread over the surface of a sphere 500 AU in radius to view the sky?

    • AlexT May 16, 2018, 2:51

      I suppose this only solution to make this idea to work somehow :-)
      Sensors also should be spaced very thightly, because focus will be so sharp from this huge lens :-) I suppose we should build something like Dyson sphere here.
      Without this sensor’s tight spacing system will work exactly like the broken clock – “it will show precision time once per 24 hour, only in this case 24 hours are translated to rotation period of 550AU object.
      In addition such system will have very limited bandwidth available for communication, caused by gigantic lens size.

  • E.P. Grondine May 15, 2018, 12:13

    One earlier idea was to look for their radars, as these would be their most powerful radio signals

    Following this line of reasoning, any extra-terrestrial advanced civilization is likely to have an active impactor (cometary impactor) detection system, either in the optical or radio range.

    Calculate systems’ power and frequency shifts, an focus your detection efforts there. Perhaps persistent fast radio bursts…

    • J. Jason Wentworth May 15, 2018, 15:50

      In “Rama II” (written with Gentry Lee), Arthur C. Clarke–who seldom portrayed totally made-up technological devices; they were usually based on plausible extensions of known science or speculation–described an extremely long range radar called Excalibur, which could detect starships (like the next Rama ships) or potentially hazardous long-period comets far beyond the Kuiper belt. Powered by a thermonuclear bomb detonation, Excalibur produced a single, extremely powerful radar pulse, whose echoes were analyzed by a supercomputer to glean information about the reflecting objects, and:

      If any other civilizations have such impactor detection systems, their single pulses would be detectable at interstellar differences, and they would “sound” like FRBs (Fast Radio Bursts). In systems with a lot of debris, even multiple H-bombs to power such radars would be cheap insurance to protect their worlds from catastrophic impacts.

  • Harold Shaw May 15, 2018, 12:53

    Doesn’t this imply that natural electromagnetic signals could propagate further and for greater duration. As well, would we expect any given signal to appear where it isn’t expected?

    Could a stellar object be modified into a beacon designed to take advantage of the network described?

    • J. Jason Wentworth May 16, 2018, 7:01

      I would agree. Using the steady radio emissions of the Sun (there are portions of its RF spectrum where the radio output is steady), a relatively low-powered transmitter could be heterodyned against the Sun’s radio emissions to produce “beats,” which could be arranged to occur so as to produce “dots and dashes” with intervals of (relative) silence between them. The Sun would provide nearly all of the RF output power for such signals, and:

      The frequency-varying, heterodyne-generating radio transmitter need not be very powerful (possibly on the order of a radar telescope’s transmitter, if directional heterodyned solar signals were desired). Using the Sun as a non-directional transmitter would require a more powerful heterodyne-generating transmitter, but even its RF output power need not necessarily be of Brobdingnagian intensity. Even in the 1950s, magnetrons of 1,000 to 1 signal output/input strength ratios existed (higher-performance ones are undoubtedly available today), so that a magnetron-equipped transmitter, especially if operated in a pulsed transmission mode, wouldn’t need a dedicated hydroelectric dam or municipal power plant to power it. Also:

      An endlessly-repeating sequence of precisely-timed beats, counting out the first ten prime numbers, would be unmistakably of artificial origin, and could serve as an attention-attracting “palimpsest beacon” for an information-richer “nested” message on a nearby solar frequency, “beat out” with a frequently-repeated “key” to the code being used. The messages could be pictographs on prime number grids, like the famous 1974 Arecibo message (and earlier pictures of this type that Frank Drake and his colleagues developed). The “key” could be something very simple, such as a pictograph square with an inscribed “X” or “+” (running between its opposite corners or opposite sides, respectively), whose symmetrical appearance would come out the same (just with transposed 0’s and 1’s (or black and white squares or dots [or whatever different ‘spots’ the aliens used]) regardless of which way they oriented the prime number grid. In addition:

      This “key” image’s obviously intentional shape would give them a clue in case they oriented rectangular prime number message grids–or square message grids containing non-symmetrical illustrations–in the wrong order (19 wide x 17 high rather than 17 wide x 19 high, for example). Simply be reversing the order, such pictographs would be displayed correctly.

  • DCM May 15, 2018, 15:28

    Finding other intelligences is interesting but is it immediately important? We might learn ABOUT them but not necessarily any useable lessons in self-improvement, which seems to have been the motive since George Adamski.
    They may have no similar concepts and if they do they’ll still likely be quite different from us.
    The sky isn’t Heaven. Or even a psychiatrist’s office.
    Occupy as much of space as we can.

    • Alex Tolley May 15, 2018, 16:14

      Finding other intelligences is interesting but is it immediately important? We might learn ABOUT them but not necessarily any useable lessons in self-improvement,

      One could make the same argument about other ancient or historic cultures or civilizations on Earth. That would imply that archaeologists, historians, and other related studies are a waste of time. There does not have to be direct utility for knowledge to have value, and importance is contextual.

      • DCM May 15, 2018, 20:32

        Not a good comparison. Historical records and artifacts are likely to be destroyed by development or fanaticism or indifference. They are relevant to us. As it happens I see history as useful knowledge.
        We simply don’t know anything about any other intelligent life forms or whether they exist. We aren’t destroying traces of them as far as we can tell; if we did know we’d have a handle on them.
        But I’ve known too many people who actually believe aliens will solve all our problems for us — the Heaven’s Gate cult was all over the news for mass suicide in order to encounter them. Carl Sagan seems to have believed they’d be eager to help us. I knew guys in the 1950s who received “enlightenment” from aliens who produced symbols from Mayan, Egyptian, Hindu, and other cultures. They were just ordinary persons last I saw them.
        I’m all for listening but I’m not sure an immediate dialog (as immediate as it can be at stellar distances) is for now a good idea if we do find them.
        I’m for developing our available worlds as we can and building others. We don’t know what any aliens may be like but need to be more powerful and numerous than now if we find them.

        • AlexT May 16, 2018, 3:19

          DCM – I fully share your point of view.
          But “technological” ideas described in discussed topic cannot work ,even theoretically, so it cannot create any problem to anyone :-)

        • J. Jason Wentworth May 16, 2018, 8:48

          If we ever do come across another technological civilization via Earth-based radio or optical SETI searches, or via Bracewell probes (ours, or one of theirs that comes [or came] here), I suspect that Carl Sagan’s expectation will turn out to be correct, but not for the reason he thought it would be:

          He was a “Drake equation optimist,” to the point that he even said that “the stars are humming with signals from countless civilizations in the Galaxy.” Given [1] what we now know from a fair sample of exoplanetary systems, plus [2] the “eerie silence” that SETI searches have faced for decades now, as well as [3] the cautious, less-than-sanguine attitudes of most biologists and paleontologists about the odds of intelligent alien life since the beginning of SETI (only *one* twig–of many–on one branch of the tree of life on Earth reached high intelligence *with* manipulative organs, and developed a technological civilization, after billions of years), I have a gnawing feeling that technological civilizations (and perhaps even simpler life) isn’t at all common, and may even be very rare. Also:

          Life is an extravagantly complex, entirely unnecessary solution to the problem faced by atoms of all elements (except the noble gases and, in most cases–unless fluorine is present, which it seldom is–the refractory metals): to combine into compounds as needed, in order to reach the lowest energy states. The familiar chemical compounds that we find on Earth and on other worlds are entirely adequate for achieving those lowest energy states (even normally-reactive molecular fragments, such as the cyanogen [CN, a fragment of the hydrogen cyanide and sodium cyanide molecules] found in comets, is perfectly adequate for the task on such low-temperature bodies), so:

          If technological civilizations are rare (and the more time that passes with only silence [except for the natural radio and optical din of the universe], the rarer our neighbors–if any–appear to be), if we ever do stumble across another technological society (or vice-versa), it would not be surprising if they felt lonely, too, and then felt relief and/or joy after *finally* finding someone else to talk with. Even if they were by far our elders, they might feel a desire to help us–even if only for the “selfish” reason of having a comparably-capable civilization which could collaborate with them in exploring the galaxy (via instruments and/or starprobes), jointly (even though ^physically^ separately) working on intractable problems in mathematics, philosophy, etc.). Plus:

          If they had searched for other civilizations with no previous success (before they and we finally found each other) for far longer than we have, that would emphasize, as perhaps nothing else could, the extreme rarity and preciousness of life in the galaxy (and, likely, in the rest of the universe as well). Such sobering knowledge would tend to encourage humanity to stop “keeping all of its eggs in just one planetary ‘basket’,”) and to stop preparing endlessly for World War III (Einstein’s warning that “World War IV would be fought with sticks and rocks” would acquire more moral force, too). The other civilization would presumably also–if it had any of the same problems–find itself similarly encouraged to abandon such self-destructive and self-limiting attitudes and behaviors. As well:

          Another possible–though unlikely–case could involve a Bracewell probe from another civilization, which had ceased to exist some time later. If the probe was conscious, self-aware, and “human-like” enough to have feelings (such attributes seem impossible, but while they are beyond current human technological capabilities, they may not always be so [Michael McCollum’s novels “Life Probe” and “Procyon’s Promise” involve such an alien Bracewell probe and its interactions with humanity]), what a crushing blow that would be–to have its very purpose and reason for being cease to be. (In the first novel, the probe planned to destroy itself after an attack by a backward group of nations damaged it severely, so that it couldn’t return home with the knowledge it had collected; it was persuaded not to by sympathetic human beings who promised to send the knowledge to its creators, and who asked it to be a teacher–with its vast knowledge–to humanity, most of which welcomed its presence in the Solar System.) Were such a thing to happen in real life (if it couldn’t return home, or if its makers had died off), such an ancient, advanced machine might find–or be offered–such reasons to keep going, much like another, very rare, technological civilization with which we had made contact, or which had contacted us.

        • Alex Tolley May 16, 2018, 9:34

          Any knowledge, even just the existence of an ETI, would have an impact on our civilization and therefore be “useful” for us. On Earth, just having evidence that higher animals have intelligence and emotions alters our interactions with them and improves our civilization. ETI, especially technologically advanced ones, would alter our perceptions of ourselves, and our goals. If nothing else, it would imply that “the great filter” may be behind us, not in front of us, removing that existential threat from our future.

          • AlexT May 17, 2018, 2:22

            Long long tima ago Homo Sapience invented relision and Gods that plays in our day-day life the same role that you dedicate now to technologocally advanced ETI. Are goods helped us to be better?
            Multiple holy wars, inquisition, conquests proves opposite.
            Exactly same behavior we should expect from cosequences of ETI finding.
            I think that ETI it is God replacement for some atheists, that want their atheistic Paradise too.

    • J. Jason Wentworth May 15, 2018, 16:32

      Carl Sagan may have been a little “starry-eyed” regarding this, but something that he pointed out makes sense:

      If we made contact with a technological civilization that has been a technological civilization for millions of years, just the demonstrated fact of their existence would indicate that intelligent beings’ societies *can* live stably with high technology without destroying themselves, which would bode well for (and would provide hope for) the prospect that human beings could so the same. The aliens could also offer us advice for achieving their state of stability. Also:

      While what worked for them might not be applicable to human beings (as you correctly pointed out), it would suggest that some other, human-appropriate course of action with the same objective (getting to that state via a different path) might work in humanity’s case. Their are no guarantees that this could be achieved, of course, but having the benefit of another, older race’s perspective (maybe they would even know another, more-or-less human-like race which achieved stability) on this could inspire ideas that we’ve never had before, and:

      Regardless of how young humanity might be–and how limited human perspectives might be compared to them and to theirs, respectively–they might be interested in humanity nonetheless, simply because many if not most human perspectives would be different from theirs. (This is one reason why anthropologists study “primitive” [they are not primitive in all respects] societies; they and their perspectives are different.)

      • AlexT May 16, 2018, 3:40

        Our own civilization long period (10000 years?) living with concept that there is exists some super intelegent persone (God) , this concept is supported by multiple religions existing on our planet.
        So we do not need to search any additional extra civilisation (as example of “good” life), we already invented it…
        Does this fact maid Homo Sapience “better”?
        The fact is – No, just remember about multiple “holy wars”.
        So ETI finding cannot make as better, we are that we are.
        But if ETI civilization is ruled in similar way like our, and technologically more advanced than we are – it will be better to us , never contact and meet them, oposite we will repeat the fate of American natives (in best case).

        • ljk May 16, 2018, 9:52

          Hiding from the galaxy isn’t going to work, except to make us even less aware of who and what is out there with the result that if there are hostile forces, we will be unaware and unprepared for them.

          You can hide your children away from all the bad things in this world, but in the end you just end up with highly dysfunctional adults who won’t be able to cope with real life, bringing about the very thing you tried to avoid for them.

          • AlexT May 16, 2018, 12:36

            No calling to someone does not mean hiding :-)
            No calling , does not mean to stop searches too, opposite – it will be more clever to find and know about existence of potential danger to our civilization.
            We cannot escape possibility to be found, but “no calling” can earn some important time to develope our possibilty to protect our civilization.
            Our earth’s life is not the idealistic “peace” , it is non stop expansion and extinction , there is good reason to suppose that it is basic law of our Univers.
            We do not have any evidence or example that METI will bring us the Paradise…

            • ljk May 16, 2018, 14:47

              I have never thought that finding ETI would “save” us, at least in the sense that advanced aliens would literally come to Earth and rescue us from our bad behaviors.

              We will learn a lot from their discovery, starting with the fact that there is life beyond Earth and moving up from there. What we do with what we learn from them is up to us, but humans are pretty good at gleaming much from even seemingly meager data.

              By the way, I am doubtful that ETI are beaming the equivalent of the Encyclopedia Galactica around the Milky Way just to share their information with one and all. Unless such beings are very altruistic or fearless or both, it does not make much sense to share everything you know with strangers.

              Neither do I think that ETI are either angels or monsters, though they could be beings with sets of morality and ethics that would be truly alien to our own. They could be meaningless to us, or they could inadvertently harm us even if the ETI did not intend such results.

              But the Universe is out there, in whatever form it takes. And humanity has not been quiet, not just due to all our electromagnetic leakage but also due to deliberate METI. With 7.6 billion humans on this planet, we can forget trying to police everyone. As a prime example, if China wants to start broadcasting into the galaxy with their FAST radio telescope (and they have already officially said they want to become the first nation to detect an ETI with it), who is going to stop them? We already have other examples on smaller scales, such as the fools who beamed the awful 2008 remake of the SF film The Day the Earth Stood Still into space.

              Even if it goes nowhere and is indecipherable, it just shows that we are better off preparing for the potential consequences rather than insisting everyone behave like a good little impartial, unemotional scientist – who don’t exist, either, despite the stereotypes.

              • AlexT May 17, 2018, 1:44

                This your messge very strongly contradicts with your prvious texts… where you very detailed in colors described how many happiness will bring us ETI :-)
                I am not a policmen, it is only my opinion. For sure China, Russia, EU, USA etc. will do what they decide to do, I hope that economic reason will convince governments better than any anonimous text in internet.
                After reading topics and comments on this very interesting web site (I very like to read it), I understand very well why USA government and NASA cut financial support of SETI program – it was only clever solution, too many people assosiated with SETI are not scientists , but mostly fantasy and fiction writers, to much wishful thinking and little bit science.
                Yes I see that SETI comunity here on this site mostly following their emotions… and utopic dreams about communistic future after METI :-)

                • ljk May 17, 2018, 9:19

                  My attitude towards ETI follows the military mantra of trust, but verify. I think the discovery of alien life will do humanity a lot of good, but I am not foolish enough to think there may not be any consequences. But I also think it is inevitable so I prefer to be prepared rather than hope every human on Earth is going to behave themselves and follow strict protocols about dealing with ETI.

                  Your quote:

                  “…too many people assosiated with SETI are not scientists…”

                  Oooh, don’t tell Frank Drake and Jill Tarter that, as just two names out of many real scientists who did and do SETI.

                  To repeat what I said above, I don’t think aliens will be our actual saviors, as I personally am tired of how the human race constantly seems to just sit and hope some savior will automatically come along and rescue them, when they could far more easily and quickly get off their butts and work as a vast group to solve their own problems.

                  What I do think is that learning about and from aliens will be of benefit to our species, if we handle and apply what we learn properly. As usual, it is up to us in the end to save ourselves.

                  Sorry to see you have so many issues with science fiction and its practitioners. I know the difference between the two. Many others who do not are usually harmless, so I would not be so adamant against them.

                  • AlexT May 18, 2018, 3:24

                    >“…too many people assosiated with SETI are not scientists…”

                    >Oooh, don’t tell Frank Drake and Jill Tarter that
                    Sorry , but “too many” , does not mean ALL…

                    >Sorry to see you have so many issue with science fiction
                    I very like to read science fiction books, I read many such books in my life, but SETI , as well as I know, claims to be science , i.e. without fiction

          • DCM May 16, 2018, 15:42

            Hiding isn’t what I have in mind as much as using the time to develop and improve our technology and knowledge of the universe.

            • ljk May 17, 2018, 9:08

              Unless we have a radical change in SETI/METI and space utilization, you will probably have plenty of time for those things.

        • DCM May 16, 2018, 15:40

          Right. When Cortez set out across Mexico the Aztecs followed their customs, believing that sending him valuable gifts including gold and silver, would induce him to turn around and leave. He did pause to massacre a number of inhabitants, following his own culture’s custom of inducing peace and cooperation. (Giving time for Panfilo de Narvaez, sent out by the suspicious governor of Cuba, to do the same and catch up along with a soldier carrying smallpox….)

          • ljk May 17, 2018, 9:06

            The Aztecs also had a fair number of local enemies, having conquered neighboring tribes long before Cortez showed up. Their desire to see the Aztec Empire fall was just as instrumental in helping Cortez defeat the Aztecs as anything else that happened.

            Decades of revisionist history have changed attitudes towards Native Americans from ignorant savages in need of “saving” by white European colonists to peace-loving saints who were just sitting quietly in the Americas when the mean white guys came along and wrecked everything.

            The truth, of course, is somewhere in the middle. Native tribes fought and committed atrocities to each other long before any Europeans came along. The Maya civilization fell long before the first Europeans showed up as just one example.

            Native Americans had various reactions to their white invaders: Some fought back, some ran, other cooperated, including using the whites to destroy their enemies. Remember the Sioux in Dances with Wolves? They were the conquering power in the region just like the Aztecs were in Mexico and they too had lots of native enemies.

            These are things to consider the next time someone brings up that tired analogy about how if ETI find us, it will be like when Europe came to the Americas. There may be similarities, but it will not be the same, because we are dealing with huge distances that need to be crossed and two literally alien species.

            • DCM May 17, 2018, 15:50

              Just what I’m getting at. The Mexican Indians, though the same species, had quite different customs, including those about diplomacy and warfare, from the Medieval Spanish. Warfare seems to have been a kind of ritual involving shared religious concepts while the Spanish had engaged in centuries of vicious total war with Moslem invaders.
              I’m sure alien creatures will be very different and unsure what we intend and will understand.
              All I’m saying is we shouldn’t approach any possible aliens with firm preconceived notions, least of all that they’re the ideal of Western civilization or filled with ancient Atlantean wisdom.
              Continue improving our knowledge and technology — and inhabited area.

            • AlexT May 18, 2018, 3:46

              It is not important who was a “good guy” and who was a “bad” one in history of America’s conquest.
              There is only on fact – all Indian civilisation are vanished, and it is direct result of arrival (and fallowing conquest) of alien (to Indian) visitors.
              I do not want to be eliminated by very human and “good” ETI :-)

              • ljk May 18, 2018, 12:29

                I am far more concerned about the actions of some real humans than any distant hypothetical aliens.

                • AlexT May 19, 2018, 3:16

                  Me too, much more concerned by our local problems , that cosmic one, I suppose that , if it unescapable scenario (end of our own civilization) we will make it by our own efforts, no ETI and no huge asteroid will eliminate us, but we self can do it better and much more probable than any other factors.
                  As sequence, exactly because we have our own bad example, we cannot expect from ETI better behavior , present time we do not have any other and “better” example of intelegent and not intelegent life.

                  • ljk May 21, 2018, 11:35

                    I do not expect ETI to be better or worse than us so much as just different. Different enough that their behaviors may either mean nothing to us (and vice versa) or harm us unintentionally.

                    As just one example, we don’t mean to step on an ant colony, but it happens.

                    One other big difference between the example of Europeans encountering Native Americans: The distance involved and the medium that needs to be traveled through. While interstellar space may not stop someone intent on harm, it does mean that the casually malevolent are not just going to head off after prey on a whim.

                    • AlexT May 24, 2018, 3:33

                      Relatively to ant colony, many time people destroy ant colony intentionally , because ant are bothering (for human) and cause lot of troubles (to human), it is fact, so you used wrong example to prove your point of view. Homo sapiens – ant relations is good example that ant should prefer that human race will not exists on the Earth at all…
                      Your notes about distance I cannot accept too, distance and media problems are not absolute and probably advanced civilisation can find the good solution for space travel , i.e. hiw to cross Universe exactly like human find the solution how to cross the ocean.
                      If the space travel is imposible in reasonable time (during individual life span), so we should not afraid from any ETI visit (METI), but still can expect some unexpected bomb-surprise (artificial comet ) visit…

              • DCM May 19, 2018, 16:00


  • DCM May 16, 2018, 3:18

    I don’t doubt it’s possible for an intelligent species to last for millions of years and more. The notion they’ll likely “destroy themselves” is a historical artifact that grew out of World War II (and World War I, which it followed in a couple of decades). It can’t be taken as a universal truth, despite being taken up by environmentalists and echoing historians who claim history is a semi-biological entity that moves in cycles. History is a record of events, not an inevitable process, though it reveals consistencies in behavior.
    One thing I’ve see from it is that whoever develops new societies in new places is usually successful. That’s why I emphasize making use of nearby planets and constructing space biospheres, and not expecting any kind of salvation from aliens — besides which for all we know we’re the first.

  • Michael Fidler May 16, 2018, 5:52

    The way ET is going to set up transmitters is around white dwarfs, pulsars and black holes. Most will last for ever, the gravitational lens is of very short focal length so easy and quick to change targets. Redshift of em waves should indicate artificial orgin.

    • Michael Fidler May 16, 2018, 6:02

      A interferometer transmiter at the focal of a white dwarfs could be used to transmit multi coded parts to a distant specific location that could only be deciphered at that location.

      • AlexT May 17, 2018, 2:40

        Do you know what is interferometer?
        How do you imagine “interferometer transmitter”?

        • Michael Fidler May 17, 2018, 14:25

          AlexT please stop making stupid remarks, and try and be a little more creative. If you want to insult people please go some place else.

          • AlexT May 19, 2018, 3:29

            Sorry to hurt you, but you are using some phrase like “interferometer transmitter”, that not only me with my limited knowledge, but even Google cannot fing it in it’s huge database.
            As sequence , I cannot catch any connection between “white dwarfs “ and this unknown (but seams to be miraculous ) instrument, and what information it can send or measure to/from the Universe.

      • Michael May 19, 2018, 9:57

        “A interferometer transmiter at the focal of a white dwarfs could be used to transmit multi coded parts to a distant specific location that could only be deciphered at that location.”

        The information is able to be intercepted along the transmission surface with an interferometer, white dwarfs are not that big, about Earth size .

    • AlexT May 19, 2018, 3:58

      Should we conclude from your proposition, that Redshift of distant Galaxies is indicating artifical origin?

  • Michael May 16, 2018, 16:32

    “If you have any suggestions or comments, or think I am completely nuts please feel free…”

    I think you are amongst equals here, sometimes thinking outside the box, well leaves you outside the box. The trick is knowing how to get back in the box to protect ones sanity. I have always struggled with that, the former that is, although the latter has fled my mind sometimes!

  • Harry R Ray May 17, 2018, 9:50

    TWO THINGS! FIRST: The “fl” part of the Drake Equation has NOW, for the FIRST TIME, apparently been SUCCESSFULLY CONSTRAINES STATISTICALLY. ArXiv: 1805.o6329 “Expanding cosmological civilizations on the back of an envelope.” by S. Jay Olson. The premise here is that a large fraction of life is transported to planets able to SUSTAIN life but did not DEVELOP any YET by “expansionistic civilizations” and CONTINUE to flourish EVEN AFTER these civilizations have disappeared. SECOND: Breakthrough Initiatives pledged to follow up on the 234 Bourra/Trottier stars with Dopplar Spectroscopy observations to confirm or deny their allegations of possible ETI signals. Has this been done already? Has anything been PUBLISHED. Keep in mind, that; even if the 234 “signals” are NOT false positives, they may be due to unknown types of stellar behavior instead of ETI>

    • ljk May 17, 2018, 16:03


      Expanding cosmological civilizations on the back of an envelope

      S. Jay Olson

      (Submitted on 15 May 2018)

      We present a simplified description of expansionistic life in the standard relativistic cosmology. The resulting model is exactly integrable, yielding a simple set of predictive formulas. This allows one to quickly propose new scenarios for the life appearance rate and the dominant expansion speed and evaluate the observable consequences. These include the expected number and angular size of visible expanding domains, the total eclipsed fraction of the sky, and the life-saturated fraction of the universe.

      We also propose a simple anthropic bound on observable quantities, as a function of the dominant expansion velocity alone.

      The goal is to create a simple and intuition-building tool for use in the context of cosmology, extragalactic SETI, and futures studies.

      We discuss the general predictions of this framework, including conditions giving rise to an “extragalactic Fermi paradox,” in which zero civilizations are visible beyond the Milky Way. This can occur even if a substantial fraction of the universe is already saturated with ambitious life.

      Comments: 7 pages, 3 figures

      Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

      Cite as: arXiv:1805.06329 [astro-ph.CO]
      (or arXiv:1805.06329v1 [astro-ph.CO] for this version)

      Submission history

      From: Stephan Olson [view email]

      [v1] Tue, 15 May 2018 17:57:59 GMT (83kb,D)


  • ljk May 17, 2018, 10:37

    Dutch radio antenna to depart for the Moon on Chinese mission

    Thu, 17/05/2018 – 08:30

    On 21 May 2018, the Chinese space agency will launch the relay satellite Chang’e 4 to an orbit behind the Moon. On board will be a Dutch radio antenna, the Netherlands Chinese Low-Frequency Explorer (NCLE). The radio antenna is the first Dutch-made scientific instrument to be sent on a Chinese space mission, and it will open up a new chapter in radio astronomy. The is instrument developed and built by engineers from ASTRON, the Netherlands Institute for Radio Astronomy in Dwingeloo, the Radboud Radio Lab of Radboud University in Nijmegen, and the Delft-based company ISIS.

    With the instrument, astronomers want to measure radio waves originating from the period directly after the Big Bang, when the first stars and galaxies were formed.

    Full article here:


    To quote:

    Why is it so important for the measuring instruments to be placed behind the Moon? Professor of Astrophysics from Radboud University and ASTRON Heino Falcke: “Radio astronomers study the universe using radio waves, light coming from stars and planets, for example, which are not visible with the naked eye. We can receive almost all celestial radio wave frequencies here on Earth. We cannot detect radio waves below 30 MHz, however, as these are blocked by our atmosphere. It is these frequencies in particular that contain information about the early universe, which is why we want to measure them.”

  • ljk May 17, 2018, 11:12
  • ljk May 21, 2018, 12:49

    If aliens beam us a signal, what should we expect?

    Aliens could be trying to get through to us right now and we might not even know it. Even if another intelligent species was trying to transmit a message to Earth, a weak radio signal from some distant galaxy could get lost in the chaos of light and noise from cell phones, wifi, TV and radio broadcasts, satellites, microwaves, traffic jams and cities that never sleep.

    That signal also has to contend with disruptive cosmic phenomena like black hole collisions and fast radio bursts being zapped through space before it reached a network of SETI (search for extraterrestrial intelligence) radio telescopes.

    “By far the biggest challenge in radio SETI is what we call radio frequency interference,” UC Berkeley SETI Research Center director Andrew Siemion told Seeker. “Because we use our own technology as an example of what we should be looking for we in fact find many many examples of our own technology and those examples actually pollute the signal that we see especially with radio telescopes.”

    Full article here:


  • ljk May 21, 2018, 13:09
  • ljk May 23, 2018, 11:53
  • ljk May 28, 2018, 16:05

    How do we get our message across to the extraterrestrials? The answers are evolving

    BY ALAN BOYLE on May 27, 2018 at 6:31 pm

    LOS ANGELES — Last year, scientists sent a binary-coded message telling the aliens what time it was. Next year, it’ll be the periodic table of the elements. And someday, they hope to transmit a universal language that even extraterrestrials might relate to.

    “I think we should treat this as a multigenerational, true experiment as opposed to an observational exercise, like archaeology,” said Doug Vakoch, a veteran of the search for extraterrestrial intelligence who is now president of METI International.

    Vakoch and other researchers, including linguists, gathered here this weekend at the National Space Society’s International Space Development Conference to consider the content for future messages to E.T.

    In the process, they considered the meaning of language as well.

    “The ideal is, we get a reply back to the experiment,” Vakoch, who has his Ph.D. in clinical psychology, told GeekWire. “But I also think there’s a social value.”

    Vakoch has spent almost two decades thinking about how to design messages for the aliens, first as director of interstellar message composition at the SETI Institute, and since 2016 as METI’s president. (You can probably guess that METI stands for “messaging extraterrestrial intelligence.”)

    Some deep thinkers, including the late physicist Stephen Hawking, have said sending signals to an unknown alien civilization out there is just asking for trouble. “Meeting an advanced civilization could be like Native Americans encountering Columbus,” Hawking once said. “That didn’t turn out so well.”

    But Vakoch argues that it’s already too late, because for decades we’ve been sending out signals that could be detected by civilizations more advanced than ours.

    “I wish I could tell people that somehow we are going to be safer if we don’t transmit, but in good conscience, I can’t,” he said.

    So, he and his fellow METI advocates figure that we might as well be intentional about what we send, and let any alien civilizations know that we’re ready to engage.

    “It’s a way of testing the zoo hypothesis,” Vakoch explains. “What happens if a zebra at the zoo turns toward us and starts pounding out prime numbers? That radically changes the dynamic. Now we’ve got to figure out how to communicate back with it.”

    Full article here:


    To quote:

    This weekend, researchers delved into the nitty-gritty of linguistics to lay the groundwork for the next METI message, which Vakoch said is due to be sent by the end of 2019. Like past messages, this one will be based on scientific and mathematical concepts that the aliens are likely to understand.

    “Any mathematical systems are going to have to be functionally equivalent to each other, or they’re going to be so complicated that they won’t be useful,” Vakoch said.

    The Arecibo message tried to keep it simple, by sending the atomic numbers for the chemical constituents of DNA: hydrogen, carbon, nitrogen, oxygen and phosphorus. But what if alien life isn’t based on DNA?

    “This next round, we’ll be unpacking it,” Vakoch said. “We’ll unpack it and describe the periodic table.”

    The METI team will also be trying to incorporate principles that appear to be common to most if not all earthly languages — for example, the way words are put together to form sentences, or the recursive structure of complex expressions. The papers presented this weekend include a study that has famed linguist Noam Chomsky as author.

    “This opens us up to new rounds of messages,” Vakoch said.

    He doesn’t expect the message that’s readied for next year to be the perfect pitch to the aliens. And he’s not sure the world’s linguists would be as ready to respond to an alien message as the character played by Amy Adams was in the movie “Arrival.”

    “I am so jealous of Amy Adams, because the aliens come to her,” Vakoch said.

    But even if humans don’t hear back from faraway civilizations for 1,000 years, that’d be OK with Vakoch. The way he sees it, the important thing is that humans see the value of communicating with the cosmos, and continue to keep up the conversation.

    “To me, that would be a tremendous success,” Vakoch said. “Sometimes, we become what we’re looking for.”

  • ljk May 28, 2018, 18:49

    Want to get the public not only more interested in SETI and METI but also turn their enthusiasm into something productive for the fields? Here is one way…


    To quote:

    An experiment performed recently by Wells-Jensen shows why we may need the power of the human hive-mind. She presented college students with several puzzles that had been coded in the manner of Lincos, a constructed language designed to be understood by intelligent extraterrestrials. The students figured out the simple stuff, such as basic mathematical functions, quite well — but things got dicey when the concepts got more complicated.

    For example, Wells-Jensen gave the students the equation for the circumference of a circle, as well as a lightly coded representation of “pi” (the ratio of a circle’s circumference to its diameter).

    “And I said, ‘OK, what is this real word?’ And they came up with all kinds of crazy things,” she said. “Some made poetic jumps and said, ‘world’; some of them made an opposite poetic jump and said, ‘infinity.’ Some of them thought that I meant that the diameter of the circle ended at a wall, and said ‘prison.'”

    And that’s for a message drawn up by a fellow human. It will doubtless be much tougher to decode something devised by creatures from a distant solar system who share no cultural or evolutionary history with us, who may rely upon different senses to perceive their environment and to communicate, and who are probably far more advanced technologically than we are.

  • ljk May 31, 2018, 10:57

    I get that the Voyager Interstellar Record is an imperfect way to communicate with ETI. But do these folks, and especially the media, realize the record team only had a matter of weeks to plan and assemble their data? And in the pre-Internet age and under the watchful eye of a less-than-thrilled space agency?


    To quote:

    “What this project has shown me is that we can’t really control the impression we make,” said Orchard. “I think the fact of the satellite itself will do a lot of the talking. I would hope that the mere fact that we’ve endeavoured to send a record of humanity shows something about our humanity.”

  • ljk June 1, 2018, 13:06

    Pastor with ties to San Antonio searches for extraterrestrial intelligence

    By René A. Guzman

    Updated 6:00 pm, Thursday, May 31, 2018

    The Rev. John Fluth has long turned his thoughts to the heavens — in more ways than one.

    Fluth, the pastor of First United Methodist Church in Del Rio, has been a minister for almost 19 years. He also has devoted more than 20 years to the search for extraterrestrial intelligence, or SETI research, which since the 1960s has analyzed signals from across the cosmos for evidence of intelligent life elsewhere in the universe.

    Full article here:


    To quote:

    Fluth has yet to spot that signal. But for his “Vice” appearance, he did deliver his first sermon about his SETI work and his belief that God could have created intelligent life in other parts of the universe.

    “I was very surprised how positive the congregation was, and asking very good questions that I didn’t expect” he said. “Like for instance, if we found intelligent life on another planet, would that intelligent life have any concept of original sin.”

    The new “Vice” episode also features conversations with astronomer Frank Drake, considered the father of SETI research, and former NASA chief scientist Ellen Stofan. Drake created the so-called Drake Equation in 1961 to calculate the odds of contact with extraterrestrials.

    Fluth believes China’s current efforts to put a radio receiver on the dark side of the Moon will help pick up signals that otherwise would be tainted by all the noise coming off the Earth. He hopes China and SETI can coordinate efforts to begin crunching that information.

    In the meantime, Fluth hopes his talk about SETI gets more people talking about, and especially listening for, what’s out there.

    “There is a hard task to reconcile science and faith,” Fluth said. “But I feel a need to say we need to be able to talk about this. We need to be friends, we need to play well with each other when we’re talking about this.”

  • ljk June 1, 2018, 13:36


    How to Communicate with Aliens

    Some interesting ideas bounced around at a recent workshop.

    By Dirk Schulze-Makuch

    May 31, 2018

    At a recent “Language in the Cosmos” workshop organized by San Francisco-based METI (Messaging Extraterrestrial Intelligence) as part of this year’s International Space Development Conference, participants tackled a big subject: how to communicate with intelligent aliens, and whether “we” would be able to understand “their” language.

    Several speakers were optimistic that we might. Two presentations, one with Jeffrey Punske from Southern Illinois University as first author, and the other with Ian Roberts from the University of Cambridge as first author, put forth the argument that there is a universal grammar of languages on Earth, and that this grammar should extend to extraterrestrial languages, especially in their syntax.

    Gonzalo Munevar from Lawrence Technological University was more pessimistic. He speculated that aliens would have different brains (if they have brains at all!) and therefore might perceive and conceptualize their universe in ways that remain forever mysterious to us—or any other alien species.

    His skepticism seems in order, considering that we humans are still not close to fully understanding other intelligent species on our own planet, such as dolphins—even though we’re closely related to them. And no relationship whatsoever would be expected with an alien species.

    The idea of using mathematics as a common basic language was elaborated in a talk by Douglas Vakoch from METI. But this traditional approach is not foolproof either, as evidenced by research conducted by Rebecca Orchard and Sheri Wells-Jensen of Bowling Green State University on interpretations of the Voyager Golden Record. The recording, now bound for interstellar space on two spacecraft, included sounds and images meant to portray the diversity of cultures on Earth to an alien civilization. But even before it was launched, there were doubts as to whether an alien civilization would be able to interpret the message correctly. In their talk, Orchard and Wells-Jensen showed several ways in which it could be misunderstood. If it confuses humans, one can only wonder how aliens—having no common cultural background with us—would interpret it.

    Of course, the answer to our dilemma may depend on how first contact occurs. If it happens via long-distance communication, I would prefer Vakoch’s mathematical approach, at least initially. Eventually, though, we would have to go beyond that. How could we express emotions or feelings mathematically? Language has a higher potential for conveying feelings, but comes with its own problems. Misunderstandings are common even between English speakers from different cultural backgrounds.

    Perhaps neither math nor language would be suitable. So how would we do it? We are at a juncture where we have more questions than answers. In the 2016 film “Arrival,” the heroine, a linguist, is—after much struggle—able to communicate with visiting aliens. If that day were to come, we might have to come up with solutions, probably using language, very quickly. So this type of workshop is very much needed to evaluate where we stand science-wise. And we might need the answer sooner than we think.

    Wait, what’s that glowing light in my backyard?

  • ljk June 4, 2018, 12:49

    Aliens Might Never Appreciate How Cool Voyager’s Golden Record Is

    If they find it, they may just be confused.

    by Cara Giaimo

    June 01, 2018

    In the late summer of 1977, NASA launched a pair of interstellar probes, Voyager 1 and 2. Like most spacecrafts, these two were built to gather information about unknown realms. More unusually, they also had something to give in return: Each held a copy of what’s known as the Golden Record, a set of images and sounds carefully chosen to give anyone who might find them a taste of Earthly life.

    More than 40 years after its launch, the Golden Record hasn’t found any extraterrestrial listeners—that we know of. It does, however, enjoy serious hometown fandom. Here on Earth, it’s been the subject of poetry books, an as-yet unproduced screenplay, and at least one SXSW panel. Last year, after a successful Kickstarter campaign, it even got a vinyl re-release.

    In a way, the record has already found its intended audience. As consultant B.M. Oliver wrote in a history of the project, “its real function … is to appeal to and expand the human spirit.”

    But at least two diehard fans think there’s something to be gained from considering alternative audiences a bit more rigorously.

    “Every time you try to communicate, you have an intention you are after,” says Sheri Wells-Jensen, a linguistics professor at Bowling Green University, and a board member of Messaging Extraterrestrial Intelligence (METI), an organization dedicated to reaching out to aliens. “But you have no idea how you’re going to be received.”

    Full article here:


    So apparently there is a screenplay about the Golden Record that has been sitting on a shelf more or less since 2013:


    Aaron Kandell, Jordan Kandell
    The true story of how Carl Sagan fell in love while leading the wildest mission in NASA history: a golden record to encapsulate the experience of life on earth for advanced extraterrestrial life.
    Agency: Verve
    Agents: Tanya Cohen, Rob Hertling, Adam Levine
    Management: Hopscotch Pictures
    Manager: Sukee Chew
    Producer: Hopscotch Pictures

  • ljk June 4, 2018, 12:57

    Alien languages might not be that different from ours

    ETs may share a kind of ‘universal grammar’ with us, say leading linguists like Noam Chomsky.

    by Eric Mack

    May 26, 2018 at 10:00 AM PDT

    It could be a Star Trek or Star Wars universe after all. One where a diverse set of intelligent extraterrestrial species from across the galaxies all easily communicate despite some pretty dramatic biological differences.

    Some of the world’s leading linguists argue that human languages are connected by a shared “universal grammar.” And now some, including perhaps the most well-known linguist, say they’re optimistic that connection could extend to extraterrestrial languages too.

    “To put it whimsically, the Martian language might not be so different from human language after all,” explained Noam Chomsky and Jeffrey Watumull in a presentation at the International Space Development Conference (ISDC) in Los Angeles on Saturday.

    Chomsky is a noted author on both linguistics and global politics and is often referred to as the “father of modern linguistics” who pioneered the notion of a universal grammar.

    Full article here:


    To quote:

    “The whole universe is subject to the same laws of physics. For example, there are not that many ways a signal can be transmitted, particularly over large distances,” they explained to me in an email. “Also, we can expect that extraterrestrial languages … have a vocabulary consisting of building blocks of meaning that can be combined to create more complex meanings.”

  • ljk June 6, 2018, 9:42

    Language in the Cosmos II: Hello There GJ273b

    Article written: 5 June 2018

    by Paul Patton

    The ‘Language in the Cosmos’ symposium

    Three times in October, 2017 researchers turned a powerful radar telescope near Tromsø, Norway towards an invisibly faint star in the constellation Canis Minor (the small dog) and beamed a coded message into space in an attempt to signal an alien civilization. This new attempt to find other intelligent life in the universe was reported in a presentation at the ‘Language in the Cosmos’ symposium held on May 26 in Los Angeles, California.

    METI International sponsored the symposium. This organization was founded to promote messaging to extraterrestrial intelligence (METI) as a new approach to in the search for extraterrestrial intelligence (SETI). It also supports other aspects of SETI research and astrobiology. The symposium was held as part of the International Space Development Conference sponsored by the National Space Society. It brought together linguists and other scientists for a daylong program of 11 presentations. Dr. Sheri Wells-Jensen, who is a linguist from Bowling Green State University in Ohio, was the organizer.

    Full article here:


    The music

    Each transmission included a different selection of music, with the works of 38 different musicians included in all. You can hear recordings of all this music at the Sónar Calling GJ273b website.


  • ljk June 6, 2018, 9:47

    Language in the Cosmos I: Is Universal Grammar Really Universal?

    Article written: 4 June 2018
    Updated: 5 June 2018

    by Paul Patton

    This article is the first in a two part series. It will focus on one of the most fundamental issues addressed at the conference. This is the question of whether the deep underlying structure of language would likely be the same for extraterrestrials as for us. Linguists understand the deep structure of language using the theory of ‘universal grammar’. The eminent Linguist Noam Chomsky developed this theory in the middle of the twentieth century.

    Two interrelated presentations at the symposium addressed the issue of universal grammar. The first was by Dr. Jeffery Punske of Southern Illinois University and Dr. Bridget Samuels of the University of Southern California. The second was given by Dr. Jeffrey Watumull of Oceanit, whose coauthors were Dr. Ian Roberts of the University of Cambridge, and Dr. Noam Chomsky himself, of the Massachusetts Institute of Technology.

    Full article here:


    Universal grammar and messages for aliens

    What are the consequences of this new way of thinking about the structure of language for practical attempts to create interstellar messages? Watumull thinks the new thinking is a challenge to “the pessimistic relativism of those who think it overwhelmingly likely that terrestrial (i.e. human) intelligence and extraterrestrial intelligence would be (perhaps in principle) mutually unintelligible”. Punske and Samuels agree, and think that “math and physics likely represent the best bet for common concepts that could be used as a starting point”.

    Watumull supposes that while the minds of aliens or artificial intelligences may be qualitatively similar to ours, they may differ quantitatively in having bigger memories, or the ability to think much faster than us. He is confident that an alien language would likely include nouns, verbs, and clauses. That means they could probably understand an artificial message containing such things. Such a message, he thinks, might also profitably include the structure and syntax of natural human languages, because this would likely be shared by alien languages.

    Punske and Samuels seem more cautious. They note that “There are some linguists who don’t believe nouns and verbs are universal human language categories”. Still, they suspect that “alien languages would be built of discrete meaningful units that can combine into larger meaningful units”. Human speech consists of a linear sequence of words, but, Punske and Samuels note that “Some of the linearity imposed on human language may be due to the constraints of our vocal anatomy, and already starts to break down when we think about signed languages”.

    Overall, the findings foster new hope that devising a message comprehensible to extraterrestrials is feasible. In the next installment, we will look at a new example of such a message. It was transmitted in 2017 towards a star 12 light years from our sun.

  • ljk June 8, 2018, 9:58

    Showing Off to the Universe: Beacons for the Afterlife of Our Civilization

    January 25, 2018

    The Nature of the Problem

    Let’s say we had a way to distribute beacons around our solar system (or beyond) that could survive for billions of years, recording what our civilization has achieved. What should they be like?

    It’s easy to come up with what I consider to be sophomoric answers. But in reality I think this is a deep—and in some ways unsolvable—philosophical problem, that’s connected to fundamental issues about knowledge, communication and meaning.

    Still, a friend of mine recently started a serious effort to build little quartz disks, etc., and have them hitch rides on spacecraft, to be deposited around the solar system. At first I argued that it was all a bit futile, but eventually I agreed to be an advisor to the project, and at least try to figure out what to do to the extent we can.

    But, OK, so what’s the problem? Basically it’s about communicating meaning or knowledge outside of our current cultural and intellectual context. We just have to think about archaeology to know this is hard. What exactly was some arrangement of stones from a few thousand years ago for? Sometimes we can pretty much tell, because it’s close to something in our current culture. But a lot of the time it’s really hard to tell.

    Full article here:


    Science Fiction and Beyond

    For our beacons project, we want to create human artifacts that will be recognized even by aliens. The related question of how alien artifacts might be recognizable has been tackled many times in science fiction.

    Most often there’s something that just “doesn’t look natural”, either because it’s obviously defying gravity, or because it’s just too simple or perfect. For example, in the movie 2001, when the black cuboid monolith with its exact 1:4:9 side ratios shows up on Stone Age Earth or on the Moon, it’s obvious it’s “not natural”.

    On the flip side, people in the 1800s argued that the fact that, while complex, a human-made pocket watch was so much simpler than a biological organism meant that the latter could only be an “artifact of God”. But actually I think the issue is just that our technology isn’t advanced enough yet. We’re still largely relying on engineering traditions and structures where we readily foresee every aspect of how our system will behave.

    But I don’t think this will go on much longer. As I’ve spent many years studying, out in the computational universe of all possible programs it’s very common that the most efficient programs for a particular purpose don’t look at all simple in their behavior (and in fact this is a somewhat inevitable consequence of making better use of computational resources). And the result is that as soon as we can systematically mine such programs (as Darwinian evolution and neural network training already begin to), we’ll end up with artifacts that no longer look simple.

    Ironically—but not surprisingly, given the Principle of Computational Equivalence—this suggests that our future artifacts will often look much more like “natural systems”. And indeed our current artifacts may look as primitive in the future as many of those produced before modern manufacturing look to us today.

  • Babak Farhang June 8, 2018, 19:09

    “SETI researchers, in the past, have often speculated on self replicating robots that could travel to distant planets and recreate themselves by using local materials, but the complexity of such a device boggles the mind.”

    True, but having witnessed how we build complexity in software, the evolution of self replicating bots must be more analogous to the evolution of, say, the C-compliler. Only the first iterations of the yet completed compiler are written in assembly language; thereafter, the compiler is completed in the language it is to compile C.

    Continuing with this analogy, the compiler (a self replicating bot) can receive “code” beamed to it remotely. Code to build new things, code to build improved things. In other words, evolving.

    Finally, if you can build (eg print) things efficiently, there might be little reason not to clean up and not leave a physical mess around. In a sense you become more informational with few material traces.


  • ljk June 11, 2018, 10:23

    The Habitability Paradox –“Alien Astronomers Could Have Thought Earth Lifeless for Billions of Years” (Today’s Most Popular)

    June 10, 2018

    “The phrase Earth-like does not refer to a planet that necessarily resembles modern-day Earth at all,” said Stephanie Olson, an astrobiologist at the University of California, Riverside. “It’s actually a very broad term that encompasses a broad variety of worlds. It includes hazy worlds like the Archean; it includes icy worlds like the ‘snowball Earth’ intervals; it includes anoxic worlds with exclusively microbial ecosystems; it includes worlds with complex and intelligent life; and it includes worlds that we haven’t even seen yet.”

    For billions of years of Earth history, an alien astronomer may have even been sufficiently misled to conclude that Earth was sterile—despite the fact that life was flourishing in our ocean at the time,” says Olson.

    In a 2018 paper in Science Advances, Olson and her colleagues simulated how Earth’s atmosphere has changed over time. Even three billion years ago, aliens may have been able to infer life by sniffing out methane and carbon dioxide in the early atmosphere. But our modern atmosphere—a literal beacon for life—arrived only about 500 million years ago.

    Full article here:


    To quote:

    Early Earth would yield compelling clues for life, says Joshua Krissansen-Totton of the University of Washington. “The presence of life on Earth has been fairly obvious for the last 4 billion years to anyone who could build a big telescope,” he says in an email. “If there was anything nasty out there, then they would have extinguished life on Earth long ago. I think we are safe inviting them over to visit and exchange notes on the cosmos.”

    By studying the atmospheric contents of ancient and present-day Earth, scientists say they’ve discovered specific chemical combinations that could reveal the presence of biological activity on other planets. These biosignatures, described in the journal Science Advances, could offer a key tool in the search for extraterrestrial life.

    “There’s a direct path from the conclusions of our work to the possible discovery, which would be an historic one, of life elsewhere,” said senior author David Catling, a planetary scientist and astrobiologist at the University of Washington in Seattle.

  • ljk June 13, 2018, 12:14

    Does Climate Change Explain Why We Don’t See Any Aliens Out There? – Universe Today


  • ljk June 15, 2018, 9:49


    Taxonomy and Jargon in SETI as an Interdisciplinary Field of Study

    Jason T. Wright

    (Submitted on 19 Mar 2018)

    While SETI is often thought of as a part of radio astronomy with optical SETI, artifact SETI, METI, and other approaches to finding intelligent life considered to be allied fields, SETI is better understood as an interdisciplinary field with many subfields, approaches, and components.

    In particular, Robert Bradbury has argued for a broad view of SETI between two extremes: “orthodox SETI,” or radio communication SETI, and a “Dysonian Approach” that searches for the extreme effects of alien life on its environment.

    Here, I build on these ideas and attempt to organize the terminology and efforts of SETI within a single framework for SETI as an interdisciplinary and multipronged approach.

    Comments: 3pp, 1 figure, presented as a white paper to the SETI Decoding Alien Intelligence Workshop held at the SETI Institute in Mountain View, CA from 14-16 March 2018. Presented at the workshop by Sofia Sheikh. Workshop white papers available at this https URL

    Subjects: Popular Physics (physics.pop-ph)

    Cite as: arXiv:1803.06972 [physics.pop-ph]
    (or arXiv:1803.06972v1 [physics.pop-ph] for this version)

    Submission history

    From: Jason Wright [view email]

    [v1] Mon, 19 Mar 2018 15:02:16 GMT (309kb)


  • ljk July 3, 2018, 13:47

    Review: Light of the Stars

    What does the search for extraterrestrial intelligences have to do with dealing with human-made changes to the Earth’s climate? Jeff Foust reviews a book that attempts to argue how those civilizations—if they exist—can teach us about how to deal with life in the Anthropocene.

    Monday, July 2, 2018


    To quote:

    Ultimately, though, this “astrobiology of the Anthropocene” approach is unsatisfying. There are interesting arguments in the book about the likelihood of intelligent life elsewhere in the universe, and a compelling case that human activities are altering the climate with significant, and deleterious, effects in the years and decades to come. But the combination of the two seems forced and unnecessary. It’s hard to see how models of hypothetical alien civilizations will convince people to take action to protect our own planet. Why not model our own world, which we know infinitely better?

    There is also, at times, almost an arrogance in Frank’s arguments about alien life. “It’s up to the naysayers to demonstrate how, with so many worlds and so many possibilities over the whole of cosmic space and time, we somehow are the first and the only,” he writes. But that’s not how science works: it’s not up to the “naysayers” to prove a negative—there is no other intelligent life in the universe—but rather for scientists like Frank to find evidence of such life. And, so far, that search has turned up empty: we’re the only life, intelligent or otherwise, known to exist. Perhaps, in the decades to come, we’ll find evidence of past or present primitive life on Mars, Europa, or Enceladus, or biosignatures on a distant exoplanet. Or, possibly, a SETI search will finally find a signal of extraterrestrial origin. However, it’s up to scientists to find that evidence to prove the existence of life beyond Earth, not “naysayers” to prove it doesn’t.

  • ljk July 9, 2018, 10:52

    Dysonian SETI With Machine Learning (Kaggle Kernel)

    By Jose Solorzano | July 8, 2018 08:54 AM


    To quote:

    There was a paper a few months back (Zackrisson et al. 2018) that proposed a methodology for the detection of stars that host artificial megastructures big enough to produce noticeable dimming (e.g. Dyson Swarms).

    Zackrisson et al. (2018) singled out one star: TYC 6111-1374-1. This is unrelated to the kernel, but there is an interesting observation I can make about TYC 6111-1374-1. If you look at a periodogram of its DASCH light curve, the second best periodicity peak is ~4.31 years, which is nearly a exact match of a well-known claim (Sacco et al. 2017) about a key periodicity of KIC 8462852, the only other star within the purview of Dysonian SETI at the time. The peak is not the main peak and it fails to reach significance, which is why I don’t have a technical write-up about it. I did, of course, communicate this curious find to Gary Sacco privately.

  • ljk July 16, 2018, 10:15

    Why Kids May Be the Key to Communicating With Alien Life

    In a hypothetical first contact situation, toddlers may be our best hope.

    By Kate Morgan

    July 12, 2018 • 4:02 PM


  • ljk July 24, 2018, 12:36

    Advancing the SETI Quest

    By: David Grinspoon | July 16, 2018

    Hope, perseverance, and the courage of their convictions sustain those seeking hints of alien civilizations.

    In March I attended a SETI Institute workshop, where a multidisciplinary group of astronomers, neuroscientists, anthropologists, philosophers, and historians pondered new approaches to expanding the search for extraterrestrial intelligence. Discussions ranged from the physics of planet formation, through the origin and evolution of life and the prospects for complex life and intelligence, to coming hunts for both biosignatures and “technosignatures” on exoplanets.

    To me, the way these topics flowed together at the meeting served as a reminder that the distinction between astrobiology and SETI is completely artificial. It might exist in terms of bureaucracies and funding streams, but intellectually the quest to know how we — and living things in general — fit into the universe is all part of the same nested series of questions:

    How does matter turn into living cells? Is this unlikely or inevitable? What is required of a planet to support this and the subsequent transitions to differentiated cells, multicellular life, cognition, curiosity, and technology? What planetary transitions accompanied, enabled, or were caused by these biological leaps? Should these have occurred on other types of planets that we know or suspect exist, and how would we recognize them?

    Full article here:


    SETI Quest. Hey, that would be a great name for a SETI magazine…


  • ljk November 2, 2018, 9:18

    Astronomer Jill Tarter discusses the search for intelligent life

    November 2, 2018

    by Colleen Walsh, Harvard University

    The question of whether we’re alone in the universe has haunted humankind for thousands of years, and it’s one astronomer Jill Tarter has tried to answer for much of her life. Tarter, chair emeritus of the Center for SETI Research, worked as a project scientist for NASA’s SETI program, which aimed to detect transmissions from alien intelligence. She currently serves on the board for the Allen Telescope Array, a group of more than 350 telescopes north of San Francisco.

    “We are looking for signals at some frequency, some wavelength that don’t look like what Mother Nature produces,” she said in 2014.

    Tarter, an inspiration behind the novel and film “Contact,” visited campus last week for the Radcliffe Institute for Advanced Study’s science symposium “The Undiscovered,” which addressed how scientists “explore realities they cannot anticipate.” We spoke with her about her work and why it matters.


    To quote:

    GAZETTE: You spoken a lot about the importance of perspective. What would finding other intelligent life do to our perspective on life in the universe and our own lives?

    TARTER: Even not finding it but trying to find it is important because it helps to give people a more cosmic perspective. I usually send people home from a lecture with a homework assignment, which is to go and alter their profiles on all of their social media so that the first thing they say about themselves is that they are an Earthling, because I think that this is the kind of perspective we are going to need to figure out how to solve all these really difficult challenges we have that don’t respect national boundaries. We’ve got to do it in a systemic global way, and I think the first step to getting there is to see ourselves in that context.

    GAZETTE: You famously disagreed with Stephen Hawking when he said that he feared the potentially aggressive nature of any intelligent life we might one day encounter.

    TARTER: Stephen was a brilliant man, but neither of us has any data on this point other than our own terrestrial history. My point of view is the kind of scenario that’s being posited is that they are going to show up and do us harm. Well, if they can get here, their technology is far more advanced than ours, and I don’t know how you get to be an advanced older technology and have a long history unless you outgrow the aggression that probably helped you to get smart in the first place. So, I think an old technology, if such a thing exists, is going to be stable and it’s going to have gone through the kind of cultural evolution, the kind of social evolution that [Harvard Professor] Steven Pinker talks about. So, from my point of view, if they are coming from an older technology and can get here, they don’t have bad intentions. It doesn’t mean that the interaction will be rosy, because there are often unintended consequences.

    GAZETTE: Final question: Contact excluded, favorite alien or space movie?

    TARTER: Oh, I like 2001: A Space Odyssey.