Citizen SETI

by Paul Gilster on December 21, 2016

I love watching people who have a passion for science constructing projects in ways that benefit the community. I once dabbled in radio astronomy through the Society of Amateur Radio Astronomers, and I could also point to the SETI League, with 1500 members on all seven continents engaged in one way or another with local SETI projects. And these days most everyone has heard the story of Planet Hunters, the citizen science project that identified the unusual Boyajian’s Star (KIC 8462852). When I heard from Roger Guay and Scott Guerin, who have been making their own theoretical contributions to SETI, I knew I wanted to tell their story here. The post that follows lays out an alien civilization detection simulation and a tool for visualizing how technological cultures might interact, with an entertaining coda about an unusual construct called a ‘Dyson shutter.’ I’m going to let Roger and Scott introduce themselves as they explain how their ideas developed.

by Roger Guay and Scott Guerin

Citizen Science plays an increasingly important role across several scientific disciplines and especially in the fields of astronomy and SETI. Tabby’s star, discovered by members of the Planet Hunters project and the SETI@home project are recent examples of massively parallel citizen-science efforts. Those large-scale projects are counterbalanced by individuals whose near obsession with a subject compels them to study, write, code, draw, design, talk about, or build artifacts that help them understand the ideas that excite them.

Roger Guay and Scott Guerin, working in isolation, recently discovered parallel evolution in their thinking about SETI and the challenges of interstellar detection and communication. Guay has undertaken the programming of a 10,000 x 8,000 light year swath of a typical galaxy and populates it with random radiating communicating civilizations. His model allows users to tweak basic parameters to see how frequently potential detections occur. Guerin is more interested in a galaxy-wide model and has used worksheets and animations to bring his thoughts to light. His ultimate goal is to develop a parametric civilization model so that interactions, if any, can be studied. However, at the core, both efforts were attempts at visualizing the Fermi Paradox across space-time, and both experimenters show how fading electromagnetic halos may be all that’s left for us to discover of an extraterrestrial civilization, if we listen hard enough.

The backgrounds, mindsets, and tool kits available to Roger and Scott play an important role in their path to this blog.

Roger Guay

I am a retired Physicist and Technical Fellow Emeritus from Boeing in Seattle. I can’t remember when I first became interested in being a scientist (it was in grade school) but I do remember when I first became obsessed with the Fermi paradox. It was during a discussion while on a road trip with a colleague. At first, this discussion mainly revolved around the almost unfathomable vastness of space and time in our galaxy, but then turned to parameters of the Drake equation. The one that was the most controversial was L, the lifetime of an Intelligent Civilization or IC.

The casual newcomer to the Drake equation will tend to assume a relatively long lifetime for an IC, but when considering detection methods such as SETI uses, one must adjust L to reflect the lifetime of the technology of the detection method. For example, SETI is listening for electromagnetic transmissions in the microwave to radio and TV range. So, L has to be the estimated lifetime of that technology. For SETI’s technology, we’ll call this the Radio Age. On Earth, the Radio Age started about 100 years ago and has already fallen off due to technological advances such as the internet and satellite communication. So I argued, an L = 150 ± 50 years might be a more reasonable assumption for the Drake equation when considering the detection method of listening for radio signals.

At this point the discussion was quite intense! When I thought about an L equal to a few hundred years in a galaxy that continues to evolve over a 13-billion-year lifespan, the image that came to my mind was that of fireflies in the night. And that was the precursor for my Alien Civilization Detection or ACD simulation.

One can imagine electromagnetic or “radio” bubbles appearing randomly in time and space and growing in size over time. At any instant in time the bubble from an IC will have a radius equal to the speed of light times the amount of time since that IC first began broadcasting. These bubbles will continue to grow at the speed of light. When the IC stops broadcasting for whatever reason, the bubble will become hollow and the shell thickness will reflect the time duration of that IC’s Radio Age lifetime.

If the age of our galaxy is compressed into one year, we on Earth have been “leaking” radio and television signals into space for only a small fraction of a second. And, considering the enormity of space and the fact that our “leakage” radiation has only made it to a few hundred stars out of the two to four hundred billion in our galaxy, one inevitably realizes there must be a significant synchronization problem that arises when ICs attempt to detect one another. So what does this synchronicity problem look like visually?

To answer this question my tasks became clear: dynamically generate and animate radio bubbles randomly in space and time, grow them at the speed of light at very fast accelerated rate in a highly compressed region of the galaxy, fade them over time for inverse square law decay, and then analyze the scene for detection. No Problem!!!

Using LiveCode, a modern derivative of HyperCard on steroids, I began my 5-year project to scientifically simulate this problem. Using the Monte Carlo Method whereby randomly generated rings denoting EM radiation from ICs pop into existence in a 8,000 X 10,000 LY region of the galaxy* centered on our solar system at a rate of about 100 years per second, the firefly analogy came to life. And the key to determining detection potential is to recognize that it can only occur when a radiation bubble is passing over another IC that is actively listening. This is the synchronicity problem that is dramatically apparent when the simulation is run!

To be scientifically accurate and meaningful, some basic assumptions were required:

  • 1. ICs will appear not only randomly in space, but also randomly in time.
  • 2. ICs will inevitably transition into (and probably out of) a Radio/TV age where they too will “leak” electromagnetic radiation into space.
  • 3. The radio bubbles are assumed to be spherically homogeneous**.

To use the ACD simulation, the user chooses and adjusts parameters such as Max Range, Transmit and Listen times*** and N, the Drake equation estimate of the number of ICs in the galaxy at any given instant. During a simulation run, potential detections are tallied and the overall probability of detection is displayed.

About two years ago, as the project continued to evolve, I became aware of Stephan Webb’s encyclopedic book on the Fermi Paradox, If the Universe is Teeming with Aliens … Where is Everybody? This book was most influential in my thinking and the way I shaped the existing version of the ACD simulation.


A snapshot of the main screen of the ACD simulation midway through a 10,000 year run.

A Webb review of the ACD simulation is available here:

And you can download it here at this Dropbox link:

Conclusions? The ACD simulation dramatically demonstrates that there is indeed a synchronicity problem that automatically arises when ICs attempt to detect one another. And for reasonable (based on Earth’s specifications) Drake equation parameter selections, detection potentials are shown to be typically hundreds of years apart. In other words, we can expect to search for a few hundred years before finding another IC in our section of the galaxy. When you consider Occam’s razor, is not this synchronicity problem the most logical resolution to the Fermi Paradox?


* The thickness of the Milky Way is small compared to its diameter. So for regions close to the center of the thickness, we can approximate with a 2-dimensional model.

** Careful consideration has to be given to this last assumption: Of course, it is not accurate in that the radiation from a typical IC is assumed to be composed of many different sources and have widely varying parameters, as they are on Earth. But the bottom line is that the homogenous distribution gives the best case scenario of detection potential. An example of when to apply this thinking is to consider laser transmission vs radio broadcast. Since a laser would presumably by highly directed and therefore more intense at greater distances, the user of the ACD simulation might choose a Higher Max Range but at the same time realize that pointing problems will make detection potential much smaller than the ACD indicates. The ACD does not take this directly into consideration. Room for the ACD to grow?

*** One of the features of this simulation is that the user can make independent selections of both the transmit and listening times of ICs, whereas the Drake equation lumps them together in the lifetime parameter.

Scott Guerin

I grew up north of Milwaukee, Wisconsin and was the kid in 5th grade who would draw a nuclear reactor on the classroom’s chalkboard. My youthful designs were influenced by Voyage to the Bottom of the Sea, Lost in Space, everything NASA, and 2001: a Space Odyssey. In the mid 70s, I was a technical illustrator at the molecular biology laboratory at UW Madison and, after graduation with a fine arts degree, I went on to a 30-year career as an interpretive designer of permanent exhibits in science and history museums.

I began visually exploring SETI over two years ago in order to answer three questions: First, why is such a thought-provoking subject so often presented only in math and graphs thereby limiting information to experts? Secondly, why is the Fermi Paradox a paradox? Thirdly, what form might an interstellar “we are here” signaling technology take?

Using Sketchup, I built a simple galactic model to see what scenarios matched the current state of affairs: silence and absence. At a scale of 1 meter = 1 light year, I positioned Sol appropriately, and randomly “dropped” representations of civilizations (I refer to them as CivObjects) into the model. Imagine dropping a cup full of old washers, nails, wires, and screws onto a flat, 10” plate and seeing if any happen to overlap with a grain-of-salt-sized solar system (and that speck is still ~105 too large).

The short answer is that they didn’t overlap and I’ve concluded that the synchronicity issue, combined with weak listening and looking protocols is a strong answer to the paradox. When synchronicity is considered along with sheer rarity of emitting civilizations (my personal stance), the silence makes even more sense.


For scale, the green area at lower right represents the Kepler star field if it were a ~6,000 LY diameter sphere. The solid discs represent currently emitting civilizations, the halos represent civilizations that have stopped emissions over time, and the lines and wedges represent directed communications. I sent this diagram to Paul and Marc at Centauri Dreams who were kind enough to pass it on to several leading scientists and they graciously, and quickly, replied with encouragement.

Curtis Charles Mead’s 2013 Harvard dissertation “A Configurable Terasample-per-second Imaging System for Optical SETI,” George Greenstein’s Understanding the Universe, Tarter’s, and the Benford’s papers, among others, were influential in my next steps. I realized the halos were unrealistic representations of a civilization’s electromagnetic emissions and that if you could see them from afar, they could be visualized as prickly, 3-dimensional sea urchin-like artifacts with tight beams of powerful radar, microwave, and laser emanating from a mushy sphere of less directional, weaker electromagnetic radiation.


From afar, Earth’s EM halo is a lumpy, flattened sphere some 120LY in radius dating to the first radio experiments in the late 1890’s. The 1974 Arecibo message toward M13 is shown being emitted at the 10 o’clock position.

From Tarter’s 2001 paper “At current levels of sensitivity, targeted microwave searches could detect the equivalent power of strong TV transmitters at a distance of 1 light year (the red sphere at center in the diagram), or the equivalent power of strong military radars to 300 ly, and the strongest signal generated on Earth (Arecibo planetary radar) to 3000 ly, whereas sky surveys are typically two orders of magnitude less sensitive. The sensitivity of current optical searches could detect megajoule pulses focused with a 10-m telescope out to a distance of 200 ly.”


In this speculative diagram, two civilizations “converse” across 70 LY. Mead’s paper confirms the aiming accuracy needed to correct for the the proper motion of the stars, given a laser beam just a handful of AU wide at the distance illustrated, is within human grasp. The civilizations shown would most likely have been emitting EM for hundreds of years so that their raw EM halos are so large and diffuse they cannot be shown in the diagram. The magenta blob represents the elemental EM “hum” of a civilization within a couple LY, the green spikes represent tightly beamed microwaves for typical communications and radar , while the yellow spikes are lasers reaching out to probes, being used as light-sail boosters, and fostering long distance high-bandwidth communications. Each civilization has an EM fingerprint, affected by their system’s ecliptic angle and rotation, persistence of ability, and types of technologies deployed — these equate to a unique CivObject.

In advance of achieving the goal of a fully parametric 3D model, I manually animated several kinds of civilizations and their interactions by imagining a CivObject as a variant of a Minkowski space-time cone. I move the cone’s Z axis (time) through a galactic hypersurface to illustrate a civilization’s history of passive and intentional transmission, as well as probes at sub-lightspeed. A CivObject’s anatomy reveals the course of a civilization’s history and I like to think of them as distant cousins of Hari Seldon’s prime radiant. password: setiwow!

The anatomy of a CivObject allows arbitrary time scales to be visualized as function of xy directionality, EM strength, and type of emission. Below is Earth’s as a reference. Increasing transmission power is suggested by color.


I found it easy to animate transmissions but continue to struggle with visualizing periods of listening and the strength of receivers. Like Guay, I concluded that a potential detection can occur only when a transmission passes through a listening civilization. A “Conversing” model designed to actually simulate communication interactions needs to address both ends of “the line” with a full matrix of transmitter/receiver power ratios as well as sending/listening durations, directions, sensitivities, and intensities. In addition, a more realistic galactic model including 3d star locations, the GHZ, and interstellar extinction/absorption rates is needed.

And now for some sci-fi

A few months before KIC 8462852 was announced and Dyson Swarms became all the rage, I noticed one of those old ventilators on top of a barn roof and thought that if a Kardashev II civilization scaled it up to +-1AU diameter, it would become a solar powered, omni-directional signalling device capable of sending an “Intelligence was here” message across interstellar space. I called it a Dyson Shutter.

Imagine a star surrounded by a number of ribbon-like light sails connected at their poles. Each vane’s stability, movement, and position is controlled by the angle of sail relative to incoming photons from the central star. The shutter would be a high tech, ultra-low bandwidth, scalable construct. I have imagined that each sail, at the equator, would be no less than one Earth diameter wide which is at the lower end of Kepler-grade detection.

Depending on the number constructed, the vanes could be programmed to shift into simple configurations such as fibonacci and prime number sequences.



I imagine the Dyson Shutter remains in a stable message period for hundreds of rotations. Perhaps there are “services” for the occasional visitor, perhaps it has defenses against comets, incoming asteroids, or inter-galactic graffiti artists. Perhaps it is an intelligent being itself but is it a lure, a trap, a collector, or colleague? Is it possible Tabby’s star is a Dyson Shutter undergoing a multi-year message reconfiguration?


The shutter’s poles are imagined to be filled with command and control systems, manufacturing facilities, spaceports, etc.


We hope that our work as presented here might inspire some of you to join the ranks of the Citizen Scientist. There are many opportunities and science needs the help. With today’s access to information and digital tools, anyone with a little passion for their ideas and a lot of imagination and persistence can help communicate complex issues to the public and make contributions to science. We hope that our stories resonate with at least some of you. Please let us know what you think and let’s all push back on the frontiers of ignorance!


{ 57 comments… read them below or add one }

ljk December 21, 2016 at 13:53

Avalanche statistics suggest Tabby’s star is near a continuous phase transition

December 20, 2016

by Siv Schwink

In its search for extrasolar planets, the Kepler space telescope looks for stars whose light flux periodically dims, signaling the passing of an orbiting planet in front of the star. But the timing and duration of diminished light flux episodes Kepler detected coming from KIC 846852, known as Tabby’s star, are a mystery. These dimming events vary in magnitude and don’t occur at regular intervals, making an orbiting planet an unlikely explanation. The source of these unusual dimming events is the subject of intense speculation.

Suggestions from astronomers, astrophysicists, and amateur stargazers have ranged from asteroid belts to alien activity.

Now a team of scientists at the University of Illinois at Urbana-Champaign—physics graduate student Mohammed Sheikh, working with Professors Karin Dahmen and Richard Weaver—proffer an entirely novel solution to the Tabby’s star puzzle. They suggest the luminosity variations may be intrinsic to the star itself. Tabby’s star is in most regards a standard F-class star, located in the constellation Cygnus, approximately 1,276 light years from Earth. Its unusual light curve—the graph of its light intensity as a function of time—shows intense dimming events of up to 20 percent, punctuated with smaller irregular dimming events.

Full article here:


Ron S December 21, 2016 at 15:16

“When you consider Occam’s razor, is not this synchronicity problem the most logical resolution to the Fermi Paradox?”

I would say: unlikely. The premise here is that EM is purely for communications and that detection is purely incidental. The true scope could extend far beyond this, and I believe almost certainly would.

First, there is METI. That is, EM transmissions with the objective of being detected. If an IC has this objective these transmissions could continue for far longer than the use of EM for communications. Transmissions could also be highly directive based on high quality candidate targets. More than this, since these IC have already passed through the EM stage they will have a deeper understanding of how to direct their METI attempts since they will have a great understand of how to reach civilizations at our stage of technology and cultural development. They know better than to use modulated neutrino streams to talk to us!

Second, EM is used for more than communications. There are remote sensing technologies such as radar and LiDAR and even ionosondes that could continue long after EM is no longer common for communications.

Third, there are the social aspects. Consider that if such a detection, whether incidental or directed, is possible then it has most likely already occurred, perhaps multiple times. That is, between two alien civilizations. When this occurs the game changes. Based on what transpires as a result, they will likely go one of two ways. One is to cease all EM transmissions to avoid future contacts. The other is to cooperate and even to use their joint knowledge and resources to enhance detection by civilizations like ours.

Simple models are interesting and useful but not even close to what may be truly going on out there.


Dana Andrews December 21, 2016 at 15:36

Great article, most thought provoking. I think this could finally answer much of the Fermi Paradox. Civilizations are too far apart and rise and fall too quickly.


james stilwell December 21, 2016 at 16:04

This material should go to Scientific American…starting on the cover…
A really great post…this one will inspire many for years to come…


Roger Guay December 22, 2016 at 22:15

Thank you, James. Would you be willing to nominate us for Nobel?


Janw Pool December 21, 2016 at 16:56

Thanks for this post. Great read.
Nevertheless… I think the silence is more of a “don’t interfere” kind, if you look at the topic of communication. This does not exclude the ideas of both writers, though.


DCM December 21, 2016 at 18:02

Listen much, reveal little.


Roger Guay December 22, 2016 at 22:26

Many, including Stephen Hawking, agree with you.


Joe December 21, 2016 at 19:42

So Roger, if “detection potentials are shown to be typically hundreds of years apart” in your model, how far apart would detection potentials be if one or more ICs used METI instead of just SETI?


Roger Guay December 22, 2016 at 22:44

Excellent question! But consider this. No matter what technology you consider, and given our current understanding of Physics, we are ultimately dealing with EM radiation. We are therefore limited by the speed of light and the vastness of both space and time. METI does not solve the “synchronicity” problem. It only increase the distance over which detection could occur. OTH, pointing and signal duration would work against you.


Scott Guerin December 26, 2016 at 12:13

The “Benford Boys” have written extensively on the technical and economic implications sending and receiving technologies and strategies. Do a search for “Building and Searching for Cost-Optimized Interstellar Beacons” and you’ll discover another puzzling piece of the Fermi Paradox. That is, a significant beacon or receiving station is well within human capabilities and we could detect signals across vast distances in either radio or optical wavelengths: why haven’t we? I think the simplest answer is two-fold: we haven’t listed very much: the synchronicity argument; and beacons are rare: the uniqueness argument, or (and I think _much_ less likely) the “Dark Forest” argument.


hiro December 21, 2016 at 20:47

The thought that using radio communication because it’s cheap only works in our case, any advanced civilization that has existed for more than +1 M years still has that pathetic boom-bust economic cycles really having some serious issues. It’s best to drop the L term and focus on something else. A biased personal estimate that human species will either evolve to unknown forms or begin to extinct within 300 years, that “technological singularity conjecture” might seem unreal but it could be attained partially.


ljk December 21, 2016 at 22:03

This article needs a more dynamic and eye catching title. Dyson Spheres as Interstellar Beacons c’mon!


Wojciech J December 22, 2016 at 6:41

Could you do a similar simulation, but using transmission of detectable biomarkers from our biosphere(in atmosphere) instead of radio signals ?
Using parameters such as detectability in certain radius, age of life on Earth as starting point, known limits of detectability over certain range for theoretical hyper-telescopes, gravity lensing etc ?
This could allow us to deduct the range in which other civilizations would be able to detect life on Earth and the time in which it could happen.

Would it be possible to create such simulation?


Scott Guerin December 26, 2016 at 11:50

The James Webb Telescope (launch date October 2018) is designed with the ability to analyze the spectrum of exoplanet atmospheres and will be able to detect biomarkers. Scientists are already simulating the results. For example, see .

Also see for a fascinating article on detecting exoplanet industrial pollution.


Mick December 22, 2016 at 8:54

It is said that a spacefaring civilisation could spread throughout the galaxy in under 100k years. This being so, the above article does not even address the question “where are they” let alone answer it. I suspect evolutionary probability and/or the Great Filter are involved in Fermi’s Paradox.


ljk December 22, 2016 at 10:22

Spread in what manner and where? The entire Milky Way galaxy? We are talking 400 billion star systems across 100,000 light years. They would have to be going at light speed and dropping off at least one colony each Earth year just to even do a token “spreading” in the time period you state.

Assuming there are more than a few ETI societies which even have the interstellar capability, do they all want to colonize space? Are all solar systems viable for living in – and I am not even taking into account the potential variety of species or what they might consider a habitable world. Would each new colony be churning out new interstellar colonies at a steady pace even if they could and wanted to?

I have more than a few issues with the idea that since ETI haven’t come knocking on our door yet or even given us a call they therefore must not exist. If you add in the distances involved between stars and the logistics of mounting even an interstellar science expedition (just read the latest post in this blog about Breakthrough Starshot to see how engineers and scientists are running into all kinds of issues with the plan, and this is “just” a one-way interstellar probe mission), plus the fact that they might have other things to worry about than contacting some fancy primates with car keys on some obscure planet, and you will find these among many other reasons why an ETI might not be showing up yet still somehow exist.

Were you perhaps referring to this paper when you came up with your estimate:

As reality shows all the time, just because something can be shown mathematically does not mean that it will actually happen. If ETI are not colonizers then no amount of math is going to change that.

This is why I want to see SETI ramped up, because I really want to know if humanity and its attitudes and behaviors are commonplace or a fluke. This would include the desire/need to colonize new places.


ljk December 22, 2016 at 10:38

I forgot to add: There may be a relatively simple reason why ETI have not colonized the Sol system – they simply do not want to deal with the hassle of trying to live and work in a system that is already occupied, even if the natives would be relatively easy to remove from the equation.

I am not even talking about some kind of Star Trekkian Prime Directive here: If nearly every star has planets as the Kepler data would appear to indicate, then the odds are there must be plenty of places that have no native life forms or at least nothing that would interfere with a colonization effort.

These colonizing ETI could even use the free-floating chunks of vital resources that permeate our star system – the comets and planetoids – as a sort of pit stop. They could do this without bothering us or even getting our attention. I know there have been a few calls in the past f0r SETI to monitor the planetoid and comet belts, but how many are actually doing that now? And if they did detect something suspicious, would a professional astronomer bring it up as an idea to their colleagues? Well, there is Tabby’s Star, but that world is safely 1,500 light years away. A possible mining ETI in our own celestial backyard is another matter.

So let’s just say at this point in human history that ETI could do everything short of setting off fireworks and holding up giant signs saying WE ARE HERE! and our species would be unaware of their existence, or readily dismiss the few who might think otherwise. Again, Tabby’s Star may be the game changer here, but note how science is doing its best to have it be anything but aliens.


Harry R Ray December 22, 2016 at 11:03

Scott Guerin: Your “Dyson Shutter undergoing a multi-year message reconfiguration seems to me to be a little too much “Aliens of the gaps” mode for me to take TOO SERIOUSLY at this time. Right now there are ONLY TWO(one NATURAL and one non-natural)that fit the D792(or “Q8″)light curve PRECICELY! The natural fit can be found in “Mysterious Eclipses in the Light Curve of KIC8462852: A Possible Explanaton.” by Neslusan l., and Budaj J. The non-natural fit is Eduard Heindl’s “starlifting” theory. I find Heindl’s theory a bit too Aliens of the gapsy and the Neslusian and Budaj paper WAY too Dust Shells around massive(in the mass RANGE of Ceres to the Moon)objects of the gapsy. Your idea would be the THIRD one, but, not to be TOO “gapsy” a message must be found in EXISTING data! A particularly fascinating ASPECT of the “Q8″ is the ingress to egress RATIO! ALL of the major dips exhibit shallow ingresses and steep egresses, but the ratio if ingress to egress is so close to 2 to 1 that EXACTLY 2 to 1 is well within the margin of error! If the ratios of the other major dips also reveal INTEGERS within the margin of error, this COULD BE some sort of message being delivered in an ONGOING FASHION!


Scott Guerin December 26, 2016 at 12:33

Harry: I love the turn of phase “aliens of the gaps”: yes, ETs are like interstellar spray foam! The shutter is a thought experiment, sci-fi as my title suggested. However, I’d be very interested if an orbital/sail expert would comment on its stability and movement as I imagine there is a tension between the orbital mechanics of the structure and the photon pressure that sets the vanes in non-orbital motion. I also wondered if it would be torn apart by comets and asteroids?


Harry R Ray December 27, 2016 at 14:09

I heard about the “Aliens of the gaps” concept from a comment on this website from ljk AND from a blog on the Science 2.0 website by Jose Solorzano, a lightcurve SPECIALIST who has posted NUMEROUS COMMENTS on r/reddit:KIC8462852. You should try to contact him with your “shutter concept graphics and ask him to run them through his computer program. I also hope that BOTH OF YOU would COLLABORATE on an attempt to decipher ANY POSSIBLE PESSAGES based on integers in the ENTIRITY of the Kepler lightcurve!


Harry R Ray December 29, 2016 at 12:09

6 hours ago on by trailrunnerlife:”Star lifting induces magnetic instability(which may be enhanced by harmonics/resonances, etc.)and may be compatible with the apparent power law curves discussed in another recent publication. Power law properties are found in sociology, economics, financial markets, etc., not just strictly in natural systems, and often as a result of resource optimization efforts. I find that a specific mechanism(such as star lifting)which explains many or all of the facets of the perplexing data from KIC8462852 appealing, but it remains to be seen whether a natural process could result in such plumes and mass loss. If no astrophysical mechanism can be identified, this theory could become distinct from an ‘aliens of the gaps’ proposal.


James Stilwell December 22, 2016 at 11:16

Many here seem to think that curiosity is a dead issue…maybe so…


ljk December 22, 2016 at 13:59

Children are all about curiosity and being amateur scientists. Then most of them grow up and become practical and logical. Or superstitious zealots. The most they become curious about are what celebrity is doing what to whom and how well their 401Ks are doing.

This is one of many reasons why we have yet to find alien life.


ljk December 22, 2016 at 14:27

Just read this at lunch today, interestingly enough:

“There is an incessant influx of novelty into the world, and yet we tolerate incredible dullness. I need only suggest what kind of sermons are still listened to in the most enlightened countries. There are such words as joy and sorrow, but they are only the burden of a psalm, sung with a nasal twang, while we believe in the ordinary and mean. We think that we can change our clothes only. It is said that the British Empire is very large and respectable, and that the United States are a first-rate power. We do not believe that a tide rises and falls behind every man which can float the British Empire like a chip, if he should ever harbor it in his mind. Who knows what sort of seventeen-year locust will next come out of the ground? The government of the world I live in was not framed, like that of Britain, in after-dinner conversations over the wine.”

By Henry David Thoreau, from Walden, Chapter 18, “Conclusion”:


Mick December 22, 2016 at 11:17

So make it 10 million or 100 million years. Point is there has been ample time. Several billion years. I believe Fermi was asking why they are not here, rather than why they are not making very occasional little lights in the sky. No I’m not quoting the paper you mention.


ljk December 22, 2016 at 13:57

So you didn’t mean 100,000 exactly. It was more like one saying “I’ve told you a million times not to exaggerate!” Sigh….

In any event, say aliens explored Earth 100 million years ago, because who can say when and where such beings might show up on our planet, assuming they landed here. Would anything be left of their expedition to our time? And if an archaeologist did find something of theirs, would it be believed?

Isn’t it amazing that in the 4.6 billion year history of Earth, that – if UFO reports have any validity at all – aliens are just showing up NOW? The vastness of space and time that is our Universe makes the chances that we and ETI should encounter each other now, when we at least have some awareness of such beings, seeming rather slight. That does not negate the possibility of their existence, if not now then sometime in the past or some day in the future.


ljk December 22, 2016 at 14:03

I direct you to this article:

And this article linked to in the above article in particular:


Bill St. Arnaud December 22, 2016 at 14:45

I undertook a similar analysis several years ago (mine was the back of a napkin) and came to the same conclusion that you did. As a result I started speculated on an alternative approach to SETI and challenged some of the basic assumptions underlying SETI – especially the concept of comunications.

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.


James Stilwell December 22, 2016 at 18:37

Newton was curious to know why the apple fell from the tree…
It was not idle curiosity…but to pursue his thirst for knowledge…
But the empire of knowledge began in curiosity…


ljk December 22, 2016 at 18:51

Apollo 12 left the first art exhibit on the Moon:

Apollo 15 carried art as well and a Bible to the Moon and left them on the lunar surface:

Some scientists actually advocate the sending of physical messages over electromagnetic ways. The background along with the pros and cons of such a method of interstellar communications here:


Mick December 23, 2016 at 5:56

ljk – I direct you to this – “January 21, 2012
New mathematical study reveals that our Galaxy should have been colonized by now ”
The site is
best wishes


ljk December 23, 2016 at 15:21

Yes, that is the site I originally linked you to above when I asked if you got your idea for galactic colonization from it.


Coacervate December 23, 2016 at 6:16

How can we make ourselves special and interesting enough to attract a signal from ET? First our O2 rich air places us in the “has life” bin. Second, Kepler only looked for special planets…those that transit their star relative to the satellite. Similarly, we might be detected the same way by ET’s version of Kepler. It is not my idea but one that I think deserves more consideration: Keep the sun to our backs and listen for signals from those who find us special.


Silent Hunter December 23, 2016 at 14:25

How likely do you think that a starfaring species discovers another alien race by chance? Such as while travelling out to explore another system, it detects their ‘radio sphere’ as it approaches or on arrival.


xcalibur December 23, 2016 at 21:58

Synchronicity is an important factor to help explain the Fermi Paradox, but it is not the only one.

My theory is that intelligence and commonality of life are inversely proportional. By my reckoning, alien microbes and sponges are abundant, but ETI civilizations are rare.

This ties into the filter/great filter idea. There are a number of filters on life and civilization. I believe the most significant is encephalization — which explains why we humans are the only intelligent civilization on Earth. But there are also other filters to consider — those behind encephalization, such as multiple cells, and those ahead, such as building a civilization that does not self-destruct.

We must not assume that every ETI civilization has the prerogative of colonizing solar systems. While it is reasonable to assume that at least some ETI civilizations would colonize space (since that is conducive to survival and growth of civilization) that is not necessarily the case for all. There may be planet-bound ETI civilizations which either lack spacefaring technology or simply don’t want to use it (perhaps they chose to turn inward instead, creating a “matrix” way of life).

In addition, is it possible for an ETI civilization to develop technology which doesn’t tend to leak electromagnetic radiation? I think it’s unlikely that they wouldn’t at least go through a phase of broadcasting, but this is something to consider.

In conclusion, there are many filters to explain the Fermi Paradox: synchronicity, rarity of ETI and ETI civilization, and the tendency (or lack thereof) to colonize space and/or broadcast their presence.


joe December 27, 2016 at 17:27

Inhabitants on a planet with no moon to serve as “training wheels” for their spaceships might never try to reach more distant planets. Also if a system doesn’t have at least one additional interesting world (like Mars) then a society might never see a purpose in developing space flight.


Andrei December 24, 2016 at 18:29

Thank you for an excellent article.

Many years ago I argued along somewhat similar lines, though only with words and one Gedankenexperiment and no hard math. Yet even so it was met with stares of disbelief.

In my thought experiment the IC would only broadcast actively for a comparatively short time, and then stop the active broadcasts for a number of possible reasons, not to mention a very large energy cost.

But by the time the radio halo might reach another civilization, the first one might simply have vanished, met with a disaster environmental or trough conflict or went on a completely different path.

When questioned I had some difficulty to come up with more than one or two examples of what that might have been.
But today we have a number of existing and emerging technologies and trends that provide us with examples of why a civilization might loose interest or the ability to get in touch with other beings in the near part of the universe around them.

A: One example might not sound plausible, yet if you met anyone who have been caught in one online game to the extent to loose interest in the world around one can more easily envision a civilization that get caught in a Virtual reality world.
Let say they withdraw to spend all their time in an alien version of WorldOfWarcraft and only work with the most necessary tasks to get enough funds to spend another day or year in the virtual world.
(A variation on that theme is that they upload their minds to computer storage and then get caught by a game or virtual world.)

B: A civilization that adopt the idea that the universe is a simulation, which make any endeavor pointless.

C: They create their own disaster by fundamentalist thinking, pressure from economic interests or political agenda. Our own continuous use of fossil fuels
even for the electrical power industry is patently absurd. When there are so many other means to provide energy, here we have so many examples from Thorium fission, or not to mention provide adequate funding to start a crash program to finally solve how to create working fusion program.
But even now when we find ourselves in the middle of a human created mass extinction event from coral reefs in the tropics to moors in the high arctic that now melt – we continue this “business as usual” burning of coal and oil.

Other civilizations might do the same or a similar mistake by stating that ‘this worked in the past, no reason to change the blueprint of how to do things’ – and so go toward a crash with open eyes and loose ability or capacity for interstellar communication.

I could give more examples, but will limit myself to those.
The point is that I agree with the authors here, the active broadcasting time might be very short indeed. And the listening phase no longer than the lifetime of civilizations that stay in the active exploring curious stage for more than 10 000 year on average.

My conclusion were quite similar to that presented here, meaning that the sphere of radio emissions would pass each other at a time in the future when not just one but both have stopped or care to be listening when it pass by. And therefore it would even be pointless to actively broadcast our presence.

When pressed I did admit that there might be special cases where one civilization might broadcast for a longer time.
Now those was rather weird ones, and accepting that notion led me into the realm of the less believable.
What is worse, such a civilization might broadcast for reasons that might be less beneficial to us, such as beings who are followers of some odd cult religion or philosophy.
Or the leader of a dictatorship regime who wish to declare their greatness to the universe as a whole.
Even though such ideas usually have not tended to be long lived on Earth, it might not necessarily be so for aliens with a different attitude or mindset so such a society could be more stable over longer time.
But due to the very nature of such a broadcast, they might not even care to listen for any reply. They simply send their message to ‘enlighten’ others about their ‘superior’ philosophy or as a testament of their civilizations ‘greatness’. Again, it would be no point in trying to broadcast anything, these oddball civilizations simply do not try to listen.

This do not mean that we should not try to listen.
But even so the example in the main text here do tell us that we first need to get a much better sensitivity before we will have a chance of picking up the weak hiss of a civilization that no longer exist who sent their last piece of their encyclopedia, their philosophical manifest or the episodes of their most amusing soap opera from the other side of the galaxy 100 000 years ago.


Roger Guay December 24, 2016 at 18:29

For those interested in the many solutions to the Fermi paradox, I recommend “If the Universe is Teeming with Aliens . . . Where is Everybody?” by Stephen Webb.


Scott Guerin December 26, 2016 at 12:53

I highly recommend this very informative and summative 2003 paper:
“Fermi’s Paradox – The Last Challenge for Copernicanism?” by Milan M. Cirkovic


ljk December 27, 2016 at 9:36

Webb came to the conclusion that Earth is the only planet harboring intelligent life. Makes me wonder if he has a hidden religious agenda.


Roger Guay December 27, 2016 at 18:20

I can assure you that I do not have a hidden religious agenda and I could not detect any in Webb’s book. IMO, It is pure science of the highest caliber.


ljk February 4, 2017 at 0:33

Well Webb wouldn’t come right out and say such a thing, now would he?

At least not like the authors of this book, who wear their religious convictions on their sleeves and let it cloud and spoil whatever science they were trying to utilize:


Andrew Palfreyman December 24, 2016 at 20:53

Were it the case that hyperspace existed and could be used for at least communication (if not also transportation), then simply observing our mundane 3+1D spacetime would reveal nothing of the bustling interstellar societies going about their business “beneath the surface” in hyperspace. It is certain that once hyperspace and its associated technology were discovered, its spread across the galaxy and beyond would be all but instantaneous on cosmic timescales.


Janw Pool December 26, 2016 at 4:39

Yes… Ursula le Guin’s Werwort comes to mind. Any news on quantum entanglement, lately? Don’t set your bets on beaming a soul (whatever that may be) from one chair to another in your living room, however…


JOE December 25, 2016 at 13:56

It seems unlikely to me that an IC would abandon broadcast communications all at once. Like Earth, other ICs might have their equivalant of third world nations that would continue using broadcast long after more advance nations switched to fiber optics or other methods of communications.


ljk December 30, 2016 at 10:19

If we want some idea of dealing with an actual alien mind, then we should study the octopi and other cephalopods even more:

Interesting that so many of the smartest beings on Earth are aquatic. This may also explain our so far lack of success with SETI.

To quote:

In the words of Peter Godfrey-Smith, “If we can make contact with cephalopods as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over. This is probably the closest we will come to meeting an intelligent alien.”


ljk December 30, 2016 at 14:31
Scott Guerin December 30, 2016 at 19:51


I gave the book to my wife for Christmas. It’s a most relevant topic to SETI, and I can’t wait to read it. He was interviewed here

The application of human-like motivations to other species (ET or Earthbound) is as slippery a slope as the Octopuses’ skin. While the physics and technology behind receiving and transmitting Radio and Optical EM is robust and universal, ambition and motivation are the ringers. The silence and absence is easy to model, we could be it. But if you apply human technology and motivation to the model, the Paradox rings loud and modeling becomes more complex.


ljk December 30, 2016 at 14:29
Yvan Dutil December 31, 2016 at 14:04

Jut for teh record, I did this calculation by hand almost 30 years ago, while in college.


Scott Guerin December 31, 2016 at 19:53

Can you elaborate, Yvan?


Harry R Ray January 9, 2017 at 20:07

Five minutes ago Jason Wright tweeted that Boyajian’s Star is being observed in the X band by BOTH ATA and GREEN BANK AT THE EXACT SAME TIME. Just a co-incedence, or is it something else?


ljk February 4, 2017 at 0:37

If you want to see SETI proliferate, then let us save the second largest radio telescope on Earth:


Roger Guay February 4, 2017 at 11:53

For those who might not know about the Discovery Institute,


ljk February 19, 2017 at 15:49

SETI Dashboard

by Dermot McDonagh on February 18, 2017

In May 2015, Russian astronomers detected a signal from a star system 94 light-years away. It took over a year for the signal to be checked by a SETI array in the USA due to the Russians being “shy”.

My solution would be to create a SETI dashboard connecting radio telescopes around the World that could notify each other of signal detection in real time. I added other features such as live weather updates for scheduling scans on clear skies.

See the full presentation here:


Scott Guerin February 19, 2017 at 20:24


Very cool idea! A summative dashboard of what’s going on. Will Breakthrough Listen do something like it? I like your wide ranging view of things!


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