The Laser SETI campaign we looked at on Friday is one aspect of a search for intelligent life in the universe that is being addressed in many ways. In addition to optical methods, we look of course at radio wavelengths, and as we begin to characterize the atmospheres of rocky exoplanets, we’ll also look for signs of atmospheric modification that could indicate industrial activity. But we have to be careful. Because SETI looks for evidence of alien technology, it is a search for civilizations about whose possible activities we know absolutely nothing.
So we can’t make assumptions that might blind us to a detection. Getting the blinders off also means extending our reach. If successful, the Laser SETI project will do two things we haven’t been able to do before — it will scan the entire sky and, because it is always on, it will catch optical transients we are missing today, and tell us whether any of these are repeating.
In radio terms, think of the famous WOW! signal of 1977, detected at Ohio State University’s Big Ear radio telescope. Seeming to come out of the constellation Sagittarius, it fit our ideas of what an extraterrestrial signal could look like, but we can’t draw any conclusions because we’ve never seen it again. If the signal intrigues you, Robert Gray’s book The Elusive WOW (Palmer Square, 2011) goes into it in great depth, including Gray’s 1987 and 1989 attempts to find it. Gray would search again in the mid 90’s using the Very Large Array, and again in 1999 with the University of Tasmania’s Mount Pleasant Radio Observatory, with null results.
The Elusive WOW is a splendid page-turner that captures the drama of the hunt. It also reminds us how frustrating a transient can be — here today, gone in moments, never seen again. Did the WOW signal reappear at some time that we weren’t pointing our instruments at it? Is it repeating on some schedule we haven’t figured out?
All-sky surveys like Laser SETI weren’t on the mind of Giuseppe Cocconi and Philip Morrison when they wrote their ground-breaking paper “Searching for Interstellar Communications” in Nature (1959), one that is mostly commonly cited as launching SETI. But for optical SETI’s origins, we can look back with equal admiration at R. N. Schwartz and Charles Townes’ “Interstellar and Interplanetary Communication by Optical Masers,” which ran two years later in the same journal. The author’s vision encapsulates the idea:
We propose to examine the possibility of broadcasting an optical beam from a planet associated with a star some few or some tens of light-years away at sufficient power-levels to establish communications with the Earth. There is some chance that such broadcasts from another society approximately as advanced as we are could be adequately detected by present telescopes and spectrographs, and appropriate techniques now available for detection will be discussed. Communication between planets within our own stellar system by beams from optical masers appears a fortiori quite practical.
Image: Charles Hard Townes, at the National Institute of Biomedical Imaging and Bioengineering’s 5th Anniversary Symposium, held in June 2007. Credit: NIBIB.
Optical SETI Scenarios
We saw Friday that a petawatt laser of the kind that has been built at Lawrence Livermore National Laboratory could be transformed into an optical SETI beacon, working in conjunction with a huge mirror like that found on our largest telescopes. Indeed, the Sun can be outshone by a factor of 10,000, a bright and, one would assume, obviously artificial beacon. But the complexities involved in targeting another star — and aiming the beam to lead the moving target, one that will be many light years away, make targeted laser beacons difficult.
Surely the challenges of laser beacons — not to mention their cost — could be overcome by advanced civilizations, although the idea of a less targeted beacon seems to make more sense; i.e., a beacon that sweeps a region of the sky on a recurrent basis, assuming the intent here is simply to announce the presence of the extraterrestrial civilization as widely as possible. But perhaps it’s much more likely that, if we do detect a laser signal from another civilization, it will be in the form of a chance interception of a technology at work.
Image: The power of laser technology even today. Credit: Eliot Gillum/SETI Institute.
Detecting communications within an exoplanetary system presents serious problems of geometry, given that these optical beams would be broadcast to specific targets and are unlikely to be pointing by chance at the Earth. But there is a scenario that could work: We’ve learned all about exoplanet detection through planetary transits from the Kepler mission. A planetary system that was co-planar with our own could produce a communications beam between its own planets that swept past us with each orbital revolution. Even then, the target planet would likely absorb enough of the signal that detection would be unlikely.
But there are other kinds of detections. James Guillochon and Abraham Loeb have looked at the possibility that beaming to interstellar sailcraft would produce leakage that might be observable to our detectors (see SETI via Leakage from Light Sails in Exoplanetary Systems). Both interplanetary as well as interstellar transportation systems leave possible signatures.
And consider Boyajian’s Star (KIC 8462852), whose odd light curves drew it to the attention of citizen scientists at the Planet Hunters project and subsequent worldwide scrutiny. Numerous natural phenomena have been put forward to explain what we are seeing here, but light curves like this could also be the sign of an extraterrestrial civilization working on some kind of massive project (a Dyson sphere inevitably comes to mind, but who knows?)
It made sense, then, to make Boyajian’s Star a SETI target, which is why the SETI Institute used the Allen Telescope Array to search for radio emissions, a two-week survey that produced no evidence of artificial radio signals coming from the system. For more on this investigation, see Jim and Dominic Benford’s Quantifying KIC 8462852 Power Beaming, which analyzed the ATA results at radio wavelengths. But note the following, which summarizes what the Benfords believe would be detectable given the instruments used in the attempt. As you can see, not all detectable signals would come from power beamed, for example, to an interstellar mission. Some of them definitely include applications within the target system:
Orbit raising missions, which require lower power, are not detectable at the thresholds of the Allen Array.
Launch from a planetary surface into orbits would be bright enough to be seen by the 100 kHz observations. However, the narrow bandwidth 1 Hz survey would not see them.
Interplanetary transfers by beam-driven sails should be detectable in their observations, but are not seen. This is for both the narrow 1 Hz and for the “wideband” 100 kHz observations.
Starships launched by power beams with beamwidths that we happen to fall within would be detectable, but are not seen.
Image: Power beaming to drive an interstellar lightsail. Credit: Adrian Mann.
But let’s move back into the optical. Nate Tellis (UC-Berkeley) recently worked with astronomer Geoff Marcy to analyze Keck data archives on 5,600 stars observed between 2004 and 2016, using a computer algorithm fine-tuned to detect laser light (see A Search for Laser Emission with Megawatt Thresholds from 5600 FGKM Stars,” preprint here). The search was an excellent way to put thousands of hours of accumulated astronomical data to work — who knows what discoveries may lurk within such datasets? As a part of the effort, the astronomers studied Boyajian’s Star, again finding no detectable signals. Potential candidates that did emerge in the survey all turned out to be the result of natural processes.
But power beaming is a possible observable as any local civilization goes about moving things around in its own system. Leakage from a beamed power infrastructure is something we’ve focused on here frequently (see, for example, Power Beaming Parameters & SETI re KIC 8462852). Power beaming could be what enables a space-based infrastructure, one that would be capable of large-scale engineering and also of producing the kind of power beams that could drive spacecraft at high velocity to other stars.
But we needn’t exclude communications entirely. Jim Benford has pointed out that any civilization using large-scale power beaming would be aware that its activities could be visible to others. If it had the desire to communicate on such a random basis, the ETI civilization could embed a message within the beam. A kind of interstellar message in a bottle, thrown into the cosmic sea with each sweeping power beam that does local work.
All of this should reinforce the key issue that the Laser SETI project addresses — such beams, working within their own planetary system, would appear in our sky as transients. We return to the core issue, the need for an all-sky survey that observes continuously. Making no assumptions about any desire to communicate, such a survey nonetheless is capable of spotting the signs of a working civilization going about its business. It should, I would wager, also pick out new astrophysical phenomena that will add to our knowledge of the galaxy.
Twitter action has been fast and furious with this morning’s news of the first clear dip in light from Boyajian’s Star (KIC 8462852) since the Kepler data.
When I was growing up, there was a small outbuilding between my house and the stand of woods behind our property. The previous owner had built it as a little house in its own right, everything on a miniature scale, so that while it looked like an actual house — with front door, nice windows, even a porch and small deck on the back — it was comprised of only one room inside. This man’s kids had used it as a playhouse, but when I got my hands on it, I turned it into what a young boy thought of as his ‘lab,’ with microscope, chemistry set and telescope.
On the walls I put photographs I had bought at Chicago’s Adler Planetarium, and I can still see those blurry images of Saturn, Jupiter and the Milky Way, all taken at the Palomar Observatory, and almost as breathtaking for what they didn’t reveal as what they did. I gradually augmented these photos with sky charts and other imagery, and would use these to plan my observing sessions with the 3-inch reflector I would take out into the yard.
Image: A classic photo (though not one of my Palomar images). This is M31, then known as the Great Andromeda Nebula, its nature as a separate galaxy not being known when the photograph was taken in 1888 by Sir Isaac Roberts. Reproduced in A Selection of Photographs of Stars, Star-clusters and Nebulae, Volume II (The Universal Press, London, 1899), this is the image whose long exposure time first.revealed M31’s spiral structure. Photos like these may look quaint compared to the brilliant detail and color of today’s work, but studying the sky over long periods of time may tease out new information, making even our older datasets useful tools for exploration. Credit: Isaac Roberts.
You would think old astronomical photographs would have a place only in memories like these, but I’m reminded of the vigorous debate that broke out not long ago over the anomalous star KIC 8462852, and Bradley Schaefer’s contention that, on the basis of archival imagery, it could be shown to have undergone a long-term dimming (see KIC 8462852: A Century Long Fade? for more on this — there are likewise numerous articles in the archive).
Schaefer was using a collection of some 500,000 sky photographs in the archives of Harvard College Observatory, covering the period from 1890 to 1989. A program called Digital Access to a Sky Century@Harvard (DASCH) has been digitizing the observatory’s archives, offering a way for astronomers to re-examine historical imagery. DASCH has only digitized a fraction of the archives but it’s a work in progress. What else can we do to reinvigorate such material?
One answer is a project called Astronomy Rewind, whose aim is to restore tens of thousands of astronomical images — photographs, radio maps and other sky-related material — from a wide variety of sources, placing them into context in digital sky atlases and catalogs. The project is part of the Zooniverse platform that gave us Galaxy Zoo a decade ago and now includes ‘citizen science’ projects in a variety of disciplines. Here the idea is to turn our attention to the contents of scientific journals and collate their imagery over time.
American Astronomical Society journals go back to the 19th Century and became accessible electronically in the 1990s. The volunteers will catalog the types of images, separating photographs with and without sky coordinates, maps of planets with or without latitude and longitude grids, graphs and diagrams, focusing on labeled images or those with sufficient detail to make a clear determination of orientation and sky position. Other images will be sent to Astrometry.net, which identifies areas of sky by comparing photos to star catalogs.
The project depends upon human judgement and pattern recognition at a large scale:
“You simply couldn’t do a project like this in any reasonable amount of time without ‘crowdsourcing,'” says Julie Steffen, AAS Director of Publishing. “Astronomy Rewind will breathe new life into old journal articles and put long-lost images of the night sky back into circulation, and that’s exciting. But what’s more exciting is what happens when a volunteer on Zooniverse looks at one of our journal pages and goes, ‘Hmm, that’s odd!’ That’ll be the first step toward learning something new about the universe.”
Image: An early view of Orion. This is a digital print of a photographic plate from the Ritchey 60-inch telescope at Mount Wilson Observatory, made in 1908. Credit: Mt. Wilson Observatory.
The journals involved at present are The Astronomical Journal, Astrophysical Journal, Astrophysical Journal Letters and the ApJ Supplement Series. Images are to be annotated and extracted into digital files that will end up in data repositories as well as becoming part of the Astronomy Image Explorer and becoming viewable in the data visualization tool and sky atlas WorldWide Telescope.
Once up to speed, Astronomy Rewind hopes to process 1,000 journal pages daily, with each page examined by at least five different people to produce consensus. This number is based upon other projects at Zooniverse, where 1.6 million volunteers have classified 4 billion images over the last ten years. Peer-reviewed publications, over 100 of them, have flowed from the Zooniverse work, and as the KIC 8462852 story shows, the potential for discovery is here.
We have to remember as we look into old astronomical materials that we continue to accumulate data at a faster and faster rate. We’re learning how to sift through older material as we build the database from which details that may have escaped our attention decades ago can come to light, perhaps to be reinterpreted in the context of subsequent findings. An earlier effort, the ADS All-Sky Survey, was originally set up to analyze imagery from old astronomy papers, but using computers for the job wasn’t always effective. Now we turn volunteer eyes on the cosmos as we bring digital technologies and older printed journals together.
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.
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?
Footnotes:
* 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. https://vimeo.com/195239607 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.
Wrap
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!
Have we, as some have argued, entered a new ‘age of humanity,’ the so-called Anthropocene? The notion is controversial in many quarters, but it addresses the growing concern about our human influence on the Earth and the nature of planetary change. David Grinspoon’s new book Earth in Human Hands (Grand Central Publishing, 2016) has much to say about the Anthropocene, but as anyone who has read the work of this canny scientist knows, he’s not one to let facile assumptions get by unquestioned.
For if the activity of humans is now emerging as an agent of geological change, then we are discussing our civilization in the same terms we talk about planetary forces like tectonic movement and the carbon cycle. This makes us major players whose effects we can begin to chart in terms of the effects of our technology on Earth’s living systems. If the Anthropocene is happening, it presents us not only with danger but the prospect of a long-term future. And its implications take in not just our movement into space but our search for other civilizations.
Hence Grinspoon’s view that while we are leaving an unmistakable footprint on our planet’s living substrate, this is not something to be deplored as much as understood and put to good use, the theory being that living things have always shaped the world around them, in ways as profound as the Great Oxygenation Event of 2.5 billion years ago. Earth in Human Hands is rich in discussion of what it would be like to enter what Grinspoon calls the ‘mature Anthropocene,’ in which humans acting wisely and with long-term horizons learn to use technology to repair past damage and introduce a new era of planetary stability.
In this view, our current dilemma is that we are achieving global impact without any sense of global control. The analysis is filled with Grinspoon’s experience as an astrobiologist and it draws together themes that are at the heart of how we consider our own future and how we look at other civilizations. For make no mistake, when we examine SETI, we’re forced to address questions like the lifespan of a technological civilization. If such societies persist, how do they do it, and equally of interest, what sort of signature would they leave? Stanislaw Lem comes to mind, and Grinspoon quotes him from his Summa Technologiae:
We need to overcome the habit of considering outcomes of human activity as more imperfect than those of nature’s activity — understandable as such a habit may be at the current stage of development — if we are to talk about what is going to happen in a faraway future.
Are we not ourselves a part of the nature we study, and rather than deploring the fact, should we not be considering how to make our own contribution to the mindfulness that intelligent life brings to the universe? You may pick up a bit of Sagan in these themes, particularly the Sagan (and Shklovskii) of the 1966 masterwork Intelligent Life in the Universe. The connection is borne out by Grinspoon’s relationship with Sagan, who worked with the author’s father at Harvard and shaped his boyhood and early career. No wonder Sagan and Shklovskii’s influence on SETI play such a vital and entertaining role in his book.
A Third Route for SETI
A confluence of events marks the beginning of SETI, with Frank Drake’s early efforts at Project Ozma following swiftly after the famous “Searching for Interstellar Communications” paper by Giuseppe Cocconi and Philip Morrison. But I think you could say that the discipline put down its formative roots at two conferences, the first being the one Drake hosted at Green Bank in 1961, the second the First All-Union Conference on Extraterrestrial Civilizations and Interstellar Communication, which was held in 1964 at the Byurakan Astrophysical Observatory in Soviet Armenia. Between the two we see a foundational SETI defined.
Frank Drake’s famous equation emerged from Green Bank, a conference with only 11 attendees that took SETI out of the realm of theory and into observational science. At Byurakan, Iosif Shklovskii criticized the Cocconi and Morrison paper for being too restrictive — the authors, Shklovskii argued, assumed that extraterrestrial civilizations would be on approximately the same level as ourselves. Shklovskii believed that any civilizations we detected would be far more advanced technologically than ourselves, for “We are only infants as far as science and technology are concerned,” and technology’s growth is rapid.
Grinspoon’s treatment of SETI is relaxed and knowledgeable, but it is the weaving of the anthropocene theme into SETI’s subsequent development that gives these chapters punch. For Nikolai Kardashev, then a young student of Shklovskii’s, was also at Byurakan to make the case for his three types of technological civilization, based on what he saw as a predictable and steady increase in the use of energy. Thus the categories most Centauri Dreams readers have come to be familiar with:
Type I: A civilization that can use all the energy resources of its own planet.
Type II: A civilization using all the energy resources available from its star. This is a civilization that has mastered its own stellar system and travels readily in space.
Type III: A civilization that can harness the energy of its entire galaxy. This is obviously an interstellar culture that moves freely between stars.
Image: Astrobiologist and author David Grinspoon, now a senior scientist at the Planetary Science Institute in Tucson.
We have often considered in these pages how advanced civilizations might present themselves to a distant observer; i.e., what kind of signature their engineering might leave in star systems and, indeed, in entire galaxies. Searches for Dyson spheres and odd stellar phenomena like the light curves of KIC 8462852 (Boyajian’s Star) continue to push the boundaries of radio and optical SETI. At a second conference in Byurakan, put together by Sagan and Shklovskii following the success of their book, the discussions of advanced technologies clustered around the Kardashev scale and its potential observables.
Radio and optical SETI, the first level of SETI, are complemented by a Dysonian SETI (level 2) that looks through our astronomical data for the signs of technological activity. But Grinspoon points out the key assumption of the Kardashev scale: That civilizations will inevitably increase their energy use in order to fuel a continuing expansion into the cosmos.
This is an idea of progress that is generally accepted — Grinspoon calls it the ‘inevitable expansion fallacy’ — but it is one that doesn’t take into account that key term (L in Drake’s equation) about the lifetime of a technological civilization. What if, in short, expanding in the Kardashev manner is the most likely way to end the growth of a culture?
A third level of SETI now emerges. You can see how Grinspoon is tying this back into the idea of an Anthropocene epoch on Earth. Let me quote him on this:
…it is reasonable to suppose that truly successful, long-lived species have all discarded the expansion imperative, and replaced it with an ethic of sustainability, of valuing longevity of expansion. If technological intelligence has a true and lasting form, one of its basic properties must be that it moves beyond the exponential expansion phase (characteristic of simple life in a petri dish or on a finite planet) before it hits the top of the S-curve and crashes. For us, achieving this kind of planetary intelligence will require critically examining our inherited biological habits and shedding those that have become liabilities.
And what exactly does a planetary intelligence involve? Grinspoon explains it as:
…thoughtful control over one’s self, escape from the mindless drives to multiply, to expand, to lay waste, kill, and drown in your own waste. Perhaps this is why we will not find what Shklovskii called ‘miracles,’ the highly visible works of vastly expanded super-advanced civilizations. Because advanced intelligences are not stupid.
At this point, we’ve stood Kardashev’s ideas on their head, for what Grinspoon is saying is that the kind of technological intelligence that lasts is one that has the ability to overcome its biological need for exponential growth. If this is the case, then we are confronted with the possibility that the more advanced a technological civilization becomes, the less likely we will be to distinguish it from natural phenomena. We may confront a cosmos rife with advanced civilizations whose work is so harmonized with their surroundings as to be invisible.
In earthly terms, the ‘mature Anthropocene’ is where we begin to move out of the era when the changes we make to our planet are beyond our comprehension, and into the era when we begin to consciously shape the Earth’s future, a time when, as Grinspoon writes:
…we fully incorporate our uniquely human powers of imagination, abstraction, and foresight into our role as an integral part of the planetary system. The mature Anthropocene differentiates conscious, purposeful global change from the inadvertent, random changes that have largely brought us to this point.
In SETI terms, consider the Anthropocene a metaphor for what can happen on other worlds. As we first confront the danger of technological over-reach in our environment and then learn to heal the wounds that limit sustainable growth, we may turn toward a balance that sustains our planetary ecology while ensuring the survival of our civilization. What Grinspoon calls the ‘Sapiezoic’ eon would be the long-lived stage of technological civilization that leads conceivably to immortality. Exponential expansion may simply be an evolutionary dead end, and the likelihood of finding civilizations that are learning this lesson the hard way is vanishingly small. They are simply not in existence long enough for us to see them.
Do we have a chance at detecting a civilization that operates according to the long-term model? Let’s talk about that tomorrow as we continue to look at this third route for SETI. We’ll also see that in Grinspoon’s view, expansion into space has a major role to play in the survival of long-haul civilizations. Developing a stable relationship with world-changing technologies is the key.
In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).
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