The end of one year and the beginning of the next seems like a good time to back out to the big picture. The really big picture, where cosmology interacts with metaphysics. Thus today’s discussion of evolution and development in a cosmic context. John Smart wrote me after the recent death of Russian astronomer Alexander Zaitsev, having been with Sasha at the 2010 conference I discussed in my remembrance of Zaitsev. We also turned out to connect through the work of Clément Vidal, whose book The Beginning and the End tackles meaning from the cosmological perspective (see The Zen of SETI). As you’ll see, Smart and Vidal now work together on concepts described below, one of whose startling implications is that a tendency toward ethics and empathy may be a natural outgrowth of networked intelligence. Is our future invariably post-biological, and does such an outcome enhance or preclude journeys to the stars? John Smart is a global futurist, and a scholar of foresight process, science and technology, life sciences, and complex systems. His book Evolution, Development and Complexity: Multiscale Evolutionary Models of Complex Adaptive Systems (Springer) appeared in 2019. His latest title, Introduction to Foresight, 2021, is likewise available on Amazon.
by John Smart
In 2010, physicists Martin Dominik and John Zarnecki ran a Royal Society conference, Towards a Scientific and Societal Agenda on Extra-Terrestrial Life addressing scientific, legal, ethical, and political issues around the search for extra-terrestrial intelligence (SETI). Philosopher Clement Vidal and I both spoke at that conference. It was the first academic venue where I presented my Transcension Hypothesis, the idea that advanced intelligence everywhere may be developmentally-fated to venture into inner space, into increasingly local and miniaturized domains, with ever-greater density and interiority (simulation capacity, feelings, consciousness), rather than to expand into “outer space”, the more complex it becomes. When this process is taken to its physical limit, we get black-hole-like domains, which a few astrophysicists have speculated may allow us to “instantly” connect with all the other advanced civilizations which have entered a similar domain. Presumably each of these intelligent civilizations will then compare and contrast our locally unique, finite and incomplete science, experiences and wisdom, and if we are lucky, go on to make something even more complex and adaptive (a new network? a universe?) in the next cycle.
Clement and I co-founded our Evo-Devo Universe complexity research and discussion community in 2008 to explore the nature of our universe and its subsystems. Just as there are both evolutionary and developmental processes operating in living systems, with evolutionary processes being experimental, divergent, and unpredictable, and developmental processes being conservative, convergent, and predictable, we think that both evo and devo processes operate in our universe as well. If our universe is a replicating system, as several cosmologists believe, and if it exists in some larger environment, aka, the multiverse, it is plausible that both evolutionary and developmental processes would self-organize, under selection, to be of use to the universe as complex system. With respect to universal intelligence, it seems reasonable that both evolutionary diversity, with many unique local intelligences, and developmental convergence, with all such intelligences going through predictable hierarchical emergences and a life cycle, would emerge, just as both evolutionary and developmental processes regulate all living intelligences.
Once we grant that developmental processes exist, we can ask what kind of convergences might we predict for all advanced civilizations. One of those processes, accelerating change, seems particularly obvious, even though we still don’t have a science of that acceleration. (In 2003 I started a small nonprofit, ASF, to make that case). But what else might we expect? Does surviving universal intelligence become increasingly good, on average? Is there an “arc of progress” for the universe itself?
Developmental processes become increasingly regulated, predictable, and stable as function of their complexity and developmental history. Think of how much more predictable an adult organism is than a youth (try to predict your young kids thinking or behavior!), or how many less developmental failures occur in an adult versus a newly fertilized embryo. Development uses local chaos and contingency to converge predictably on a large set of far-future forms and functions, including youth, maturity, replication, senescence, and death, so the next generation may best continue the journey. At its core, life has never been about either individual or group success. Instead, life’s processes have self-organized, under selection, to advance network success. Well-built networks, not individuals or even groups, always progress. As a network, life is immortal, increasingly diverse and complex, and always improving its stability, resiliency, and intelligence.
But does universal intelligence also become increasingly good, on average, at the leading edge of network complexity? We humans are increasingly able to use our accelerating S&T to create evil, with ever-rising scale and intensity. But are we increasingly free to do so, or do we grow ever-more self-regulated and societally constrained? Steven Pinker, Rutger Bregman, and many others argue we have become increasingly self- and socially-constrained toward the good, for yet-unclear reasons, over our history. Read The Better Angels of Our Nature, 2012 and Humankind, 2021 for two influential books on that thesis. My own view on why we are increasingly constrained to be good is because there is a largely hidden but ever-growing network ethics and empathy holding human civilizations together. The subtlety, power, and value of our ethics and empathy grows incessantly in leading networks, apparently as a direct function of their complexity.
As a species, we are often unforesighted, coercive, and destructive. Individually, far too many of us are power-, possession- or wealth-oriented, zero-sum, cruel, selfish, and wasteful. Not seeing and valuing the big picture, we have created many new problems of progress, like climate change and environmental destruction, that we shamefully neglect. Yet we are also constantly progressing, always striving for positive visions of human empowerment, while imagining dystopias that we must prevent.
Ada Palmer’s science fiction debut, Too Like the Lightning, 2017 (I do not recommend the rest of the series), is a future world of technological abundance, accompanied by dehumanizing, centrally-planned control over what individuals can say, do, or believe. I don’t think Palmer has written a probable future. But it is plausible, under the wrong series of unfortunate and unforesighted future events, decisions and actions. Imagining such dystopias, and asking ourselves how to prevent them, is surely as important as positive visions to improving adaptiveness. I am also convinced we are rapidly and mostly unconsciously creating a civilization that will be ever more organized around our increasingly life-like machines. We can already see that these machines will be far smarter, faster, more capable, more miniaturized, more resource-independent, and more sustainable than our biology. That fast-approaching future will be importantly different from (and better than?) anything Earth’s amazing, nurturing environment has developed to date, and it is not well-represented in science-fiction yet, in my view.
On average, then, I strongly believe our human and technological networks grow increasingly good, the longer we survive, as some real function of their complexity. I also believe that postbiological life is an inevitable development, on all the presumably ubiquitous Earthlike planets in our universe. Not only does it seem likely that we will increasingly choose to merge with such life, it seems likely that it will be far smarter, stabler, more capable, more ethical, empathic, and more self-constrained than biological life could ever be, as an adaptive network. There is little science today to prove or disprove such beliefs. But they are worth stating and arguing.
Arguing the goodness of advanced intelligence was the subtext of the main debate at the SETI conference mentioned above. The highlight of this event was a panel debate on whether it is a good idea to not only listen for signs of extraterrrestrial intelligence (SETI), but to send messages (METI), broadcasting our existence, and hopefully, increase the chance that other advanced intelligences will communicate with us earlier, rather than later.
One of the most forceful proponents for such METI, Alexander Zaitsev, spoke at this conference. Clement and I had some good chats with him there (see picture below). Since 1999, Zaitsev has been using a radiotelescope in the Ukraine, RT-70, to broadcast “Hello” messages to nearby interesting stars. He did not ask permission, or consult with many others, before sending these messages. He simply acted on his belief that doing so would be a good act, and that those able to receive them would not only be more advanced, but would be inherently more good (ethical, empathic) than us.
Image: Alexander Zaitsev and John Smart, Royal Society SETI Conference, Chicheley Hall, UK, 2010. Credit: John Smart.
Sadly, Zaitsev has now passed away (see Paul Gilster’s beautiful elegy for him in these pages). It explains the 2010 conference, where Zaitsev debated others on the METI question, including David Brin. Brin advocates the most helpful position, one that asks for international and interdisciplinary debate prior to sending of messages. Such debate, and any guidelines it might lead to, can only help us with these important and long-neglected questions.
It was great listening to these titans debate at the conference, yet I also realized how far we are from a science that tells us the general Goodness of the Universe, to validate Zaitsev’s belief. We are a long way from his views being popular, or even discussed, today. Many scientists assume that we live in a randomness-dominated, “evolutionary” universe, when it seems much more likely that it is an evo-devo universe, with both many unpredictable and predictable things we can say about the nature of advanced complexity. Also, far too many of us still believe we are headed for the stars, when our history to date shows that the most complex networks are always headed inward, into zones of ever-greater locality, miniaturization, complexity, consciousness, ethics, empathy, and adaptiveness. As I say in my books, it seems that our destiny is density, and dematerialization. Perhaps all of this will even be proven in some future network science. We shall see.
As we puzzle out the best observing strategies to pick up a bio- or technosignature, we’re also asking in what ways our own world could be observed by another civilization. If such exist, they would have a number of tools at their disposal by which to infer our existence and probe what we do. Extrapolation is dicey, but we naturally begin with what we understand today, as Brian McConnell does in this, the third of a three-part series on SETI issues. A communications systems engineer, Brian has worked with Alex Tolley to describe a low-cost, high-efficiency spacecraft in their book A Design for a Reusable Water-based Spacecraft Known as the Spacecoach (Springer, 2015). His latest book is The Alien Communication Handbook — So We Received A Signal, Now What? recently published by Springer Nature. Is our existence so obvious to the properly advanced observer? That doubtless depends on the state of their technology, about which we know nothing, but if the galaxy includes billion-year old cultures, it’s hard to see how we might be missed.
by Brian McConnell
In SETI discussions, it is often assumed that an ET civilization would be unaware of our existence until they receive a signal from us. I Love Lucy is an often cited example of early broadcasts they might stumble across. Just as we are developing the capability to directly image exoplanets, a more astronomically advanced civilization may already be aware of our existence, and may have been for a long time. Let’s consider several methods by which an ET could take observations of Earth:
- Spectroscopic analysis of Earth’s atmosphere
- Deconvolution of Earth’s light curve
- Solar gravitational lens telescopes
- Solar system scale interferometers
- High speed flyby probes (e.g. Starshot)
- Slow traveling probes that loiter in near Earth space (Lurkers, Bracewell probes)
We are already capable of conducting spectroscopic analysis of the light passing through exoplanet atmospheres, and as a result, are able to learn about their general characteristics. This capability will soon be extended to include Earth sized planets. An ET astronomer that had been studying Earth’s atmosphere over the past several centuries would have been able to see the rapid accumulation of carbon dioxide and other fossil fuel waste gases. This signal is plainly evident from the mid 1800s onward. Would this be a definitive sign of an emergent civilization? Probably not, but it would be among the possible explanations, and perhaps a common pattern as an industrial civilization develops. Other gases, such as fluorocarbons (CFCs and HFCs) have no known natural origin, and would more clearly indicate more recent industrial activity.
There is also no reason not to stop at optical/IR, and not conduct similar observations in the microwave band, both to look for artificial signals such as radars, but also to study the magnetic environment of exoplanets, much like we are using the VLA to study the magnetic fields of exoplanets. It’s worth noting that most of the signals we transmit are not focused at other star systems, and would appear very weak to a distant observer, though they might notice a general brightening in the microwave spectrum, much like artificial illumination might be detectable. This would be a sure sign of intelligence, but we have not been “radio bright” for very long, so this would only be visible to nearby systems.
Even if we can only obtain a single pixel image of an exoplanet, we can use a technique called deconvolution to develop a low resolution image of it by measuring how its brightness and color varies as the planet rotates. This is not unlike building an image by moving a light meter across a surface to build a map of light levels that can be translated into an image. It won’t be possible to build a high resolution image, but it will be possible to see large-scale features such as oceans, continents and ice caps. While it would not be possible to directly see human built structures, it would be clear that Earth has oceans and vegetation. Images of Pluto taken before the arrival of the New Horizons probe offer an example of what can be done with a limited amount of information.
Comparison of images of Pluto taken by the New Horizons probe (left) and the Hubble Space Telescope via light curve reconstruction (right). Image credit: NASA / Planetary Society.
Svetlana Berdyugina and Jeff Kuhn presented a presentation on this topic at the 2018 NASA Techno Signatures symposium where they simulated what the Earth would look like through this deconvolution process. In the simulated image, continents, oceans and ice caps are clearly visible, and because the Earth’s light curve can be split out by wavelength, it would be possible to see evidence of vegetation.
Solar Gravitational Lens Telescopes
A telescope placed along a star’s gravitational lens focal line will be able to take multi pixel images of exoplanets at considerable distances. Slava Turyshev et al show in this NASA NIAC paper that it will be possible to use an SGL telescope to image exoplanets at 1 kilometer per pixel resolution out to distances of 100 light years. A SGL telescope pointed at Earth might be able to see evidence of large scale agriculture, urban centers, night side illumination, reservoirs, and other signs of civilization. Moreover, pre-industrial activity and urban settlements might be visible to this type of instrument, which raises the possibility that an ET civilization with this capability would have been able to see evidence of human civilization centuries ago, perhaps Longer.
A simulated image of an exoplanet as seen from an SGL telescope. Image credit: NASA/JPL
A spacefaring civilization that happens to have access to a nearby black hole would have an even better lens to use (the Sun’s gravitational lens is slightly distorted because of the Sun’s rotation and oblate shape).
Solar System Scale Interferometers
The spatial resolution of a telescope is a function of its aperture size and the wavelength of the light being observed. Using interferometry, widely separated telescopes can combine their observations, and increase the effective aperture to the distance between the telescopes. The Black Hole Event Horizon Telescope used interferometry to create a virtual radio telescope whose aperture was the size of Earth. With it, we were able to directly image the accretion disc of galaxy M87’s central black hole, some 53 million light years away.
Synthetic microwave band image of M87’s central black hole’s shadow and nearby environment. Image credit: Event Horizon Telescope
Now imagine a fleet of optical interferometers in orbit around a star. They would have an effective aperture measuring tens to hundreds of millions of kilometers, and would be able to see small surface details on distant exoplanets. This is beyond our capabilities to build today, but the underlying physics say they will be possible to build, which is to say it is an expensive and difficult engineering problem, something a more advanced civilization may have built. Indeed, we began to venture down this path with the since canceled SIM (Space Interferometry Mission) and LISA (Laser Interferometer Space Antenna) telescopes.
A solar system scale constellation of optical interferometers would be able to resolve surface details of distant objects at a resolution of 1-10 meters per pixel, comparable to satellite imagery of the Earth, meaning that even early agriculture and settlements would be visible to them.
Fast Flyby Probes
Fast lightsail probes, similar to the Breakthrough Starshot probes that we hope to fly in a few decades, will be able to take high resolution images of exoplanets as the probes fly past target planets. Images taken of Pluto by the New Horizons probe probably give an idea of what to expect in terms of resolution. It was able to return images at a resolution of less than 100 meters per pixel, smaller than a city block.
The primary challenges in obtaining high resolution images from probes like these are: the speed at which the probe flies past its target (0.2c in the case of the proposed starshot probe),and transmitting observations back to the home system. Both of these are engineering problems. For example, the challenge of capturing images can be solved by taking as many images as possible during the flyby and then using on board post processing to create a synthesized image. Communication is likewise an engineering problem that can be solved with better onboard power sources and/or large receiving facilities at the home system. If the probe itself is autonomous and somewhat intelligent, it can also decide which parts of the collected imagery are most interesting and prioritize their transmission.
The Breakthrough Starshot program envisions launching a large number of cheap, lightweight lightsails on a regular cadence, so while an individual probe might only be able to capture a limited set of observations, in aggregate they may be able to return extensive observations and imagery over an extended period of time.
Slow Loitering Probes (Lurkers and Bracewell Probes)
An ET civilization that has worked out nuclear propulsion would be able to send slower traveling probes to loiter in near Earth space. These probes could be long lived, and could be designed for a variety of purposes. Being in close proximity to Earth, they would be able to take high resolution images over an extended period of time. Consider that the Voyager probes, among the first deep space probes we built, are still operational today. ET probes could be considerably more long lived and capable of autonomous operation. If they are operating in our vicinity, they would have been able to see early signs of human activity back to antiquity. One important limitation is that only nearby civilizations would be able to launch probes to our vicinity within a few hundred years.
The implication of this is not just that an ETI could be able to see us today, they could have been able to study the development of human civilization from afar, over a period spanning centuries or millennia. Beyond that, Earth has had life for 3.5 billion years, and life on land for several hundred million years. So if other civilizations are surveying habitable worlds on an ongoing basis, Earth may have been noticed and flagged as a site of interest long before we appeared on the scene.
One of the criticisms of SETI is that the odds of two civilizations going “online” within an overlapping time frame may be vanishingly small, which implies that searching for signals from other civilizations may be a lost cause. But what if early human engineering projects, such as the Pyramids of Giza, had been visible to them long ago? Then the sphere of detectability expands by orders of magnitude, and more importantly, these signals we have been broadcasting unintentionally have been persistent and visible for centuries or millennia.
This has ramifications for active SETI (METI) as well. Arguments against transmitting our own artificial signals, on the basis that we might be risking hostile action by neighbors, may be moot if most advanced civilizations have some of the capabilities mentioned in this article. At the very least, they would know Earth is an inhabited world and a site for closer study, and may well have been able to see early signs of human civilization long ago. So perhaps it is time to revisit the METI debate, but this time with a focus on understanding what unintentional signals or techno signatures we have been sending and who could see them.
The fact that we have three functioning spacecraft outside the orbit of Pluto fills me with holiday good spirits. Of the nearest of the three, I can say that since New Horizons’ January 1, 2019 encounter with the Kuiper Belt Object now known as Arrokoth, I have associated the spacecraft with holidays of one kind or another The July 14, 2015 flyby of Pluto/Charon wasn’t that far off the US national holiday, but more to the point, I was taking a rare beach vacation during the last of the approach phase, most of my time spent indoors with multiple computers open tracking events at system’s edge. It felt celebratory, like an extended July 4, even if the big event was days later.
Also timely as the turn of the year approaches is Alan Stern’s latest PI’s Perspective, a look at what’s ahead for the plucky spacecraft. Here January becomes a significant time, with the New Horizons team working on the proposal for another mission extension, the last of which got us through Arrokoth and humanity’s first close-up look at a KBO. The new proposal aims at continued operations from 2023 through 2025, which could well include another KBO flyby, if an appropriate target can be found. That search, employing new machine learning tools, continues.
Image: Among several discoveries made during its flyby of the Kuiper Belt object Arrokoth in January 2019, New Horizons observed the remarkable and enigmatic bright, symmetric, ring-like “neck” region at the junction between Arrokoth’s two massive lobes. Credit: NASA/Johns Hopkins APL/Southwest Research Institute.
But what happens if no KBO is within reach of the spacecraft? Stern explains why the proposed extension remains highly persuasive:
If a new flyby target is found, we will concentrate on that flyby. But if no target is found, we will convert New Horizons into a highly-productive observatory conducting planetary science, astrophysics and heliospheric observations that no other spacecraft can — simply because New Horizons is the only spacecraft in the Kuiper Belt and the Sun’s outer heliosphere, and far enough away to perform some unique kinds of astrophysics. Those studies would range from unique new astronomical observations of Uranus, Neptune and dwarf planets, to searches for free floating black holes and the local interstellar medium, along with new observations of the faint optical and ultraviolet light of extragalactic space. All of this, of course, depends on NASA’s peer review evaluation of our proposal.
Our only spacecraft in the Kuiper Belt. What a reminder of how precious this asset is, and how foolish it would be to stop using it! Here my natural optimism kicks in (admittedly beleaguered by the continuing Covid news, but determined to push forward anyway). One day – and I wouldn’t begin to predict when this will be – we’ll have numerous Kuiper Belt probes, probably enabled by beamed sail technologies in one form or another as we continue the exploration of the outer system, but for now, everything rides on New Horizons.
The ongoing analysis of what New Horizons found at Pluto/Charon is a reminder that no mission slams to a halt when one or another task is completed. For one thing, it takes a long time to get data back from New Horizons, and we learn from Stern’s report that a good deal of the flyby data from Arrokoth is still on the spacecraft’s digital recorders, remaining there because of higher-priority transmission needs as well as scheduling issues with the Deep Space Network. We can expect the flow of publications to continue. 49 new scientific papers came out this year alone.
That Arrokoth image above is still a stunner, and the inevitable naming process has begun not only here but on Pluto as well. The KBO’s largest crater has been christened ‘Sky,’ while Ride Rupes (for astronaut Sally Ride) and Coleman Mons (for early aviator Bessie Coleman) likewise will begin to appear on our maps of Pluto. All three names have been approved by the International Astronomical Union. ‘Rupes’ is the Latin word for ‘cliff,’ and here refers to an enormous feature near the southern tip of Pluto’s Tombaugh Regio. Ride Rupes is between 2 and 3 kilometers high and about 250 kilometers long, while Coleman Mons is a mountain, evidently recently created and thus distinctive in a region of older volcanic domes.
Image: Close-up, outlines of Ride Rupes (left) and Coleman Mons on the surface Pluto. Credit: NASA/Johns Hopkins APL/Southwest Research Institute/SETI Institute/Ross Beyer.
As the New Horizons team completes the mission extension proposal, it also proceeds with uploading another instrument software upgrade, this one to the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) charged-particle spectrometer. And while spacecraft power levels have continued to decline, as is inevitable given the half-life of the nuclear battery’s plutonium, Stern says the spacecraft should be able to maintain maximum data transmission rates for another five years. That new power-saving capability, currently being tested, should strengthen the upcoming proposal and bodes well for any future flyby.
Those of you with an investigative bent should remember that 2021’s data return, along with six associated datasets, is available to researchers whether professional or working in a private capacity, within NASA’s Planetary Data System. This is an active mission deeply engaged with the public as well as its natural academic audience, as I’m reminded by the image below. Here the New Horizons spacecraft has captured a view taken during departure from Pluto, seeing however faintly the ‘dark side’ that was not illuminated by the Sun during the approach.
Image: Charon-lit-Pluto: The image shows the dark side of Pluto surrounded by a bright ring of sunlight scattered by haze in its atmosphere. But for a dark crescent zone to the left, the terrain is faintly illuminated by sunlight reflected by Pluto’s moon Charon. Researchers on the New Horizons team were able to generate this image using 360 images that New Horizons captured as it looked back on Pluto’s southern hemisphere. A large portion of the southern hemisphere was in seasonal darkness similar to winters in the Arctic and Antarctica on Earth, and was otherwise not visible to New Horizons during its 2015 flyby encounter of Pluto.
Credit: NASA/Johns Hopkins APL/Southwest Research Institute/NOIRLab.
This is Pluto’s southern hemisphere during the long transition into winter darkness; bear in mind that a winter on the distant world lasts 62 years. The all too faint light reflecting off Charon’s icy surface allows researchers to extract information. Tod Lauer (National Optical Infrared Astronomy Research Observatory, Tucson), lead author of a paper on the dark side work, compares available light here to moonlight on Earth:
“In a startling coincidence, the amount of light from Charon on Pluto is close to that of the Moon on Earth, at the same phase for each. At the time, the illumination of Charon on Pluto was similar to that from our own Moon on Earth when in its first-quarter phase.”
That’s precious little to work with, but the New Horizons Long Range Reconnaissance Imager (LORRI) made the best of it despite the fierce background light and the bright ring of atmospheric haze. We’ll have to wait a long time before the southern hemisphere is in sunlight, but for now, Pluto’s south pole seems to be covered in material darker than the paler surface of the northern hemisphere, with a brighter region midway between the south pole and the equator. In that zone we may have a nitrogen or methane ice deposit similar to the Tombaugh Regio ‘heart’ that is so prominent in the flyby images from New Horizons.
For more, see Lauer et al., “The Dark Side of Pluto,” Planetary Science Journal Vol. 2, No. 5 (20 Ocober 2021), 214 (abstract).
Of course, there is another mission that will forever have a holiday connection, at least if its planned liftoff on Christmas Eve happens on schedule. Dramatic days ahead.
If you were crafting a transmission to another civilization — and we recently discussed Alexander Zaitsev’s multiple messages of this kind — how would you put it together? I’m not speaking of what you might want to tell ETI about humanity, but rather how you could make the message decipherable. In the second of three essays on SETI subjects, Brian McConnell now looks at enclosing computer algorithms within the message, and the implications for comprehension. What kind of information could algorithms contain vs. static messages? Could a transmission contain programs sufficiently complex as to create a form of consciousness if activated by the receiver’s technnologies? Brian is a communication systems engineer and expert in translation technology. His book The Alien Communication Handbook (Springer, 2021) is now available via Amazon, Springer and other booksellers.
by Brian S McConnell
In most depictions of SETI detection scenarios, the alien transmission is a static message, like the images on the Voyager Golden Record. But what if the message itself is composed of computer programs? What modes of communication might be possible? Why might an ETI prefer to include programs and how could they do so?
As we discussed in Communicating With Aliens : Observables Versus Qualia, an interstellar communication link is essentially an extreme version of a wireless network, one with the following characteristics:
- Extreme latency due to the speed of light (eight years for round trip communication with the nearest solar system), and in the case of an inscribed matter probe, there may be no way to contact the sender (infinite latency).
- Prolonged disruptions to line of sight communication (due to the source not always being in view of SETI facilities as the Earth rotates).
- Duty cycle mismatch (it is extremely unlikely that the recipient will detect the transmission at its start and read it entirely in one pass).
Because of these factors, communication will work much better if the transmission is segmented so that parcels received out of order can be reassembled by the receiver, and so that those segments are encoded to enable the recipient to detect and correct errors without having to contact the transmitter and wait years for a response. This is known as forward error correction and is used throughout computing (to catch and fix disc read errors) and communication (to correct corrupted data from a noisy circuit).
While there are simple error correction methods, such as the N Modular Redundancy or majority vote code, these are not very robust and dramatically reduce the link’s information carrying capacity. There exist very robust error correction methods, such as the Reed Solomon coding used for storage media and space communication. These methods can correct for prolonged errors and dropouts, and the error correction codes can be tuned to compensate for an arbitrary amount of data loss.
In addition to being unreliable, the communication link’s information carrying capacity will likely be limited compared to the amount of information the transmitter may wish to send. Because of this, it will be desirable to compress data, using lossless compression algorithms, and possibly lossy compression algorithms (similar to the way JPEG and MPEG encoders work). Astute readers will notice a built-in conflict here. Data that is compressed and encoded for error correction will look like a series of random numbers to the receiver. Without knowledge about how the encoding and compression algorithms work, something that would be near impossible to guess, the receiver will be unable to recover the original unencoded data.
The iconic Blue Marble photo taken by the Apollo 17 astronauts. Credit: NASA.
The value of image compression can be clearly shown by comparing the file size for this image in several different encodings. The source image is 3000×3002 pixels. The raw uncompressed image, with three color channels with 8 bits per pixel per color channel, is 27 megabytes (216 megabits). If we apply a lossless compression algorithm, such as the PNG encoding, this is reduced to 12.9 megabytes (103 megabits), a 2.1:1 reduction. Applying a lossy compression algorithm, this is further reduced to 1.1 megabytes (8.8 megabits) for JPEG with quality set to 80, and 0.408 megabytes (3.2 megabits) for JPEG with quality set to 25, which results in a 66:1 Reduction.
Lossy compression algorithms enable impressive reductions in the amount of information needed to reconstruct an image, audio signal, or motion picture sequence, at the cost of some loss of information. If the sender is willing to tolerate some loss of detail, lossy compression will enable them to pack well over an order of magnitude more content into the same data channel. This isn’t to say they will use the same compression algorithms we do, although the underlying principles may be similar. They can also interleave compressed images, which will look like random noise to a naive viewer, with occasional uncompressed images, which will stand out, as we showed in Communicating with Aliens : Observables Versus Qualia.
So why not send programs that implement error correction and decompression algorithms? How could the sender teach us to recognize an alien programming language to implement them?
A programming language requires a small set of math and logic symbols, and is essentially a special case of a mathematical language. Let’s look at what we would need to define an interpreted language, call it ET BASIC if you like. An interpreted language is abstract, and is not tied to a specific type of hardware. Many of the most popular languages in use today, such as Python, are interpreted languages.
We’ll need the following symbols:
- Delimiter symbols (something akin to open and close parentheses, to allow for the creation of nested or n-dimensional data structures)
- Basic math operations (addition, subtraction, multiplication, division, modulo/remainder)
- Comparison operations (is equal, is not equal, is greater than, is less than)
- Branching operations (if condition A is true, do this, otherwise do that)
- Read/write operations (to read or write data to/from virtual memory, aka variables, which can also be used to create input/output interfaces for the user to interact with)
- A mechanism to define reusable functions
Each of these symbols can be taught using a “solve for x” pattern within a plaintext primer that can be interleaved with other parts of the transmission. Let’s look at an example.
1 ? 1 = 2
1 ? 2 = 3
2 ? 1 = 3
2 ? 2 = 4
1 ? 3 = 4
3 ? 1 = 4
4 ? 0 = 4
0 ? 4 = 4
We can see right away that the unknown symbol refers to addition. Similar patterns can be used to define symbols for the rest of the basic operations needed to create an extensible language.
The last of the building blocks, a mechanism to define reusable functions, is especially useful. The sine function, for example, is used in a wide variety of calculations, and can be approximated via basic math operations using the Taylor series shown below:
And in expanded form as:
This can be written in Python as:
The sine() function we just defined can later be reused without repeating the lower level instructions used to calculate the sine of an angle. Notice that the series of calculations used reduce down to basic math and branching operations. In fact any program you use, whether it is a simple tic-tac-toe game or a complex simulation, reduces down to a small lexicon of fundamental operations. This is one of the most useful aspects of computer programs. Once you know the basic operations, you can build an interpreter that can run programs that are arbitrarily complex, just as you can run a JPEG viewer without knowing a thing about how lossy image compression works.
In the same way, the transmitter could define an “unpack” function that accepts a block of encoded data from the transmission as input, and produces error corrected, decompressed data as output. This is similar to what low level functions do to read data off a storage device.
Lossless compression will significantly increase the information carrying capacity of the channel, and also allow for raw, unencoded data to be very verbose and repetitive to facilitate compression. Lossy compression algorithms can be applied to some media types to achieve order of magnitude improvements, with the caveat that some information is lost during encoding. Meanwhile, deinterleaving and forward error correction algorithms can ensure that most information is received intact, or at least that damaged segments can be detected and flagged. The technical and economic arguments for including programs in a transmission are so strong, it would be surprising if at least part of a transmission were not algorithmic in nature.
There are many ways a programming language can be defined. I chose to use a Python based example as it is easy for us to read. Perhaps the sender will be similarly inclined to define the language at a higher level like this, and will assume the receiver can work out how to implement each operation in their hardware. On the other hand, they might describe a computing system at a lower level, for example by defining operations in terms of logic gates, which would enable them to precisely define how basic operations will be carried out.
Besides their practical utility in building a reliable communication link, programs open up whole other realms of communication with the receiver. Most importantly, they can interact with the user in real-time, thereby mooting the issue of delays due to the speed of light. Even compact and relatively simple programs can explain a lot.
Let’s imagine that ET wants to describe the dynamics of their solar system. An easy way to do this is with a numerical simulation. This type of program simulates the gravitational interactionsof N number of objects by summing up gravitational forces acting on each object and steps forward an increment of time to forecast where they will be, and then repeats this process ad infinitum. The program itself might only be a few kilobytes or tens of kilobytes in length since it just repeats a simple set of calculations many times. Additional information is required to initialize the simulation, probably on the order of about 50 bytes or 400 bits per object, enough to encode position and velocity in three dimensions at 64 bit accuracy. Simulating the orbits of the 1,000 most significant objects in the solar system would require less than 100 kilobytes for the program and its starting conditions. Not bad.
This is just scratching the surface of what can be done with programs. Their degree of sophistication is really only limited by the creativity of the sender, who we can probably assume has a lot more experience with computing than we do. We are just now exploring new approaches to machine learning, and have already succeeded at creating narrow AIs that exceed human capabilities in specialized tasks. We don’t know yet if generally intelligent systems are possible to build, but an advanced civilization that has had eons to explore this might have hit on ways to build AIs that are better and more computationally efficient than our state of the art. If that’s the case, it’s possible the transmission itself may be a form of Intelligence.
How would we go about parsing this type of information, and who would be involved? Unlike the signal detection effort, which is the province of a small number of astronomers and subject experts, the process of analyzing and comprehending the contents of the transmission will be open to anyone with an Internet connection and a hypothesis to test. One of the interesting things about programming languages is that many of the most popular languages were created by sole contributors, like Guido van Rossum, the creator of Python, or by small teams working within larger companies. The implication being that the most important contributions may come from people and small teams who are not involved in SETI at all.
For an example of a fully worked out system, Paul Fitzpatrick, then with the MIT CSAIL lab, created Cosmic OS, which details the ideas explored in this article and more. With Cosmic OS, he builds a Turing complete programming language that is based on just four basic symbols: 0 and 1, plus the equivalent of open and close parentheses.
There are risks and ethical considerations to ponder as well. In terms of risk, we may be able to run programs but not understand their inner workings or purpose. Already this is a problem with narrow AIs we have built. They learn from sets of examples instead of scripted instructions. Because of this they behave like black boxes. This poses a problem because an outside observer has no way of predicting how the AI will respond to different scenarios (one reason I don’t trust the autopilot on my Tesla car). In the case of a generally intelligent AI of extraterrestrial provenance, it goes without saying that we should be cautious in where we allow it to run.
There are ethical considerations as well. Suppose the transmission includes generally intelligent programs? Should they be considered a form of artificial life or consciousness? How would we know for sure? Should terminating their operation be considered the equivalent of murder, or something else? This idea may seem far fetched, but it is worthwhile to think about issues like this before a detection event.
We’ve been learning about the solar wind ever since the first interplanetary probes began to leave our planet’s magnetosphere to encounter this rapidly fluctuating stream of plasma. Finding a way to harness the flow could open fast transport to the outer Solar System if we can cope with the solar wind’s variability – no small matter – but in any case learning as much as possible about its mechanisms furthers our investigation of possible propulsive techniques. On this score and for the sake of solar science, we have much reason to thank the Parker Solar Probe and its band of controllers as the spacecraft continues to tighten its approaches to the Sun.
The spacecraft’s repeated passes by the Sun, each closer than the last, take advantage of speed and a heat shield to survive each perihelion event, and the last for which we have data was noteworthy indeed. During it, the Parker Solar Probe moved three separate times into and out of the Sun’s corona. This is a region where magnetic fields dominate the movement of particles. The Alfvén critical surface, which the spacecraft repeatedly crossed, is the boundary where the solar atmosphere effectively ends and the solar wind begins. Solar material surging up from below reaches a zone where gravity and magnetic fields can no longer hold it back. Breaking free, the solar wind effectively breaks the connection with the solar corona once across the Alfvén boundary.
So, as with our Voyagers moving past the heliopause and into interstellar space, we’ve accomplished another boundary crossing of consequence. A crossing into and back out of the corona helps define the location of the Alfvén critical surface, which turns out to be close to earlier estimates. These targeted a range between 10 and 20 solar radii. In its most recent passes by the Sun, the Parker Solar Probe has been below 20 solar radii, and on April 28 of this year, at 18.8 solar radii, it penetrated the Alfvén surface.
Nour Raouafi is a Parker project scientist at the Johns Hopkins Applied Physics Laboratory (JHU/APL):
“Flying so close to the Sun, Parker Solar Probe now senses conditions in the magnetically dominated layer of the solar atmosphere – the corona – that we never could before. We see evidence of being in the corona in magnetic field data, solar wind data, and visually in images. We can actually see the spacecraft flying through coronal structures that can be observed during a total solar eclipse.”
Image: As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses. Credit: NASA/Johns Hopkins APL/Naval Research Laboratory.
It’s clear from Parker data that the Alfvén surface is anything but smooth, and the spacecraft’s crossing into the corona did not in fact occur at perihelion on this particular pass, an indication of the varied structures within the region. As seen above, streamers and so-called pseudostreamers are found here, large magnetic-field structures streaming out of regions of the same magnetic polarity that are separated by an inner zone of opposite polarity. Caltech’s Christina M. S. Cohen explains the situation this way in a useful overview of the coronal crossing that notes the spacecraft’s fleeting passage through the boundary:
The center of a pseudostreamer is a region of enhanced magnetic field and reduced plasma density. This combination can push the Alfvén surface higher up in the corona, explaining why PSP’s orbit was able to cut across it…The period of time PSP spent below the Alfvén surface was too short to fully characterize the boundary and explore the inner region. Researchers expect that such a full characterization will require multiple expeditions carried out over different magnetic configurations and solar conditions.
It’s interesting to learn that we’re behind in acquiring data from the Parker Solar Probe because its high-gain antenna cannot be pointed toward Earth until it is far enough from the Sun on its current close pass to protect the equipment. Thus while the current data are from April of 2021, there was a likely crossing of the Alfvén critical surface again in November, when the probe reached a perihelion of 13.6 solar radii. This is close enough to suggest a longer period within the corona, something we won’t know until data download of that pass in late December.
Image: The solar corona during a total solar eclipse on Monday, August 21, 2017, above Madras, Oregon. The red light is emitted by charged iron particles at 1 million degrees Celsius and the green are those at 2 million degrees Celsius. On April 28, 2021, NASA’s Parker Solar Probe crossed the so-called Alfvén surface, entering, for the first time, a part of the solar corona that is “magnetically dominated.” Credit: M. Druckmuller / Christina M. S. Cohen.
Just as the Alfvén critical surface is anything but smooth, so too is the solar wind full of structure as it moves into the realm of the planets. So-called switchbacks were first detected by the Ulysses probe in the 1990s, what NASA describes as “bizarre S-shaped kinks in the solar wind’s magnetic field lines” which deflect charged particle paths as they move away from the Sun. The Parker Solar Probe discovered just how common these switchbacks were back in 2019, with later data showing that at least some switchbacks originate in the photosphere.
Switchbacks also align with magnetic funnels that emerge out of the photosphere between the convection cell structures called supergranules. It may be, then, that we can trace the origins of the solar wind at least partially to these magnetic funnels, as Stuart Bale (University of California, Berkeley) suggests:
“The structure of the regions with switchbacks matches up with a small magnetic funnel structure at the base of the corona. This is what we expect from some theories, and this pinpoints a source for the solar wind itself. My instinct is, as we go deeper into the mission and lower and closer to the Sun, we’re going to learn more about how magnetic funnels are connected to the switchbacks.”
Whether switchbacks are produced by the process of magnetic reconnection at the boundaries of magnetic funnels, or are produced by moving waves of plasma, is a question scientists hope the Parker Solar Probe will be able to answer. Just how the solar wind connects to switchbacks may help to explain how the corona is heated to temperatures far above that of the solar surface below. Bear in mind that the corona itself will be expanding as the Sun goes through its normal eleven year activity cycle, so we’ll have more opportunities for the Probe to pass through it.
Parker will eventually reach 8.86 solar radii, a scant 6.2 million kilometers from the solar surface, so this is a story that is far from over. The next flyby will be in January of 2022.
Findings from the recent Parker Solar Probe milestone will be published in The Astrophysical Journal, and are also examined in a paper by Kasper et al., “Parker Solar Probe Enters the Magnetically Dominated Solar Corona,” Physical Review Letters 127 (14 December 2021), 255101 (abstract).