The Tools Humanity Will Need for Living in the Year 1 Trillion

Since the 1990s, astrophysicists have known that for the past few billion years, the Universe has been experiencing an accelerated rate of expansion. This gave rise to the theory that the Universe is permeated by a mysterious invisible energy known as “dark energy”, which acts against gravity and is pushing the cosmos apart. In time, this energy will become the dominant force in the Universe, causing all stars and galaxies to spread beyond the cosmic horizon.

At this point, all stars and galaxies in the Universe will no longer be visible or accessible from any other. The question remains, what will intelligent civilizations (such as our own) do for resources and energy at this point? This question was addressed in a recent paper by Dr. Abraham Loeb – the  Frank B. Baird, Jr., Professor of Science at Harvard University and the Chair of the Harvard Astronomy Department.

The paper, “Securing Fuel for our Frigid Cosmic Future“, recently appeared online. As he indicates in his study, when the Universe is ten times its current age (roughly 138 billion years old), all stars outside the Local Group of galaxies will no be accessible to us since they will be receding away faster than the speed of light. For this reason, he recommends that humanity follow the lesson from Aesop’s fable, “The Ants and the Grasshopper”.

This classic tale tells the story of ants who spent the summer collecting food for the winter while the grasshopper chose to enjoy himself. While different versions of the story exist that offer different takes on the importance of hard work, charity, and compassion, the lesson is simple: always be prepared. In this respect, Loeb recommends that advanced species migrate to rich clusters of galaxies.

These clusters represent the largest reservoirs of matter bound by gravity and would therefore be better able to resist the accelerated expansion of the Universe. As Dr. Loeb told Universe Today via email:

“In my essay I point out that mother Nature was kind to us as it spontaneously gave birth to the same massive reservoir of fuel that we would have aspired to collect by artificial means. Primordial density perturbations from the early universe led to the gravitational collapse of regions as large as tens of millions of light years, assembling all the matter in them into clusters of galaxies – each containing the equivalent of a thousand Milky Way galaxies.”

Dr. Loeb also indicated where humanity (or other advanced civilizations) should consider relocating to when the expansion of the Universe causes the stars of the Local Group to expand beyond the cosmic horizon. Within 50 million light years, he indicates, likes the Virgo Cluster, which contains about a thousands times more matter than the Milky Way Galaxy. The second closest is the Coma Cluster, a collection of over 1000 galaxies located about 336 million light years away.

Diagram showing the Virgo Supercluster. Credit: Wikipedia Commons/Andrew Z. Colvin

In addition to offering a solution to the accelerating expansion of the Universe, Dr. Loeb’s study also presents some interesting possibilities when it comes to the search for extra-terrestrial intelligence (SETI). If, in fact, there are already advanced civilizations migrating to prepare for the inevitable expansion of the Universe, they may be detectable by various means. As Dr. Loeb explained:

“If traveling civilizations transmit powerful signals then we might be able to see evidence for their migration towards clusters of galaxies. Moreover, we would expected a larger concentration of advanced civilization in clusters than would be expected simply by counting the number of galaxies there. Those that settle there could establish more prosperous communities, in analogy to civilizations near rivers or lakes on Earth.”

This paper is similar to a study Dr. Loeb conducted back in 2011, which appeared in the Journal of Cosmology and Astroparticle Physics under the title “Cosmology with Hypervelocity Stars“. At the time, Dr. Loeb was addressing what would happen in the distant future when all extragalactic light sources will cease to be visible or accessible due to the accelerating expansion of the Universe.

This study was a follow-up to a 2001 paper in which Dr. Loeb addressed what would become of the Universe in billions of years – which appeared in the journal Physical Review Letters under the title “The Long–Term Future of Extragalactic Astronomy“. Shortly thereafter, Dr. Loeb and Freeman Dyson himself began to correspond about what could be done to address this problem.

An artist’s conception of a hypervelocity star that has escaped the Milky Way. Credit: NASA

Their correspondence was the subject of an article by Nathan Sanders (a writer for Astrobites) who recounted what Dr. Loeb and Dr. Dyson had to say on the matter. As Dr. Loeb recalls:

“A decade ago I wrote a few papers on the long-term future of the Universe, trillions of years from now. Since the cosmic expansion is accelerating, I showed that once the universe will age by a factor of ten (about a hundred billion years from now), all matter outside our Local Group of galaxies (which includes the Milky Way and the Andromeda galaxy, along with their satellites) will be receding away from us faster than light. After one of my papers was posted in 2011, Freeman Dyson wrote to me and suggested to a vast “cosmic engineering project” in which we will concentrate matter from a large-scale region around us to a small enough volume such that it will stay bound by its own gravity and not expand with the rest of the Universe.”

At the time, Dr. Loeb indicated that data gathered by the Sloan Digital Sky Survey (SDSS) indicated that attempts at “super-engineering” did not appear to be taking place. This was based on the fact that the galaxy clusters observed by the SDSS were not overdense, nor did they exhibit particularly high velocities (as would be expected). To this, Dr. Dyson wrote: “That is disappointing. On the other hand, if our colleagues have been too lazy to do the job, we have plenty of time to start doing it ourselves.”

A similar idea was presented in a recent paper by Dr. Dan Hooper, an astrophysicist from the Fermi National Accelerator Laboratory (FNAL) and the University of Chicago. In his study, Dr. Hooper suggested that advanced species could survive all stars in the Local Group expanding beyond the cosmic horizon (100 billion years from now), by harvesting stars across tens of millions of light years.

Artist impression of the 14 galaxies detected by ALMA as they appear in the very early, very distant universe. These galaxies are in the process of merging and will eventually form the core of a massive galaxy cluster. Credit: NRAO/AUI/NSF; S. Dagnello

This harvesting would consist of building unconventional Dyson Spheres that would use the energy they collected from stars to propel them towards the center of the species’ civilization. However, only stars that range in mass of 0.2 to 1 Solar Masses would be usable, as high-mass stars would evolve beyond their main sequence before reaching the destination and low-mass stars would not generate enough energy for acceleration to make it in time.

But as Dr. Loeb indicates, there are additional limitations to this approach, which makes migrating more attractive than harvesting.

“First, we do not know of any technology that enables moving stars around, and moreover Sun-like stars only shine for about ten billion years (of order the current age of the Universe) and cannot serve as nuclear furnaces that would keep us warm into the very distant future. Therefore, an advanced civilization does not need to embark on a giant construction project as suggested by Dyson and Hooper, but only needs to propel itself towards the nearest galaxy cluster and take advantage of the cluster resources as fuel for its future prosperity.”

While this may seem like a truly far-off concern, it does raise some interesting questions about the long-term evolution of the Universe and how intelligent civilizations may be forced to adapt. In the meantime, if it offers some additional possibilities for searching for extra-terrestrial intelligences (ETIs), then so much the better.

And as Dr. Dyson said, if there are currently no ETIs preparing for the coming “cosmic winter” with cosmic engineering projects, perhaps it is something humanity can plan to tackle someday!

Further Reading: arXiv, Journal of Cosmology and Astroparticle Physics, astrobites, astrobites (2)

New Model Predicts That We’re Probably the Only Advanced Civilization in the Observable Universe

The Fermi Paradox remains a stumbling block when it comes to the search for extra-terrestrial intelligence (SETI). Named in honor of the famed physicist Enrico Fermi who first proposed it, this paradox addresses the apparent disparity between the expected probability that intelligent life is plentiful in the Universe, and the apparent lack of evidence of extra-terrestrial intelligence (ETI).

In the decades since Enrico Fermi first posed the question that encapsulates this paradox (“Where is everybody?”), scientists have attempted to explain this disparity one way or another. But in a new study conducted by three famed scholars from the Future of Humanity Institute (FHI) at Oxford University, the paradox is reevaluated in such a way that it makes it seem likely that humanity is alone in the observable Universe.

The study, titled “Dissolving the Fermi Paradox“, recently appeared online. The study was jointly-conducted by Anders Sandberg, a Research Fellow at the Future of Humanity Institute and a Martin Senior Fellow at Oxford University; Eric Drexler, the famed engineer who popularized the concept of nanotechnology; and Tod Ord, the famous Australian moral philosopher at Oxford University.

The Drake Equation, a mathematical formula for the probability of finding life or advanced civilizations in the universe. Credit: University of Rochester

For the sake of their study, the team took a fresh look at the Drake Equation, the famous equation proposed by astronomer Dr. Frank Drake in the 1960s. Based on hypothetical values for a number of factors, this equation has traditionally been used to demonstrate that – even if the amount of life developing at any given site is small – the sheer multitude of possible sites should yield a large number of potentially observable civilizations.

This equation states that the number of civilizations (N) in our galaxy that we might able to communicate can be determined by multiplying the average rate of star formation in our galaxy (R*), the fraction of those stars which have planets (fp), the number of planets that can actually support life (ne), the number of planets that will develop life (fl), the number of planets that will develop intelligent life (fi),  the number civilizations that would develop transmission technologies (fc), and the length of time that these civilizations would have to transmit their signals into space (L). Mathematically, this is expressed as:

N = R* x fp x ne x fl x fi x fc x L

Dr. Sandberg is no stranger to the Fermi Paradox, nor is he shy about attempting to resolve it. In a previous study, titled “That is not dead which can eternal lie: the aestivation hypothesis for resolving Fermi’s paradox“, Sandberg and his associates proposed that the Fermi Paradox arises from the fact that ETIs are not dead, but currently in a state of hibernation – what they called “aestivation” – and awaiting better conditions in the Universe.

In a study conducted back in 2013, Sandberg and Stuart Armstrong (also a research associate with the FHI and one of the co-authors on this study) extended the Fermi Paradox to look beyond our own galaxy, addressing how more advanced civilizations would feasibly be able to launch colonization projects with relative ease (and even travel between galaxies without difficulty).

As Dr. Sandberg told Universe Today via email:

“One can answer [the Fermi Paradox] by saying intelligence is very rare, but then it needs to be tremendously rare. Another possibility is that intelligence doesn’t last very long, but it is enough that one civilization survives for it to become visible. Attempts at explaining it by having all intelligences acting in the same way (staying quiet, avoiding contact with us, transcending) fail since they require every individual belonging to every society in every civilization to behave in the same way, the strongest sociological claim ever. Claiming long-range settlement or communication are impossible requires assuming a surprisingly low technology ceiling. Whatever the answer is, it more or less has to be strange.”

In this latest study, Sandberg, Drexler and Ord reconsider the parameters of the Drake Equation by incorporating models of chemical and genetic transitions on paths to the origin of life. From this, they show that there is a considerable amount of scientific uncertainties that span multiple orders of magnitude. Or as Dr. Sandberg explained it:

“Many parameters are very uncertain given current knowledge. While we have learned a lot more about the astrophysical ones since Drake and Sagan in the 1960s, we are still very uncertain about the probability of life and intelligence. When people discuss the equation it is not uncommon to hear them say something like: “this parameter is uncertain, but let’s make a guess and remember that it is a guess”, finally reaching a result that they admit is based on guesses. But this result will be stated as single number, and that anchors us to an *apparently* exact estimate – when it should have a proper uncertainty range.  This often leads to overconfidence, and worse, the Drake equation is very sensitive to bias: if you are hopeful a small nudge upwards in several uncertain estimates will give a hopeful result, and if you are a pessimist you can easily get a low result.”

Frank Drake writing his famous equation on a white board. Credit: SETI.org

As such, Sandberg, Drexler and Ord looked at the equation’s parameters as uncertainty ranges. Instead of focusing on what value they might have, they looked at what the largest and smallest values they could have based on current knowledge. Whereas some values have become well constrained – such as the number of planets in our galaxy based on exoplanet studies and the number that exist within a star’s habitable zone – others remain far more uncertain.

When they combined these uncertainties, rather than the guesswork that often go into the Fermi Paradox, the team got a distribution as a result. Naturally, this resulted in a broad spread due to the number of uncertainties involved. But as Dr. Sandberg explained, it did provide them with an estimate of the likelihood that humanity (given what we know) is alone in the galaxy:

“We found that even using the guesstimates in the literature (we took them and randomly combined the parameter estimates) one can have a situation where the mean number of civilizations in the galaxy might be fairly high – say a hundred – and yet the probability that we are alone in the galaxy is 30%! The reason is that there is a very skew distribution of likelihood.

“If we instead try to review the scientific knowledge, things get even more extreme. This is because the probability of getting life and intelligence on a planet has an *extreme* uncertainty given what we know – we cannot rule out that it happens nearly everywhere there is the right conditions, but we cannot rule out that it is astronomically rare. This leads to an even stronger uncertainty about the number of civilizations, drawing us to conclude that there is a fairly high likelihood that we are alone. However, we *also* conclude that we shouldn’t be too surprised if we find intelligence!”

Is anybody out there? Anybody at all? Credit: UCLA SETI Group/Yuri Beletsky, Carnegie Las Campanas Observatory

In the end, the team’s conclusions do not mean that humanity is alone in the Universe, or that the odds of finding evidence of extra-terrestrial civilizations (both past and present) is unlikely. Instead, it simply means that we can say with greater confidence – based on what we know – that humanity is most likely the only intelligent species in the Milky Way Galaxy at present.

And of course, this all comes down to the uncertainties we currently have to contend with when it comes to SETI and the Drake Equation. In that respect, the study conducted by Sandberg, Drexler and Ord is an indication that much more needs to be learned before we can attempt to determine just how likely ETI is out there.

“What we are not showing is that SETI is pointless – quite the opposite!” said Dr. Sandberg. “There is a tremendous level of uncertainty to reduce. The paper shows that astrobiology and SETI can play a big role in reducing the uncertainty about some of the parameters. Even terrestrial biology may give us important information about the probability of life emerging and the conditions leading to intelligence. Finally, one important conclusion we find is that lack of observed intelligence does not strongly make us conclude that intelligence doesn’t last long: the stars are not foretelling our doom!”

So take heart, SETI enthusiasts! While the Drake Equation may not be something we can produce accurate values for anytime soon, the more we learn, the more refined the values will be. And remember, we only need to find intelligent life once in order for the Fermi Paradox to be resolved!

Further Reading: arXiv

How an Advanced Civilization Could Stop Dark Energy From Preventing Their Future Exploration

During the 1930s, astronomers came to realize that the Universe is in a state of expansion. By the 1990s, they realized that the rate at which it is expansion is accelerating, giving rise to the theory of “Dark Energy”. Because of this, it is estimated that in the next 100 billion years, all stars within the Local Group – the part of the Universe that includes a total of 54 galaxies, including the Milky Way – will expand beyond the cosmic horizon.

At this point, these stars will no longer be observable, but inaccessible – meaning that no advanced civilization will be able to harness their energy. Addressing this, Dr. Dan Hooper  – an astrophysicist from the Fermi National Accelerator Laboratory (FNAL) and the University of Chicago – recently conducted a study that indicated how a sufficiently advanced civilization might be able to harvest these stars and prevent them from expanding outward.

For the sake of his study, which recently appeared online under the title “Life Versus Dark Energy: How An Advanced Civilization Could Resist the Accelerating Expansion of the Universe“, Dr. Dan Hooper considered how civilizations might be able to reverse the process of cosmic expansion. In addition, he suggests ways in which humanity might looks for signs of such a civilization.

To put it simply, the theory of Dark Energy is that space is filled with a mysterious invisible force that counteracts gravity and causes the Universe to expand at an accelerating rate. The theory originated with Einstein’s Cosmological Constant, a term he added to his theory of General Relativity to explain how the Universe could remain static, rather than be in a state of expansion or contraction.

While Einstein was proven wrong, thanks to observations that showed that the Universe was expanding, scientists revisited the concept in order to explain how cosmic expansion has sped up in the past few billion years. The only problem with this theory, according to Dr. Hooper’s study, is that the dark energy will eventually become dominant, and the rate of cosmic expansion Universe will increase exponentially.

As a result, the Universe will expand to the point where all stars are so far apart that intelligent species won’t even be able to see them, let alone explore them or harness their energy. As Dr. Hooper told Universe Today via email:

“Cosmologists have learned over the last 20 years that our universe is expanding at an accelerating rate. This means that over the next 100 billion years or so, most of the stars and galaxies that we can now see in the sky will disappear forever, falling beyond any regions of space that we could reach, even in principle. This will limit the ability of a far-future advanced civilization to collect energy, and thus limit any number of things they might want to accomplish.”

Illustration showing the Lamba Cold Dark Matter (LCDM) model, which indicates how the influence of dark energy has led to an accelerated rate of cosmic expansion. Credit: Wikipedia Commons/Alex Mittelmann

In addition to being the Head of the Theoretical Astrophysics Group at the FNAL, Dr. Hooper is also an Associate Professor in the Department of Astronomy and Astrophysics at the University of Chicago. As such, he is well versed when it comes to the big questions of extra-terrestrial intelligence (ETI) and how cosmic evolution will affect intelligent species.

To tackle how advanced civilizations would go about living in such a Universe, Dr. Hooper begins by assuming that the civilizations in question would be a Type III on the Kardashev scale. Named in honor of Russian astrophysicist Nikolai Kardashev, a Type III civilization would have reached galactic proportions and could control energy on a galactic scale. As Hooper indicated:

“In my paper, I suggest that the rational reaction to this problem would be for the civilization to expand outward rapidly, capturing stars and transporting them to the central civilization, where they could be put to use. These stars could be transported using the energy they produce themselves.”

As Dr. Hooper admits, this conclusion relies on two assumptions – first, that a highly advanced civilization will attempt to maximize its access to usable energy; and second, that our current understanding of dark energy and the future expansion of our Universe is approximately correct. With this in mind, Dr. Hooper attempted to calculate which stars could be harvested using Dyson Spheres and other megastructures.

This harvesting, according to Dr. Hooper, would consist of building unconventional Dyson Spheres that would use the energy they collected from stars to propel them towards the center of the species’ civilization. High-mass stars are likely to evolve beyond the main sequence before reaching the destination of the central civilization and low-mass stars would not generate enough energy (and therefore acceleration) to avoid falling beyond the horizon.

For these reasons, Dr. Hooper concludes that stars with masses of between 0.2 and 1 Solar Masses will be the most attractive targets for harvesting. In other words, stars that are like our Sun (G-type, or yellow dwarf), orange dwarfs (K-type), and some M-type (red dwarf) stars would all be suitable for a Type III civilization’s purposes. As Dr. Hooper indicates, there would be limiting factors that have to be considered:

“Very small stars often do not produce enough energy to get them back to the central civilization. On the other hand, very large stars are short lived and will run out of nuclear fuel before they reach their destination. Thus the best targets of this kind of program would be stars similar in size (or a little smaller) than the Sun.”

Based on the assumption that such a civilization could travel at 1 – 10% the speed of light, Dr. Hooper estimates that they would be able to harvest stars out to a co-moving radius of approximately 20 to 50 Megaparsecs (about 65.2 million to 163 million light-years). Depending on their age, 1 to 5 billion years, they would be able to harvest stars within a range of 1 to 4 Megaparsecs (3,260 to 13,046 light-years) or up to several tens of Megaparsecs.

In addition to providing a framework for how a sufficiently-advanced civilization could survive cosmic acceleration, Dr. Hooper’s paper also provides new possibilities in the search for extra-terrestrial intelligence (SETI). While his study primarily addresses the possibility that such a mega-civilization will emerge in the future (perhaps it will even be our own), he also acknowledges the possibility that one could already exist.

In the past, scientists have suggested looking for Dyson Spheres and other megastructures in the Universe by looking for signatures in the infrared or sub-millimeter bands. However, megastructures that have been built to completely harvest the energy of a star, and use it to transport them across space at relativistic speeds, would emit entirely different signatures.

In addition, the presence of such a mega-civilization could be discerned by looking at other galaxies and regions of space to see if a harvesting and transport process has already begun (or is in an advanced stage). Whereas past searchers for Dyson Spheres have focused on detecting the presence of structures around individual stars within the Milky Way, this kind of search would focus on galaxies or groups of galaxies in which most of the stars would be surrounded by Dyson Spheres and removed.

“This provides us with a very different signal to look for,” said Dr. Hooper. “An advanced civilization that is in the process of this program would alter the distribution of stars over regions of space tens of millions of light years in extent, and would likely produce other signals as a result of stellar propulsion.”

In the end, this theory not only provides a possible solution for how advanced species might survive cosmic expansion, it also offers new possibilities in the hunt for extra-terrestrial intelligence. With next-generation instruments looking farther into the Universe and with greater resolution, perhaps we should be on the lookout for hypervelocity stars that are all being transported to the same region of space.

Could be a Type III civilization preparing for the day when dark energy takes over!

Further Reading: arXiv

One Way to Find Aliens Would be to Search for Artificial Rings of Satellites: Clarke Belts

When it comes to the search for extra-terrestrial intelligence (SETI) in the Universe, there is the complicated matter of what to be on the lookout for. Beyond the age-old question of whether or not intelligent life exists elsewhere in the Universe (statistically speaking, it is very likely that it does), there’s also the question of whether or not we would be able to recognize it if and when we saw it.

Given that humanity is only familiar with one form of civilization (our own), we tend to look for indications of technologies we know or which seem feasible. In a recent study, a researcher from the Instituto de Astrofísica de Canarias (IAC) proposed looking for large bands of satellites in distant star systems – a concept that was proposed by the late and great Arthur C. Clarke (known as a Clarke Belt).

The study – titled “Possible Photometric Signatures of Moderately Advanced Civilizations: The Clarke Exobelt” – was conducted by Hector Socas-Navarro, an astrophysicist with the IAC and the Universidad de La Laguna. In it, he advocates using next-generation telescopes to look for signs of massive belts of geostationary communication satellites in distant star systems.

This proposal is based in part on a paper written by Arthur C. Clarke in 1945 (titled “Peacetime Uses for V2“), in which he proposed sending “artificial satellites” into geostationary orbit around Earth to create a global communications network. At present, there are about 400 such satellites in the “Clarke Belt” – a region named in honor of him that is located 36,000 km above the Earth.

This network forms the backbone of modern telecommunications and in the future, many more satellites are expected to be deployed – which will form the backbone of the global internet. Given the practicality of satellites and the fact that humanity has come to rely on them so much, Socas-Navarro considers that a belt of artificial satellites could naturally be considered “technomarkers” (the analogues of “biomarkers”, which indicate the presence of life).

As Socas-Navarro explained to Universe Today via email:

“Essentially, a technomarker is anything that we could potentially observe which would reveal the presence of technology elsewhere in the Universe. It’s the ultimate clue to find intelligent life out there. Unfortunately, interstellar distances are so great that, with our current technology, we can only hope to detect very large objects or structures, something comparable to the size of a planet.”

In this respect, a Clarke Exobelt is not dissimilar from a Dyson Sphere or other forms of megastructures that have been proposed by scientists in the past. But unlike these theoretical structures, a Clarke Exobelt is entirely feasible using present-day technology.

Graphic showing the cloud of space debris that currently surrounds the Earth. Credit: NASA’s Goddard Space Flight Center/JSC

“Other existing technomarkers are based on science fiction technology of which we know very little,” said Socas-Navarro. “We don’t know if such technologies are possible or if other alien species might be using them. The Clarke Exobelt, on the other hand, is a technomarker based on real, currently existing technology. We know we can make satellites and, if we make them, it’s reasonable to assume that other civilizations will make them too.”

According to Socas-Navarro, there is some “science fiction” when it comes to Clarke Exobelts that would actually be detectable using these instruments. As noted, humanity has about 400 operational satellites occupying Earth’s “Clarke Belt”. This is about one-third of the Earth’s existing satellites, whereas the rest are at an altitude of 2000 km (1200 mi) or less from the surface – the region known as Low Earth Orbit (LEO).

This essentially means that aliens would need to have billions more satellites within their Clarke Belt – accounting for roughly 0.01% of the belt area – in order for it to be detectable. As for humanity, we are not yet to the point where our own Belt would be detectable by an extra-terrestrial intelligence (ETI). However, this should not take long given that the number of satellites in orbit has been growing exponentially over the past 15 years.

Based on simulations conducted by Socas-Navarro, humanity will reach the threshold where its satellite band will be detectable by ETIs by 2200. Knowing that humanity will reach this threshold in the not-too-distant future makes the Clarke Belt a viable option for SETI. As Socas-Navarro explained:

“In this sense, the Clarke Exobelt is interesting because it’s the first technomarker that looks for currently existing technology. And it goes both ways too. Humanity’s Clarke Belt is probably too sparsely populated to be detectable from other stars right now (at least with technology like ours). But in the last decades we have been populating it at an exponential rate. If this trend were to continue, our Clarke Belt would be detectable from other stars by the year 2200. Do we want to be detectable? This is an interesting debate that humanity will have to resolve soon.

An exoplanet transiting across the face of its star, demonstrating one of the methods used to find planets beyond our solar system. Credit: ESA/C. Carreau

As for when we might be able to start looking for Exobelts, Socas-Navarro indicates that this will be possible within the next decade. Using instruments like the James Webb Space Telescope (JWST), the Giant Magellan Telescope (GMT), the European Extremely Large Telescope (E-ELT), and the Thirty Meter Telescope (TMT), scientists will have ground-based and space-based telescopes with the necessary resolution to spot these bands around exoplanets.

As for how these belts would be detected, that would come down to the most popular and effective means for finding exoplanets to date – the Transit Method (aka. Transit Photometry). For this method, astronomers monitor distant stars for periodic dips in brightness, which are indications of an exoplanet passing in front of the star. Using next-generation telescopes, astronomers may also be able to detect reflected light from a dense band of satellites in orbit.

“However, before we point our supertelescopes to a planet we need to identify good candidates,” said Socas-Navarro. “There are too many stars to check and we can’t go one by one. We need to rely on exoplanet search projects, such as the recently launched satellite TESS, to spot interesting candidates. Then we can do follow-up observations with supertelescopes to confirm or refute those candidates.”

In this respect, telescopes like the Kepler Space Telescope and the Transiting Exoplanet Survey Telescope (TESS) will still serve an important function in searching for technomarkers. Whereas the former telescope is due to retire soon, the latter is scheduled to launch in 2018.

Artist’s impression of an extra-solar planet transiting its star. Credit: QUB Astrophysics Research Center

While these space-telescopes would search for rocky planets that are located within the habitable zones of thousands of stars, next-generation telescopes could search for signs of Clarke Exobelts and other technomarkers that would be otherwise hard to spot. However, as Socas-Navarro indicated, astronomers could also find evidence of Exobands by sifting through existing data as well.

“In doing SETI, we have no idea what we are looking for because we don’t know what the aliens are doing,” he said. “So we have to investigate all the possibilities that we can think of. Looking for Clarke Exobelts is a new way of searching, it seems at least reasonably plausible and, most importantly, it’s free. We can look for signatures of Clarke Exobelts in currently existing missions that search for exoplanets, exorings or exomoons. We don’t need to build costly new telescopes or satellites. We simply need to keep our eyes open to see if we can spot the signatures presented in the simulation in the flow of data from all of those projects.”

Humanity has been actively searching for signs of extra-terrestrial intelligence for decades. To know that our technology and methods are becoming more refined, and that more sophisticated searches could begin within a decade, is certainly encouraging. Knowing that we won’t be visible to any ETIs that are out there for another two centuries, that’s also encouraging!

And be sure to check out this cool video by our friend, Jean Michael Godier, where he explains the concept of a Clarke Exobelt:

Further Reading: IAC, The Astrophysical Journal

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

In the 1950s, famed physicist Enrico Fermi posed the question that encapsulated one of the toughest questions in the Search for Extra-Terrestrial Intelligence (SETI): “Where the heck is everybody?” What he meant was, given the age of the Universe (13.8 billion years), the sheer number of galaxies (between 1 and 2 trillion), and the overall number of planets, why has humanity still not found evidence of extra-terrestrial intelligence?

This question, which has come to be known as the “Fermi Paradox”, is something scientists continue to ponder. In a new study, a team from the University of Rochester considered that perhaps Climate Change is the reason. Using a mathematical model based on the Anthropocene, they considered how civilizations and planet systems co-evolve and whether or not intelligent species are capable of living sustainability with their environment.

The study, titled “The Anthropocene Generalized: Evolution of Exo-Civilizations and Their Planetary Feedback“, recently appeared in the scientific journal Astrobiology. The study was led by Adam Frank, a professor of physics and astronomy at the University of Rochester, with the assistance of Jonathan Carroll-Nellenback (a senior computational scientist at Rochester) Marina Alberti of the University of Washington, and Axel Kleidon of the Max Planck Institute for Biogeochemistry.

Today, Climate Change is one of the most pressing issues facing humanity. Thanks to changes that have taken place in the past few centuries – i.e. the industrial revolution, population growth, the growth of urban centers and reliance on fossil fuels – humans have had a significant impact on the planet. In fact, many geologists refer to the current era as the “Anthropocene” because humanity has become the single greatest factor affecting planetary evolution.

In the future, populations are expected to grow even further, reaching about 10 billion by mid-century and over 11 billion by 2100. In that time, the number of people who live within urban centers will also increase dramatically, increasing from 54% to 66% by mid-century. As such, the quesiton of how billions of people can live sustainably has become an increasingly important one.

Prof. Frank, who is also the author of the new book Light of the Stars: Alien Worlds and the Fate of the Earth (which draws on this study), conducted this study with his colleagues in order to address the issue Climate Change in an astrobiological context. As he explained in a University of Rochester press release:

“Astrobiology is the study of life and its possibilities in a planetary context. That includes ‘exo-civilizations’ or what we usually call aliens. If we’re not the universe’s first civilization, that means there are likely to be rules for how the fate of a young civilization like our own progresses.”

Using the Anthropocene as an example, one can see how civilization-planet systems co-evolve, and how a civilization can endanger itself through growth and expansion – in what is known as a “progress trap“. Basically, as civilizations grow, they consume more of the planet’s resources, which causes changes in the planet’s conditions. In this sense, the fate of a civilization comes down to how they use their planet’s resources.

In order to illustrate this process Frank and his collaborators developed a mathematical model that considers civilizations and planets as a whole. As Prof. Frank explained:

“The point is to recognize that driving climate change may be something generic. The laws of physics demand that any young population, building an energy-intensive civilization like ours, is going to have feedback on its planet. Seeing climate change in this cosmic context may give us better insight into what’s happening to us now and how to deal with it.”

The model was also based on case studies of extinct civilizations, which included the famous example of what became of the inhabitants of Rapa Nui (aka. Easter Island). According to archaeological studies, the people of the South Pacific began colonizing this island between 400 and 700 CE and its population peaked at 10,000 sometime between 1200 and 1500 CE.

Professor Adam Frank, who led the study in how civilization-planet systems evolve. Credit: University of Rochester photo / J. Adam Fenster

By the 18th century, however, the inhabitants had depleted their resources and the population declined to just 2000. This example raises the important concept known as “carrying capacity”, which is the maximum number of species an environment can support. As Frank explained, Climate Change is essentially how the Earth responds to the expansion of our civilization:

“If you go through really strong climate change, then your carrying capacity may drop, because, for example, large-scale agriculture might be strongly disrupted. Imagine if climate change caused rain to stop falling in the Midwest. We wouldn’t be able to grow food, and our population would diminish.”

Using their mathematical model, the team identified four potential scenarios that might occur on a planet. These include the Die-Off scenario, the Sustainability scenario, the Collapse Without Resource Change scenario, and the Collapse With Resource Change scenario. In the Die-Off scenario, the population and the planet’s state (for example, average temperatures) rise very quickly.

This would eventually lead to a population peak and then a rapid decline as changing planetary conditions make it harder for the majority of the population to survive. Eventually, a steady population level would be achieved, but it would only be a fraction of what the peak population was. This scenario occurs when civilizations are unwilling or unable to change from high-impact resources (i.e. oil, coal, clear-cutting) to sustainable ones (renewable energy).

Four scenarios for the fate of civilizations and their planets, based on mathematical models developed by Adam Frank and his collaborators. Credit: University of Rochester illustration / Michael Osadciw

In the Sustainability scenario, the population and planetary conditions both rise, but eventually come to together with steady values, thus avoiding any catastrophic effects. This scenario occurs when civilizations recognize that environmental changes threaten their existence and successfully make the transition from high-impact resources to sustainable ones.

The final two scenarios  – Collapse Without Resource Change and Collapse With Resource Change – differ in one key respect. In the former, the population and temperature both rise rapidly until the population reaches a peak and begins to drop rapidly – though it is not clear if the species itself survives. In the latter, the population and temperature rise rapidly, but the populations recognizes the danger and makes the transition. Unfortunately, the change comes too late and the population collapses anyway.

At present, scientists cannot say with any confidence which of these fates will be the one humanity faces. Perhaps we will make the transition before it is too late, perhaps not. But in the meantime, Frank and his colleagues hope to use more detailed models to predict how planets will respond to civilizations and the different ways they consume energy and resources in order to grow.

From this, scientists may be able to refine their predictions of what awaits us in this century and the next. It is during this time that crucial changes will be taking place, which include the aforementioned population growth, and the steady rise in temperatures. For instance, based on two scenarios that measured CO2 increases by the year 2100, NASA indicated that global temperatures could rise by either 2.5 °C (4.5 °F) or  4.4 °C (8 °F).

In the former scenario, where CO2 levels reached 550 ppm by 2100, the changes would be sustainable. But in the latter scenario, where CO2 levels reached 800 ppm, the changes would cause widespread disruption to systems that billions of humans depends upon for their livelihood and survival. Worse than that, life would become untenable in certain areas of the world, leading to massive displacement and humanitarian crises.

In addition to offering a possible resolution for the Fermi Paradox, this study offers some helpful advice for human beings. By thinking of civilizations and planets as a whole – be they Earth or exoplanets – researchers will be able to better predict what changes will be necessary for human civilization to survive. As Frank warned, it is absolutely essential that humanity mobilize now to ensure that the worst-case scenario does not occur here on Earth:

“If you change the earth’s climate enough, you might not be able to change it back. Even if you backed off and started to use solar or other less impactful resources, it could be too late, because the planet has already been changing. These models show we can’t just think about a population evolving on its own. We have to think about our planets and civilizations co-evolving.”

And be sure to enjoy this video that addresses Prof. Frank and his team’s research, courtesy of the University of Rochester:

Further Reading: University of Rochester, Astrobiology

Breakthrough Starshot is Now Looking for the Companies to Build its Laser-Powered Solar Sails to Other Stars

In 2015, Russian billionaire Yuri Milner established Breakthrough Initiatives, a non-profit organization dedicated to enhancing the search for extraterrestrial intelligence (SETI). In April of the following year, he and the organization be founded announced the creation of Breakthrough Starshot, a program to create a lightsail-driven “wafercraft” that would make the journey to the nearest star system – Proxima Centauri – within our lifetime.

In the latest development, on Wednesday May 23rd, Breakthrough Starshot held an “industry day” to outline their plans for developing the Starshot laser sail. During this event, the Starshot committee submitted a Request For Proposals (RFP) to potential bidders, outlining their specifications for the sail that will carry the wafercraft as it makes the journey to Proxima Centauri within our lifetimes.

As we have noted in several previous articles, Breakthrough Starshot calls for the creation of a gram-scale nanocraft being towed by a laser sail. This sail will be accelerated by an Earth-based laser array to a velocity of about 60,000 km/s (37,282 mps) – or 20% the speed of light (o.2 c). This concept builds upon the idea of a solar sail, a spacecraft that relies on solar wind to push itself through space.

An artist’s illustration of a light-sail powered by a radio beam (red) generated on the surface of a planet. Credit: M. Weiss/CfA

At this speed, the nanocraft would be able to reach the closest star system to our own – Proxima Centauri, located 4.246 light-years away – in just 20 years time. Since its inception, the team behind Breakthrough Starshot has invested considerable time and energy addressing the conceptual and engineering challenges such a mission would entail. And with this latest briefing, they are now looking to move the project from concept to reality.

In addition to being the Frank B. Baird, Jr. Professor of Science at Harvard University, Abraham Loeb is also the Chair of the Breakthrough Starshot Advisory Committee. As he explained to Universe Today via email:

“Starshot is an initiative to send a probe to the nearest star system at a fifth of the speed of light so that it will get there within a human lifetime of a couple of decades. The goal is to obtain photos of exo-planets like Proxima b, which is in the habitable zone of the nearest star Proxima Centauri, four light years away. The technology adopted for fulfilling this challenge uses a powerful (100 Giga-watt) laser beam pushing on a lightweight (1 gram) sail to which a lightweight electronics chip is attached (with a camera, navigation and communication devices). The related technology development is currently funded at $100M by Yuri Milner through the Breakthrough Foundation.”

In addition to outlining BI’s many efforts to find ETI – which include Breakthrough Listen, Breakthrough Message and Breakthrough Watch – the RFP focused on Starshot’s Objectives. As was stated in the RFP:

“The scope of this RFP addresses the Technology Development phase – to explore LightSail concepts, materials, fabrication and measurement methods, with accompanying analysis and simulation that creates advances toward a viable path to a scalable and ultimately deployable LightSail.”

A phased laser array, perhaps in the high desert of Chile, propels sails on their journey. Credit: Breakthrough Initiatives

As Loeb indicated, this RFP comes not long after another “industry day” that was related to the development of the technology of the laser – termed the “Photon Engine”. In contrast, this particular RFP was dedicated to the design of the laser sail itself, which will carry the nanocraft to Proxima Centauri.

“The Industry Day was intended to inform potential partners about the project and request for proposals (RFP) associated with research on the sail materials and design,” added Loeb. “Within the next few years we hope to demonstrate the feasibility of the required sail and laser technologies. The project will allocate funds to experimental teams who will conduct the related research and development work. ”

The RFP also addressed Starshot’s long-term goals and its schedule for research and development in the coming years. These include the investment in $100 million over the next five years to determine the feasibility of the laser and sail, to invest the value of the European Extremely Large Telescope (EELT) from year 6 to year 11 and build a low-power prototype for space testing, and invest the value of the Large Hardon Collider (LHC) over a 20 year period to develop the final spacecraft.

“The European Extremely Large Telescope (EELT) will cost on order of a billion [dollars] and the Large Hadron Collider cost was ten times higher,’ said Loeb. “These projects were mentioned to calibrate the scale of the cost for the future phases in the Starshot project, where the second phase will involve producing a demo system and the final step will involve the complete launch system.”

Artist’s impression of Proxima b, which was discovered using the Radial Velocity method. Credit: ESO/M. Kornmesser

The research and development schedule for the sail was also outlined, with three major phases identified over the next 5 years. Phase 1 (which was the subject of the RFP) would entail the development of concepts, models and subscale testing. Phase 2 would involve hardware validation in a laboratory setting, while Phase 3 would consist of field demonstrations.

With this latest “industry day” complete, Starshot is now open for submissions from industry partners looking to help them realize their vision. Step A proposals, which are to consist of a five-page summary, are due on June 22nd and will be assessed by Harry Atwater (the Chair of the Sail Subcommittee) as well as Kevin Parkin (head of Parkin Research), Jim Benford (muWave Sciences) and Pete Klupar (the Project Manager).

Step B proposals, which are to consist of a more detailed, fifteen-page summary, will be due on July 10th. From these, the finalists will be selected by Pete Worden, the Executive Director of Breakthrough Starshot. If all goes according to plan, the initiative hopes to launch the first lasersail-driven nanocraft in to Proxima Centauri in 30 years and see it arrive there in 50 years.

So if you’re an aerospace engineer, or someone who happens to run a private aerospace firm, be sure to get your proposals ready! To learn more about Starshot, the engineering challenges they are addressing, and their research, follow the links provided to the BI page. To see the slides and charts from the RFP, check out Starshot’s Solicitations page.

Further Reading: Centauri Dreams, Breakthrough Starshot

If We Do Hear Signals From Aliens, They’re Probably Long Gone

In 1961, famed astrophysics Frank Drake proposed a formula that came to be known as the Drake Equation. Based a series of factors, this equation sought to estimate the number of extra-terrestrial intelligences (ETIs) that would exist within our galaxy at any given time. Since that time, multiple efforts have been launched to find evidence of alien civilizations, which are collectively known as the search for extra-terrestial intelligence (SETI).

The most well-known of these is the SETI Institute, which has spent the past few decades searching the cosmos for signs of extra-terrestrial radio communications. But according to a new study that seeks to update the Drake Equation, a team of international astronomers indicate that even if we did find signals of alien origin, those who sent them would be long dead.

The study, titled “Area Coverage of Expanding E.T. Signals in the Galaxy: SETI and Drake’s N“, recently appeared online. The study was led by Claudio Grimaldi of the Ecole Polytechnique Federale de Lausanne (EPF-Lausanne), with the help of Geoffrey W. Marcy and Nathaniel K. Tellis (a Professor Emeritus and astronomer from the University of California Berkeley, respectively) and Francis Drake himself – who is now a professor emeritus at the SETI Institute and the University of California, Santa Cruz.

Frank Drake writing his famous equation on a white board. Credit: SETI.org

To recap, the Drake Equation states that the number of civilizations in our galaxy can be calculated by multiplying the average rate of star formation in our galaxy (R*), the fraction of stars that have planets ( fp), the number of planets that can support life (ne), the number of planets that will develop life (fl), the number of planets that will develop intelligent life (fl), the number that will develop transmissions technologies (fc), and the length of time that these civilizations will have to transmit signals into space (L).

This can be expressed mathematically as: N = R* x fp x ne x fl x fi x fc x L. For the sake of their study, the team began by making assumptions about two key parameters of the Drake Equation. In short, they assume that civilizations emerge in our galaxy (N) at a constant rate, and that they will not emit electromagnetic radiation (i.e. radio transmissions) indefinitely, but will experience some type of limiting event over time (L).

As Dr. Grimaldi explained to Universe Today via email:

“We assume that hypothetical communicating civilizations (the emitters) send isotropic electromagnetic signals for a certain duration of time L, and that the birthrate of the emissions is constant. Each emission process gives rise to a spherical shell of thickness cL (where c is the speed of light) filled by electromagnetic waves. The outer radii of the spherical shells grow at the speed of light.”

360-degree panorama view of the Milky Way (an assembled mosaic of photographs) by the ESO. Credit: ESO/S. Brunier

In short, they assumed that technologically-advanced civilizations are born and die in our galaxy at a constant rate. However, these civilizations do not produce communications at an indefinite rate, but their communications will still be traveling outwards at the speed of light, where they will be detectable within a certain volume of space. The team then developed a model of our galaxy to determine whether humanity would have any change at detecting these signals.

This model treated alien communications as a donut-shaped (annulus) shell that gradually passes through our galaxy. As Dr. Grimaldi explained:

“We model the Galaxy as a disk. The emitters occupy random positions in the disk. Each spherical shell intersects the disk in annuli. The probability that an annulus crosses any given point of the disk (e.g. the Earth) is just the ratio between the area of the annuli and the area of the galactic disk. The total area of the annuli over the area of the galactic disk gives the mean number (N) of electromagnetic signals that intersect any given point (e.g. the Earth). This mean number is a key quantity, because SETI can detect signals only if these cross the Earth at the time of measurement.”

As they determined from their calculations, two cases emerge from this model based on whether the radiation shells are (1) thinner than the size of the Milky Way or (2) thicker. These correspond to the lifetimes of technologically-advanced civilizations (L), which could be less than or greater than the time it takes for light to cross our Milky Way (i.e. ~100,000 years). As Dr. Grimaldi explained:

“The mean number (N) of signals crossing Earth depends on the signal longevity (L) and their birthrate. We find that N is just L times the birthrate, which coincides with Drake’s N (that is, the mean number of currently emitting civilizations). This result (mean number of signals crossing Earth = Drake’s N) arises naturally from our assumption that the birthrate of signals is constant.”

Photo of the central region of the Milky Way Credit: UCLA SETI Group/Yuri Beletsky, Carnegie Las Campanas Observatory

In the first case, each shell wall would have a thickness smaller than the size of our galaxy and would fill only a fraction of the galaxy’s volume (thus inhibiting SETI detection). However, if there is a high enough birthrate of detectable civilizations, these shell walls may fill our galaxy and even overlap. In the second case, each radiation shell would be thicker than the size of our galaxy, making SETI detection more likely.

From all this, the team also calculated that the average number of E.T. signals crossing Earth at any given time would equal the number of civilizations currently transmitting. Unfortunately, they also determined that the civilizations we would be hearing from would have long since gone extinct. So basically, the civilizations we would be hearing from would not be the same ones that were presently broadcasting.

As Dr. Grimaldi explained, this raises a rather interesting implication when it comes to SETI research:

“Instead of viewing the Drake’s N as a product of probability factors for the development of communicating civilizations, our results imply that Drake’s N is a directly measurable quantity (at least in principle) because it coincides with the mean number of signals crossing Earth.”

For those hoping to find evidence of extra-terrestrial intelligence in our lifetime, this is likely to be a bit discouraging. On the one hand (and depending on the number of alien civilizations that exist in our galaxy), we may have a hard time picking up extra-terrestrial transmissions. On the other, those that we do find may be coming from a civilization that has long since gone extinct.

Radio-telescopes in SETI’s Allen Telescope Array (ATA) hard at work with the Milky Way in the background. Image: SETI

It also means that if any civilization should pick up our radio wave transmissions someday, we won’t be around to meet them. However, it does not rule out the possibility that we will find evidence that intelligent life has existed within our galaxy in the past. In fact, over the course of own our civilization’s lifetime, humanity may find evidence of multiple ETIs that existed at one time.

In addition, none of this negates the possibility of finding evidence of an existing civilization. It’s just not likely we’ll be able to sample their music, entertainment or messages first!

Further Reading: Science News, arXiv, Nature

If We Receive a Message From Aliens, Should We Delete it Without Reading it?

Roughly half a century ago, Cornell astronomer Frank Drake conducted Project Ozma, the first systematic SETI survey at the National Radio Astronomy Observatory in Green Bank, West Virginia. Since that time, scientists have conducted multiple surveys in the hopes of find indications of “technosignatures” – i.e. evidence of technologically-advanced life (such as radio communications).

To put it plainly, if humanity were to receive a message from an extra-terrestrial civilization right now, it would be the single-greatest event in the history of civilization. But according to a new study, such a message could also pose a serious risk to humanity. Drawing on multiple possibilities that have been explored in detail, they consider how humanity could shield itself from malicious spam and viruses.

The study, titled “Interstellar communication. IX. Message decontamination is impossible“, recently appeared online. The study was conducted by Michael Hippke, a independent scientist from the Sonneberg Observatory in Germany; and John G. Learned, a professor with the High Energy Physics Group at the University of Hawaii. Together, they examine some of the foregone conclusions about SETI and what is more likely to be the case.

Frank Drake writing his famous equation on a white board. Credit: SETI.org

To be fair, the notion that an extra-terrestrial civilization could pose a threat to humanity is not just a well-worn science fiction trope. For decades, scientists have treated it as a distinct possibility and considered whether or not the risks outweigh the possible benefits. As a result, some theorists have suggested that humans should not engage in SETI at all, or that we should take measures to hide our planet.

As Professor Learned told Universe Today via email, there has never been a consensus among SETI researchers about whether or not ETI would be benevolent:

“There is no compelling reason at all to assume benevolence (for example that ETI are wise and kind due to their ancient civilization’s experience). I find much more compelling the analogy to what we know from our history… Is there any society anywhere which has had a good experience after meeting up with a technologically advanced invader? Of course it would go either way, but I think often of the movie Alien… a credible notion it seems to me.”

In addition, assuming that an alien message could pose a threat to humanity makes practical sense. Given the sheer size of the Universe and the limitations imposed by Special Relativity (i.e. no known means of FTL), it would always be cheaper and easier to send a malicious message to eradicate a civilization compared to an invasion fleet. As a result, Hippke and Learned advise that SETI signals be vetted and/or “decontaminated” beforehand.

The Arecibo Radio Telescope in Puerto Rico was the site of NASA’s High Resolution Microwave Survey, a search for extraterrestrial radio messages. Credit: US NSF

In terms of how a SETI signal could constitute a threat, the researchers outline a number of possibilities. Beyond the likelihood that a message could convey misinformation designed to cause a panic or self-destructive behavior, there is also the possibility that it could contain viruses or other embedded technical issues (i.e. the format could cause our computers to crash).

They also note that, when it comes to SETI, a major complication arises from the fact that no message is likely to received in only one place (thus making containment possible). This is unlikely because of the “Declaration of Principles Concerning Activities Following the Detection of Extraterrestrial Intelligence”, which was adopted by the International Academy of Astronautics in 1989 (and revised in 2010).

Article 6 of this declaration states the following:

“The discovery should be confirmed and monitored and any data bearing on the evidence of extraterrestrial intelligence should be recorded and stored permanently to the greatest extent feasible and practicable, in a form that will make it available for further analysis and interpretation. These recordings should be made available to the international institutions listed above and to members of the scientific community for further objective analysis and interpretation.”

Voyager included a golden record with images and sounds of Earthly life recorded on it… just in case. Credit: NASA

As such, a message that is confirmed to have originated from an ETI would most likely be made available to the entire scientific community before it could be deemed to be threatening in nature. Even if there was only one recipient, and they attempted to keep the message under strict lock and key, it’s a safe bet that other parties would find a way to access it before long.

The question naturally arises then, what can be done? One possibility that Hippke and Learned suggest is to take a analog approach to interpreting these messages, which they illustrate using the 2017 SETI Decrypt Challenge as an example. This challenge, which was issued by René Heller of the Max Planck Institute for Solar System Research, consisted of a sequence of about two million binary digits and related information being posted to social media.

In addition to being a fascinating exercise that gave the public a taste of what SETI research means, the challenge also sough to address some central questions when it came to communicating with an ETI. Foremost among these was whether or not humanity would be bale to understand a message from an alien civilization, and how we might be able to make a message comprehensible (if we sent one first). As they state:

“As an example, the message from the “SETI Decrypt Challenge” (Heller 2017) was a stream of 1,902,341 bits, which is the product of prime numbers. Like the Arecibo message (Staff At The National Astronomy Ionosphere Center 1975) and Evpatoria’s “Cosmic Calls” (Shuch 2011), the bits represent the X/Y black/white pixel map of an image. When this is understood, further analysis could be done off-line by printing on paper. Any harm would then come from the meaning of the message, and not from embedded viruses or other technical issues.”

The Wow! signal represented as “6EQUJ5”. Credit: Big Ear Radio Observatory/NAAPO

However, where messages are made up of complex codes or even a self-contained AI, the need for sophisticated computers may be unavoidable. In this case, the authors explore another popular recommendation, which is the use on quarantined machines to conduct the analysis – i.e. a message prison. Unfortunately, they also acknowledge that no prison would be 100% effective and containment could eventually fail.

“This scenario resembles the Oracle-AI, or AI box, of an isolated computer system where a possibly dangerous AI is ‘imprisoned’ with only minimalist communication channels,” they write. “Current research indicates that even well-designed boxes are useless, and a sufficiently intelligent AI will be able to persuade or trick its human keepers into releasing it.”

In the end, it appears that the only real solution is to maintain a vigilant attitude and ensure that any messages we send are as benign as possible. As Hippke summarized: “I think it’s overwhelmingly likely that a message will be positive, but you can not be sure. Would you take a 1% chance of death for a 99% chance of a cure for all diseases? One learning from our paper is how to design own message, in case we decide to send any: Keep it simple, don’t send computer code.”

Basically, when it comes to the search for extra-terrestrial intelligence, the rules of internet safety may apply. If we begin to receive messages, we shouldn’t trust those that come with big attachments and send any suspicious looking ones to our spam folder. Oh, and if a sender is promising the cure for all known diseases, or claims to be the deposed monarch of Andromeda in need of some cash, we should just hit delete!

Further Reading: arXiv

Researchers Just Scanned 14 Worlds From the Kepler Mission for “Technosignatures”, Evidence of Advanced Civilizations

When it comes to looking for life on extra-solar planets, scientists rely on what is known as the “low-hanging fruit” approach. In lieu of being able to observe these planets directly or up close, they are forced to look for “biosignatures” – substances that indicate that life could exist there. Given that Earth is the only planet (that we know of) that can support life, these include carbon, oxygen, nitrogen and water.

However, while the presence of these elements are a good way of gauging “habitability”, they are not necessarily indications that extra-terrestrial civilizations exist. Hence why scientists engaged in the Search for Extra-Terrestrial Intelligence (SETI) also keep their eyes peeled for “technosignatures”. Targeting the Kepler field, a team of scientists recently conducted a study that examined 14 planetary systems for indications of intelligent life.

The study, titled “A search for technosignatures from 14 planetary systems in the Kepler field with the Green Bank Telescope at 1.15-1.73 GHz“, recently appeared online and is being reviewed for publication by The Astronomical Journal. The team was led by Jean-Luc Margot, the Chair of the UCLA Department of Earth, Planetary, and Space Sciences (UCLA EPSS) and a Professor with UCLA’s Department of Physics and Astronomy.

The Green Bank Telescope is the world’s largest, fully-steerable telescope, which is currently being used in a new SETI (Search for Extraterrestrial Intelligence) attempt to look for possible alien radio signals from Tabby’s Star. Credit: NRAO/AUI/NSF

In addition to Margot, the team consisted of 15 graduate and undergraduate students from UCLA and a postdoctoral researcher from the Green Bank Observatory and the Center for Gravitational Waves and Cosmology at West Virginia University. All of the UCLA students participated in the 2016 course, “Search for Extraterrestrial Intelligence: Theory and Applications“.

Together, the team selected 14 systems from the Kepler catalog and examined them for technosignatures. While radio waves are a common occurrence in the cosmos, not all sources can be easily attributed to natural causes. Where and when this is the case, scientists conduct additional studies to try and rule out the possibility that they are a technosignature. As Professor Margot told Universe Today via email:

“In our article, we define a “technosignature” as any measurable property or effect that provides scientific evidence of past or present technology, by analogy with “biosignatures,” which provide evidence of past or present life.”

For the sake of their study, the team conducted an L-band radio survey of these 14 planetary systems. Specifically, they looked for signs of radio waves in the 1.15 to 1.73 gigahertz (GHz) range. At those frequencies, their study is sensitive to Arecibo-class transmitters located within 450 light-years of Earth. So if any of these systems have civilizations capable of building radio observatories comparable to Arecibo, the team hoped to find out!

Spring 2016 UCLA SETI class with Larry Lesyna. Credit: UCLA

“We searched for signals that are narrow (< 10 Hz) in the frequency domain,” said Margot. “Such signals are technosignatures because natural sources do not emit such narrowband signals… We identified approximately 850,000 candidate signals, of which 19 were of particular interest. Ultimately, none of these signals were attributable to an extraterrestrial source.”

What they found was that of the 850,000 candidate signals, about 99% of them were automatically ruled out because they were quickly determined to be the result of human-generated radio-frequency interference (RFI). Of the remaining candidates, another 99% were also flagged as anthropogenic because their frequencies overlapped with other known sources of RFI – such as GPS systems, satellites, etc.

The 19 candidate signals that remained were heavily scrutinized, but none could be attributed to an extraterrestrial source. This is key when attempting to distinguish potential signs of intelligence from radio signals that come from the only intelligence we know of (i.e. us!) Hence why astronomers have historically been intrigued by strong narrowband signals (like the WOW! Signal, detected in 1977) and the Lorimer Burst detected in 2007.

In these cases, the sources appeared to be coming from the Messier 55 globular cluster and the Large Magellanic Cloud, respectively. The latter was especially fascinating since it was the first time that astronomers had observered what are now known as Fast Radio Bursts (FRBs). Such bursts, especially when they are repeating in nature, are considered to be one of the best candidates in the search for intelligent, technologically-advanced life.

The UCLA SETI Group banner, featuring a photo of the central region of the Milky Way Galaxy. Credit: Yuri Beletsky/Carnegie Las Campanas Observatory

Unfortunately, these sources are still being investigated and scientists cannot attribute them to unnatural causes just yet. And as Professor Margot indicated, this study (which covered only 14 of the many thousand exoplanets discovered by Kepler) is just the tip of the iceberg:

“Our study encompassed only a small fraction of the search volume.  For instance, we covered less than five-millionths of the entire sky.  We are eager to scale the effort to sample a larger fraction of the search volume. We are currently seeking funds to expand our search.”

Between Kepler‘s first and second mission (K2), a total of 5,118 candidates and 2,538 confirmed exoplanets have been discovered within our galaxy alone. As of February 1st, 2018, a grand total of 3,728 exoplanets have been confirmed in 2,794 systems, with 622 systems having more than one planet. On top of that, a team of researchers from the University of Oklahoma recently made the first detection of extra-galactic planets as well!

It would therefore be no exaggeration to say that the hunt for ETI is still in its infancy, and our efforts are definitely beginning to pick up speed. There is literally a Universe of possibilities out there and to think that there are no other civilizations that are also looking for us seems downright unfathomable. To quote the late and great Carl Sagan: “The Universe is a pretty big place. If it’s just us, seems like an awful waste of space.”

And be sure to check out this video of the 2017 UCLA SETI Group, courtesy of the UCLA EPSS department:

Further Reading: arXiv

Breakthrough Detects Repeating Fast Radio Bursts Coming from Distant Galaxy

In July of 2015, Russian billionaire Yuri Milner announced the creation of Breakthrough Listen, a decade-long project that would conduct the largest survey to date for signs of extra-terrestrial communications (ETI). As part of his non-profit organization, Breakthrough Initiatives, this survey would rely on the latest in instrumentation and software to observe the 1,000,000 closest stars and 100 closest galaxies.

Using the Green Bank Radio Telescope in West Virginia, the Listen science team at UC Berkeley has been observing distant stars for over a year now. And less than a week ago, they observed 15 Fast Radio Bursts (FRBs) coming from a dwarf galaxy located three billion light-years away. According to a study that described their findings, this was the first time that repeating FRBs have been seen coming from this source at these frequencies.

The team’s study, titled “FRB 121102: Detection at 4 – 8 GHz band with Breakthrough Listen backend at Green Bank“, was recently published in The Astronomers Telegraph. Led by Dr. Vishal Gajjar – a postdoctoral researcher at the University of California, Berkeley – the team conducted a detailed survey of FRB 121102. This repeating FRB source is located in a dwarf galaxy in Auriga constellation, some 3 billion light-years from Earth.

The NSF’s Arecibo Observatory, which is located in Puerto Rico, is the world largest radio telescope. Credit: NAIC

To clarify, FRBs are brief, bright pulses of radio waves that are periodically detected coming from distant galaxies. This strange astronomical phenomena was first detected in 2007 by Duncan Lorimer and David Narkovic using the Parkes Telescope in Australia. To honor their discovery, FRBs are sometimes referred to as “Lorimer Bursts”. Many FRB sources have been confirmed since then, some of which were found repeating.

The source known as FRB 121101 was discovered back on November 2nd, 2012, by astronomers using the Arecibo radio telescope. At the time, it was the first FRB to be discovered; and by 2015, it became the first FRB to be seen repeating. This effectively ruled out the possibility that repeating FRBs were caused by catastrophic events, which had previously been theorized.

And in 2016, FRB 121102 was the first FRB to have its location pinpointed to such a degree that its host galaxy could be identified. As such, the Listen science team at UC Berkeley was sure to add FRB 121102 to their list of targets. And in the early hours of Saturday, August 26th, Dr. Vishal Gajjar – a postdoctoral researcher at UC Berkeley – observed FRB 121102 using the Green Bank Radio Telescope (GBRT) in West Virginia.

Using the Digital Backend instrument on the GBRT, Dr. Gajjar and the Listen team observed FRB 121102 for five hours. From this, they accumulating 400 terabytes of data in the entire 4 to 8 GHz frequency band which they then analyzed for signs of short pulses over a broad range of frequencies. What they found was evidence of 15 new pulses coming from FRB 121102, which confirmed that it was in a newly active state.

The Green Bank Telescope, located in West Virginia. Credit: NRAO

In addition, their observations revealed that the brightest of these 15 emissions occurred at around 7 GHz. This was higher than any repeating FRBs seen to date, which indicated for the first time that they can occur at frequencies higher than previously thought. Last, but not least, the high-resolution data the Listen team collected is expected to yield valuable insights into FRBs for years to come.

This was made possible thanks to the Digital Backend instrument on the GBRT, which is able to record several GHz of bandwidth simultaneously and split the information into billions of individuals channels. This enables scientists to study the proprieties and the frequency spectrum of FRBs with greater precision, and should lead to new theories about the causes of these radio emissions.

So even if these particular signals should prove to not be an indication of extra-terrestrial intelligence, Listen is still pushing the boundaries of what is possible with radio astronomy. And given that Breakthrough Listen is less than two years into its proposed ten-year survey, we can expect many more sources to be observed and studied in the coming years. If there’s evidence of ETI to be found, we’re sure to find out about it sooner or later!

And be sure to check out this video of the Green Bank Telescope and the surveys it allows for, courtesy of Berkeley SETI:

Further Reading: Breakthrough Initiatives