From SETI Institute: “If Extraterrestrials are out there, why haven’t we found them?”

From SETI Institute

Jun 18, 2018
Seth Shostak, Senior Astronomer

The Fermi Paradox, named for Dr. Enrico Fermi, describes the apparent contradiction between the lack of evidence of extraterrestrial civilizations and the high probability that such alien life exists. AP

“Where is everybody?”

For those who want to understand why we haven’t found any space aliens, the Fermi Paradox is as popular as cheeseburgers. First proposed by physicist Enrico Fermi in 1950, this perennial head-scratcher rests on the idea that it would take only a few tens of millions of years for an advanced civilization to colonize the Milky Way — leaving their mark on every last star system in the galaxy.

So why hasn’t some ambitious race of aliens done that? After all, the Milky Way is three times older than Earth, so they’ve had plenty of opportunity to finish the project. We should see outposts of someone’s galactic empire in every direction. Why don’t we?

As Fermi put it, “Where is everybody?”

A Russian physicist named A.A. Berezin recently addressed this cosmic conundrum in a short paper. He thinks he knows why we haven’t espied aliens. Mind you, he’s not the first. The Fermi Paradox has prompted dozens if not hundreds of explanations. One possibility is that colonizing the galaxy is simply too costly. Or maybe alien societies are out there, but we lack the instruments to find them. Others favor the idea that extraterrestrials find Homo sapiens inconsequential and juvenile — so they keep a low profile and avoid us.

Berezin suggests something else. He presumes that at some point in the 13.8 billion years since the Big Bang, an extraterrestrial civilization managed to develop the capability to travel between the stars. Soon thereafter, they embarked on a project to spread out. But as they — or their robot underlings — took over the galaxy, they eradicated everyone else. Some of this might have been inadvertent, in the same way that construction crews mindlessly obliterate ants.

Does this sound like a variation on Douglas Adams’ “Hitchhiker’s Guide to the Galaxy,” in which Earth is unintentionally destroyed to make way for a hyperspace bypass? Well, it’s the same basic idea. But unlike Adams’ story, Berezin’s doesn’t make much sense. To begin with, it’s unclear how this suggestion really differs from the original paradox. If some ancient society of Galactans took over our galaxy (and maybe all the nearby galaxies too — there’s been time enough), why don’t we see evidence of that?

By 200 A.D., the Roman Empire had infested nearly all the lands edging the Mediterranean. If you were living within the empire, you’d definitely know it — you could find fluted architecture just about everywhere. So if the Galactans have been all over the place, why don’t we notice? In addition, these hypothesized alien colonists couldn’t just sweep through the Milky Way once and leave it at that. A new species — such as Homo sapiens — might arise at any time, offering a new challenge to imperial dominance and forcing the Galactans to clean house again.

Keeping control of the galaxy would be an endless project, and one that couldn’t be managed from some central “headquarters.” Even at the speed of light, it takes tens of thousands of years to get from one random spot in the Milky Way to another. Compare that to the response time for Rome — the time between learning that there was trouble afoot and getting their armies in place to confront it. That was typically weeks, not tens of thousands of years.

Ask yourself: Would the Roman Empire have existed if the legions took centuries or more to trudge to Germania every time the troublesome Alemanni crossed the Rhine? Germania would cease being Roman before you could say “barbarian.”

It seems clear that Galactans would have to adopt the Roman strategy: Station some defensive infrastructure throughout the Milky Way so it’s possible to deal with problems quickly. Sounds easy, but it would present a difficult logistical problem. How do you adequately maintain and update such a massive network when travel times are measured in millennia?

Berezin’s idea of how to resolve the puzzle presented by the Fermi Paradox seems neither more convincing nor more plausible than many of the others. It replaces one paradox with another by arguing that the galaxy is, indeed, inhabited everywhere by a pervasive culture that presumably sprang up billions of years ago but somehow manages to evade all our detection efforts.

The paradox continues to fuel many lunchtime conversations, which at least is a nice diversion from gossip or politics. But if we someday find a signal from space, Fermi’s question will become nothing more than an historical curiosity — a bit of misplaced musing that confounded Homo sapiens for a few decades.

Meanwhile the aliens — and who could doubt they exist? — keep their own company.

Originally published at https://www.nbcnews.com/mach/science/if-space-aliens-are-out-there-why-haven-t-we-ncna881951

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From SETI Institute: “Scientists say space aliens could hack our planet”

SETI Institute

February 26, 2018 [What took so long to get this into social media?]
Seth Shostak, Senior Astronomer

The 64-meter radio telescope at Parkes Observatory, Image credit CSIRO

With all the news stories these days about computer hacking, it probably comes as no surprise that someone is worried about hackers from outer space. Yes, there are now scientists who fret that space aliens might send messages that worm their way into human society — not to steal our passwords but to bring down our culture.

How exactly would they do that? Astrophysicists Michael Hippke and John Learned argue in a recent paper that our telescopes might pick up hazardous messages sent our way — a virus that shuts down our computers, for example, or something a bit like cosmic blackmail: “Do this for us, or we’ll make your sun go supernova and destroy Earth.” Or perhaps the cosmic hackers could trick us into building self-replicating nanobots, and then arrange for them to be let loose to chew up our planet or its inhabitants.

Mind you, making a small star like the sun go supernova would be a mind-boggling trick — one that would impress astrophysicists (if any were left). As for the nanobots, I figure the aliens need only wait a century or two, and we’ll make the little devils ourselves, without any help.

LIKE THREATENING NEANDERTHALS

It’s indisputable that space aliens, if they do exist, might not be friendly. But it’s hard to think of things that we could do for agile, technically sophisticated aliens that they couldn’t accomplish more easily on their own. Imagine modern humans threatening Neanderthals with nuclear war unless they washed our cars. Would that make any sense?

The astrophysicists also suggest that the extraterrestrials could show their displeasure (what did we do?) by launching a cyberattack. Maybe you’ve seen the 1996 film “Independence Day,” in which odious aliens are vanquished by a computer virus uploaded into their machinery. That’s about as realistic as sabotaging your neighbor’s new laptop by feeding it programs written for the Commodore 64.

In other words, aliens that could muster the transmitter power (not to mention the budget) to try wiping us out with code are going to have a real compatibility problem. The Stuxnet virus that took out Iran’s enrichment centrifuges was designed to target a contemporary bit of software: the Windows operating system.

If these nasty aliens are more than 40 light-years away, they won’t know that we have personal computers, let alone which operating system they should target. If they’re more than 80 light-years away, they won’t know that we have computers of any kind.

Maybe they’ll try to disable our abacuses.

A DANGEROUS GIFT

It’s worth remarking that today’s SETI experiments — in which large antennas are used to search for signals from alien societies — are largely impervious to any of this chicanery. SETI receivers integrate incoming signals (which is to say, they average them) over seconds or minutes. That would turn any message into digital goo, and no pernicious content would remain. Yes, that’s a technical point, but I think it’s highly unlikely we’ll ever have computers susceptible to Klingon code.

Yet there is a way that messages from space might be disruptive. Extraterrestrials could simply give us some advanced knowledge — not as a trade, but as a gift. How could that possibly be a downer? Imagine: You’re a physicist who has dedicated your career to understanding the fundamental structure of matter. You have a stack of reprints, a decent position, and a modicum of admiration from the three other specialists who have read your papers. Suddenly, aliens weigh in with knowledge that’s a thousand years ahead of yours. So much for your job and your sense of purpose.

If humanity is deprived of the opportunity to learn things on its own, much of its impetus for novelty might evaporate. In a society where invention and discovery are written out of the script, progress and improvement would suffer.

Then again, aliens would likely have real trouble transmitting knowledge to us. In movies, extraterrestrials often communicate with us in colloquial English. But a real message from space is likely to be no more understandable than a digital TV signal would be to Guglielmo Marconi. An alien transmission is unlikely to be a Trojan horse — but it would at least tell us that there’s someone outside the gates.

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From Futurism: “Phoning Home: Is Intelligent Alien Life Really Out There?”

Futurism

January 31, 2018
Seth Shostak, SETI Institute

Tag Hartman-Simkins/Stellan Johnson

Despite an observable universe sprinkled with several trillion galaxies, each stuffed with a trillion planets, we see no evidence of anyone. No signals, no megastructures, no interstellar rockets. While astronomers routinely uncover puzzling objects in the sky, these always turn out to be manifestations of natural phenomena.

Without mincing words, we can state that the cosmos has offered us no hint of the presence of beings as clever as, or cleverer than, Homo sapiens.

It’s tempting to jump from this observational fact to a disappointing conclusion: There’s no one out there. That’s not to say that the universe is sterile. Most astrobiologists seem comfortable with the premise that life might be widespread. But their optimism doesn’t always extend to complex, intelligent life.

It’s possible that we inhabit a universe whose occupants are mostly pond scum. After decades of seeing semi-humanoid aliens strut across the silver screen, it would be more than a little disappointing to think that the actual cosmic bestiary largely consists of plants and animals that are microscopic, or at best, no smarter than cane toads.

That situation would make humans very special, a circumstance that seems at odds with the enormous amount of real estate available for life, as well as the billions of years since the Big Bang during which intelligence could arise.

So, could there be a plausible explanation for why the universe seems so short on keen-witted company?

Filtering Out Intelligent Life

Economist Robin Hanson has suggested that life inevitably encounters a barrier on its evolutionary path to thinking critters – a Great Filter that keeps down the average IQ of the universe.

What could this barrier be? Perhaps life itself is rare because it’s difficult to cook up in the first place. Maybe the transition from single-celled to multi-celled organisms is a bridge too far for most ecosystems. Possibly the emergence of intelligence is a fluke, like winning the Powerball, or perhaps all thinking beings inevitably engineer their own destruction shortly after developing technology.

The idea that there are insurmountable hurdles in the path to intelligence leads to an interesting corollary. Consider the possibility that we’ll someday find microbes under the dry surface of Mars, or beneath the frozen ice of a moon like Enceladus or Europa. That would tell us that one hurdle – the origin of life – can be removed from the list. After all, if biology began on both Earth and another nearby world, then it’s a safe bet that it’s commonplace. No strong filter there.

If we were to discover more sophisticated life somewhere, perhaps equivalent to trilobites or dinosaurs, that would also eliminate some of the postulated filters. Indeed, Nick Bostrom, at Oxford University, has said that it would be horrifyingly bad news to find such complex organisms on another world. Doing so would tell us that the Great Filter is in our future, not our past, and we are doomed. Homo sapiens will come up against a wall that keeps us from extending our dominion beyond Earth. Our species, as lovely and promising as it is, would would have a destiny that is short and dismal.

The appeal of the Great Filter idea is that it takes a fairly limited observation – we don’t see any evidence of aliens in the night sky – and draws an astounding (if dystopian) conclusion about humanity’s destiny.

Could the Great Filter Theory be Full of Holes?

One could argue whether the various hurdles that have been suggested are really all that daunting. For example, the claim that the evolutionary step from insensate creatures to thinking beings could be incredibly unlikely.

A premise of the Rare Earth hypothesis, put forward in a book by Peter Ward and Don Brownlee, published nearly two decades ago, is that the physical conditions of our planet are both finely tuned for our existence and seldom encountered elsewhere. Yes, smart creatures arose on Earth, but that’s because our planet is really special. However, the recent detection of thousands of planets around other stars suggests that terrestrial worlds are hardly in short supply. If there is a Great Filter, it’s not likely to be lack of suitable habitats.

Other suggested barriers to intelligence are less easily dismissed because they depend as much on sociology as on astronomy. Many people seem almost proud to bray that humanity is going to Hades in a handbasket. If nuclear war doesn’t do us in, climate change will. But given that we have at least a chance of being smart about these threats and avoiding total self-destruction, it seems pretty clear that some reasonable fraction of alien societies will also be able to keep themselves alive and kicking for the long term.

Indeed, it’s my opinion that the Great Filter idea falters not on the merits or otherwise of the proposed filters, but on the initial premise: Namely that, because we don’t see any evidence for other intelligence, we require some general mechanism to keep the cosmos short on sentience. Sure, it’s amusing to enumerate some of the difficulties in going from murky chemical soup to space-faring beings, but it seems far more likely that the problem here is a too-hasty conclusion about the prevalence of cosmic confreres.

The efforts to find radio and light signals from other worlds, known as SETI (the Search for Extraterrestrial Intelligence), has so far failed to uncover any hailing signals from aliens. But these experiments are both underfunded and still in their early days. Even if the universe is chock-a-block with transmitting societies, SETI could easily miss them, simply because of inadequate instrument sensitivity or the fact that only a small number of star systems have yet to be searched.

A common, and regrettable, error is committed when people note that the SETI scientists have been toiling for more than 50 years without a discovery, as if that suggests that intelligence is rare. It doesn’t. Throughout most of that period, observations were restricted by the lack of telescope time or by receivers that could only examine small slices of the radio dial.

In addition, it’s worth remarking that humanity is in the process of developing artificial intelligence, a technological trajectory that other sophisticated societies could very well follow. Unlike biological intelligence, AI can self-improve at tremendous speed. Also, there aren’t obvious limitations to the spread of machines throughout the cosmos. The implication of this observation is that the majority of the intelligence in the universe is likely to be synthetic. And machine intelligence might be small, localized, and cryptic.

The absence of evidence would hardly qualify as evidence of absence. The Great Filter theory, in other words, could be no more than an appealing solution looking for a problem.

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From Nautilus: “Why We’ll Have Evidence of Aliens—If They Exist—By 2035”

Nautilus

Oct 04, 2017

SETI astronomer Seth Shostak

Seth Shostak

SETI Institute

The search for alien technology is about to get much more efficient. No image credit.

I’ve bet a cup of coffee to any and all that by 2035 we’ll have evidence of E.T. To many of my colleagues, that sounds like a losing proposition. For more than a half-century, a small coterie of scientists has been pursuing the Search for Extraterrestrial Intelligence, or SETI. And we haven’t found a thing.

I’m optimistic by nature—as a scientist, you have to be. But my hopeful feeling is not wishful thinking; it is firmly grounded in the logic of SETI.

Half a century sounds like a long time, but the search is truly in its early days. Given the current state of SETI efforts and abilities, I feel that we’re on the cusp of learning something truly revolutionary.

Most of our experiments so far have used large radio antennas in an effort to eavesdrop on radio signals transmitted by other societies, an approach that was dramatized by Jodie Foster in the 1997 movie Contact.

NAIC/Arecibo Observatory, Puerto Rico, USA

SETI@home, BOINC project at UC Berkeley Space Science Lab

Anybody out there: Jodie Foster as Ellie Arroway in the 1997 movie Contact, which was based on the bestseller by Carl Sagan. Getty Images

Unlike other alien potboilers, Contact’s portrayal of how we might search for extraterrestrials was reasonably accurate. Nonetheless, that film reinforced the common belief that SETI practitioners paw through cosmic static looking for unusual patterns, such as a string of prime numbers. The truth is simpler: We have been searching for narrow-band signals. “Narrow-band” means that a large fraction of the transmitter power is squeezed into a tiny part of the radio dial, making the transmission easier to find. This is analogous to the way a laser pointer, despite having only a few milliwatts of power, nonetheless looks bright because the energy is concentrated into a narrow wavelength range.

A modern SETI receiver simultaneously examines tens or even hundreds of millions of channels, each having a cramped 1-hertz bandwidth. That bandwidth is 5 million times narrower than a TV signal and lacks the capacity to carry information—a message. But the idea is to first discover aliens that are on the air, after which a far larger instrument would be built to dig out any modulation.

To aim our antennas, SETI has traditionally used two approaches. One is to scan as much of the sky as possible; the other is to zero in on nearby star systems. You might think that the former would have an edge, since it makes no assumptions about where the aliens might be hanging out. But a sky survey spends most of its time looking at empty space. If you subscribe to the conventional view that extraterrestrials will most likely be ensconced on planets or moons, then it’s better to devote precious telescope time to examining nearby star systems.

One current targeted search is the SETI Institute’s red dwarf survey, which takes place at the Allen Telescope Array, an ensemble of 42 antennas hunkered down in the California Cascades.

SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA

We are going down a list of 20,000 small stars that are prime candidates for hosting habitable planets. These ruddy runts are both numerous and, on average, old. Most have been around for billions of years, the time it took life on Earth to evolve from microscopic slime to high-tech hominids. Astronomers estimate that roughly one-half of all red dwarfs might have a rocky world in the habitable zone, where temperatures would abide liquid water.

The SETI Institute is not the only band of alien hunters. Buoyed by a large infusion of money from the Russian billionaire Yuri Milner, the SETI group at the University of California, Berkeley, is renting time on the Green Bank Telescope in West Virginia and the Parkes Radio Telescope in the sheep country west of Sydney, Australia. Their decade-long project, known as Breakthrough Listen, also homes in on individual star systems.

Breakthrough Listen Project

Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

GBO radio telescope, Green Bank, West Virginia, USA

CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

By Hilary Lebow

The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

“Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

UCSC alumna Shelley Wright, now an assistant professor of physics at UC San Diego, discusses the dichroic filter of the NIROSETI instrument. (Photo by Laurie Hatch)

Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

“The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

“We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

“This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

“Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.

While these efforts are broadly similar to what’s been done for decades, they are not your daddy’s SETI. The rapid growth in digital processing means that far larger swaths of the radio dial can be examined at one go and—in the case of the Allen array—many star systems can be checked out simultaneously. The array now examines three stars at once, but additional computer power could boost that to more than 100. Within two decades, SETI experiments will be able to complete a reconnaissance of 1 million star systems, which is hundreds of times more than have been carefully examined so far. SETI practitioners from Frank Drake to Carl Sagan have estimated that the galaxy currently houses somewhere between 10,000 and a few million broadcasting societies.

Carl Sagan

Frank Drake

Drake Equation, Frank Drake, Seti Institute

If these estimates are right, then examining 1 million star systems could well lead to a discovery. So, if the premise of SETI has merit, we should find a broadcast from E.T. within a generation. That would spare me the expense of buying you a cup of coffee.

Furthermore, scientists have been diversifying. For two decades, some SETI researchers have used conventional optical telescopes to look for extremely brief laser flashes coming from the stars. In many ways, aliens might be more likely to communicate by pulsed light than radio signals, for the same reason that people are turning to fiber optics for Internet access: It can, at least in principle, send 100,000 times as many bits per second as radio can. These so-called optical SETI experiments have been limited to looking at one star system at a time. But like their radio cousins, they’re poised to become speedier as new technology allows them to survey ever-wider tracts of sky.

NEUTRINOS IN THE ICE: The IceCube neutrino observatory in Antarctica has been searching for energetic cosmic neutrinos, which some astronomers have proposed—probably quixotically—as a medium for extraterrestrial communications.NSF/B. Gudbjartsson

Physicists have also proposed wholly new modes of communications, such as neutrinos and gravitational waves. Some of my SETI colleagues have mulled these options, but we don’t see much merit in them at the moment. Both neutrinos and gravitational waves are inherently hard to create and detect. In nature, it takes the collapse of a star or the merger of black holes to produce them in any quantity. The total energy required to send “Hello, Earth” would be daunting, even for a civilization that could command the resources of a galaxy.

IceCube, the University of Wisconsin’s big neutrino detector in Antarctica, is sensitive only to very high-energy particles, which are precisely those that would be costliest to produce.

U Wisconsin ICECUBE neutrino detector at the South Pole

In all the years it has been operating, the instrument has detected a total of a few dozen of these particles, even though it is a cubic kilometer in size. As for gravitational waves, the Laser Interferometric Gravitational-Wave Observatory has been able to detect colliding black holes over the final second of their infall.

VIRGO Gravitational Wave interferometer, near Pisa, Italy

Caltech/MIT Advanced aLigo Hanford, WA, USA installation

Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

ESA/eLISA the future of gravitational wave research

Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

It is hard to imagine that aliens would go to the trouble of smashing together two huge black holes for a second’s worth of signal.

But there is a completely different approach that has yet to be explored in much detail: to look for artifacts—engineering projects of an advanced society. Some astronomers have suggested an alien megastructure, possibly an energy-collecting Dyson sphere, as the explanation for the mysterious dimming of Tabby’s star (officially known as KIC 8462852). It is a serious possibility, but no evidence has yet been found to support it.

This artist’s concept shows a swarm of comets passing before a star. NASA / JPL-Caltech

It’s also conceivable that extraterrestrials could have left time capsules in our own solar system, perhaps millions or billions of years ago, on the assumption that our planet might eventually evolve a species able to find them. The Lagrange points in the Earth-moon system—locations where the gravity of Earth, moon, and sun are balanced, so that an object placed there will stay there—have been suggested as good hunting grounds for alien artifacts, as has the moon itself.

LaGrange Points map. NASA

Another idea is that we should search for the high-energy exhausts of interstellar rockets. The fastest spacecraft would presumably use the most efficient fuel: matter combining with antimatter. Their destructive “combustion” would not only shoot the craft through space at a fair fraction of the speed of light, but would produce a gamma-ray exhaust, which we might detect. Rockets could be sorted out from natural gamma ray sources by their relatively quick motion across the sky.

The appealing thing about artifacts is that finding them is not time-critical. In contrast, to search for signals, you need to activate your instruments at the right time. It doesn’t help to look for radio pings, laser flashes, or neutrino bursts if E.T. reached out to touch us during the reign of the dinosaurs or will do so a hundred million years from now. Artifacts have no such synchronicity problem. That said, looking for artifacts has its own bummer factors. Anything beyond our solar system would need be truly huge to be visible; cousins of the starship Enterprise would be very difficult to find.

SETI is not a traditional science problem in which a hypothesis can be falsified. We can never prove that the aliens are not out there, only that they are. But our ability to search improves with every technological innovation. I compare the situation to the year 1491. European civilization had been around for 2,500 years, yet the Americas were not on any map. Mesoamerican civilization, for its part, had been around for about as long, but also was ignorant of what lay over the oceans. With a glimpse and a shout from a sailor on the Pinta, everything changed.

[No mention of Laser SETI, the latest attempt from The SETI Institute.

Laser SETI

Seth Shostak is the senior astronomer at the SETI Institute. He chaired the International Academy of Astronautics’s SETI Permanent Study Group for a decade and hosts the SETI Institute’s weekly hour-long science radio show, “Big Picture Science.” He is the co-author of a textbook on astrobiology and of Confessions of an Alien Hunter: A Scientist’s Search for Extraterrestrial Intelligence. Follow him on Twitter @SethShostak.

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Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

From Seth Shostak at SETI: “World’s Biggest Radio Ear”

SETI Institute

10.6.16

Seth Shostak

It’s now the biggest single-dish radio telescope on Earth. Settled down in the bumpy karst of China’s Guizhou province, about 1200 miles southwest of Beijing, this newest instrument for studying the heavens is very similar in design to the famed Arecibo dish, renown both for its science accomplishments and its performance in two popular films, “Contact” and “Goldeneye.”

FAST radio telescope located in the Dawodang depression in Pingtang county Guizhou Province, South China

But FAST, the Five hundred meter Aperture Spherical Telescope, is Arecibo on steroids. The latter has a dish diameter of 300 meters, so FAST is, in principle, almost three times more sensitive. Put another way, it can reach 70 percent farther into space with the same sensitivity, which could increase the number of “targets” within its purview by roughly 4.6 times.

These are merely brute-force consequences of FAST’s size, however. This new telescope, which is younger than its Puerto Rican cousin by more than a half-century, is also able to see more of the sky – up to 40 degrees from its “straight overhead”, or zenith, pointing. While Arecibo can track objects for as much as 40 minutes, FAST can do this for as long as 6 hours. That would gain it another factor of three advantage in sensitivity.

In order to keep the telescope free of man-made interference, the government plans to relocate more than 9 thousand people living nearby.

For the first several years, FAST will be in shakedown mode. After that, research on galaxies, pulsars, and other astronomical objects will begin, and foreign researchers will also have access. The Chinese have said that their new telescope will also be used for SETI, making it the most sensitive such device in the world in the frequency range of 70 MHz to 3 GHz. (Note that the Allen Telescope Array, used by the SETI Institute, has extended frequency coverage to 14 GHz.)

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From SETI Institute: “A SETI Signal?”

SETI Institute

8.29.16
Seth Shostak, Senior Astronomer

The RATAN-600 radio telescope, credit: nat-geo.ru

A star system 94 light-years away is in the spotlight as a possible candidate for intelligent inhabitants, thanks to the discovery of a radio signal by a group of Russian astronomers.

HD 164595, a solar system a few billion years older than the Sun but centered on a star of comparable size and brightness, is the purported source of a signal found with the RATAN-600 radio telescope in Zelenchukskaya, at the northern foot of the Caucasus Mountains. This system is known to have one planet, a Neptune-sized world in such a very tight orbit, making it unattractive for life. However, there could be other planets in this system that are still undiscovered.

The signal seems to have been discussed in a presentation given by several Russian astronomers as well as Italian researcher, Claudio Maccone, the chair of the International Academy of Astronautics Permanent SETI Committee. Maccone has recently sent an email to SETI scientists in which he describes this presentation, including the signal ascribed to star system HD 164595.

Could it be a transmission from a technically proficient society? At this point, we can only consider what is known so far. This is a technical story, of course.

First, is the detected signal really coming from the direction of HD 164595? The RATAN-600 is of an unusual design (a ring on the ground of diameter 577 meters), and has an unusual “beam shape” (the patch of sky to which it is sensitive). At the wavelength of the reported signal, 2.7 cm – which is equivalent to a frequency of 11 GHz – the beam is about 20 arcsec by 2 arcmin. In other words, it’s a patch that’s highly elongated in the north-south direction.

The patch from which the signal seems to be coming agrees in the east-west direction (the narrow part of the beam) with HD 165695’s sky coordinates, so that’s the basis of the assumption by the discoverers that this is likely to be coming from that star system. But of course, that’s not necessarily the case.

Second is the question of the characteristics of the signal itself. The observations were made with a receiver having a bandwidth of 1 GHz. That’s a billion times wider than the bandwidths traditionally used for SETI, and is 200 times wider than a television signal. The strength of the signal was 0.75 Janskys, or in common parlance, “weak.” But was it weak only because of the distance of HD 164595? Perhaps it was weak because of “dilution” of the signal by the very wide bandwidth of the Russian receiver? Just as a pot pie, incorporating lots of ingredients, can make guessing the individual foodstuffs more difficult, a wide-bandwidth receiver can dilute the strength of relatively strong narrow-band signals.

Now note that we can work backwards from the strength of the received signal to calculate how powerful an alien transmitter anywhere near HD 164595 would have to be. There are two interesting cases:

(1) They decide to broadcast in all directions. Then the required power is 1020 watts, or 100 billion billion watts. That’s hundreds of times more energy than all the sunlight falling on Earth, and would obviously require power sources far beyond any we have.

(2) They aim their transmission at us. This will reduce the power requirement, but even if they are using an antenna the size of the 1000-foot Arecibo instrument, they would still need to wield more than a trillion watts, which is comparable to the total energy consumption of all humankind.

Both scenarios require an effort far, far beyond what we ourselves could do, and it’s hard to understand why anyone would want to target our solar system with a strong signal. This star system is so far away they won’t have yet picked up any TV or radar that would tell them that we’re here.

Enter the Allen Telescope Array

The chance that this is truly a signal from extraterrestrials is not terribly promising, and the discoverers themselves apparently doubt that they’ve found ET. Nonetheless, one should check out all reasonable possibilities, given the importance of the subject.

Consequently, the Allen Telescope Array (ATA) was swung in the direction of HD 164595 beginning on the evening of August 28. According to our scientists Jon Richards and Gerry Harp, it has so far not found any signal anywhere in the very large patch of sky covered by the ATA.

However, we have not yet covered the full range of frequencies in which the signal could be located, if it’s of far narrower bandwidth than the Russian 1 GHz receiver. We intend to completely cover this big swath of the radio dial in the next day or two. A detection, of course, would immediately spur the SETI and radio astronomy communities to do more follow-up observations.

We will continue to monitor this star system with the Array.

One particularly noteworthy thing about this discovery is the fact that the signal was apparently observed in May, 2015 (it seems that this was the only time in 39 tries that they saw this signal). The discoverers didn’t alert the SETI community to this find until now, which is not as expected. According to both practice and protocol, if a signal seems to be of deliberate and extraterrestrial origin, one of the first things to do is to get others to attempt confirming observations. That was not done in this case.

So what’s the bottom line? Could it be another society sending a signal our way? Of course, that’s possible. However, there are many other plausible explanations for this claimed transmission – including terrestrial interference. Without a confirmation of this signal, we can only say that it’s “interesting.”

See the full article here .

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From Seth Shostak at SETI: “Danger, Will Robinson”

SETI Institute

Seth Shostak, Senior Astronomer

8.2.16

The night sky, at least when you can see it, appears placid, serene and as inviting as a cold brew on a muggy afternoon.

Don’t be fooled. The real universe is a nasty mélange of stuff that’s mostly scorching hot or bitterly cold. The blackness of space is shot through with lethal particles and radiation. Without doubt, the “final frontier,” often depicted as a beguiling playground for our Spandex-attired descendants, is deceptively treacherous.

NASA

Not only that, it’s out to get you.

How’s that? Well, you can start with the usual litany of heavenly harm: Asteroids that can mindlessly cannon our world, revenging their own destruction with ours, or solar flares, which could fatally sicken any humans who dare to rocket themselves to Mars. Then there’s Mars itself, which even on a good day is less hospitable than the worst environment on Earth.

This cast of cosmic unpleasantries is well known. But there are other baddies whose malevolence is on a grander scale.

Consider gravitational waves. Their discovery is trumpeted as perhaps the most significant science result of the past thousand days. The waves themselves are feebler than the Lichtenstein Navy, as anyone who has read about the LIGO instrument knows. But that’s because these waves come from far away. The slight shaking of space-time that made the headlines in February resulted from the collision of two black holes having a combined mass of five dozen suns. Their mutually assured destruction quickly released as much energy as all the stars in our galaxy have belched into space since Aristotle wrote rhetoric.

That prodigious, black hole crash twiddled the cosmos here at Earth, more than a billion light-years from the collision, and it may also have let loose a burst of radiation which, if you were near enough to the action, could ruin your whole planetary day.

It was an explosion of incomparable vigor, and explosions can be dangerous. But you may figure this is someone else’s problem, and maybe not even that. After all, who’s going to be hanging out in the vicinity of a pair of suicidal black holes?

But there’s another threat that’s more worrisome: Gamma Ray Bursts, the result of a slightly different variety of cosmic mishap. When large stars die, they don’t go gently into the night. Single stars can implode, or two small, dead stars can collide. Either way, the resulting black hole is celebrated with a brief flash of gamma rays a million trillion times brighter than the Sun.

Because most of this energy is shot out in two, oppositely directed beams, it’s highly concentrated. It could damage the atmospheres of planets even light-years away, which would be bad news for any biology.

GRBs are not rare. Astronomers find a new one just about every day. And this points out the fact that the universe is a war zone in which random and lethal explosions occur in the star clouds of every galaxy.

This has led some scientists to speculate that the majority of cosmic real estate is essentially a no man’s land for life. A recent suggestion is that GRBs rule out 90 percent of all galaxies for life, and even the Milky Way is probably barren except for its outer realms (where we are).

That may sound like really bad news for biology. But wolves in the forest are bad news too, although there are still plenty of creatures out there. Only 15 percent of Earth’s surface is arable, but nonetheless, there are billions of humans. So sure, most cosmic real estate may be worthless, but that may be OK.

However, the discovery of these mega-dangers does raise a maddening question: Why is the universe set up in such a way that GRBs don’t happen a hundred times more often, or aren’t a hundred times more energetic? After all, if that were the case, you wouldn’t be reading this.

And there would be no one else able to read it either, in all the vast expanse of space.

Are we that lucky? If you believe in multiple universes, then maybe the correct answer to that question is yes. Sure, most of these hypothesized, other universes would be sterile. But not ours: we’re just a winner in the most powerful of powerball lotteries, marveling at our fortune at being in a cosmos that is at least partially habitable.

If this seems too contrived — if you’re not a fan of this idea — then science can’t help you. Yet.

See the full article here .

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From Seth Shostak at SETI: “ATA Checks Out Nearby Planetary System”

SETI Institute

6.22.16

Seth Shostak, Senior Astronomer

Could extraterrestrial intelligence be relatively nearby? With that possibility in mind, the Allen Telescope Array has been used to observe planets around the star Trappist 1 – a target that is a mere 40 light-years distant.

Trappist 1 system. Credit: ESO/M. Kornmesser.

In general, SETI has preferentially swung its antennas in the directions of star systems with known planets, preferably of the potentially habitable variety. Many of these candidate systems were discovered using NASA’s Kepler Space Telescope. The detailed working of that instrument mandate that the discovered exoplanets are at quite large distances, typically between 500 and 1500 light-years.

The consequences of this limitation can be demonstrated in the case of Kepler object KIC 8462852, also known as “Tabby’s Star”. This stellar system is in the news because of the provocative speculation that it might be the site of a megastructure constructed by advanced extraterrestrials, perhaps an ensemble of solar panels for collecting energy. This widespread interest prompted scientists at the SETI Institute to use the Allen Telescope Array to search for radio transmissions coming from its direction. None were found, but because of the considerable distance to this object (1470 light-years), it is impossible to rule out the existence of reasonably powerful transmissions that were – at this remove – simply too weak to be detected.

SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA

By contrast, Trappist 1, which was discovered by a group of exoplanet researchers led from the University of Liege in Belgium, is in our cosmic backyard. It offers a more-than-thousand-fold improvement in sensitivity to any transmissions. The three detected planets around this dim, red dwarf are roughly the same size as the Earth, with orbital periods of a few days to possibly as much as 2-1/2 months. They are, quite obviously, in very tight orbits. But because their host star is so dim, all three could be “habitable” in the sense of (1) being rocky worlds like Earth or Mars, and (2) sporting temperatures that would permit liquid water oceans and an atmosphere. A further, more speculative consideration is that any stellar system with more than one habitable planet could host a civilization for which interplanetary communication links would be important – a possible source of detectable signals.

The Allen Telescope Array is uniquely capable of observing targets of opportunity, so for two days in early May it searched for narrow-band radio signals (~1 Hz or less) coming from the direction of Trappist 1.

This was not an entirely easy task. As Institute engineer Jon Richards notes, “Every day, Trappist 1 passes near the belt of geosynchronous satellites that orbit the Earth, and consequently there’s a lot of signal interference. Without the Array’s unique beamforming scheme and interference mitigation software we would have been stymied in our attempts to observe this system.”

The radio spectrum between 1 and 10 GHz was examined, and no signals above 3 10-24 watts/m2-Hz were found. The import of that upper limit to signal strength can be demonstrated with an example. If Trappist 1 has inhabitants sending a signal in our direction with an antenna 300 m in size (the same as the Arecibo telescope in Puerto Rico), then our observations would be able to find it if the transmitter had a power of 300 kilowatts or more. That is hardly an implausible power level.

See the full article here .

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From Seth Shostak at SETI Institute: “The Other Way to Find Life Out There”

SETI Institute

6.4.26

Seth Shostak, Senior Astronomer, SETI Institute

In the three-way horse race to prove that biology is not just a terrestrial aberration, there’s one steed that many people ignore: sampling the air of distant planets to see if they contain the exhaust gases of life, or in the jargon of astrobiologists, biosignatures.

No image caption. No image credit

Everyone knows the other horses: (1) Finding biology in the solar system by hurling rockets to Mars or some of the moons of Jupiter or Saturn, and (2) expanding our SETI experiments to eavesdrop on radio or laser signals from clever beings on distant worlds.

The former has the advantage that, if microbes have sprung up elsewhere in the solar system, we might be able to bring them back, dead or alive. We’d have aliens on Earth, an idea that would electrify astrobiologists.

The latter horse – SETI – endeavors to discover the most interesting variety of extraterrestrial, namely those that are technically advanced. But a difficulty with SETI is that we need to be aiming our telescopes in the direction of signals while they wash over our planet, neither before nor after. There’s a synchronicity problem.

Bugle call, and the third horse – a contender not hobbled by the inconvenience of synchronicity. Consider: the Earth’s atmosphere is roughly 21 percent oxygen, a consequence of billions of years of photosynthetic activity. Oxygen is an exhaust gas of greenery. You can blame the rusted out-body of that clunker in your driveway on plants.

The neat thing about this is that the oxygen signature in Earth’s air has been present for roughly two billion years. For all that time, oxygen has been broadcasting its existence into space. It could be easily detected by any advanced extraterrestrials with enlightened astronomy budgets, even from vast distances. There’s no synchronicity problem, because this signal lasts for eons.

That’s nag number three’s tempting appeal, and Daniel Angerhausen, a researcher at NASA’s Goddard Spaceflight Center, is betting on it. He’s used telescopes on the ground, in the air, and in orbit to look for the spectral signatures of not just oxygen, but other biology “tells,” such as methane.

The obvious way to do this would be to just train a telescope on an exoplanet – a planet around another star – and analyze the reflected light. That approach is dead obvious but extremely difficult, given that precious few such worlds can be directly imaged with today’s instruments.

Angerhausen’s scheme is to observe exoplanets that regularly pass in front of their home suns. When they do, they cause a slight dimming of the starlight. This is, of course, the technique wielded by NASA’s Kepler telescope to uncover thousands of (still-invisible) worlds. Kepler senses mini-eclipses taking place many hundreds of light-years away.

Angerhausen’s trick is to subtract the spectrum – the rainbow spread of light – from a star when a planet is not passing in front or behind it, from spectra taken when it is. Think about it: Most of the time what your telescope sees is a combination of both starshine and light reflected off the planet. But when the planet is silhouetted in front or hidden behind the star, you only see the starshine. Taking the difference removes the contribution of the star, and leaves you with the spectrum of the planet’s atmosphere.

This is easier to describe than to do, and for all the usual reasons. Stars are bright and planets are dim, so the measurement is maddeningly difficult. Using a space-borne telescope avoids problems introduced by Earth’s churning atmosphere. But telescopes in orbit are generally small, and whatever instruments are on-board are the instruments you’re stuck with.

So Angerhausen has tried another possibility – SOFIA, a cleverly acronymed telescope with a 2.7 meter mirror that rides around in a Boeing 747.

NASA/DLR SOFIA, SOFIA/Forcast, SOFIA GREAT

Cruising through the night at high altitude, this instrument is above 90 percent of Earth’s pesky atmosphere. And when it lands, there’s ample opportunity to change out the instrumentation or make other improvements.

Still, no joy. No clues to alien biology.

So let’s tell it like it is: The biggest telescopes are neither in space nor the stratosphere. They’re on mountain tops, and Angerhausen has tried them. He’s not yet found biology-produced gases in a distant planet’s air with these glassy behemoths, but he has reason to remain sanguine about the chances. He’s counting on the relentless improvement in telescope technology – a trend that can be safely assumed for decades into the future, unless you’re a fan of imminent Armageddon.

So what would it mean if he found, say, oxygen and methane together in some other world’s atmosphere? Sure, you’d have to check carefully to make sure the gases were truly biogenic. And even then, they might only say that there’s chlorophyll or its alien opposite number on that planet: in other words, the extraterrestrials might be no more than salad ingredients.

But if other worlds can spawn lettuce or maybe just algae, there’s at least some chance that they could also grow something a little more interesting. Horse number three may be the race card’s least-known contender, but it has a shot.

See the full article here .

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From INVERSE: “The Search for Extraterrestrial Life Puts Astronomers at Odds, Not in Conflict”

INVERSE

May 3, 2016
Neel V. Patel

Researchers can’t agree on when we’ll find alien life or how we’ll find it. But they are talking it out.

Seth Shostak, director for the Center of SETI Research at the SETI Institute, once told an audience he was speaking to that he bet humans would find signs of extraterrestrial life within two-dozen years. At a panel entitled “When Will We Find Life Beyond Earth? hosted by the SETI Institute today, he doubled-down on that bet. Based on what exoplanet researchers have been discovering these days, he explained, “current wisdom is that one in five stars may be a locale for life.” The reasonable conclusions based on reasonable extrapolation? We’re going to find life soon.

But reason sometimes splinters. What was most remarkable out the panel — other than that it was attended by a murderer’s row of astronomical minds — was how much well reasoned disagreement there was. Even the éminence grises of the SETI community, people who have worked together and seem to respect each other, agree on shockingly little. . The event, however, underscored a truth about extraterrestrial, exoplanet, and astrobiology research that isn’t always expressed well to the public: Scientists in the field agree on fact, but not their significance.

Access mp4 video here . 1 hour 13 minutes

Shostak, in case you haven’t already discerned, is avowedly optimistic about the finding extraterrestrials — especially intelligent extraterrestrials. His life’s work is dedicated to listening in for radio signals originating from an intelligent source, and he’s very encouraged by the direction the research is going.

He analogizes SETI research to looking for a needle in a haystack a daunting task, yes, but only if you dont know what you’re. In his mind, there are three major questions: how big is the haystack, how fast we’re able to look through the haystack, and how many needles there are in the damn thing. Shostak thinks we already have answers to the first two — we know relatively how big the universe is and how many stars there are, and we’re able to scan outer space like never before.

Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

Our speed at conducting SETI experiments doubles every five years — “and they keep getting faster. We will go through a mission star systems,” within the next two-dozen years, so hes holding tight to his bet.

So the only question is, how many needles are there anyway — i.e. how many alien civilizations are out there?

That’s a question better suited for the the other three panelists. Up next: Fergal Mullally, a scientist working with the Kepler Space Telescope at NASA’s Ames Research Center.

NASA/Kepler Telescope

Given his role, Mullally is primarily interested in exoplanets. He thinks the data from Kepler has created two major effects.

The first: “In our galaxy, we now know there are more planets than stars out there,” he says.

Milky Way NASA/JPL-Caltech /ESO R. Hurt

Whereas we previously thought of planets as a rare phenomenon, “we now know [planets] are very common.” And the data shows that an estimated two to 25 percent of those star systems are thought to have an Earth-like planet.

That’s incredible, but lets remember that’s a huge range. Plus, the definition of “Earth-like” encompasses a lot. When scientists use that phrase, they aren’t talking about blue oceans, rolling green hills, and amber waves of grain. They might simply be talking about the bare-bone things that make Earth, well, Earth — liquid water, an atmosphere with some trace amounts of oxygen, a rocky surface, and temperatures that aren’t boiling or causing water to instantly freeze. It’s not a settled science, said Mullally.

Meanwhile, you have Nathalie Cabrol, an astrobiologist and the director for the Carl Sagan Center at the SETI Institute, specializes in an understanding of what we might find in the solar system.

Our Solar system, NASA/Chandra

And for her, the key potential demographic of alien life is microbes. “You do have to think of life as a continuum,” says Cabrol — and that means remembering that life starts out as primitive, single-celled organisms.

Cabrol may be the most vocal enthusiast about astrobiological research on Mars than any other scientists. “This is the first place where we have started to look at habitability,” said Cabrol. “And were going to start to look for life [there] soon, actually.

Last but not least, the panel feature Mark Showalter, the senior research scientists at the SETI Institute, in the role of skeptic. According to him, life on other planets might be extremely common, or extremely rare. “We don’t know” he said. He emphasizes that it took two billion years to go from single-celled bacterial to multi-cellular humans. And he questions the logic that intelligence is foreordained. When you take into account energy and metabolism, “big brains are not the natural end state of evolution, he said.

Overall, Showalter thinks we need to take into account the mathematical biases that run contrary to the optimism espoused by the other three panelists. In a tongue-in-cheek compromise, he expressed his belief the odds of finding E.T. were 50-50.

Nevertheless, the search for alien life will continue with unbridled excitement. And how could it not? We’re finding more and more exoplanets that look that might be habitable in some capacity.

Habitable planets Current Potential Planetary Habitability Laboratory U Puerto Rico Arecibo

Even private citizens are gearing up to get in on the search, such as in the recent launch of the Breakthrough Starshot initiative.

What’s perhaps most exciting, however, is that we don’t know what might stumble upon. The possibilities are nearly endless. “We are searching for something we don’t know,” Cabrol told the audience Tuesday. And, in a sense, that’s always been true.

See the full article here .

Please help promote STEM in your local schools.

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