BLOGS

The Bulletin of the Atomic Scientists shifted the Doomsday Clock to 90 seconds to midnight at a news conference in January 2023. From left, Siegfried Hecker, Daniel Holz, Sharon Squassoni, Mary Robinson and Elbegdorj Tsakhia (Photo credit: Patrick Semansky).

Topics: Astrobiology, Civilization, Existentialism, Science Fiction, SETI, Space Exploration

A few weeks ago, I posted “Wine of Consciousness” on Friday without commentary. There were many directions I could have taken. I did want to see how readers would react. As I postulated, the viewership was limited. There were many directions that I COULD have taken the post. Still, I decided every iteration was getting a little too “pop science” for my taste, and that can quickly cross over into pseudo without critical thinking.

Avi Loeb is popularly known for his hypothesis that Oumuamua (“scout” in Polynesian) wasn’t a meteor or comet but a possible extraterrestrial probe sent by an intelligence with a similar understanding of physics and the limitations of intergalactic travel: without something like 99% the speed of light (warp velocity is still the providence of science fiction), such journeys are not possible within the normal span of lifetimes. Dr. Loeb is a theoretical physicist in the Department of Astronomy at Harvard.

I’m from the generation that grew up hearing about “UFOs” (unidentified flying objects), “flying saucers,” and “little green men.” Green succumbed to gray, grey, or “the grays/greys” (E.T.: The Extra-Terrestrial), and now we’re discussing UAPs (unidentified aerial phenomena).

Another theoretical physicist has tackled the challenge by publishing another book: “UFOs: Unidentified Aerial Phenomena: Observations, Explanations, and Speculations (Paperback)” in what appears to be a lucrative cottage industry.

When someone asks me if I believe there is life elsewhere in the universe, I will say yes. Amoeba is life, bacteria is life, viruses: the jury is still out on whether or not they are alive in the biological sense.

I have often wondered if intelligence is its own Entropy: that the very systems any sentient species would create for itself in governing resources, governments, commerce, and space exploration would be its undoing, which might answer The Fermi Paradox.

The hope of extraterrestrials existing and interacting with Earth mortals might be a cultural wish: a hope that despite our alarming tendency to screw things up, we either might survive our boundless hubris, or SOMEONE will save us from our stupidity, Deus ex machina, or benevolent Vulcans.

Homo Sapiens is Latin for “wise men.”

Homo Stultus (“stupid men”) seems more apropos.

Is a More Advanced Civilization an Oxymoron? Avi Loeb, Medium

Life on other planets might not look like any beings we’re used to on Earth. It may even be unrecognizable at first to scientists searching for it. Credit: William Hand

Topics: Astrobiology, Astronomy, Astrophysics, Planetary Science, SETI, Space Exploration

Sarah Stewart Johnson was a college sophomore when she first stood atop Hawaii’s Mauna Kea volcano. Its dried lava surface differed from the eroded, tree-draped mountains of her home state of Kentucky. Johnson wandered away from the other young researchers she was with and toward a distant ridge of the 13,800-foot summit. Looking down, she turned over a rock with the toe of her boot. To her surprise, a tiny fern lived underneath it, sprouting from ash and cinder cones. “It felt like it stood for all of us, huddled under that rock, existing against the odds,” Johnson says.

Her true epiphany, though, wasn’t about the hardiness of life on Earth or the hardships of being human: It was about aliens. Even if a landscape seemed strange and harsh from a human perspective, other kinds of life might find it quite comfortable. The thought opened up the cosmic real estate and the variety of life she imagined might be beyond Earth’s atmosphere. “It was on that trip that the idea of looking for life in the universe began to make sense to me,” Johnson says.

Later, Johnson became a professional at looking. As an astronomy postdoc at Harvard University in the late 2000s and early 2010s, she investigated how astronomers might use genetic sequencing—detecting and identifying DNA and RNA—to find evidence of aliens. Johnson found the work exciting (the future alien genome project!), but it also made her wonder: What if extraterrestrial life didn’t have DNA, RNA, or other nucleic acids? What if their cells got instructions in some other biochemical way?

As an outlet for heretical thoughts like this, Johnson started writing in style too lyrical and philosophical for scientific journals. Her typed musings would later turn into the 2020 popular science book The Sirens of Mars. Inside its pages, she probed the idea that other planets were truly other. So their inhabitants might be very different, at a fundamental and chemical level, from anything in this world. “Even places that seem familiar—like Mars, a place that we think we know intimately—can completely throw us for a loop,” she says. “What if that’s the life case?”

The Search for Extraterrestrial Life as We Don’t Know It, Sarah Scoles, Scientific American

Searches for alien civilizations often involve listening for radio transmissions from distant stars, but the possible extraterrestrial origins of UFOs have some scientists looking closer to home. Credit: Luc Novovitch/Alamy Stock Photo

Topics: Astrophysics, NASA, SETI

I was startled, to say the least, that this story appears in Scientific American, and that NASA and theoretical astrophysicist Avi Loeb is interested in it. The nut job "giggle factor" has given way to curiosity about things humans cannot explain, and that bothers us as a species.

My concern is if the question "are we alone?" has the answer "we are not," the next question is "why Earth?" What if the answer is "because we're someone's territory," and they regard Homo Sapiens (the only race we truly are) as a bipedal herd? That gives for the pilots of UAPs (if any found) humanity the same regard as we give a frog on a dissecting table.

On June 9, with only a few hours' notice, NASA held a press conference to announce a study it was commissioning on unidentified aerial phenomena (UAPs). The acronym is a rebranding of what is more popularly known as unidentified flying objects, or UFOs, a topic usually associated with purported extraterrestrial visitations and government conspiracy theories. The question on the public’s mind was why one of the U.S.’s premier scientific agencies was getting involved in something often considered to be at the farthest fringes of respectability.

Yet the pronouncement also fit in with the suddenly more open-minded zeitgeist regarding UAPs. Last year saw the publication of a much-anticipated report on the Department of Defense’s own investigations into the subject, following the release of first-person accounts and video from U.S. fighter pilots claiming to show encounters with strange objects in the skies. High-profile coverage in mainstream media and open congressional hearings about UAPs have kept the matter circulating in the public realm. A month after the Pentagon’s report came out, theoretical astrophysicist Avi Loeb, former chair of Harvard University’s astronomy department, announced a private initiative called the Galileo Project, which is aimed at searching for potential evidence of alien technology here on Earth.

What NASA can bring to this discussion is as yet unclear. The agency has set aside a slim $100,000 for the nine-month study—less than the typical funding it provides for exploratory studies of unconventional technologies such as space telescopes with kilometer-scale mirrors or interstellar probes propelled by giant laser beams. Helmed by the well-respected Princeton University astrophysicist David Spergel, the investigation intends to identify existing and future data sets scientists could use to advance their understanding of UAPs. Even if it uncovers little of interest, the study’s existence suggests that something the agency once avoided talking about at all costs is on the cusp of becoming an appropriate topic of inquiry.

With New Study, NASA Seeks the Science behind UFOs, Adam Mann, Scientific American

Image: Artist’s impression of a Dyson sphere under construction. Credit: Steve Bowers.

Topics: Astronomy, Astrophysics, Dyson Sphere, SETI

Although the so-called Dysonian SETI has been much in the air in recent times, its origins date back to the birth of SETI itself. It was in 1960 – the same year that Frank Drake used the National Radio Astronomy Observatory in Green Bank, West Virginia to study Epsilon Eridani and Tau Ceti – that Freeman Dyson proposed the Dyson sphere. In fiction, Olaf Stapledon had considered such structures in his novel Star Maker in 1937. As Macy Huston and Jason Wright (both at Penn State) remind us in a recent paper, Dyson’s idea of energy-gathering structures around an entire star evolved toward numerous satellites around the star rather than a (likely unstable) single spherical shell.

We can’t put the brakes on what a highly advanced technological civilization might do, so both solid sphere and ‘swarm’ models can be searched for, and indeed have been, for in SETI terms we’re looking for infrared waste heat. And if we stick with Dyson (often a good idea!), we would be looking for structures orbiting in a zone where temperatures would range in the 200-300 K range, which translates into searching at about 10 microns, the wavelength of choice. But Huston and Wright introduce a new factor, the irradiation from the interior of the sphere onto the surface of the star.

This is intriguing because it extends our notions of Dyson spheres well beyond the habitable zone as we consider just what an advanced civilization might do with them. It also offers up the possibility of new observables. So just how does such a Dyson sphere return light back to a star, affecting its structure and evolution? If we can determine that, we will have a better way to predict these potential observables. As we adjust the variables in the model, we can also ponder the purposes of such engineering.

Think of irradiation as Dyson shell ‘feedback.’ We immediately run into the interesting fact that adding energy to a star causes it to expand and cool. The authors explain this by noting that total stellar energy is a sum of thermal and gravitational energies. Let’s go straight to the paper on this. In the clip below, E_* refers to the star’s total energy, with E_therm being thermal energy:

When energy is added to a star (E_∗ increases), gravitational energy increases and thermal energy decreases, so we see the star expand and cool both overall (because E_therm is lower) and on its surface (because being larger at the same or a lower luminosity its effective temperature must drop). A larger star should also result in less pressure on a cooler core, so we also expect its luminosity to decrease.

Dyson Sphere ‘Feedback’: A Clue to New Observables? Paul Gilster, Centauri Dreams

Evolutionary and Observational Consequences of Dyson Sphere Feedback, Macy Huston, Jason Wright, Astrophysical Journal

Topics: Astrobiology, Astronomy, Astrophysics, Carl Sagan, James Webb Space Telescope, SETI

The relief was as deep as the stakes were high. At 7:20 A.M. (ET), the rocket carrying the largest, most ambitious space telescope in history cleared the launchpad in French Guiana, and the members of mission control at the Space Telescope Science Institute in Baltimore roared their elation.

The suspense was not quite over. Half an hour postlaunch, the telescope still needed to decouple from its host rocket, after which it had to deploy solar panels to partly power its journey. Only after that first deployment proved successful, said a NASA spokesperson in a statement to Scientific American, would “we know we have a mission.”

Astronomers have more riding on the rocket than the James Webb Space Telescope (JWST). Also at risk is the viability of NASA’s vast space-science portfolio, if not the future of astronomy itself. As the successor to the Hubble Space Telescope (HST), JWST is one of those once-in-a-generation scientific projects that can strain the patience of government benefactors, as well as the responsible agency’s credibility, but also define a field for decades to come—and possibly redefine it forever.

The telescope that would become JWST was already under discussion even before HST launched in April 1990. By orbiting Earth, HST would have a line of sight free of the optical distortions endemic to our planet’s atmosphere. It would therefore be able to see farther across the universe (and, given that the speed of light is finite, farther back in time) than any terrestrial telescope.

The James Webb Space Telescope Has Launched: Now Comes the Hard Part, Richard Panek, Scientific American

The depiction of tentacled extraterrestrials (above) in the recent science-fiction film, "Arrival, "indicates divergence from aliens reported by supposed eyewitness accounts. Paramount. Source: Wrinkles, tentacles and oval eyes: How depictions of aliens have evolved, CNN Style

Topics: Astrobiology, Philosophy, SETI, Space Exploration

In my freshman seminar at Harvard last semester, I mentioned that the nearest star to the sun, Proxima Centauri, emits mostly infrared radiation and has a planet, Proxima b, in the habitable zone around it. As a challenge to the students, I asked: “Suppose there are creatures crawling on the surface of Proxima b? What would their infrared-sensitive eyes look like?” The brightest student in class responded within seconds with an image of the mantis shrimp, which possesses infrared vision. The shrimp’s eyes look like two ping-pong balls connected with cords to its head. “It looks like an alien,” she whispered.

When trying to imagine something we’ve never seen, we often default to something we have seen. For that reason, in our search for extraterrestrial life, we are usually looking for life as we know it. But is there a path for expanding our imagination to life as we don’t know it?

In physics, an analogous path was already established a century ago and turned out to be successful in many contexts. It involves conducting laboratory experiments that reveal the underlying laws of physics, which in turn apply to the entire universe. For example, around the same time when the neutron was discovered in the laboratory of James Chadwick in 1932, Lev Landau suggested that there might be stars made of neutrons. Astronomers realized subsequently that there are, in fact, some 100 million neutron stars in our Milky Way galaxy alone—and a billion times more in the observable universe. Recently, the LIGO experiment detected gravitational wave signals from collisions between neutron stars at cosmological distances. It is now thought that such collisions produce the precious gold that is forged into wedding bands. The moral of this story is that physicists were able to imagine something new in the universe at large and search for it in the sky by following insights gained from laboratory experiments on Earth.

How to Search for Life as We Don't Know It, Avi Loeb, Scientific American

Image Source: Link below

Topics: Astrophysics, Planetary Science, SETI, Space Exploration

Even as a child, before he devoted his life to the search for extraterrestrial life, Frank Drake wondered whether Earth was alone in its ability to harbor life. He wasn’t the first or the only one to wonder. There’s a reason so many are fascinated by the question: Its answer helps reveal humankind’s place in the cosmos.

Drake’s musings inspired him to pursue astronomy, serving as director of the Arecibo Observatory in Puerto Rico and president of the SETI Institute — which, as the acronym suggests, is devoted to the Search for Extraterrestrial Intelligence, and exploring the possibilities of life elsewhere in the universe. Drake is perhaps most famous for his eponymous equation — an estimate of how many alien civilizations might exist in our galaxy. Presented in 1961, the equation is generally considered as the start of a new era of searches for extraterrestrial intelligence.

But decades after the invention of that famous equation, Drake has conceded that his estimates were overly conservative. Among the too-moderate assumptions was that a potentially inhabited other world must be orbiting a star — overlooking the possibility of life on rogue planets.

Sometimes called “nomads of the galaxy” or “orphan planets,” these cold, dark worlds careen through space with no home, no solar system, no sun to orbit. Long ago, they formed around a star but were flung out, abandoned by their parents. There are billions of rogue planets — astronomers estimate there could be at least one for every star — wandering the galaxy.

It may seem futile to search for life in such cold, desolate environments, but over the last two decades, astronomers have come up with a number of possible scenarios that would make life possible on a planet without a star.

Can Life Exist on a Rogue Planet? Katie McCormick, Discovery Magazine

Image Source: Link below

Topics: Astrophysics, Electromagnetic Radiation, Entanglement, SETI

When we gaze up at the night sky, we might be accidentally eavesdropping on an alien conversation.

At least, that’s according to Imperial College London quantum physicist Terry Rudolph, who last week published preprint research theorizing that an advanced extraterrestrial civilization might alter the light coming off stars in order to communicate across a great distance, almost like a series of interstellar smoke signals.

The physics of the ordeal gets a bit dense — which is probably reasonable if aliens are rapidly communicating across star systems — but the basic idea is to use entangled photons from different stars to transmit messages that appear to be random twinkling to any nosy onlookers.

Roaming Charges

The idea, Rudolph notes, is technically possible as far as the physics are concerned, but pure speculation when it comes to any discussion of alien technology. But as he writes in the paper, any entangled communication among stars “can be rendered in principle indiscernible to those of us excluded from the conversation.”

So if there were a mega-advanced civilization out there colonizing the Milky Way galaxy, communication along the lines of what Rudolph has proposed could explain why we haven’t found any evidence of life beyond Earth.

Scientists Claim That Aliens May Be Communicating Via Starlight, Dan Robitzski, Futurism

Topics: Barrow Scale, Kardashev Scale, Exoplanets, SETI

The Kardashev Scale is a discussion, and ranking of civilizations based on energy output:

Type I: able to marshal energy resources for communications on a planet-wide scale, equivalent to the entire present power consumption of the human race, or about 10¹⁶ watts. Here, Carl Sagan begged to differ, due to power gradation, we're more like (on his measure) a 0.7 civilization, or 7 x 10¹⁵ watts. We have pockets of deployed resources, but definitely not "planet-wide," else there would be no economic distinctions: east/south side to west side; 1st and 3rd worlds. Perhaps we could edge up our score with renewable alternatives?
Type II: surpasses this by a factor of approximately ten billion, making available 10²⁶ watts, by exploiting the total energy output of its central star, using a Dyson sphere.
Type III: evolved enough to tap the energy resources of an entire galaxy, ~ 10³⁶ watts.
Type IV and V here.

Professor John D. Barrow is an astrophysicist and mathematician at Cambridge. His take is going not from the aspect of starships, instead of from ever-shrinking technology to make advanced control of energy, and technology possible.

On the Barrow Scale, we're clearly in the Barrow Three minus or nanotechnology. Arthur C. Clarke said "any sufficiently advanced technology is indistinguishable from magic," and kind of gives a runway that is the impossible-to-design Trek technobabble.

Could we go further?

Well, that depends on whether the purveyors of this technological node haven't blown ourselves to smithereens, [climate] changed ourselves to death, or ignored another zoonotic virus and comforted ourselves with throwing caution to the winds, taking vitamins, and jogging to the self-made apocalypse. Sorry for being cynical.

Also, each technological node is driven by industry, and at the top of that are apex predators also known as CEOs/billionaires who have a propensity to not share the resources they plunder. Also after seeing the Netflix documentary: "The Social Dilemma," I wonder what an AI-enabled-Planck-technology Internet, or economy would LOOK like, and who would it ultimately favor? Billionaires don't occur naturally, and trillionaires, quadrillion, or quintillion-empowered varieties would likely be tyrannical, and obscene.

Though this tech through-line is ambitious, bold, imaginative, it has a Pollyannaish feel to it, dependent on the benevolence of our fellow human beings, and a shared vision of humanity's progress.

Then, there are those apex predators that won't pay taxes, give a damn, or build starships so they can first ride on for their three minutes of narcissistic pleasure. Star Trek and a United Federation of Planets post-scarcity is still a Gene Roddenberry dream.

An unidentified flying object as seen in a declassified Department of Defense video, DoD

Topics: Aerodynamics, Applied Physics, Biology, Exoplanets, General Relativity, SETI

May 17, 2019- No, little green men aren't likely after the conquest of humanity. Boyd's piece for Phys.org highlights the reason why the Pentagon wants to identify UFOs: they're unidentified. If a warfighter on the ground or in the sky can't ID an object, that creates an issue since they don't know if it's friendly, adversarial, or neutral.

U.S. Navy pilots and sailors won't be considered crazy for reporting unidentified flying objects, under new rules meant to encourage them to keep track of what they see writes Iain Boyd for Phys.org.

Why is the Pentagon interested in UFOs? Intelligent Aerospace

The Pentagon refers to them as "transmedium vehicles," meaning vehicles moving through air, water, and space. Carolina Coastline breathlessly uses the term "defying the laws of physics." So I looked at what the paper might have meant. The objects apparently exceed the speed of sound without a sonic boom (signature of breaking the barrier). Even though this is reported by Popular Mechanics, they're quoting John Ratcliffe, whose name somehow sounds like a pejorative. Consider the source.

U.S. Navy F/A-18 flying faster than the speed of sound. The white cloud is formed by decreased air pressure and temperature around the tail of the aircraft.
ENSIGN JOHN GAY, U.S. NAVY

The speed of sound is 343 meters per second (761.21 miles per hour, 1,100 feet per second). Mach 1 is the speed of sound, Mach 2 is 1522.41 mph, Mach 3 is 2283.62 mph. NASA's X-43A scramjet sets the record at Mach 9.6 (7,000 mph), so, it's easy to see where Star Trek: The Next Generation got its Warp Speed analog from. The top speed of the F/A-18 is 1,190 mph. Pilots and astronauts under acceleration experience G Forces, and have suits to keep them from blacking out in a high-speed turn.

A Science Magazine article in 1967 reported the dimensions and speeds for the object were undeterminable. History.com reported an object exceeding 70 knots, or 80.5546 mph underwater (twice the speed of a nuclear submarine, so I can see the US Navy's concern). I found some of the descriptions on the site interesting:

5 UFO traits:

1. Anti-gravity lift (no visible means of propulsion), 2. Sudden and instantaneous acceleration (fast), 3. Hypersonic velocities without signatures (no sonic boom), 4. Low observability, or cloaking (not putting this on Romulans, or Klingons), 5. Trans-medium travel (air, water, space).

When I look at these factors, I don't get "little green men." First caveat: there are a lot of planets between us, and them with resources aplenty. Second caveat: any interest an alien intelligence might have in us is as caretakers of an experiment, or cattle. That's disturbing: ever see a rancher have conversations with a chicken, sow, or steer before slaughter?

My hypothesis (Occam's razor) - these are projections, but of a special kind:

For the first time, a team including scientists from the National Institute of Standards and Technology (NIST - 2016) have used neutron beams to create holograms of large solid objects, revealing details about their interiors in ways that ordinary laser light-based visual holograms cannot.

Holograms -- flat images that change depending on the viewer's perspective, giving the sense that they are three-dimensional objects -- owe their striking capability to what's called an interference pattern. All matter, such as neutrons and photons of light, has the ability to act like rippling waves with peaks and valleys. Like a water wave hitting a gap between the two rocks, a wave can split up and then re-combine to create information-rich interference patterns.

Move over, lasers: Scientists can now create holograms from neutrons, too, Science Daily

This of course doesn't explain the decades of observations, since holograms came into being in a 1948 paper by the Hungarian inventor Denis Gabor: “The purpose of this work is a new method for forming optical images in two stages. In the first stage, the object is lit using a coherent monochrome wave, and the diffraction pattern resulting from the interference of the secondary coherent wave coming from the object with the coherent background is recorded on the photographic plate. If the properly processed photographic plate is placed after its original position and only the coherent background is lit, an image of the object will appear behind it, in the original position.” Gabor won the Nobel Prize in 1971 for "his invention and development of the holographic method." Also: History of Holography

This is purely speculative. I have no intelligence other than what I've shared. It does in my mind, explain the physics-defying five traits described above. It does not explain the previous supposition of sightings since humans started recording history, or trying to hypothesize their sightings in antiquity. Solid objects flying at hypersonic speeds make sonic booms; projections - ball lightning, 3D laser, or solid neutron holograms - likely won't.

If these are projections (adversary, friendly, neutral), who is doing them, and why?

The mysterious object ‘Oumuamua passed through our solar system in 2017. Loeb has suggested it could have been sent by extraterrestrials. (Credit: European Southern Observatory/Kornmesser)

Topics: Astrobiology, Biology, Cosmology, SETI

Life, for all its complexities, has a simple commonality: It spreads. Plants, animals, and bacteria have colonized almost every nook and cranny of our world.

But why stop there? Some scientists speculate that biological matter may have proliferated across the cosmos itself, transported from planet to planet on wayward lumps of rock and ice. This idea is known as panspermia, and it carries a profound implication: Life on Earth may not have originated on our planet.

In theory, panspermia is fairly simple. Astronomers know that impacts from comets or asteroids on planets will sometimes eject debris with enough force to catapult rocks into space. Some of those space rocks will, in turn, crash into other worlds. A few rare meteorites on Earth are known to have come from Mars, likely in this fashion.

“You can imagine small astronauts sitting inside this rock, surviving the journey,” says Avi Loeb, an astrophysicist at Harvard University and director of the school’s Institute for Theory and Computation. “Microbes could potentially move from one planet to another, from Mars to Earth, from Earth to Venus.” (You may recognize Loeb’s name from his recent book Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, which garnered headlines and criticism from astronomers for its claim that our solar system was recently visited by extraterrestrials.)</p>

Loeb has authored a number of papers probing the mechanics of panspermia, looking at, among other things, how the size and speed of space objects might affect their likelihood of transferring life. While Loeb still thinks it’s more likely that life originated on Earth, he says his work has failed to rule out the possibility that it came from somewhere else in space.

Did Life On Earth Come From Outer Space? Nathaniel Scharping, Discover Magazine

Topics: Astrobiology, Astronomy, Cosmology, SETI

I would extend his theme to cover something that comes naturally to us all, which I’ll call Pseudo-exceptionalism—the unearned conviction that we are exceptional, superior to others because we were born...us.

We simply assume that we’re kinder, more honest, more realistic, more wholesome than those around us. After all, we’re married to ourselves for life, so we make accommodations: We cut ourselves slack. We’re fast to forgive ourselves. When challenged, we’re much better at making our case than our opponent’s. We spot injustices to ourselves far faster than we spot our injustices to others.</em>

Why Some People (Maybe Even Us) Think They're So Special
… and what to do about it. Jeremy E. Sherman Ph.D., MPP, Psychology Today

It is presumptuous to assume that we are worthy of special attention from advanced species in the Milky Way. We may be a phenomenon as uninteresting to them as ants are to us; after all, when we’re walking down the sidewalk we rarely if ever examine every ant along our path.

Our sun formed at the tail end of the star formation history of the universe. Most stars are billions of years older than ours. So much older, in fact, that many sunlike stars have already consumed their nuclear fuel and cooled off to a compact Earth-size remnant known as a white dwarf. We also learned recently that of order half of all sunlike stars host an Earth-size planet in their habitable zone, allowing for liquid water and for the chemistry of life.

Since the dice of life were rolled in billions of other locations within the Milky Way under similar conditions to those on Earth, life as we know it is likely common. If that is indeed the case, some intelligent species may well be billions of years ahead of us in their technological development. When weighing the risks involved in interactions with less-developed cultures such as ours, these advanced civilizations may choose to refrain from contact. The silence implied by Fermi's paradox (“Where is everybody?”) may mean that we are not the most attention-worthy cookies in the jar.

Why Do We Assume Extraterrestrials Might Want to Visit Us? Avi Loeb, Scientific American

Topics: Astrobiology, Astronomy, Astrophysics, SETI

Cultural references: The post title refers to NC A&T Alumni, and Civil Rights icon Reverend Jesse Jackson's appearance on Saturday Night Live, and the Wow! signal. Personal note: This signal appeared on the same day my granddaughter was born.

<p>On April 29, 2019, the Parkes Radio Telescope in Australia began listing to the radio signals from the Sun’s nearest neighbor, Proxima Centauri, just over 4 lightyears away. The telescope was looking for evidence of solar flares and so listened for 30 minutes before retraining on a distant quasar to recalibrate and then pointing back.

In total, the telescope gathered 26 hours of data. But when astronomers analyzed it in more detail, they noticed something odd — a single pure tone at a frequency of 982.02 MHz that appeared five times in the data.

The signal was first reported last year in The Guardian, a British newspaper. The article raised the possibility that the signal may be evidence of an advanced civilization on Proxima Centauri, a red dwarf star that is known to have an Earth-sized planet orbiting in its habitable zone.

But researchers have consistently played down this possibility saying that, at the very least, the signal must be observed again before any conclusions can be drawn. Indeed, the signal has not been seen again, despite various searches.

Now Amir Siraj and Abraham Loeb from Harvard University in Cambridge, Massachusetts, have calculated the likelihood that the signal came from a Proxima Centauri-based civilization, even without another observation. They say the odds are so low as to effectively rule out the possibility — provided the assumptions they make in their calculations are valid.</p>

Why The Recent Signal That Appeared to Come From Proxima Centauri Almost Certainly Didn't, Physics arXiv Blog, Discovery Magazine

A meme of past memes - seemed apropos.

Topics: Astrophysics, Humor, Science Fiction, SETI

Note: I use three sources for the commentary I've seen breathlessly displayed on the Internet speculating there may be 36 communicative (but, noticeably silent) civilizations in the Milky Way Galaxy. I grinned, and composed the combo meme above. Two words came to mind on my social media feed: click bait.

*****

The number 42 is, in The Hitchhiker's Guide to the Galaxy by Douglas Adams, the "Answer to the Ultimate Question of Life, the Universe, and Everything", calculated by an enormous supercomputer named Deep Thought over a period of 7.5 million years. Unfortunately, no one knows what the question is. Source: Wikipedia

*****

It's been a hundred years since Fermi, an icon of physics, was born (and nearly a half-century since he died). He's best remembered for building a working atomic reactor in a squash court. But in 1950, Fermi made a seemingly innocuous lunchtime remark that has caught and held the attention of every SETI researcher since. (How many luncheon quips have you made with similar consequence?)

The remark came while Fermi was discussing with his mealtime mates the possibility that many sophisticated societies populate the Galaxy. They thought it reasonable to assume that we have a lot of cosmic company. But somewhere between one sentence and the next, Fermi's supple brain realized that if this was true, it implied something profound. If there are really a lot of alien societies, then some of them might have spread out.

Fermi realized that any civilization with a modest amount of rocket technology and an immodest amount of imperial incentive could rapidly colonize the entire Galaxy. Within ten million years, every star system could be brought under the wing of empire. Ten million years may sound long, but in fact it's quite short compared with the age of the Galaxy, which is roughly ten thousand million years. Colonization of the Milky Way should be a quick exercise.

So what Fermi immediately realized was that the aliens have had more than enough time to pepper the Galaxy with their presence. But looking around, he didn't see any clear indication that they're out and about. This prompted Fermi to ask what was (to him) an obvious question: "where is everybody?"

SETI Institute: Fermi Paradox, Seth Shostak, Senior Astronomer

*****

How many intelligent alien civilizations are out there among the hundreds of billions of stars in the spiral arms of the Milky Way? According to a new calculation, the answer is 36.

That number assumes that life on Earth is more or less representative of the way that life evolves anywhere in the universe — on a rocky planet an appropriate distance away from a suitable star, after about 5 billion years. If that assumption is true, humanity may not exactly be alone in the galaxy, but any neighbors are probably too far away to ever meet.

On the other hand, that assumption that life everywhere will evolve on the same timeline as life on Earth is a huge one, said Seth Shostak, a senior astronomer at the SETI Institute in Mountain View, California, who was not involved in the new study. That means that the seeming precision of the calculations is misleading.

"If you relax those big, big assumptions, those numbers can be anything you want," Shostak told Live Science.

The question of whether humans are alone in the universe is a complete unknown, of course. But in 1961, astronomer Frank Drake introduced a way to think about the odds. Known as the Drake equation, this formulation rounds up the variables that determine whether or not humans are likely to find (or be found by) intelligent extraterrestrials: The average rate of star formation per year in the galaxy, the fraction of those stars with planets, the fraction of those planets that form an ecosystem, and the even smaller fraction that develop life. Next comes the fraction of life-bearing planets that give rise to intelligent life, as opposed to, say, alien algae. That is further divided into the fraction of intelligent extraterrestrial life that develops communication detectable from space (humans fit into this category, as humanity has been communicating with radio waves for about a century).

The final variable is the average length of time that communicating alien civilizations last. The Milky Way is about 14 billion years old. If most intelligent, communicating civilizations last, say, a few hundred years at most, the chances that Earthlings will overlap with their communications is measly at best.

Solving the Drake equation isn't possible, because the values of most of the variables are unknown. But University of Nottingham astrophysicist Christopher Conselice and his colleagues were interested in taking a stab at it with new data about star formation and the existence of exoplanets, or planets that circle other stars outside our own solar system. They published their findings June 15 in The Astrophysical Journal.

Are there really 36 alien civilizations out there? Well, maybe. Stephanie Pappas, Live Science

No, it's not real. Credit: Getty Images

Topics: Astronomy, Drake Equation, Existentialism, SETI

No E.T. Life Yet? That might be a warning, Kelsey Johnson, Scientific American

Salt-laden water welling up from below gives Europa’s fissures and cracks their distinctive color. Credit: NASA, JPL-Caltech and SETI Institute

Topics: Astrobiology, Exoplanets, Planetary Exploration, SETI

Water on Europa—with a Pinch of Salt, Shannon Hall, Scientific American