The celestial lighthouse

Last week I did a piece on three weird astrophysical phenomena -- odd radio circles, high-energy neutrino bursts, and fast blue optical transients -- all of which have thus far defied explanation.  And this week, a paper came out in Nature about a recent discovery adding one more to the list of unexplained celestial curiosities -- one which has the alien intelligence aficionados raising their Spock-like eyebrows in a meaningful manner (although I hasten to point out that there is no evidence that either this one, or the other three I mentioned, have anything to do with you-know-who).

However, the most recent discovery is downright bizarre.  To understand why, a bit of background.

There are many more-or-less understood phenomena in astrophysics that result in a sudden surge in electromagnetic output from an astronomical body.  Some are aperiodic, or at least infrequent, such as fast radio bursts, which were discovered back in 2007 by astrophysicists Duncan Lorimer and David Narkevic.  These are quick, transient pulses in the radio region of the spectrum, and are now thought to be due either to neutron star mergers or starquakes on the surface of magnetars.

Then there are the repeating ones, such as the fast blinking on-and-off of pulsars.  These are the rapidly whirling cores of collapsed massive stars, which funnel out beams of high-energy radiation aligned with the poles of their magnetic fields; because of the star's rotation, the beam appears to pulse, in some cases dozens of times a second.  They were discovered back in 1967 by the brilliant astronomer Jocelyn Bell Burnell, but because no one could figure out what might create a repeating signal that regular, and also because Burnell was a woman in a field almost entirely dominated by men, her discovery was derisively referred to as LGM ("Little Green Men"), and assumed to be from some sort of prosaic terrestrial source.  It was only when more of them were found that astronomers began to take her seriously.  In 1974, the Nobel Prize in Physics was awarded for the development of radio astronomy, and in particular, for the discovery of pulsars...

... to Antony Hewish and Martin Ryle.  Note who wasn't included.  Burnell has graciously stated that she "feels no bitterness toward the Nobel Committee," but in her place, I sure as hell would have.

The paper in Nature, however, describes an object that doesn't seem to fit any of the known types of electromagnetic pulses.  Called GPM J1839-10, it releases energy in the radio region of the spectrum.  But in terms of periodicity, it's somewhere between pulsars (which are so regular they've been proposed as celestial clocks) and fast radio bursts (which are apparently aperiodic).  GPM J1839-10 is slow -- its signal reaches a peak about every twenty-two minutes -- but it's not precisely regular.  The four hundred seconds centering on that twenty-two minute mark is when the peak is most likely to come, but sometimes the window will pass with no peak.  The length of the pulses is also variable, usually between thirty and three hundred seconds in length.  And unlike both fast radio bursts and pulsars, the amplitude of the peak is quite low in energy.

As science writer John Timmer put it in Ars Technica, "The list of known objects that can produce this sort of behavior... consists of precisely zero items."

What's weirdest is that going back through the records of astronomical observations, this object has been doing its thing for three decades, and only just now is attracting attention.  The astrophysicists thus far have no good explanation for what it might be.  It sits out there in space, slowly flashing on and off like some sort of interstellar lighthouse, and the the flat truth is that at the moment, no one has the slightest idea what it might be.

Of course, "We don't know" opens the door for a certain group of people to say "We do!"

As I've said before, no one would be more delighted than me if we did come across evidence of an extraterrestrial signal, but I strongly suspect this ain't it.  For one thing, the semi-regular blips it's putting out don't appear to contain any information; put a different way, the pattern isn't complex.  It could be a beacon, I suppose, but how you'd tell the difference between an alien-built celestial lighthouse and a star of some sort that is sending out pulses of radio waves is beyond me.  With nothing more to go on, by far the greater likelihood is that there is some natural explanation for this slowly-pulsing object -- we just haven't found it yet.

Even so, it's intriguing.  I've always loved a mystery, and this certainly is one.  It's possible that we've missed other objects of this type; the kind of detailed repeated scans of the sky in the radio region of the spectrum that it would take to detect a pulsation this slow have only begun to be done with any kind of thoroughness.  Like with Burnell's discovery of pulsars, it took finding others before astronomers had enough data to start putting together an explanation.

But if no others are found, what then?  It'll be added to the list of astronomical mysteries, of which there are plenty.  It's a big old universe, and filled with wonders, many of which we are only just beginning to understand.

And those are cool enough without the aliens.  Although, of course, I wouldn't object to the aliens as well.

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Signals of interest

Usually, when people think about finding extraterrestrial intelligence, they think of radio transmissions -- a trope that has been the basis of dozens of movies and television shows (Contact and Starman immediately come to mind).  Just two days ago I looked at a new approach to detecting biosignatures -- traces of living things, usually in the context of life on other planets -- which involved arguments having to do with complex biochemistry.

Then yesterday, I ran into a new study from the SETI (Search for Extraterrestrial Intelligence) Project describing a recently-developed deep learning technique which goes back to radio astronomy -- and that has already uncovered eight "signals of interest" from previously-analyzed radio telescope data.

Now, before we go any further, allow me to state up front that no one (well, no one credible) is saying any of these signals actually come from you-know-who. 

Don't get your hopes up quite yet.

But this finding does give us alien enthusiast types some hope for answering the Fermi paradox -- "If life is common in the universe, where is everyone?" -- with two rejoinders: (1) we've only studied a vanishingly small slice of the star systems even in our own galaxy; and (2) our previous techniques for analyzing the radio emissions of the systems we have studied still missed some signals that by previously-accepted criteria should warrant a closer look.

All eight signals of interest shared the following three characteristics that put them in the "curious" column:

1. They were narrow-band -- i.e. only peak at a narrow range of frequencies.  Radio signals from natural sources tend to be broad-band.
2. They had non-zero drift rates, meaning they were not moving with the same speed as the observatory.  This rules out terrestrial sources, a constant source of interference with radio telescope data.
3. The signals occurred only at specific celestial coordinates, and the intensity fell off rapidly when the telescope moved from being aimed at those coordinates.

All of these are features you would expect from radio transmissions from an extraterrestrial intelligence.

"In total, we had searched through 150 terabytes of data of 820 nearby stars, on a dataset that had previously been searched through in 2017 by classical techniques but labeled as devoid of interesting signals," said Peter Ma of the University of Toronto, who was lead author of the paper, which appeared in Nature Astronomy.  "We're scaling this search effort to one million stars today with the MeerKAT telescope and beyond.  We believe that work like this will help accelerate the rate we're able to make discoveries in our grand effort to answer the question 'are we alone in the universe?'"

I'm delighted astronomers are continuing to push forward with the search for extraterrestrial intelligence.  They certainly could be forgiven for giving up, considering the fact that since the SETI Institute was founded in 1984, they have yet to find anything that has convinced scientists.  Even with arguments like the one I made in my post two days ago, that purely statistical arguments like the Drake equation suggest that life is common in the universe, the complete lack of hard evidence would certainly be sufficient justification for scientists to put their efforts elsewhere.

That they haven't done so is a tribute not only to their dogged determination, but the importance of the question.  Not only would finding extraterrestrial life (or even better, intelligence) have profound implications for our understanding of astronomy, biochemistry, and biology, it would create seismic shifts in everything from anthropology to theology.  Such a finding would fundamentally and permanently alter our perception of the universe and our own place in it.

Myself, I think that'd be a good thing.  Our species needs period reminders that we're not all that and a bag of crisps.  Finding out that we're only one intelligent species of many would further emphasize that we don't occupy the center of the universe in any sense -- and, hopefully, reinforce our sense of wonder at the forces that have produced life and intelligence not only here on Earth, but throughout the myriad galaxies.

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The galactic spiderweb

Saturday's post was about the bizarre behavior of matter on very small scales; today's is about the equally bizarre behavior of matter on very large scales.

I was alerted to this latest discovery by two different loyal readers of Skeptophilia, who sent me a link to an article in LiveScience describing research on cosmic radio wave sources by a team led by astrophysicist Jennifer West of the University of Toronto.  The radio region of the spectrum is made up of the longest-wavelength light, and is invisible to human eyes.  In fact, the majority of the electromagnetic spectrum is invisible to us; visible light makes up only a tiny fraction of it. 

As a brief aside, I remember being kind of blown away when I first ran into this concept, back in high school.  I subsequently found out that because the refraction of light -- key to how our lenses focus the light reflected from what we're looking at onto our retinas -- is a function of wavelength, to see light in the radio region of the spectrum we'd need eyes about ten meters across.  That's assuming they functioned in an analogous fashion to our own eyes, and that the massive retinas had a light-sensitive pigment that responded to radio waves.

Which would be cumbersome, to say the least.

Anyhow, because our eyes can't see in the radio region of the spectrum, scientists have developed radio telescopes to see what's up there emitting radio waves.  And ever since we've started analyzing those invisible-to-us wavelengths, we've found surprise after surprise, starting with the 1964 discovery of the three-centimeter cosmic background radiation by Arno Penzias and Robert Wilson -- which turned out to be the relic radiation of the Big Bang.

The research by Jennifer West et al., however, has yet to be explained.  It turns out that our region of the Milky Way is surrounded by a looped array of radio-wave-emitting magnetic filaments, some of them thousands of light years long, and which connect the North Polar Spur to the Fan Region -- two segments of the night sky on opposite sides of the Earth.

At first, it wasn't even clear how far away these radio sources are.  The authors write:

Since the time of their discoveries and right up to the present day, astronomers have questioned the origin of these two regions, with some arguing that they are local features, while others argue that they are distant, Galactic-scale features...  If these features are indeed local, understanding their structure and morphology is critical since we are embedded among the stars, dust, and gas that comprise them, and all features beyond must be observed through this local veil of material.  Features that are extremely nearby can have a very large angular size on the sky, and only with good models can we account for this “contamination” when developing large-scale models of the Galactic magnetic field and foreground models for cosmology experiments.

Further study, however, clarified a couple of points; first, they're huge; second, they're kind of everywhere you look.  These cosmic filaments are strung across the Milky Way like a giant spiderweb, and some researchers believe that they're all connected -- that together they represent pieces of a single, much larger structure.

What the night sky would look like if we had enormous eyes and could see in the radio region of the spectrum

What could create something on that scale?  The simple answer is: we don't know.  These huge magnetic tubes might have been created by the explosions of massive supernovae early in the galaxy's history; one of the theories calls the structures "galactic chimneys," with matter from the explosions being funneled along the magnetic field lines of the galaxy, much as the walls of a chimney flue constrain and direct the smoke from a fireplace. "Magnetic fields don't exist in isolation," West said.  "They all must connect to each other.  So a next step is to better understand how this local magnetic field connects both to the larger-scale galactic magnetic field and also to the smaller-scale magnetic fields of our sun and Earth...  I think it's just awesome to imagine that these structures are everywhere, whenever we look up into the night sky."

Whatever they are, and however they were formed, we're currently sitting in the middle of a huge network of them -- long, hollow filaments that crisscross the sky, invisible to human eyes but clearly visible to a radio telescope tuned to the right wavelength.  

Just as in Saturday's post about the "quantum Cheshire cat," this paper raises as many questions as it settles -- certainly one of the hallmarks of cutting-edge science  And both of these discoveries further reinforce that we live in a very bizarre universe, where the familiar objects that drive our "common sense" about how things work are caught square in the middle of a world of the submicroscopic and a world of the very macroscopic, where everything we look at seems to defy our intuition.  Which you could find exciting, or disorienting and a little frightening.

Me, I think it's both.  I love that nature keeps us a little off balance, that every time we come to the smug conclusion that we've got it all figured out, we get pitched a serious curveball.  It'd be a mighty boring place if everywhere we looked, we thought, "Meh, works pretty much like I expected."

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My master's degree is in historical linguistics, with a focus on Scandinavia and Great Britain (and the interactions between them) -- so it was with great interest that I read Cat Jarman's book River Kings: A New History of Vikings from Scandinavia to the Silk Road.

Jarman, who is an archaeologist working for the University of Bristol and the Scandinavian Museum of Cultural History of the University of Oslo, is one of the world's experts on the Viking Age.  She does a great job of de-mythologizing these wide-traveling raiders, explorers, and merchants, taking them out of the caricature depictions of guys with blond braids and horned helmets into the reality of a complex, dynamic culture that impacted lands and people from Labrador to China.

River Kings is a brilliantly-written analysis of an often-misunderstood group -- beginning with the fact that "Viking" isn't an ethnic designation, but an occupation -- and tracing artifacts they left behind traveling between their homeland in Sweden, Norway, and Denmark to Iceland, the Hebrides, Normandy, the Silk Road, and Russia.  (In fact, the Rus -- the people who founded, and gave their name to, Russia -- were Scandinavian explorers who settled in what is now the Ukraine and western Russia, intermarrying with the Slavic population there and eventually forming a unique melded culture.)

If you are interested in the Vikings or in European history in general, you should put Jarman's book in your to-read list.  It goes a long way toward replacing the legendary status of these fierce, sea-going people with a historically-accurate reality that is just as fascinating.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Unknown unknowns

One of my college physics professors made a statement to his class that was mind-boggling in its inaccuracy.  We'd been learning about the subatomic particles, and he was telling us about the smallest pieces of matter known: quarks.  Physicists had given the different types of quarks fanciful names -- up, down, top, bottom, charmed, strange.  His commentary was something of a sneer: "When scientists spend their times giving ridiculous names to physical phenomena, you know there must not be much in the way of new things waiting to be studied."

Even at the time -- I was about twenty -- it seemed humorless and mean-spirited to claim that just because scientists are having a little fun with naming stuff, they're wasting their time playing around rather than engaging in actual science.  Much later, I ran into Lord Kelvin's statement along the same line, that "There is nothing new to be discovered in physics now.  All that remains is more and more precise measurement."  

The problem was that Kelvin said this in 1900 -- immediately before Einstein and Schrödinger turned all of physics on its head with the theories of relativity and quantum mechanics, respectively.

So saying "there's nothing left to study" is not only arrogant, it's entirely inaccurate.  The preposterous implication is that right now we have a good idea of how much is left that we don't know.  It reminds me of Donald Rumsfeld's much-ridiculed statement about "known knowns, known unknowns, and unknown unknowns."  Yeah, he could have phrased it a little better, but honestly, he had a point.  There isn't any way to estimate the extent of what we're not even aware that we don't know.  The only thing we can go by is the history of science -- which pretty clearly shows that every time we think we have everything explained, the universe steps in a with a well-aimed dope slap.

I started thinking about all this because of a press release in Science Alert about a mysterious radio source near the center of the Milky Way that has astrophysicists scratching their heads.  To quell the immediate reaction a lot of folks are having, no one at this point is saying anything about aliens, or at least no one with any credibility.  But the behavior of the source is odd enough even without bringing in the Daleks or the Andorians or the Stenza or whoever your favorite extraterrestrial bad guys are.

The radio source is euphoniously named ASKAP J173608.2-321635.  (I wonder if my long-ago physics professor would have approved of that name as sufficiently serious.)  The radio emissions from ASKAP-etc. are odd in a variety of respects.  The source emits radio waves for weeks, then will suddenly "turn off" for a while before just as suddenly beginning to shine again.  The electromagnetic radiation from it is highly polarized -- the waves line up, all vibrating in the same direction, like a bunch of people creating waves in long springs, and everyone oscillating the springs up-and-down rather than each spring moving in some randomly-chosen plane of vibration.

The source was discovered through a collaboration between the Australian Square Kilometre Array Pathfinder (that's where "ASKAP" comes from) and the  MeerKAT radio telescope, near Cape Town, South Africa (speaking of whimsical names; the "KAT" part of the name stands for "Karoo Array Telescope;" "meer" is Afrikaans for "more."  It also, of course, riffs on the name of the comical little African mammal of the same name).  This isn't the first time this combo has found something strange.  Earlier this year, they found another yet-to-be-explained interstellar object, the aptly-named "Odd Radio Circles" that have bright edges and dimmer interiors, like giant gossamer soap bubbles.

A MeerKAT image of the center of the Milky Way, as viewed in radio wavelengths

Astrophysicists have considered a number of explanations for these strange objects, and so far, none of them have panned out.  "Possible identifications [include] a low-mass star/substellar object with extremely low infrared luminosity, a pulsar with scatter-broadened pulses, a transient magnetar, or a Galactic Center Radio Transient," the research team writes, "[but] none of these fully explains the observations, which suggests that ASKAP J173608.2-321635 may represent part of a new class of objects being discovered through radio imaging surveys."

So once again, we're confronted with how little we know.  We've come a long way, there's no doubt about that; our scientific achievements as a species are pretty damn impressive, especially considering that serious research has only been going on for a couple of centuries of the tens of thousands of years humans have been at least somewhat technological.  But there will always be more mysteries to solve, more puzzles to put together, more questions to ask.

I'll end with a quote from astrophysicist John Bahcall, whose research into the behavior and properties of neutrinos in the 1960s gave us a new window into why stars shine:

I do not personally want to believe that we already know the equations that determine the evolution and fate of the universe; it would make life too dull for me as a scientist…  I hope, and believe, that the Space Telescope might make the Big Bang cosmology appear incorrect to future generations, perhaps somewhat analogous to the way that Galileo’s telescope showed that the earth-centered, Ptolemaic system was inadequate...  Every time we get slapped down, we should thank Mother Nature -- because we're about to learn something important.

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London in the nineteenth century was a seriously disgusting place to live, especially for the lower classes.  Sewage was dumped into gutters along the street; it then ran down into the ground -- the same ground from which residents pumped their drinking water.  The smell can only be imagined, but the prevalence of infectious water-borne diseases is a matter of record.

In 1854 there was a horrible epidemic of cholera hit central London, ultimately killing over six hundred people.  Because the most obvious unsanitary thing about the place was the smell, the leading thinkers of the time thought that cholera came from bad air -- the "miasmal model" of contagion.  But a doctor named John Snow thought it was water-borne, and through his tireless work, he was able to trace the entire epidemic to one hand-pumped well.  Finally, after weeks and months of argument, the city planners agreed to remove the handle of the well, and the epidemic ended only a few days afterward.

The work of John Snow led to a complete change in attitude toward sanitation, sewers, and safe drinking water, and in only a few years completely changed the face of the city of London.  Snow, and the epidemic he halted, are the subject of the fantastic book The Ghost Map: The Story of London's Most Terrifying Epidemic -- and How It Changed Cities, Science, and the Modern World, by science historian Steven Johnson.  The detective work Snow undertook, and his tireless efforts to save the London poor from a horrible disease, make for fascinating reading, and shine a vivid light on what cities were like back when life for all but the wealthy was "solitary, poor, nasty, brutish, and short" (to swipe Edmund Burke's trenchant turn of phrase).

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Flash in the pan

I introduced yesterday's post, about the discovery that a large percentage of the meteorites seem to have come from a single collision event in the distant past, as "a question without an answer."  Today we're going to look at another one; fast radio bursts.

They're pretty much what they sound like; quick, high-energy flashes in the radio region of the electromagnetic spectrum.  What the name doesn't tell you, however, is how quick and high-energy they are.  They have a duration of only a few milliseconds at most; there and gone faster than a camera flash.  And their energy output is enormous -- the average fast radio burst releases as much energy in a few milliseconds as the Sun does in three days.

The trouble with studying these events is that they're over before you can get your radio telescope pointed toward them.  Until recently, there had been no coordinated effort to find fast radio bursts; how can you find them if they come from seemingly random spots in the night sky?  You would have to have the radio telescope pointed in the exactly right direction at exactly the right time in order to know one had even happened.

[Image licensed under the Creative Commons ESO/M. Kornmesser, Artist’s impression of a fast radio burst traveling through space and reaching Earth, CC BY 4.0]

This is why the first ones weren't even observed until 2007, and the number recorded in the fourteen years since was quite small.  But it was just announced this week that CHIME, the Canadian Hydrogen Intensity Mapping Experiment, has recorded 535 fast radio bursts in the one year of its operation -- quadrupling the total number ever detected.

"Before CHIME, there were less than a hundred total discovered FRBs; now, after one year of observation, we've discovered hundreds more," said study contributor Kaitlyn Shin, a graduate student in MIT's Department of Physics.  "With all these sources, we can really start getting a picture of what FRBs look like as a whole, what astrophysics might be driving these events, and how they can be used to study the universe going forward."

Because that's the problem with fast radio bursts; no known astrophysical process could produce such a sudden, short-duration explosion in the radio region of the spectrum.  More interesting still, the CHIME study showed that they seem to fall into two classes; "one-offs" and "repeaters."  So even if we figure out how they happen, we'll still be left with why some of them happen only once, and others seem to be on some kind of regular cycle.

The most perplexing thing about them, though, is how common they appear to be.  For something that is caused by a completely unknown mechanism, they're pretty much everywhere.  "That's kind of the beautiful thing about this field -- FRBs are really hard to see, but they're not uncommon," said Kiyoshi Masui, another study contributor, and a member of MIT's Kavli Institute for Astrophysics and Space Research.  "If your eyes could see radio flashes the way you can see camera flashes, you would see them all the time if you just looked up."

So there you have it; another as-yet unsolved mystery.  It seems like no matter where we look, there are three new conundrums for every one we solve.  It brings to mind the quote from biologist J. B. S. Haldane: "The universe is not only queerer than we imagine, it is queerer than we can imagine."

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I'm in awe of people who are true masters of their craft.  My son is a professional glassblower, making precision scientific equipment, and watching him do what he does has always seemed to me to be a little like watching a magic show.  On a (much) lower level of skill, I'm an amateur potter, and have a great time exploring different kinds of clays, pigments, stains, and glazes used in making functional pottery.

What amazes me, though, is that crafts like these aren't new.  Glassblowing, pottery-making, blacksmithing, and other such endeavors date back to long before we knew anything about the underlying chemistry and physics; the techniques were developed by a long history of trial and error.

This is the subject of Anna Ploszajski's new book Handmade: A Scientist's Search for Meaning Through Making, in which she visits some of the finest craftspeople in the world -- and looks at what each is doing through the lenses of history and science.  It's a fascinating inquiry into the drive to create, and how we've learned to manipulate the materials around us into tools, technology, and fine art.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Ghost rings and interstellar mysteries

I love a good mystery.  There's something about the phrase "there's something going on here, but we don't know what it is" that immediately makes my ears perk up.  And for someone of that bent, there's no field like astrophysics.

The whole science of astrophysics is a relatively new invention.  Astronomy, of course, has been around for millennia; there are complex star charts made by Chinese astronomers that date back to the eleventh century, and our observations of the constellations and planets goes back to the time of the Babylonians.  

We've been looking up for a long, long time.

The problem, of course, is that looking at the stars from a distance is one thing, but finding out anything about what they actually are when we can't physically go there is quite another.  Even finding out what they're made of was a baffling question with no obvious answer.  Up until (very) recently, our best telescopes weren't sufficient to see any detail at all on even the largest stars; even through the Mount Wilson Observatory Telescope they just look like points of light with no discernible features whatsoever.  

The first step toward seeing more than that came from research by German physicist Joseph von Fraunhofer in the early nineteenth century, when he invented the spectroscope -- basically a very well-made prism -- and found that in the light from the Sun there were dozens of dark lines (now called Fraunhofer lines in his honor).  Fraunhofer himself died at the young age of 39 without ever finding out what caused them -- poisoned by vapors from the heavy metals he used in his profession as a glassmaker -- but the research was taken over by Gustav Kirchhoff and Robert Bunsen, who showed that the lines were the absorption spectra of specific elements.  Basically, these lines occurred in the light emitted by a heated, glowing gas mixture, and could be used to identify what elements were in the mixture.  In fact, it was through its unique spectral fingerprint within the solar spectrum that British astronomer Norman Lockyer discovered the element he christened helium (after Helios, the Greek sun god) -- the first element that was identified out in space before it was detected here on Earth.

What this did was allow us to study the stars at a distance.  Their spectra told us for certain what stars thousands of light years away were composed of.  Through this new science of astrophysics we found out that most of the ordinary matter in the universe (96%, in fact) is hydrogen and helium; all of the other familiar heavier elements put together make up the other 4%.  It also led directly to the discovery of the expanding universe and the Big Bang when astronomer Edwin Hubble found that the familiar spectral lines of hydrogen in distant stars were red-shifted -- stretched out in the same fashion that the sound waves of a passing train get stretched, lowering the pitch as it passes you.  And it turns out that unlike trains, galaxies have a peculiar relationship between their distance and their speed.  The farther a galaxy is away from us, the more the spectral lines get red-shifted, so the faster it's moving.

The result: the universe is expanding, meaning at one point 13.8 billion years ago, it was coalesced into a single point.  All that, from the lines produced when you heat something hot enough to emit light.

Anyhow, all of this comes up because of a new discovery that has the scientists scratching their heads.  Astrophysicists Anna Kapinska and Emil Lenc were analyzing images from the Australian Square Kilometre Array Pathfinder (ASKAP) telescope, and found ghostly rings of radio emission that have no known source.  Here's one of them, dubbed ORC-1 ("odd radio circle"):

In an amusing parallel to the famous (and still unexplained) "Wow!" signal -- a narrow-band radio signal discovered in 1977 and so named because astronomer Jerry Ehman was so taken aback when he found it he wrote "Wow!" in the margin of the printout -- these ORCs have become known as "WTFs" because that's what Kapinska wrote on the photo of the first one she found.  Since then there have been dozens of WTFs found, and they still have no convincing explanation.  There doesn't seem to be anything at the center, such as the pulsars found in the middle of nebulae that are supernova remnants; they aren't star-formers like the Orion Nebula; and they don't show the spectral distortion you see with gravitational lensing, when a distant light source has its light warped around a massive object between it and us.

In short, we still have no idea.  Two Russian scientists have actually (seriously) suggested that we might be looking down the maw of a wormhole -- a thus-far theoretical astronomical object linking two different places in space-time, made famous by Star Trek: Deep Space Nine.  But that explanation is pretty out there (literally and figuratively), and to be scrupulously honest, at the moment they're still just... WTFs.

So once again, we have a demonstration that however far we've come from our ancestors looking up at the skies and seeing dogs and bears and scorpions and so on, we still have a long distance to cover before we'll have a convincing explanation of whatever we see up there.  I, for one, find that thrilling.  If in the past two centuries we've gone from stars being points of light to being able to detect and analyze radio emissions from billions of light years away, where will we be in another two hundred years?  And during that time, how many mysteries will cause scientists to say "WTF"?

Boggles the mind.

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What are you afraid of?

It's a question that resonates with a lot of us.  I suffer from chronic anxiety, so what I am afraid of gets magnified a hundredfold in my errant brain -- such as my paralyzing fear of dentists, an unfortunate remnant of a brutal dentist in my childhood, the memories of whom can still make me feel physically ill if I dwell on them.  (Luckily, I have good teeth and rarely need serious dental care.)  We all have fears, reasonable and unreasonable, and some are bad enough to impact our lives in a major way, enough that psychologists and neuroscientists have put considerable time and effort into learning how to quell (or eradicate) the worst of them.

In her wonderful book Nerve: Adventures in the Science of Fear, journalist Eva Holland looks at the psychology of this most basic of emotions -- what we're afraid of, what is happening in our brains when we feel afraid, and the most recently-developed methods to blunt the edge of incapacitating fears.  It's a fascinating look at a part of our own psyches that many of us are reluctant to confront -- but a must-read for anyone who takes the words of the Greek philosopher Pausanias seriously: γνῶθι σεαυτόν (know yourself).

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

A signal from our neighborhood

I try to keep my rational brain engaged, but man, sometimes it's hard going.

Like when I read the story that popped up over at Scientific American last Friday.  My ears perked up at the very first line: "It's never aliens, until it is."

Written by Jonathan O'Callaghan and Lee Billings, it tells about a recent discovery made by "Breakthrough Listen," the search-for-extraterrestrial-intelligence program launched by entrepreneur Yuri Milner in 2015.  Despite scanning the skies for five years looking for something that might be a sign of alien intelligence, Breakthrough Listen hasn't found anything that couldn't be explained using ordinary astrophysics...

... until now.

Maybe.  I hate to add that word, but... "rational brain engaged," and all.  There's a lot that's exciting about what they discovered, not least that the signal they found comes from Proxima Centauri -- the nearest star to the Sun, right in our own neighborhood at only 4.2 light years' distance.  (Okay, I probably shouldn't say "only."  4.2 light years is about 25,000,000,000,000 miles.  One of the fastest spacecraft ever made by humans, Voyager 2, would still take 73,000 years to reach Proxima Centauri -- if it were heading that way, which it's not.)

The proximity of the signal's source is hardly the only exciting thing about it.  After all, the universe has plenty of radio sources, and all the ones we've found so far have purely prosaic explanations.  The signal is weirdly compressed, occupying a narrow band of frequencies centering around 982 megahertz.  Interestingly, this is a frequency range that is usually fairly empty of transmissions, which is one of the reasons the signal stood out, and decreases the likelihood that it's some kind of human-made source being picked up accidentally.  "We don’t know of any natural way to compress electromagnetic energy into a single bin in frequency,” said astrophysicist Andrew Siemion, who is on the team that analyzed the signal.  "Perhaps, some as-yet-unknown exotic quirk of plasma physics could be a natural explanation for the tantalizingly concentrated radio waves, but for the moment, the only source that we know of is technological."

The "tantalizing" part is that we know for sure that Proxima Centauri has at least one Earth-like planet -- Proxima b, which is 1.2 times the size of the Earth, and orbits its star in eleven days.  (If that doesn't sound very Earth-like, remember that Proxima Centauri, as a red dwarf, is a lot less massive than the Sun, so its "Goldilocks zone" -- the band of orbital distances that are "just right" for the temperatures to allow liquid water" -- is a lot closer in, and the planets in that region travel a lot faster.)  Red dwarf stars are prone to solar flares, so some of the more pessimistic astrophysicists have suggested that the radiation flux and general turbulence would destroy any nearby planets' atmosphere, or at least shower the surface with sufficient ionizing radiation to prevent the development of complex biochemistry, let alone life.

But it's important to realize that this, too, is a surmise.  Truthfully, we don't know what's down there on Proxima b -- just that it's got a rocky surface and a temperature range that would allow for liquid oceans, rivers, and lakes.

Just like here.

In short, finding a suspicious radio signal from the nearest star to our own is pretty amazing, even if I *wince* *grimace* keep my rational brain engaged.

The fact is, even the scientists -- normally the most cautious of individuals -- are sounding impressed by this.  "It’s the most exciting signal that we’ve found in the Breakthrough Listen project, because we haven’t had a signal jump through this many of our filters before," said Sofia Sheikh of Pennsylvania State University, who led the team that analyzed the signal and is the lead author on an paper describing it, scheduled for publication this spring.

Honestly forces me to add that there's one bit of information about the signal that points away from it being a technosignature: unlike the signal detected at the beginning of the movie Contact, it has no internal fine structure.  “BLC1 [Breakthrough Listen Candidate 1] is, for all intents and purposes, just a tone, just one note," Siemion says.  "It has absolutely no additional features that we can discern at this point."

But even the doubters are saying it's worthy of further study.  "If it’s an ETI it must eventually be replicable, because it’s unlikely it would be a one-off,” said Shami Chatterjee, a radio astronomer at Cornell University.  "If an independent team at an independent observatory can recover the same signal, then hell yes.  I would bet money that they won’t, but I would love to be wrong."

So would a lot of us, Dr. Chatterjee.  I know we've had other strange signals before, stretching all the way back to the beginnings of radio astronomy and the discovery of incredibly rapid-fire "blinking" of a radio source discovered at Jodrell Bank by astrophysicist Jocelyn Bell Burnell in 1967.  That one also elicited the comment of "we don't know a natural process that could generate such fast oscillation" -- and the source was actually nicknamed "LGM" (Little Green Men) until Burnell showed that the signal was coming from a pulsar, a rapidly-spinning neutron star.

So it was bizarre, perhaps, but not a message from an extraterrestrial intelligence.

In any case, I'll be eagerly awaiting replication and confirmation of the discovery.  Even if it doesn't turn out to be aliens *heavy sigh* it'll probably turn out to be something interesting.  But until then... well, I guess it's premature to request transport to the mother ship, but I can still keep hoping.

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Not long ago I was discussing with a friend of mine the unfortunate tendency of North Americans and Western Europeans to judge everything based upon their own culture -- and to assume everyone else in the world sees things the same way.  (An attitude that, in my opinion, is far worse here in the United States than anywhere else, but since the majority of us here are the descendants of white Europeans, that attitude didn't come out of nowhere.)  

What that means is that people like me, who live somewhere WEIRD -- white, educated, industrialized, rich, and democratic -- automatically have blinders on.  And these blinders affect everything, up to and including things like supposedly variable-controlled psychological studies, which are usually conducted by WEIRDs on WEIRDs, and so interpret results as universal when they might well be culturally-dependent.

This is the topic of a wonderful new book by anthropologist Joseph Henrich called The WEIRDest People in the World: How the West Became Psychologically Peculiar and Particularly Prosperous.  It's a fascinating lens into a culture that has become so dominant on the world stage that many people within it staunchly believe it's quantifiably the best one -- and some act as if it's the only one.  It's an eye-opener, and will make you reconsider a lot of your baseline assumptions about what humans are and the ways we see the world -- of which science historian James Burke rightly said, "there are as many different versions of that as there are people."

[Note:  If you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

The second biggest bang

There are times in science where -- if you're going to describe something accurately -- you rapidly become lost in superlatives.

That was my reaction to a paper this week in Astrophysical Journal titled, "Discovery of a Giant Radio Fossil in the Ophiuchus Galaxy Cluster," by a team led by Simona Giacintucci of the Naval Research Laboratory.  Here's what the researchers had to say about it:

The Ophiuchus galaxy cluster exhibits a curious concave gas density discontinuity at the edge of its cool core...  Using low-frequency (72-240 MHz) radio data from MWA GLEAM and GMRT, we found that the X-ray structure is, in fact, a giant cavity in the X-ray gas filled with diffuse radio emission with an extraordinarily steep radio spectrum.  It thus appears to be a very aged fossil of the most powerful AGN [active galactic nucleus] outburst seen in any galaxy cluster (pV∼5×10^61 erg for this cavity).  There is no apparent diametrically opposite counterpart either in X-ray or in the radio.  It may have aged out of the observable radio band because of the cluster asymmetry.  At present, the central AGN exhibits only a weak radio source, so it should have been much more powerful in the past to have produced such a bubble.  The AGN is currently starved of accreting cool gas because the gas density peak is displaced by core sloshing.  The sloshing itself could have been set off by this extraordinary explosion if it had occurred in an asymmetric gas core.  This dinosaur may be an early example of a new class of sources to be uncovered by low-frequency surveys of galaxy clusters.

To say that this explosion was huge doesn't even begin to describe it.  The energy output of this outburst puts it in second place ever -- the only event we know of that was more energetic than this was the Big Bang itself.

Its size isn't the only odd thing about it.  "We've seen outbursts in the centers of galaxies before but this one is really, really massive," said Melanie Johnston-Hollitt of Curtin University's International Centre for Radio Astronomy Research, in an interview at Phys.Org.  "And we don't know why it's so big.  But it happened very slowly—like an explosion in slow motion that took place over hundreds of millions of years."

However slow it was, the explosion blew a hole in the sphere of superhot plasma surrounding the massive black hole at the center of the galaxy.  Study lead author Simona Giacintucci compares it to the pressure from the eruption of Mount Saint Helens blowing off the entire top of the mountain, leaving a crater behind.  "The difference," she said, "is that you could fit fifteen Milky Way galaxies in a row into the crater this eruption punched into the cluster's hot gas."

[Image licensed under the Creative Commons Rogelio Bernal Andreo, Rho Ophiuchus Widefield, CC BY-SA 3.0]

Johnston-Hollitt, who directs the Murchison Widefield Array in Western Australia, said that despite the enormity of the relic explosion, it was only recently observed because of a drastic improvement in astronomers' ability to observe the skies in the very-low-frequency end of the spectrum.  "It's a bit like archaeology," she said.  "We've been given the tools to dig deeper with low frequency radio telescopes so we should be able to find more outbursts like this now."

So there might be other colossal explosion remnants out there just waiting to be found.

What it brings up for me, non-researcher that I am, is to wonder what on earth could have caused a detonation on this scale.  To my knowledge, the explanation is still uncertain, and in fact can't be accounted for by any known natural process.  The lack of a mechanism and the size of the outburst led scientists at first to doubt the measurements were correct.  "People were skeptical because of the size of outburst," Johnston-Hollitt said.  "But it really is that."

And improvements to the Murchison Widefield Array is improving its sensitivity by a factor of ten, which means we're only seeing the beginning of discoveries like this, and who knows what else.  "The Universe is a weird place," Johnston-Hollitt said.

Indeed it is.  Awe-inspiring to the point of bowling over your brain, at times.  Look around you at your house, town, and region, your friends, family, and pets, even the bigger concerns of politics and global conflict -- and realize that on the grand scheme of things, we are minuscule, hardly even a blip on the surface of cosmic space-time.  Humbling and a little scary, isn't it?

But the human brain isn't built to conceptualize such enormities, and it's best not to dwell on it.  On the whole, it's probably better to have another cup of coffee and think about something else for a while.

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One of my favorite people is the indefatigable British science historian James Burke.  First gaining fame from his immensely entertaining book and television series Connections, in which he showed the links between various historical events that (seen as a whole) play out like a centuries-long game of telephone, he went on to wow his fans with The Day the Universe Changed and a terrifyingly prescient analysis of where global climate change was headed, filmed in 1989, called After the Warming.

One of my favorites of his is the brilliant book The Pinball Effect.  It's dedicated to the role of chaos in scientific discovery, and shows the interconnections between twenty different threads of inquiry.  He's posted page-number links at various points in his book that you can jump to, where the different threads cross -- so if you like, you can read this as a scientific Choose Your Own Adventure, leaping from one point in the web to another, in the process truly gaining a sense of how interconnected and complex the history of science has been.

However you choose to approach it -- in a straight line, or following a pinball course through the book -- it's a fantastic read.  So pick up a copy of this week's Skeptophilia book of the week.  You won't be able to put it down.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]