The riddle of the sun stones

When you think about it, it's unsurprising that our ancestors invented "the gods" as an explanation for anything they didn't understand.

They were constantly bombarded by stuff that was outside of the science of their time.  Diseases caused by the unseen action of either genes or microorganisms.  Weather patterns, driven by forces that even in the twenty-first century we are only beginning to understand deeply, and which controlled the all-important supply of food and water.  Earthquakes and volcanoes, whose root cause only began to come clear sixty years ago.

Back then, everything must have seemed as mysterious as it was precarious.  For most of our history, we've been at the mercy of forces we didn't understand and couldn't control, where they were one bad harvest or failed rainy season or sudden plague from dying en masse.

No wonder they attributed it all to gods and sub-gods -- and devils and demons and witches and evil spirits.

As much as we raise an eyebrow at the superstition and seeming credulity of the ancients, it's important to recognize that they were no less intelligent, on average, than we are.  They were trying to make sense of their world with the information they had at the time, just like we do.  That we have a greater knowledge base to draw upon -- and most importantly, the scientific method as a protocol -- is why we've been more successful.  But honestly, it's no wonder that they landed on supernatural, unscientific explanations; the natural and scientific ones were out of their reach.

The reason this comes up is a recent discovery that lies at the intersection of archaeology and geology, which (as regular readers of Skeptophilia know) are two enduring fascinations for me.  Researchers excavating sites at Vasagård and Rispebjerg, on the island of Bornholm, Denmark, have uncovered hundreds of flat stone disks with intricate patterns of engraving, dating from something on the order of five thousand years ago.  Because many of the disks have designs of circles with branching radial rays extending outward, they've been nicknamed "sun stones."  Why, in around 2,900 B.C.E., people were suddenly motivated to create, and then bury, hundreds of these stones, has been a mystery.

Until now.

[Image credit: John Lee, Nationalmuseet, Copenhagen, Denmark]

Data from Greenland ice cores has shown a sudden spike in sulfates and in dust and ash from right around the time the sun stones were buried -- both hallmarks of a massive volcanic eruption.  The location of the volcano has yet to be determined, but what is clear is that it would have had an enormous effect on the climate.  "It was a major eruption of a great magnitude, comparable to the well-documented eruption of Alaska’s Okmok volcano in 43 B.C.E. that cooled the climate by about seven degrees Celsius," said study lead author Rune Iversen, of the Saxo Institute at the University of Copenhagen.  "The climate event must have been devastating for them."

The idea that the volcanic eruption in 2,900 B.C.E. altered the climate worldwide got a substantial boost with the analysis of tree rings from wood in Europe and North America.  Right around the time of the sulfate spike in the Greenland ice cores, there's a series of narrow tree rings -- indicative of short growing seasons and cool temperatures.  Wherever this eruption took place, it wrought havoc with the weather, with all of the results that has on human survival.

While the connection between the eruption and the sun stones is an inference, it certainly has some sense to it.  How else would you expect a pre-technological culture to respond to a sudden, seemingly inexplicable dimming of the sun, cooler summers and bitter winters with resultant probable crop failures, and even the onset of wildly fiery sunrises and sunsets?  It bears keeping in mind that our own usual fallback of "there must be a scientific explanation even if I don't know what it is" is a relatively recent development. 

So while burying engraved rocks might seem like a strange response to a climatic change, it is understandable that the ancients looked to a supernatural solution for what must have been a mystifying natural disaster.  And we're perhaps not so very much further along, ourselves, given the way a substantial fraction of people in the United States are responding to climate change even though the models have been predicting this for decades, and the evidence is right in front of our faces.  We still have plenty of areas we don't understand, and are saddled with unavoidable cognitive biases even if we do our best to fight them.  As the eminent science historian James Burke put it, in his brilliant and provocative essay "Worlds Without End":

Science produces a cosmogony as a general structure to explain the major questions of existence.  So do the Edda and Gilgamesh epics, and the belief in Creation and the garden of Eden.  Myths provide structures which give cause-and effect reasons for the existence of phenomena.  So does science.  Rituals use secret languages known only to the initiates who have passed ritual tests and who follow the strictest rules of procedure which are essential if the magic is to work.  Science operates in the same way.  Myths confer stability and certainty because they explain why things happen or fail to happen, as does science.  The aim of the myth is to explain existence, to provide a means of control over nature, and to give to us all comfort and a sense of place in the apparent chaos of the universe.  This is precisely the aim of science.

Science, therefore for all the reasons above, is not what it appears to be.  It is not objectively impartial, since every observation it makes of nature is impregnated with theory.  Nature is so complex, and sometimes so seemingly random, that it can only be approached with a systematic tool that presupposes certain facts about it.  Without such a pattern it would be impossible to find an answer to questions even as simple as "What am I looking at?"

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Riding on a light beam

Some of you probably have read about a project called Breakthrough Starshot that began perhaps eight years ago (and which was championed by none other than Stephen Hawking), which proposed sending small remote-controlled cameras to nearby star systems, powered by lasers that could propel them up to twenty percent of the speed of light.

If something like this were launched today, it would mean we could be getting photographs back from Proxima Centauri in twenty years.

[Image licensed under the Creative Commons ESO/M. Kornmesser, Artist's impression of the planet orbiting Proxima Centauri, CC BY 4.0]

It's an ambitious project, and faces significant hurdles.  Even if propelled by lasers -- which, being light, travel at the speed thereof -- navigation becomes increasingly difficult the farther away it gets.  Just at the distance of Pluto, our intrepid little spacecraft would be 4.5 light-hours from Earth, meaning if we tried to beam it instructions to dodge around an incoming meteor, it would be 4.5 hours until the command arrived, at which point all that would be left is intrepid scrap metal.  And Proxima Centauri is 4.3 light years away.

You see the problem.  The Starshot spacecraft would have to be able, on some level, to think for itself, because there simply wouldn't be time for Mission Control to steer it to avoid danger.

There are other obstacles, though.  Besides the obvious difficulties of being in the cold vacuum of interstellar space, contending with cosmic rays and the like, there's the problem engendered by its speed.  Assuming the estimate of a maximum velocity of twenty percent of light speed is correct, even tiny particles of dust would become formidable projectiles, so Starshot is going to require some heavy-duty shielding, increasing its mass (and thus the amount of energy needed to make it go).

Three years ago we got an encouraging proof of concept, when the group working on the mission -- Russian entrepreneur Yuri Milner's Breakthrough Foundation -- launched a test of the Starshot craft.  It was a tiny little thing, small enough to fit in your hand and weighing about the same as a stick of gum, designed and built by engineers at the University of California - Santa Barbara.  In the test flight it achieved an altitude of nineteen miles, all the while functioning flawlessly, returning four thousand images of the Earth taken from aloft.

And just last week, a paper in Nature Photonics describes further research on how to overcome the weight/propulsion issue, with the creation of a fifty-nanometer-thick membrane of silicon nitride that was tested to measure the actual thrust a laser could create on something that lightweight -- a feat that has never been done before.  The miniature sail passed with flying colors.

"There are numerous challenges involved in developing a membrane that could ultimately be used as lightsail," said Harry Atwater of Caltech, who led the study.  "It needs to withstand heat, hold its shape under pressure, and ride stably along the axis of a laser beam.  But before we can begin building such a sail, we need to understand how the materials respond to radiation pressure from lasers.  We wanted to know if we could determine the force being exerted on a membrane just by measuring its movements.  It turns out we can."

The most significant remaining hurdle is to design the laser system to make Starshot move -- lasers that are extremely powerful yet so finely collimated that they can still strike a ten-centimeter craft square-on from several light years away.  The engineering director for Breakthrough, Peter Klupar, is designing a 100,000 gigawatt laser -- to be located, he says, in Chile -- that could be the answer.  Of course, such a powerful device is not without its dangers.  Reflected off a mirror in space, Klupar says, such a laser could "ignite an entire city in minutes."

Not that there's a mirror out there.  So you shouldn't worry at all about that.

"You would think that this is all impossible, but we have folks at Caltech and the University of Southampton and Exeter University working on about fifty contracts on making all [of] this happen," Klupar said.  "No one has come up with a deal-breaker that we can find yet.  It all seems real."

All of which may seem like science fiction, but it's phenomenal how fast things go from the realm of Star Trek to reality.  Klupar compares his light sails to CubeSats, tiny (ten by ten centimeters, weighing a little over a kilogram) orbiting telemetry devices that are now common.  "It feels a lot like the way CubeSats felt twenty years ago," he said.  "People were saying, 'Those are toys, they're never going to develop into anything, there's no way I can see that ever working.'  And today and look them: hundreds of millions of dollars is being spent on them."

So keep your eye on this project.  If there's a chance at a remote visit to another star system, I think this is our best bet.  The Breakthrough Foundation estimates an actual, honest-to-goodness launch toward a nearby star as early as 2030.  Meaning perhaps we could get our first photographs of planets around another star by 2050.

I'll be ninety years old at that point, but if that's what I'm waiting for, I can make it till then.

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Remembrance of things past

"The human brain is rife with all sorts of ways of getting it wrong."

This quote is from a talk by eminent astrophysicist Neil deGrasse Tyson, and is just about spot on.  Oh, sure, our brains work well enough, most of the time; but how many times have you heard people say things like "I remember that like it was yesterday!" or "Of course it happened that way, I saw it with my own eyes"?

Anyone who knows something about neuroscience should immediately turn their skepto-sensors up to 11 as soon as they hear either of those phrases.

fMRI scan of a human brain during working memory tasks [Image is in the Public Domain courtesy of the Walter Reed National Military Medical Center]

Our memories and sensory-perceptual systems are selective, inaccurate, heavily dependent on what we're doing at the time, and affected by whether we're tired or distracted or overworked or (even mildly) inebriated.  Sure, what you remember might have happened that way, but -- well, let's just say it's not as much of a given as we'd like to think.  An experiment back in 2005 out of the University of Portsmouth looked memories of the Tavistock Square (London) bus bombing, and found that a full forty percent of the people questioned had "memories" of the event that were demonstrably false -- including a number of people who said they recalled details from CCTV footage of the explosion, down to what people were wearing, who showed up to help the injured, when police arrived, and so on.

Oddly enough, there is no CCTV footage of the explosion.  It doesn't exist and has never existed.

Funny thing that eyewitness testimony is considered some of the most reliable evidence in courts of law, isn't it?

There are a number of ways our brains can steer us wrong, and the worst part of it all is that they leave us simultaneously convinced that we're remembering things with cut-crystal clarity.  Here are a few interesting memory glitches that commonly occur in otherwise mentally healthy people, that you might not have heard of:

• Cryptomnesia.  Cryptomnesia occurs when something from the past recurs in your brain, or arises in your external environment, and you're unaware that you've already experienced it.  This has resulted in several probably unjustified accusations of plagiarism; the author in question undoubtedly saw the text they were accused of plagiarizing some time earlier, but honestly didn't remember they'd read it and thought that what they'd come up with was entirely original.  It can also result in some funnier situations -- while the members of Aerosmith were taking a break from recording their album Done With Mirrors, they had a radio going, and the song "You See Me Crying" came on.  Steven Tyler said he thought that was a pretty cool song, and maybe they should record a cover of it.  Joe Perry turned to him in incredulity and said, "That's us, you fuckhead."

• Semantic satiation.  This is when a word you know suddenly looks unfamiliar to you, often because you've seen it repeatedly over a fairly short time.  Psychologist Chris Moulin of Leeds University did an experiment where he had test subjects write the word door over and over, and found that after a minute of this 68% of the subjects began to feel distinctly uneasy, with a number of them saying they were doubting that "door" was a real word.  I remember being in high school writing an exam in an English class, and staring at the word were for some time because I was convinced that it was spelled wrong (but couldn't, of course, remember how it was "actually" spelled).

• Confabulation.  This is the recollection of events that never happened -- along with a certainty that you're remembering correctly.  (The people who claimed false memories of the Tavistock Square bombing were suffering from confabulation.)  The problem with this is twofold; the more often you think about the false memory or tell your friends and family about it, the more sure you are of it; and often, even when presented with concrete evidence that you're recalling incorrectly, somehow you still can't quite believe it.  A friend of mine tells the story of trying to help her teenage son find his car keys, and that she was absolutely certain that she'd seen them that day lying on a blue surface -- a chair, tablecloth, book, she wasn't sure which, but it was definitely blue.  They turned the house upside down, looking at every blue object they could find, and no luck.  Finally he decided to walk down to the bus stop and take the bus instead, and went to the garage to get his stuff out of the car -- and the keys were hanging from the ignition, where he'd left them the previous evening.  "Even after telling me this," my friend said, "I couldn't accept it.  I'd seen those keys sitting on a blue surface earlier that day, and remembered it as clearly as if they were in front of my face."

• Declinism.  This is the tendency to remember the past as more positive than it actually was, and is responsible both for the "kids these days!" thing and "Make America Great Again."  There's a strong tendency for us to recall our own past as rosy and pleasant as compared to the shitshow we're currently immersed in, irrespective of the fact that violence, bigotry, crime, and general human ugliness are hardly new inventions.  (A darker aspect of this is that some of us -- including a great many MAGA types -- are actively longing to return to the time when straight White Christian men were in charge of everything; whether this is itself a mental aberration I'll leave you to decide.)  A more benign example is what I've noticed about travel -- that after you're home, the bad memories of discomfort and inconveniences and delays and questionable food fade quickly, leaving behind only the happy feeling of how much you enjoyed the experience.

• The illusion of explanatory depth.  This is a dangerous one; it's the certainty that you understand deeply how something works, when in reality you don't.  This effect was first noted back in 2002 by psychologists Leonid Rozenblit and Frank Keil, who took test subjects and asked them to rank from zero to ten their understanding of how common devices worked, including zippers, bicycles, electric motors, toasters, and microwave ovens, and found that hardly anyone gave themselves a score lower than five on anything.  Interestingly, the effect vanished when Rozenblit and Keil asked the volunteers actually to explain how the devices worked; after trying to describe in writing how a zipper works, for example, most of test subjects sheepishly realized they actually had no idea.  This suggests an interesting strategy for dealing with self-styled experts on topics like climate change -- don't argue, ask questions, and let them demonstrate their ignorance on their own.

• Presque vu.  Better known as the "tip-of-the-tongue" phenomenon -- the French name means "almost seen" -- this is when you know you know something, but simply can't recall it.  It's usually accompanied by a highly frustrating sense that it's right there, just beyond reach.  Back in the days before The Google, I spent an annoyingly long time trying to recall the name of the Third Musketeer (Athos, Porthos, and... who???).  I knew the memory was in there somewhere, but I couldn't access it.  It was only after I gave up and said "to hell with it" that -- seemingly out of nowhere -- the answer (Aramis) popped into my head.  Interestingly, neuroscientists are still baffled as to why this happens, and why turning your attention to something else often makes the memory reappear.

So be a little careful about how vehemently you argue with someone over whether your recollection of the past or theirs is correct.  Your version might be right, or theirs -- or it could easily be that both of you are remembering things incompletely or incorrectly.  I'll end with a further quote from Neil deGrasse Tyson: "We tend to have great confidence in our own brains, when in fact we should not.  It's not that eyewitness testimony by experts or people in uniform is better than that of the rest of us; it's all bad....  It's why we scientists put great faith in our instruments.  They don't care if they've had their morning coffee, or whether they got into an argument with their spouse -- they get it right every time."

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Unleashing the tsunami

Today I have for you two news stories that are interesting primarily in juxtaposition.

The first is a press release about a study out of Stanford University that found LGBTQ+ people have, across the board, a higher rate of mental health disorders involving stress, anxiety, and depression than straight people do.  Here's the relevant quote:

New research looking at health data of more than a quarter of a million Americans shows that LGBTQ+ people in the US have a higher rate of many commonly diagnosed mental health conditions compared to their with cisgender and straight peers, and that these links are reflective of wider societal stigma and stress.  For example, cisgender women who are a sexual minority, such as bisexual or lesbian, had higher rates of all 10 mental health conditions studied compared to straight cisgender women.  Gender diverse people, regardless of their sex assigned at birth, and cisgender sexual minority men and had higher rates of almost all conditions studied compared to straight cisgender men, with schizophrenia being the one exception.  A separate commentary says these differences are not inevitable, and could likely be eliminated through legal protections, social support, and additional training for teachers and healthcare professionals.

The second is from Newsbreak and is entitled, "Trump Signs Sweeping Executive Orders That Overhaul U.S. Education System."  The orders, as it turns out, have nothing to do with education per se, and everything to do with appeasing his homophobic Christofascist friends who are determined to remove every protection from queer young people against discrimination.  Once again, here's the quote:

The executive order titled Ending Radical Indoctrination in K-12 Schools threatens to withhold federal funding for "illegal and discriminatory treatment and indoctrination in K-12 schools," including based on gender ideology and the undefined and vague "discriminatory equity ideology."

The order calls for schools to provide students with an education that instills "a patriotic admiration" for the United States, while claiming the education system currently indoctrinates them in "radical, anti-American ideologies while deliberately blocking parental oversight."...

"These practices not only erode critical thinking but also sow division, confusion and distrust, which undermine the very foundations of personal identity and family unity," the order states.

So how is it surprising to anyone that we queer people have a higher rate of depression, stress, and anxiety?  Funny how that happens when elected officials not only claim we exist because of "radical indoctrination," but are doing their damnedest to erase us from the face of the Earth.

If you think I'm exaggerating, take a look at this:

It's a good thing I retired in 2019 (after 32 years in the classroom), because if anyone -- from a school administrator all the way up to the president himself -- told me I couldn't call a trans kid by their desired name or pronouns, or had to take down the sticker I had on my classroom door that had a Pride flag and the caption "Everyone Is Safe Here," my response would have been:

FUCK.  YOU.

And I'd probably have added a single-finger salute, for good measure.

Mr. Trump, you do not get to legislate us out of existence.  You do not get to tell us who we can be kind to, who we can treat humanely, whose rights we can honor, who we can help to feel safe and secure and accepted for who they are.  I lost four damn decades of my life hiding in the closet out of fear and shame because of the kind of thinking you are now trying to cast into law, and I will never stand silent and watch that happen to anyone else.

So maybe your yes-men and yes-women -- your hand-picked loyalist cronies who do your bidding without question and line up to kiss your ass even before you ask it -- are jumping up and down in excitement over enacting this latest outrage, but you (and they) can threaten us all you want.

I'm not complying.  I will never comply.  And I know plenty of high school teachers and administrators who feel exactly the same way I do.  You may think you've picked an easy target, but what you are doing has unveiled how deeply, thoroughly cruel your motives are -- and it will unleash a tsunami of resistance.

LGBTQ+ people and minorities and the other groups you get your jollies by bullying will always be safe with me.  And if you think any stupid fucking command from on high will change that, you'd better think again.

To put it in a way even someone of your obviously limited intellectual capacity can understand: you can take your executive order and stick it up your bloated ass.

Sideways.

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Werewolf box

Because apparently some ill-advised person uttered the dreaded words, "Well, things can't possibly get any weirder than they already are," I've been seeing a resurgence of interest in an "invention" from 1990 called the "Feraliminal Lycanthropizer."

I put "invention" in quotation marks because mostly what it seems to do is "nothing," which is hardly remarkable.  Hell, I've got three dogs who do that all day long, unless their dreaded enemy the UPS Guy shows up, at which point they sound Full Red Alert until the Guy retreats to his truck in disarray, which always happens.  This leaves them with a nice cheerful feeling of having Accomplished Something Important, at which point they resume doing nothing until the next non-crisis arises.

Anyhow, the Feraliminal Lycanthropizer, such as it is, is the brainchild of one David Woodard, who sounds like one seriously strange dude.  He is an accomplished musician who specializes in writing requiems (he once wrote one for a dead pelican he found on the beach) and "prequiems" for people who aren't technically deceased but who, in the words of Monty Python, will be stone dead in a moment.  Woodard wrote about his mystery machine in a pamphlet in 1990, describing it as a "psychotechnographic" device he'd found out about somewhere and then recreated:

The first part of the contraption's odd moniker comes from the Latin ferus (wild animal) and limen (threshold); if you think the second part sounds like it must mean "... that turns you into a werewolf," you're exactly right.  (However, it must be mentioned that after Gary Larson's immortal coinage of thagomizer for the spiky end of a stegosaurus's tail -- named, you'll probably recall, after "the late Thag Simmons" -- it's hard for me to take anything ending in -izer seriously.)

In any case, the thing supposedly creates three simultaneous infrasonic sine waves, at 0.56, 3.0, and 9.0 Hertz, respectively, which combine to create "thanato-auric waves."  After that, someone inside the box is... well, let me quote the pamphlet Woodard wrote about it:

This combination of drastically contrasting emotional trigger mechanisms results in an often profound behavioral enhancement which occurs strikingly soon (within moments) after the user enters and remains in the auricular field of the machine...   [This acts] to trigger states of urgency and fearlessness and to disarmor the intimate charms of the violent child within.  The Trithemean incantations richly pervading the machine’s aural output produce feelings of aboveness and unbridled openness.

Right!  Sure!  I mean, my only question would be, "What?"

I was disappointed to find out that even Woodard doesn't believe the Feraliminal Lycanthropizer actually turns you into a werewolf, which is a shame, because that'd be kind of cool.  I've always thought that of the horror movie bad guys, werewolves are objectively the best.  I mean, consider the advantages: (1) you only have to work one day a month; (2) there's hardly any danger because no one much carries guns with silver bullets, including in places like Texas where even the dairy cattle are packing heat; (3) you get to romp around howling at the Moon; (4) werewolves always have super ripped muscles, despite seldom being seen at the gym; and (5) no one thinks it's weird if you show up to work naked, a principle exemplified by the character Jacob Black in the movie Twilight, wherein audience members lost track of the number of times Taylor Lautner took all his clothes off.

Not that I'm complaining about that, mind you.

But all the Feraliminal Lycanthropizer allegedly does is to increase your violence and sexual desire, which seems like a bad idea to do at the same time.  Fortunately, in reality it doesn't even do that much; no less a source than  the Fortean Times said "There is no evidence the Feraliminal Lycanthropizer exists or could have such effects."  Somewhat more crudely, paranormal researcher Michael Esposito commented that the sexual effects of the Lycanthropizer could be duplicated by "leaning up against the spin cycle of a Maytag."

So an oddball made a strange claim a 35 years ago, which isn't anything out of the ordinary, because that's what oddballs do.  What's remarkable, though, is that this thing has now resurfaced, and is making the rounds of conspiracy websites (wherein it's suggested that it's somehow going to be used covertly to, I dunno, convert people into extremely horny super-soldiers or something) and even sketchier sites owned by people who are trying to figure out how to make one, because for some reason they want to feel more violent.

Since the Lycanthropizer doesn't actually do anything (Cf. paragraph 2), I suppose there are worse things the fringe element could spend their time on.  After all, the more time they waste trying to generate an "auricular field of thanato-auric waves" the less time they'll have to amass actual weapons.

So the upshot is: knock yourself out.

Anyhow, that's our News From The Outer Limits for today.  And I guess that, in fact, the world has not yet gotten as weird as it could possibly get.  But y'all'll have to excuse me, because my washing machine just went on spin, and I've got to... um... go attend to it.

 

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Out of sight

Seismologists and volcanologists are unusual amongst scientists in that for the most part, what they're studying are things that are permanently unavailable for direct observation.

Oh, sure, they can access the results on the Earth's surface; fault lines, lava flows, uplift or subsidence from magma movement, and so on.  But the actual processes -- the stuff down there that is causing it all -- is inaccessible.

The deepest hole ever dug is the Kola Superdeep Borehole, on the Kola Peninsula near the Russian border with Norway, which is an impressive twelve kilometers deep; but when you realize that's only one-thousandth of the diameter of the Earth, it puts things into perspective.  Even so, it was deep enough that the bottom had a measured temperature of 180 C -- hot enough to boil water, but far from hot enough to melt rock.  (It bears mention that a claim circulating last year that they'd gone down fourteen kilometers, hit temperatures of 1000 C, and could hear the screams of the damned -- because, apparently, they'd punctured a hole into hell -- was unfounded.)

So the fact remains that much of geological science is based upon inference -- not only using surface processes to infer what's happening in Earth's interior, but using data such as earthquake wave traveling speed to figure out what the mantle and core are made of, whether they're liquid or solid or somewhere in between, and how all that stuff in there is moving around.  And being inferential, our understanding of deep geologic processes is constantly subject to revision.

Which brings us to a study out of Utrecht University that appeared in the journal Nature last week, about a discovery showing that deep in the Earth's mantle there are two continent-sized subterranean "islands" at least a half a billion years old -- showing that the stuff down there isn't mixing around quite the way we thought it was.

The upper mantle has been thought of as basically a big recycler.  As pieces of the Earth's crust get forced down into subduction zones (marked by the oceanic trenches that neighbor some of the most tectonically-active regions on Earth), it melts and gets mixed into what's already down there.  Being colder than the surrounding rock, everyone thought the process was slow; other than the bits that get hot enough to melt and then rise to the surface, causing volcanoes like the ones in the North American Cascades, Andes, Caribbean, Italy, Japan, and Indonesia, the rest just has to sit down there till it blends into the material surrounding it.

Apparently some of this will need to be rethought, because these "islands" in the mantle are still holding together despite being so old that they "should have" completely melted away by now.

One of the chunks is under Africa and the other under the Pacific Ocean, and they were located by using the paths and speeds of seismic waves, giving them the moniker of LLSVPs (Large Low Seismic Velocity Provinces).  "Nobody knew what they are, and whether they are only a temporary phenomenon, or if they have been sitting there for millions or perhaps even billions of years," said Arwen Deuss, who co-authored the study.  "These two large islands are surrounded by a graveyard of tectonic plates which have been transported there by subduction, where one tectonic plate dives below another plate and sinks all the way from the Earth’s surface down to a depth of almost three thousand kilometers."

You might be wondering how they figured out that they are a half a billion years old, given that they're way out of reach of direct study.  That, in fact, is the most fascinating part of the study, and has to do with the fact that rocks which cool quickly (such as obsidian and basalt) have much smaller crystals than ones that cool more slowly (like granite and gabbro).  The molecular reassembly that results in crystal formation takes time, especially in thick, viscous liquids like magma, so if lava is rapidly cooled on the surface it doesn't have time to form crystals.

"Grain size is much more important," Deuss said.  "Subducting tectonic plates that end up in the slab graveyard consist of small grains because they recrystallize on their journey deep into the Earth.  A small grain size means a larger number of grains and therefore also a larger number of boundaries between the grains.  Due to the large number of grain boundaries between the grains in the slab graveyard, we find more damping, because waves lose energy at each boundary they cross.  The fact that the LLSVPs show very little damping, means that they must consist of much larger grains."

Large grain size = a long time spent underground.  Mineralogist Laura Cobden, who specializes in mineral crystallization rates in igneous rock, estimated that based on the inferred crystal size in the two "islands," they've been down there, relatively undisturbed, for around five hundred million years.

[Image from Deuss et al.]

So that's our cool science news from the geologists for today.  Two islands in the mantle that are stubbornly resisting melting away.  Why these structures have been so persistent is beyond the scope of this study; but as with all science, finding out something's there is the first step.  After that, the theorists can figure out how to explain it all.

Even if they never have a chance to see it.

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Meaningful ink

It's a little odd that someone as center-of-attention-phobic as I am has chosen something that is bound to garner close looks.  I'm referring to my tattoos, which are obvious and colorful -- and include a full sleeve, so they're a little hard to hide.

Virtually everyone who comments on them, however, is complimentary.  With good reason; my artist, James Spiers of Model Citizen Tattoos in Ithaca, New York, is -- in a word -- brilliant, and realized my vision of what I wanted just about perfectly.

 

Just after it was finished

Not everyone's a fan, of course.  I was given the stink-eye by a sour-faced old lady in a local hardware store a while back, who informed me that having tattoos meant I was going to hell.

My response was, "Lady, that ship sailed years ago."

But if I do end up in hell because of my ink, I'll have a lot of company.  Not only is tattooing pretty common these days -- since I got my first one, about twenty years ago, it's gone from being an infrequent sight to just about everywhere -- humans have been decorating their bodies for a long time.  Ötzi "the Ice Man," a five-thousand-year-old body found frozen in glacial ice on the Austrian-Italian border, had 61 tattoos, mostly on his legs, arms, and back.  (Their significance is unknown.)  In historical times, tattooing has been observed in many cultures -- it was widespread in North and South American Indigenous people and throughout east Asia and Polynesia, which is probably how the tradition jumped to Europe in the eighteenth century (and explains its associations with sailors).

The role of self-expression in tattoos varies greatly from person to person.  Ask a dozen people why they chose to get inked and you'll get a dozen wildly different answers.  For me, it's in honor of my family and ethnic roots; the Celtic snake is for my wildlife-loving, half-Scottish father, the vines for my gardener mother.  But the reasons for getting tattooed are as varied as the designs are.

The reason all this comes up is because of a discovery that was described this week in the Proceedings of the National Academy of Sciences of a twelve-hundred-year-old mummified body from the pre-Columbian Peruvian Chancay Culture, which showed some of the most intricate ancient tattoo patterns ever seen.  Virtually every square inch of the person's skin was covered with a fine latticework of black geometric designs -- the similarity was immediately noticed to the adornments on clay figurines from the same time and place.

This becomes even more amazing when you realize that the person was tattooed using the "stick-and-poke" method, which involved being jabbed over and over with implements like wooden needles, slivers of flint or obsidian, or sharpened bird bones.  This sounds a hell of a lot more painful than what I underwent, which was bad enough.

But it was still worth it. After I stopped screaming.

In any case, I find it fascinating how old the drive to adorn our bodies is, and also that the chosen designs had (and have) such depth of meaning that people were willing to wear them permanently.  For myself, I've never regretted them for a moment; I'm proud of my ink, whatever the sour-faced little old ladies of the world might think of it.  And knowing that what I have is part of a tradition that goes back thousands of years gives me a connection to the rituals and culture of the past.

And for me, that's something to cherish.  Even if I do end up in hell because of it.

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