The next phase

When I put on water for tea, something peculiar happens.

Of course, it happens for everyone, but a lot of people probably don't think about it.  For a while, the water quietly heats.  It undergoes convection -- the water in contact with the element at the bottom of the pot heats up, and since warmer water is less dense, it rises and displaces the cooler layers above.  So there's a bit of turbulence, but that's it.

Then, suddenly, a bit of the water at the bottom hits 100 C and vaporizes, forming bubbles.  Those bubbles rapidly rise, dispersing heat throughout the pot.  Very quickly afterward, the entire pot of water is at what cooks call "a rolling boil."

This quick shift from liquid to gas is called a phase transition.  The most interesting thing about phase transitions is that when they occur, what had been a smooth and gradual change in physical properties (like the density of the water in the teapot) undergoes an enormous, abrupt shift -- consider the difference in density between liquid water and water vapor.

The reason this comes up is that some physicists in Denmark and Sweden have proposed a phase transition mechanism to account for the evolution of the (very) early universe -- and that proposal may solve one of the most vexing questions in astrophysics today.

A little background.

As no doubt all of you know, the universe is expanding.  This fact, discovered through the work of astronomer Edwin Hubble and others, was based upon the observation that light from distant galaxies was significantly red-shifted, indicating that they were moving away from us.  More to the point, the farther away the galaxies were, the faster they are moving.  This suggested that some very long time in the past, all the matter and energy in the universe was compressed into a very small space.

Figuring out how long ago that was -- i.e., the age of the universe -- depends on knowing how fast that expansion is taking place.  This number is called the Hubble constant.

[Image licensed under the Creative Commons Munacas, Big-bang-universo-8--644x362, CC BY-SA 4.0]

This brings up an issue with any kind of scientific measurement, and that's the difference between precision and accuracy.  While we use those words pretty much interchangeably in common speech, to a scientist they aren't the same thing at all.  Precision in an instrument means that every time you use it to measure something, it gives you the same answer.  Accuracy, on the other hand, means that the value you get from one instrument agrees with the value you get from using some other method for measuring the same thing.  So if my car's odometer tells me, every time I drive to my nearby village for groceries, that the store is exactly eight hundred kilometers from my house, the odometer is highly precise -- but extremely inaccurate.

The problem with the Hubble constant is that there are two ways of measuring it.  One is using the aforementioned red shift; the other is using the cosmic microwave background radiation.  Those two methods, each taken independently, are extremely precise; they always give you the same answer.

But... the two answers don't agree.  (If you want a more detailed explanation of the problem, I wrote a piece on the disagreement over the value of the Hubble constant a couple of years ago.)

Hundreds of measurements and re-analyses have failed to reconcile the two, and the best minds of theoretical physics have been unable to figure out why. 

Perhaps... until now.

Martin Sloth and Florian Niedermann, of the University of Southern Denmark and the Nordic Institute for Theoretical Physics, respectively, just published a paper in Physics Letters B that proposes a new model for the early universe which makes the two different measurements agree perfectly -- a rate of 72 kilometers per second per megaparsec.  Their proposal, called New Dark Energy, suggests that very quickly after the Big Bang, the energy of the universe underwent an abrupt phase transition, a bit like the water in my teapot suddenly boiling.  At this point, these "bubbles" of rapidly dissipating energy drove apart the embryonic universe.

"If we trust the observations and calculations, we must accept that our current model of the universe cannot explain the data, and then we must improve the model," Sloth said.  "Not by discarding it and its success so far, but by elaborating on it and making it more detailed so that it can explain the new and better data.  It appears that a phase transition in the dark energy is the missing element in the current Standard Model to explain the differing measurements of the universe's expansion rate.  It could have lasted anything from an insanely short time -- perhaps just the time it takes two particles to collide -- to 300,000 years.  We don't know, but that is something we are working to find out...  If we assume that these methods are reliable -- and we think they are -- then maybe the methods are not the problem.  Maybe we need to look at the starting point, the basis, that we apply the methods to.  Maybe this basis is wrong."

It's this kind of paradigm shift in understanding -- itself a sort of phase transition -- that triggers great leaps forward in science.  To be fair, some of them fizzle.  Most of them, honestly.  But sometimes, there are visionary scientists who take previously unexplained knowledge and turn our view of the universe on its head, and those are the ones who revolutionize science.  Think of how Galileo and Copernicus (heliocentrism), Kepler (planetary motion), Darwin (biological evolution), Mendel (genetics), Einstein (relativity), de Broglie and Schrödinger (quantum physics), Watson, Crick, and Franklin (DNA), and Matthews and Vine (plate tectonics) changed our world.

Will Sloth and Niedermann join that list?  Way too early to know.  But just the fact that one shift in the fundamental assumptions about the early universe reconciled measurements that heretofore had stumped the best theoretical physicists is a hopeful sign.

Time will tell if this turns out to be the next phase in cosmology.

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The ideological minefield

A couple of days ago, I received an email through my author website that started out, "Are you by any chance the Gordon Bonnet who taught science at Finn Hill Junior High in 1987?"

It turned out that it was indeed from a former student of mine, from the very first year of my teaching career, who (alarmingly!) just turned fifty years old.  When I confirmed that I was the guy, he sent me a heartwarming response about how he had made a career working for the National Parks Service as a wilderness educator, and that his love of nature had in no small part been due to my being his teacher when he was in ninth grade.

This sort of thing is why teachers do what they do.  I can say from my own experience that three teachers -- my high school biology and creative writing teachers, and my college calculus professor -- changed my life in hugely positive ways.  But the glow of receiving that email from my former student was dimmed somewhat by the knowledge that if I were in college right now, I would never -- not in a million years -- choose teaching as a profession, and that's after a 32-year career that, all in all, was pleasant and successful.  Not only would I not recommend the profession to anyone, I would counsel current teachers to keep their options open about finding other ways to use their talents to make a living.

[Image is in the Public Domain, courtesy of Michael Anderson (Photographer), Children in a classroom]

The reason is that public education has been turned into an ideological minefield by self-serving demagogues, through the cold, calculated characterization of schools as supposed "hotbeds of indoctrination."  The far right has taken steps -- thus far, scarily successful ones -- to muzzle teachers, stifle their creativity, and prevent them from doing the job they were hired to do with any degree of autonomy.  

This is not a new trend.  I still remember when the New York State Department of Education launched the infamous "Common Core," twelve years ago or so, with the aim of trying to create a curriculum that guaranteed all students receive a certain standard set of information and skills.  While few would argue with that aim as an ideal, the implementation was not only chaotic, it attempted to solve the "standard curriculum" issue by forcing teachers into lockstep -- handing them scripts, each with a certain number of minutes they were to devote to particular topics.  It never went any further than English and math; fortunately for me, by the time they got to science, a lot of the momentum had fizzled, and what they gave us was nothing more than a weakly-revamped version of what we already had.

It's a good thing.  When I saw what was happening in English and math, I said -- in the middle of a faculty meeting -- "the day New York State hands me a script and expects me not to deviate from it will be my last day on the job."

You go through years of training, then undergo a rigorous vetting process wherein you have to demonstrate how creative and competent and knowledgeable you are, and then the b-b stackers in the Department of Education hand you a script to read.  It's maddening... and deeply insulting.

Since that time, it's only gotten worse.  The obvious example is the state of Florida, where Governor Ron DeSantis has forced teachers to dismantle or make inaccessible their classroom libraries until each book can be approved by a media specialist.  The ostensible reason is to make sure they're classroom-appropriate -- not only at the correct reading level, but that they don't have material unsuitable for the age of the student.  Just as with the Common Core, the stated goal sounds laudable enough.  Nobody's arguing for students having age-inappropriate material.

It doesn't take a rocket scientist, however, to figure out that this isn't actually about reading level.  From DeSantis's previous commitment to "anti-wokeness" there's little doubt that the whole thing is a smokescreen for what is largely an ideological move.  What likelihood do you think there is of the state-hired "media specialists" approving a book that displays LGBTQ characters in a positive light?  Or presents a realistic picture of what life was and is like for minorities, especially after his recent (successful) demand that Florida schools drop an AP African American Studies course?

The situation in Florida is that a teacher having copies of Knots on a Counting Rope (about growing up Native American) or The List of Things That Will Not Change (about a child being raised by two dads) available for students would be risking prosecution.  (Yes, both of those have already been banned in Florida schools -- along with 174 others, including the biographies of Rosa Parks, Sonia Sotomayor, Jim Thorpe, Roberto Clemente, Harvey Milk, and Jackie Robinson.  Don't even try to tell me this isn't about ideology.)

Then, a disingenuous CNN story yesterday feigned shock over the fact that in many places in the United States, there's been such a massive exodus of teachers that some schools are finding it hard to keep their doors open.  Gee whiz, I wonder why that could be?  In fact, in Florida they've recently created a "new pathway" for teaching positions to be filled by individuals who don't even have a bachelor's degree in the subject they're teaching.  The Florida Department of Education (speaking of disingenuous) not only claims this has nothing to do with the governor's anti-teacher campaign, but denies there's a teacher shortage at all.   "The purpose of this new pathway," a spokesperson said, "was to value the unique experience military service provides while simply offering additional time for these veterans to obtain a bachelor’s degree and other requirements to receive a full professional educator certification."

I'm calling bullshit on this.  Many candidates with excellent credentials are avoiding going into education, and who can blame them?  What highly-qualified individuals in their right mind would want to step into a position where they're devalued and harassed, robbed of autonomy, paid like crap, subjected to arbitrary decisions by policymakers who have never spent ten seconds in front of a group of students, and then threatened with prosecution for addressing the diversity in their own classrooms and presenting history that isn't blatantly whitewashed?  For me -- and again, I say this as a retired career educator who, by and large, had a great run -- it's a case of, "Turn and run.  Fast."

It's blatantly obvious where this is going; if you hobble educators to the point that teachers resign and public schools close, the only options for parents will be private, for-pay schools (including religious ones) where administrators have free rein to promote whatever kind of worldview they choose.  This, of course, has been the goal of the far right for as long as I can recall.  The idea of an egalitarian, even-handed public school system, where there is a set of brakes on ideologically-biased curricula, has been under fierce attack for decades.  (And it bears mention that far from being the alleged hotbeds of indoctrination the far right claims, in my thirty-plus of teaching, I only met two teachers -- one right-wing, the other left -- who honestly spent time trying to shift their students' political leanings.  Neither one, I might add, was particularly successful.  The rest of us teachers were too busy trying to get our students to reach a level of competence in our subjects to spend our time preaching politics.)

It breaks my heart to write this, but it has to be said, and said loudly.  What Ron DeSantis and others are engaging in is the classic technique of accusing the opposition of what they themselves are doing.  In this case, creating classrooms that promote a specific ideology, that turn what used to be a creative, rewarding profession into something intended to produce lockstep automata -- both the teachers and the students.

And unless things change, fast, my advice to any prospective teachers is to find some other way to help improve the world.  Because right now, the system is set up to destroy the very reasons most of us were drawn to education in the first place.

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A rare firecracker

A layperson might be excused if looking up at the night sky, (s)he concluded that other than slight variations in color and brightness, one star is pretty much like another.

I can't deny they look that way.  Even with the best telescope available to amateur astronomers, stars are featureless points of light.  About all we earthbound amateurs could discern that might clue us in to stars' wide variety of features, compositions, and behaviors is that some (many of them, in fact) are in binary or multiple star systems, and that a few fluctuate in brightness at regular intervals.  (Variable stars, in fact, were known to the ancients, and because in general our ancestors felt that the heavens should be eternal and changeless, they were viewed with great suspicion; one of the best-known, in fact, is Algol, which comes from the Arabic words for "the ghoul's head.")

First with the Hubble Space Telescope, and now with the James Webb Space Telescope, we've finally gotten the first direct photographs of stars showing any kind of detail (and the first direct photographs of exoplanetary systems).  But astrophysical data collection, often in regions of the electromagnetic spectrum the eye can't see, has given us more information about the wild variety of stars out there -- many of which are only now beginning to be understood.

Take for example the binary star system with the euphonious name CPD-29-2176, located a bit over eleven thousand light years away.  This pair is so strange that its characteristics are thought to match only one in every ten billion star systems, meaning there are probably only ten or so of them in the entire Milky Way.  (Fortunate, then, that one is close enough to study.)  First discovered from its x-ray signature by NASA's Neil Gehrels Swift Observatory and later studied by the SMARTS 1.5-meter Telescope, CPD-29-2176 is a kilonova progenitor system -- a pair of stars in which one is destined to blow up.

Artist's impression of CPD-29-2176  [Image courtesy of CTIO/NOIRLab/NSF/AURA/J. da Silva]

The mechanism is a little like a type 1a supernova, in which a white dwarf is in a close orbit with a larger main-sequence star.  The white dwarf, a dense, hot stellar nucleus of a moribund star, slowly draws off material from it partner through its intense gravitational pull, creating a whirlpool of accreting matter.  This, however, can only go on so long; once the white dwarf exceeds the Chandrasekhar limit, about 1.4 solar masses, it suddenly collapses.  The temperature skyrockets, and the former white dwarf becomes a supernova intense enough to blow the companion right out of orbit.

Here, though, the dynamics are a bit different.  If a supernova is a "holy shit!" event, a kilonova is more of a "meh."  What apparently is happening is the two stars are already so close that one is losing material to the other at a colossal rate.  The result: once the losing star burns through its fuel, at which point it should undergo the collapse/explosion cycle, there won't be enough fuel left to spike its temperature much.  It will trigger a kilonova (also called an ultra-stripped supernova), which is to an actual supernova what a wet firecracker is to a nuclear bomb.

What's even more interesting is that the same fate is predicted for the companion star; ultimately, what will be left is two neutron stars whirling around a common center of gravity, eventually falling inward and coalescing.  The release of gravitational potential energy by the merger will tear the stars apart -- stunning this could happen to objects so dense -- and the resulting debris, highly enriched in heavy elements, will be dispersed to the cosmos.

As astonishing as it sounds, all of the heavy elements -- the gold and silver in our jewelry, the mercury in our thermometers (well, old ones, at least), the uranium in our nuclear power plants, the rare earth elements in our computers -- were created in the cores of dying stars.  (If you want to learn more about this astonishing process, I did a piece here at Skeptophilia about it a couple of years ago.)

While a kilonova isn't going to be anything spectacular to watch from here on Earth, it's a rara avis indeed in the galactic zoo.  

Every time I read about some new astronomical discovery, it highlights for me how much more complex the universe is than the ancients dreamed.  Their point sources of light on crystal spheres, driven by deities and heavenly powers, miss the true intricacy of the cosmic clockwork by light years.  How delighted Galileo and Copernicus and Eratosthenes would be to know what we know -- to get a glimpse of a universe so vast, and so diverse, that it far surpasses the famous quote by Shakespeare -- "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy."

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The unanswerable

Humans are boundlessly curious, and that's a good thing.  Our drive to understand, to cure our ignorance about the world around us, is the engine that powers science.  In my 32-year career as a science teacher, one of the things I strove the hardest to accomplish was to urge my students never to be content to shrug their shoulders and stop trying to understand.

Like most things, though, this curiosity has a downside, and that is when it turns into a desperation to have an answer, any answer, whether it's supported by the evidence or not.  Saying "I don't know, and may never know" is sometimes so profoundly uncomfortable that we settle into whatever explanation sounds superficially appealing -- and forthwith stop thinking about it.

Taking a scientific, skeptical view of things requires not only that you have the drive to understand, but that you can tolerate -- and know the scope of -- the limits of your own knowledge.  As theoretical physicist John Archibald Wheeler put it, "We live on an island surrounded by a sea of ignorance.  As the island of our knowledge grows, so does the shore of our ignorance."

What got me thinking about this is a story I ran into on the site Coast to Coast, which specializes in oddball speculation about unexplained phenomena.  The headline was "Mysterious Stone Carving Stumps Archaeologists in England," just the latest in umpteen popular media stories about some new discovery that "has scientists baffled."

To read this stuff, you come away with the impression that scientists do nothing all day but sit around scratching their heads in puzzlement.

In any case, the contents of the story are interesting enough.  A curious stone carving was discovered by some archaeologists investigating a Late Bronze Age site on Nesscliffe Hill, near Shrewsbury.  Without further ado, here's the carving:

Paul Reilly, one of the archaeologists studying the site, said that the carving is "indicative of two different types of technology, grinding and carving...  It appears to depict some kind of figure with the indentation being its head and the various scratches representing two long horns and two small horns, a central body line and two arms, one held up and the other down, the upward one showing a possible hand holding a pipe or a weapon...  Placing it in historical context, however, is another challenge altogether...  The carving has similarities with Late Bronze Age carvings of figures in horned helmets.  The region was once the domain of a Roman tribe known as the Cornovii, a name that has been suggested to reference to the ‘horned ones’.  The figure also could represent a horned deity cult in the Roman army as depicted at several military sites across Britain."

Note how many times Reilly uses words like "appears" and "could be" and "possible" and "suggested."  The fact is -- as he admits up front -- he doesn't know who carved the figure and why.  Dating such finds is a challenge at best, and this one is especially problematic; it was found in loose soil that had been used to backfill a trench from an earlier dig, so it was not in what archaeologists call "a secure context" (i.e., pretty much where it had been placed when its maker set it down millennia ago).

None of this is all that unusual; this kind of thing happens all the time in archaeology, and is in fact way more common than finding an artifact and being able to ascertain exactly when it had been created, by whom, and why.  But what got me thinking about our need to find an answer, any answer, was how Tim Binnall -- who wrote the article about the discovery -- wound up his piece by asking if any of his readers could "solve the mystery of the stone carving," and asked them to submit their answers to him at Coast to Coast.

Now, I know part of this is just an attempt to engage his readers, and there's nothing wrong with that.  I always love it when readers post comments and questions here at Skeptophilia (well, almost always -- I could do without the hate mail).  But immediately I read that, my reaction was, "Why on earth would some random layperson's opinion on the carving have any relevance whatsoever?"  He is, in essence, asking people to form opinions about an artifact for which even the experts have nothing more than speculation.

This is where we cross over into the territory of preferring any answer at all over admitting that we simply don't know, and may never know.

I'm deliberately leaving this in the realm of an obscure archaeological find, because (notwithstanding Binnall's request) few of us are going to get passionately emotional about a carved piece of rock from Bronze Age England.  But I'm sure you can come up with lots of other, more highly charged, examples of this -- questions for which our desire to have answers overrides the fact that we simply don't have enough evidence to conclude anything.  And some of these answers to unanswerable questions are believed with enough fervor that people will die for them -- and there are those who will unhesitatingly kill you if your answer is different from theirs, or worse, if you state outright that you don't know, and in reality, neither do they.

These are not easy issues.  As I said earlier, a lot of it comes from a source that is, at its heart, a positive thing; the drive to know.  But honesty is as important as curiosity, and that includes an honest assessment of what we understand and what we do not.  I'll conclude with a quote from another brilliant physicist, Richard Feynman: "I would far rather have questions that cannot be answered than answers that cannot be questioned."

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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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Reversing the core

I get really frustrated with science news reporting sometimes.

I mean, on the one hand, it's better that laypeople get exposed to science somehow, instead of the usual fare of the mainstream media, which is mostly stories about seriously depressing political stuff and the latest antics of celebrities.  But there's a problem with science reporting, and it's the combination of a lack of depth in understanding by the reporters, and a more deliberate desire to create clickbaity headlines and suck people in.

Take, for example, the perfectly legitimate (although not universally accepted) piece of research that appeared on January 23 in Nature Geoscience, suggesting that the Earth's inner core oscillates in its rotational speed with respect to the rest of the planet -- first going a little faster, then slowing a bit until its rotational rate matches Earth's angular velocity, then slowing further so the rest of the planet for a time outruns the core.  Then it speeds up, and does the whole thing in reverse.  The reason -- again, if it actually happens, which is still a matter of discussion amongst the experts -- is that the speed-up/slowdown occurs because of a combination of friction with the outer core, the effects of the magnetic field, and the pull of gravity from the massive mantle that lies outside it.

[Image licensed under the Creative Commons CharlesC, Earth cutaway, CC BY-SA 3.0]

That's not how this story got reported, though.  I've now seen it several times in different mainstream media, and universally, they claim that what's happening is that the inner core has stopped, and started to spin the other way -- i.e. the inner core is now rotating once a day, but in the opposite direction from the rest of the Earth.

This is flat-out impossible.  Let's start with the fact that the inner core has a mass of about 110,000,000,000,000,000,000,000 kilograms.  A mass that huge, spinning on its axis once a day, has a stupendous amount of angular momentum.  To stop the rotation of that humongous ball of nickel and iron would take an unimaginable amount of torque, and that's not even counting overcoming the drag that would be exerted by the outer core as you tried to make the inner core slow down.  (I could calculate how much, but it's just another huge number and in any case I don't feel like it, so suffice it to say it's "a shitload of torque.")  Then, to accelerate it so it's rotating at its original rate but in the opposite direction would take that much torque again.

Where's the energy coming from to do all that?

Here, the fault partly lies with the scientists; they did use the words "reversing direction" in their press release, but what they meant was "reversing direction with respect to the motion of the rest of the Earth."  I get that relative motion can be confusing to visualize -- but giving people the impression that something has stopped the inner core of the Earth and started it rotating in the opposite direction gives new meaning to "inaccurate reporting."

Worse still, I'm already seeing the woo-woos latch onto this and claim that it's a sign of the apocalypse, that the Evil Scientists™ are somehow doing this deliberately to destroy the Earth, that it's gonna make the magnetic field collapse and trigger a mass extinction, and that it's why the climate has been so bonkers lately.  (Anything but blame our rampant fossil fuel use, apparently.)  Notwithstanding that if you read the actual paper, you'll find that (1) whatever this phenomenon is, it's been going on for ages, (2) it represents a really small shift in the inner core's angular velocity, and (3) it probably won't have any major effects on we ordinary human beings.  After all, (4) the scientists have only recently figured out it's happening, and (5) not all of them believe it is happening.

So let's just all calm down a bit, okay?

In any case, I'd really appreciate it if the people reporting science stories in the mainstream media would actually read the damn papers they're reporting on.  It'd make the job of us skeptics a hell of a lot easier.  Thanks bunches.

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Assembling aliens

There are a lot of hurdles in detecting extraterrestrial life, and that's not even counting the possibility that it might not exist.

Honestly, I don't think that last stumbling block is all that likely, and it's not just because proving we're not alone in the universe has been one of my dearest wishes since I was six years old and watching the original Lost in Space.  Since astronomer Frank Drake came up with his famous Drake equation in 1961, which breaks down the likelihood of extraterrestrial intelligence into seven individual parameters (each with its own, independent probability), the estimates of the values of those parameters have done nothing but increase.  As only one example, one of the parameters is f(p) -- the fraction of stars that have planetary systems.  When Drake first laid out his equation, astronomers had no certainty at all about f(p).  They were working off a sample size of one; we know the Solar System exists because we live in it.  But was its formation a fluke?  Were stars with planets extremely uncommon?

No one knew.

Now, exoplanet discovery has become so routine that it barely even makes the news any more.  The first exoplanet around a main-sequence star -- 51 Pegasi b -- was discovered in 1995.  Since then, astronomers have found 5,297 exoplanets, with new ones being announced literally every week.  It seems like damn near a hundred percent of stable main-sequence stars have planetary systems, and most of them have at least one planet in the "Goldilocks zone," where the temperatures are conducive to the presence of liquid water.

Even setting aside my hopes regarding aliens, the sheer probability of their existence has, from a purely mathematical standpoint based upon the current state of our knowledge of the universe, improved significantly.

But this still leaves us with a problem: how do we find it?  The distances even to the nearest stars are insurmountable unless someone comes up with warp drive.  (Where are you, Zefrem Cochrane?)  So we're left with remote sensing -- looking for biosignatures.  The most obvious biosignature would be a radio transmission that's clearly from intelligent life, such as the one Ellie Arroway found in Contact; but it bears keeping in mind that through almost all of the Earth's 3.7-billion-odd years it's been inhabited by living creatures, it would have been entirely silent.  Alien astronomers looking from their home worlds toward the Earth would not have heard so much as a whisper.  It's only since we started using radio waves to transmit signals, a century ago, that we'd be detectable that way; and given how much transmission is now done via narrow-beam satellite and fiber optics cables rather than simple wide-range broadcast, it's entirely possible that once the technology improves Earth will go silent once again.  There may only be a short period during which a technological civilization is producing signals that are potentially detectable from a long way away.

So the question remains: how could we determine if an exoplanet had life?

I'm guessing that whatever the aliens look like, it's not this.  Unfortunately.

The tentative answer is to look for other kinds of biosignatures, and the most obvious one is chemicals that "shouldn't be there" -- in other words, that would not form naturally unless there were life there producing them through its metabolic processes.  This, too, is not a simple task.  Not only is there the technological challenge of detecting what's in a distant exoplanet's atmosphere (something we're getting a lot better at, as spectroscopy improves), there's the deeper question of how we know what should be there.  If we find an odd chemical in a planet's atmosphere, how do we know if it was made by life, or by some exotic (but abiotic) chemistry based on the planet's composition and conditions?

We've gotten caught this way before; three years ago, scientists discovered traces of a chemical called phosphine in the atmosphere of Venus, and a lot of us -- myself included -- got our hopes up that it might be a biosignature of something alive in the clouds of our hostile sister planet.  The consensus now is that it isn't -- the amounts are vanishingly small, and any phosphine on Venus is a product of its wild convection and bizarre atmospheric makeup.  So once we detect a chemical on an exoplanet, is there a way to do a Drake-equation-style estimate of its likelihood of forming abiotically?

Astrobiologist Leroy Cronin, of the University of Glasgow, has proposed an answer, based on something he calls "assembly theory."  Assembly theory, significantly, doesn't rely on any kind of analogy to terrestrial life.  Cronin and others are now trying to figure out strategies to find life as we don't know it -- living creatures that might be based upon extremely different chemistry.

What he's done is given us a purely mathematical way to index chemicals according to how many independent steps it takes to create them from simple, pre-existing building blocks.  This molecular assembly number, Cronin says, is directly proportional to its likelihood of being created by a living thing.  As a simple analogy, he shows how you would find the molecular assembly number for the word abracadabra:

1. add a + b;
2. add ab + r;
3. add abr + a;
4. add abra + c;
5. add abrac + a;
6. add abraca + d;
7. add abracad + abra (we'd already created abra in step three).

Seven steps from the primordial building blocks, so the molecular assembly number for abracadabra is seven.

Replace putting letters and letter groups together with steps in a chemical reaction chain, and you have an idea how assembly theory works.

Like the Drake equation, Cronin's method isn't proof.  Finding some complex chemical in an exoplanet's atmosphere, the gas of a nebula, or a meteorite might be suggestive of life, but almost certainly wouldn't convince the doubters without a lot more in the way of evidence.  Still, just as Frank Drake did in 1961, it's nice to have a protocol for determining the likelihood of a biosignature that doesn't depend on our unavoidable Earth-centrism.  Like with the formation of the Solar System, we're familiar with only one kind of life -- the kind all around us, that we ourselves are examples of.  Shaking the bias that all life is Earth-like is not easy.

It's understandable that the creators of Lost in Space and Star Trek visualized almost all of the aliens as basically humans with odd facial excrescences, and that's granting the difficulty of finding a way to portray non-humanoid aliens convincingly using human actors.  When they did manage to get beyond humans with rubber noses, such as in the Lost in Space episode "The Derelict" and the Star Trek episodes "The Devil in the Dark" and "Obsession," the aliens were, respectively, giant mobile bubbles, a tunneling, acid-spewing rock, and a disembodied vampiric mist cloud, all of a which at least gave a shot at trying to visualize what truly non-Earthlike life might be.

I'm hopeful that the work of Cronin and others is moving the new field of astrobiology forward from simple "what ifs" to actual rigorous algorithms for analyzing the spectroscopic data we're gathering from exoplanet atmospheres.  And maybe... just maybe... within my lifetime we'll have enough data to feel confident we've identified for certain what I've been waiting for since I was six: life on another planet.

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