Scanning the skies for life

It will come as no surprise to regular readers of Skeptophilia that one of my dearest wishes is to live long enough to see incontrovertible proof of life on another planet.

Intelligent life would just be the icing on the cake, but I'm not counting on it, especially given how rare it is down here on Earth.  And the best of all -- having the intelligent life come here so I could have a talk with it -- is so unlikely as to be impossible, given the enormous (shall we say astronomical) distances involved.

But that doesn't mean we can't find out more about the conditions that could generate life and the likelihood of it being found elsewhere, as three pieces of research last week showed.

The first, which appeared in the journal Science Advances, is called "The Origin of RNA Precursors on Exoplanets," by a team of Cambridge University astrophysicists, Paul B. Rimmer, Jianfeng Xu, Samantha J. Thompson, Ed Gillen, John D. Sutherland, and Didier Queloz.  In it, we find out that the conditions for forming RNA nucleotides -- the fundamental building blocks of RNA, one of the two carriers of genetic information (and generally thought to be the one that formed first) -- have been narrowed down to a specific range of temperatures and luminance.  The authors write:

Given that the macromolecular building blocks of life were likely produced photochemically in the presence of ultraviolet (UV) light, we identify some general constraints on which stars produce sufficient UV for this photochemistry.  We estimate how much light is needed for the UV photochemistry by experimentally measuring the rate constant for the UV chemistry (“light chemistry”, needed for prebiotic synthesis) versus the rate constants for the biomolecular reactions that happen in the absence of the UV light (“dark chemistry”).  We make these measurements for representative photochemical reactions involving and HS−.  By balancing the rates for the light and dark chemistry, we delineate the “abiogenesis zones” around stars of different stellar types based on whether their UV fluxes are sufficient for building up this macromolecular prebiotic inventory.  We find that the light chemistry is rapid enough to build up the prebiotic inventory for stars hotter than K5 (4400 K).  We show how the abiogenesis zone overlaps with the liquid water habitable zone.  Stars cooler than K5 may also drive the formation of these building blocks if they are very active.

The good news, for exobiology aficionados like myself, is that this not only homes in on what conditions are likely to produce life -- telling us where to look -- they're conditions that are relatively common in the universe.  Which further bolsters something I've said for ages, which is that life will turn out to be plentiful out there.

[Image licensed under the Creative Commons ESO/M. Kornmesser/Nick Risinger (skysurvey.org), Artist impression of the exoplanet 51 Pegasi b, CC BY 4.0]

The second, which appeared in Monthly Notices of the Royal Astronomical Society, suggests one way to detect that life at a distance.  In "Biological Fluorescence Induced by Stellar UV Flares, a New Temporal Biosignature," by Jack T. O'Malley-James and Lisa Kaltenegger (both of Cornell University), we find out that class-M stars -- of which the Sun is one -- not only have the right temperature ranges to foster planets with life, but their habit of generating solar flares could tip us off as to which planets hosted life.  The phenomenon of biofluourescence -- the absorption of high-energy light (such as ultraviolet) and its conversion into lower-energy light (visible light) -- could act as a protective mechanism during solar flares.  So when a star flares up, all we have to do is look for the flash of fluorescence that follows.

"On Earth, there are some undersea coral that use biofluorescence to render the Sun’s harmful ultraviolet radiation into harmless visible wavelengths, creating a beautiful radiance," said study co-author Lisa Kaltenegger, who is the director of the Carl Sagan Institute for Astrophysics.  "Maybe such life forms can exist on other worlds too, leaving us a telltale sign to spot them."

The coolest thing is that one of the stars being studied is Proxima Centauri -- the closest star to our Solar System.  So the technique O'Malley-James and Kaltenegger propose using could find life that is, so to speak, right next door.

As a cool followup to this paper, the following day a paper appeared in arXiv by a team of astrophysicists led by Stefan Dreizler of the Georg-August-Universität Göttingen that found not one but three planets in the "Goldilocks zone" of a relatively nearby star -- GJ1061.  One of the problems with figuring out which planets to study for signs of life is that the mass of the planet and its distance from the star aren't the only factors that matter; another, and one much harder to determine from Earth, is the stability of the orbit.  I still remember when I was a kid watching the generally-abysmal 1960s science fiction show Lost in Space, and was blown away when it was revealed that the planet the Robinson family was on was in a highly elliptical orbit -- so the seasons varied from blisteringly hot at the planet's perigee and freezing cold at its apogee.  (The way it played out in the show was, predictably, kind of silly, but it was a concept I'd never run into before, and at age six I was pretty damned impressed.)

But what Dreizler et al. found was that the three planets around GJ1061 were in stable orbits, meaning it was likely that they were relatively circular.  (Elliptical orbits cross each other and therefore increase the likelihood of collisions or gravitational slingshots slinging a planet into the star or out into space.)

So this gives us another likely candidate for biosignatures.

I'm pretty encouraged at all the effort that's being expended in this endeavor.  I vividly recall watching my favorite movie -- Contact -- for the first time, and being appalled at how astronomer Ellie Arroway had to fight to be taken seriously, not only because she was a woman in what then (and still is to some extent now) was a man's world, but because her area of research was the search for extraterrestrial life.  What more fascinating research is there, to find out if life on Earth is unique -- or if, as I contend, we're just one of a multitude of planets hosting life?

I can't imagine a more deeply resonant idea, nor one that would have as profound an effect on how we see ourselves and our place in the universe.  And if that's not worth researching, I don't know what is.

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This week's Skeptophilia book recommendation is a must-read for anyone interested in astronomy -- Finding Our Place in the Universe by French astrophysicist Hélène Courtois.  Courtois gives us a thrilling tour of the universe on the largest scales, particularly Laniakea, the galactic supercluster to which the Milky Way belongs, and the vast and completely empty void between Laniakea and the next supercluster.  (These voids are so empty that if the Earth were at the middle of one, there would be no astronomical objects near enough or bright enough to see without a powerful telescope, and the night sky would be completely dark.)

Courtois's book is eye-opening and engaging, and (as it was just published this year) brings the reader up to date with the latest information from astronomy.  And it will give you new appreciation when you look up at night -- and realize how little of the universe you're actually seeing.

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

A black hole's strange glow

I think part of my enjoyment of science is that I love a good mystery.

The universe is endlessly fascinating and also endlessly complicated, and if you get into science you'll never want for new things to learn about.  You'll also be pushing the edges of what we can explain.  Some fairly simple-to-ask questions that we still haven't solved:

• Why do we dream?  It's ubiquitous amongst mammals, but its purpose is still uncertain.
• Why does space have three spatial dimensions?  There's nothing particularly special about having three dimensions, at least from what we know.  There's a conjecture that (if string theory is correct) there are eleven spatial dimensions, but if so, why are eight of them essentially undetectable?
• Is life common in the universe, or are we alone?
• Where does consciousness come from?
• What caused the Big Bang?
• What causes aging... and can it be slowed or stopped entirely?
• What causes the flow of time?  Most processes in physics are time-reversible -- they make equal sense if you watch them by running the clock backwards.  Why do we have an unshakeable sense of time's arrow only pointing one way?
• Could human cognition and personality theoretically be emulated in a machine?
• What are dark matter and dark energy?  And why can't we detect them except by their gravitational signature?

So if you like to wonder about stuff, immerse yourself in science.  I can promise you you'll never be bored.

This comes up because of some weird behavior by one of the oddest things in the universe: black holes.  You probably know that a black hole is a collapsed supergiant star, an object that is so massive that it warps space into a closed shape.  Even light can't escape (thus the name).  Around the border of a black hole is the event horizon, which is the point of no return -- when you cross it, you'll never escape, and will ultimately fall into the singularity at the center.  But you'll be dead long before then, torn to shreds by the tidal forces as you approach (a process astrophysicists have nicknamed, no lie, spaghettification.)

Black holes, though, aren't necessarily produced by the collapse of a single star.  It's thought that most galaxies have massive black holes at their center.  The Milky Way has one with the unprepossessing name Sagittarius A*, which becomes a little more impressive when you find out that it has four million times the mass of the Sun.

You might wonder how (being black) it was detected.  As matter falls into a black hole, it accelerates, and in the process emits radiation.  (Sort of an electromagnetic death scream, is how I think of it.)  Being as massive as it is, Sagittarius A* has quite a signature in the radio region of the spectrum, which is how it was first detected way back in 1931.

Sagittarius A* [Image is in the Public Domain, courtesy of NASA]

What got me thinking about this is that Sagittarius A* has been acting rather strangely of late.  Like most black holes studied, it does fluctuate in its energy output, presumably as the amount of matter falling into it varies.  But back in May of this year, its luminosity in the near-infrared region of the spectrum increased by a factor of 75...

... in a period of two hours.

"The brightness of Sgr A* varies all the time, getting brighter and fainter on the timescale of minutes to hours—it basically flickers like a candle," said study leader, UCLA astronomer Tuan Do.  "We think that something unusual might be happening this year because the black hole seems to vary in brightness more, reaching brighter levels than we've ever seen in the past...  Many astronomers are observing Sgr A* this summer.  I'm hoping we can get as much data as we can this year before the region of the sky with Sgr A* gets behind the Sun and we won't be able to observe it again until next year...  Maybe the black hole is waking up—there's a lot we don't know at this point so we need more data to understand if what we are seeing is a big change in what is feeding the black hole or this is a brief event."

Whatever it is, it certainly is intriguing.  Such a rapid and massive increase in luminosity from such an enormous object is hard even to wrap your brain around.  All of which just goes to show that even when you have a pretty good idea of how the universe works, it can turn around an astonish you.

Which, after all, is what science is all about.

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This week's Skeptophilia book recommendation is a must-read for anyone interested in astronomy -- Finding Our Place in the Universe by French astrophysicist Hélène Courtois.  Courtois gives us a thrilling tour of the universe on the largest scales, particularly Laniakea, the galactic supercluster to which the Milky Way belongs, and the vast and completely empty void between Laniakea and the next supercluster.  (These voids are so empty that if the Earth were at the middle of one, there would be no astronomical objects near enough or bright enough to see without a powerful telescope, and the night sky would be completely dark.)

Courtois's book is eye-opening and engaging, and (as it was just published this year) brings the reader up to date with the latest information from astronomy.  And it will give you new appreciation when you look up at night -- and realize how little of the universe you're actually seeing.

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

It's the end of the world, if you notice

I have commented more than once about my incredulity with regards to end-of-the-world predictions.  Despite the fact that to date, they have had a 100% failure rate, people of various stripes (usually of either the ultra-religious persuasion or the woo-woo conspiracy one) continue to say that not only is the world doomed, they know exactly when, how, and why.  (If you don't believe me, take a look at the Wikipedia page for apocalyptic predictions, which have occurred so often they had to break it down by century.)

As far as why this occurs -- why repeated failure doesn't make the true believers say, "Well, I guess that claim was a bunch of bullshit, then" -- there are a variety of reasons.  One is a sort of specialized version of the backfire effect, which occurs when evidence against a claim you believe strongly leaves you believing it even more strongly.  Way back in 1954 psychologists Leon Festinger, Henry Riecken, and Stanley Schachter infiltrated a doomsday cult, and in fact Festinger was with the cult on the day they'd claimed the world was going to end.  When 11:30 PM rolled around and nothing much was happening, the leader of the cult went into seclusion.  A little after midnight she returned with the joyous news that the cult's devotion and prayers had averted the disaster, and god had decided to spare the world, solely because of their fidelity.

Hallelujah!  We better keep praying, then!

(Note bene: The whole incident, and the analysis of the phenomenon by Festinger et al., is the subject of the fascinating book When Prophecy Fails.)

Despite this, the repeated failure of an apocalyptic prophecy can cause your followers to lose faith eventually, as evangelical preacher Harold Camping found out.  So the people who believe this stuff often have to engage in some fancy footwork after the appointed day and hour arrive, and nothing happens other than the usual nonsense.

Take, for example, the much-publicized "Mayan apocalypse" on December 21, 2012 that allegedly was predicted by ancient Mayan texts (it wasn't) and was going to herald worldwide natural disasters (it didn't).  The True Believers mostly retreated in disarray when December 22 dawned, as well they should have.  My wife and I threw a "Welcoming In The Apocalypse" costume party on the evening of December 21, and I have to admit to some disappointment when the hour of midnight struck and we were all still there.  But it turns out that not all of the Mayan apocalyptoids disappeared after the prediction failed; one of them, one Nick Hinton, says actually the end of the world did happen, as advertised...

... but no one noticed.

Hinton's argument, such as it is, starts with a bit of puzzling over why you never hear people talking about the 2012 apocalypse any more.  (Apparently "it didn't happen" isn't a sufficient reason.)  Hinton finds this highly peculiar, and points out that this was the year CERN fired up the Large Hadron Collider and discovered the Higgs boson, and that this can't possibly be a coincidence.  He wonders if this event destroyed the universe and/or created a black hole, and then "sucked us in" without our being aware of it.

[Image licensed under the Creative Commons Lucas Taylor / CERN, CMS Higgs-event, CC BY-SA 3.0]

Me, I think I'd notice if I got sucked into a black hole.  They're kind of violent places, as I described yesterday in my post about Sagittarius A*.  But Hinton isn't nearly done with his explanation.  He writes:

There's the old cliché argument that "nothing has felt right" since 2012.  I agree with this... [E]ver since then the world seems to descend more and more into chaos each day.  Time even feels faster.  There's some sort of calamity happening almost daily.  Mass shootings only stay in the headlines for like 12 hours now.  Did we all die and go to Hell?...  Like I've said, I think we live in a series of simulations.  Perhaps the universe was destroyed by CERN and our collective consciousness was moved into a parallel universe next door.  It would be *almost* identical.

Of course, this is a brilliant opportunity to bring out the Mandela effect, about which I've written before.  The idea of the Mandela effect is that people remember various stuff differently (such as whether Nelson Mandela died in prison, whether it's "Looney Tunes" or "Loony Tunes" and "The Berenstein Bears" or "The Berenstain Bears," and so forth), and the reason for this is not that people's memories in general suck, but that there are alternate universes where these different versions occur and people slip back and forth between them.

All of which makes me want to take Ockham's Razor and slit my wrists with it.

What I find intriguing about Hinton's explanation is not all the stuff about CERN, though, but his arguing that the prediction didn't fail because he was wrong, but that the world ended and six-billion-plus people didn't even notice.  Having written here at Skeptophilia for almost nine years, I'm under no illusions about the general intelligence level of humanity, but for fuck's sake, we're not that unobservant.  And even if somehow CERN did create an alternate universe, why would it affect almost nothing except for things like the spelling of Saturday morning cartoon titles?

So this is taking the backfire effect and raising it to the level of performance art.  This is saying that it is more likely that the entire population of the Earth was unaware of a universe-ending catastrophe than it is that you're wrong.

Which is so hubristic that it's kind of impressive.

But I better wind this up, because I've got to prepare myself for the next end of the world, which (according to the late psychic Jeane Dixon) was going to occur in January of 2020.  Which only gives me a few months to get ready.  So many apocalypses, so little time.

*****************************

This week's Skeptophilia book recommendation is a must-read for anyone interested in astronomy -- Finding Our Place in the Universe by French astrophysicist Hélène Courtois.  Courtois gives us a thrilling tour of the universe on the largest scales, particularly Laniakea, the galactic supercluster to which the Milky Way belongs, and the vast and completely empty void between Laniakea and the next supercluster.  (These voids are so empty that if the Earth were at the middle of one, there would be no astronomical objects near enough or bright enough to see without a powerful telescope, and the night sky would be completely dark.)

Courtois's book is eye-opening and engaging, and (as it was just published this year) brings the reader up to date with the latest information from astronomy.  And it will give you new appreciation when you look up at night -- and realize how little of the universe you're actually seeing.

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

Dust over Antarctica

Because my other choice is writing about how Donald Trump said in a public speech last week that if you use wind power to generate electricity, your television will go off if the wind stops blowing, I've decided to focus today on: supernova dust in Antarctica.

Supernovas are one of the most awesome phenomena known.  They are so powerful astronomers estimate that if one occurred within 150 light years of the Earth, it would cause planet-wide ecological catastrophe (and the evidence is strong that such events have actually contributed to or caused mass extinctions in the past).

Two things about that to keep in mind:

• There are no imminent supernovas within 150 light years of the Earth.  The nearest candidates are Eta Carinae (7,500 light years away), Betelgeuse (500 light years away), VY Canis Majoris (4,900 light years away), and Antares (550 light years away).
• Even these "nearest candidates" are almost certainly not going to explode soon, if like most of us you're thinking on human time scales.  Eta Carinae is probably the most likely to create some celestial fireworks, and the best guess for when it will go supernova is "some time in the next three million years."  So don't cancel your plans for a Labor Day picnic because you think it's likely we'll be blown to smithereens before then.

Even so, they're pretty awesome events, and I'd love to witness one, although if it was nearby the destruction of the ozone layer by the radiation pulse and the frying of every living thing on Earth that would follow would be an unfortunate downside.

[Image licensed under the Creative Commons ESA/Hubble, Artist's impression of supernova 1993J, CC BY 4.0]

Because of their violence, and the potential effects on the Earth, astronomers have been fascinated by this phenomenon for some time.  So it was pretty exciting when a recent study of snow in Antarctica found traces of dust that were produced by a nearby supernova that exploded some time in the past few million years.

The researchers melted five hundred kilograms of pristine Antarctic snow and found substantial traces of two radioactive isotopes that shouldn't exist on Earth -- iron-60 and manganese-53.  Both are produced in the cores of supernovae, and they have half-lives of 2.7 and 3.3 million years, respectively.  Because the Earth has been around about two thousand times longer than that, all of these isotopes have decayed away in the interim.  So finding them in Antarctic snow is pretty spectacular.

It's thought that the dust was brought to Earth not by being ejected at it, but because the Solar System was swept through the cloud of debris left behind as it orbits the center of the galaxy.  The authors write:

Earth is constantly bombarded with extraterrestrial dust containing invaluable information about extraterrestrial processes, such as structure formation by stellar explosions or nucleosynthesis, which could be traced back by long-lived radionuclides.  Here, we report the very first detection of a recent Fe-60 influx onto Earth by analyzing 500 kg of snow from Antarctica by accelerator mass spectrometry.  By the measurement of the cosmogenically produced radionuclide Mn-53, an atomic ratio of Fe-60/Mn-53=0.017 was found, significantly above cosmogenic production.  After elimination of possible terrestrial sources, such as global fallout, the excess of Fe-60 could only be attributed to interstellar Fe-60 which might originate from the solar neighborhood.

What I find most striking about this is that we can infer information about a supernova explosion in our near vicinity by analyzing a bunch of snow.  Our technology and scientific prowess has increased to a point that is astonishing -- and I say that even with the recognition that we still have a long, long way to go.  (C'mon, scientists.  I want my personal transporter, holodeck, and replicator.  Tea, Earl Grey, hot, anyone?)

So that's the latest in the Cool Scientific Discoveries department.  Even more amazing when you realize that our country is being led by a man who says that windmills were "Hillary Clinton's idea", and that the noise they make causes cancer.  But don't dismiss what he's saying, folks.  After all, in his own words, "I know a lot about wind."

*****************************

This week's Skeptophilia book recommendation is a must-read for anyone interested in astronomy -- Finding Our Place in the Universe by French astrophysicist Hélène Courtois.  Courtois gives us a thrilling tour of the universe on the largest scales, particularly Laniakea, the galactic supercluster to which the Milky Way belongs, and the vast and completely empty void between Laniakea and the next supercluster.  (These voids are so empty that if the Earth were at the middle of one, there would be no astronomical objects near enough or bright enough to see without a powerful telescope, and the night sky would be completely dark.)

Courtois's book is eye-opening and engaging, and (as it was just published this year) brings the reader up to date with the latest information from astronomy.  And it will give you new appreciation when you look up at night -- and realize how little of the universe you're actually seeing.

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

Don't throw out your textbooks

It'll come as no surprise to regular readers of Skeptophilia that I get really frustrated with how scientific research is portrayed in popular media.

It's not just the way it's explained -- it's the all-too-common impression media give that every new scientific discovery undoes everything that came before it.  How many times have you seen headlines that say, "Scientists Are Back to the Drawing Board Because...", as if the scientists were all sitting around sipping glasses of wine, thinking they had the entire universe figured out, when along comes some pesky upstart making a discovery that causes it all to come crashing down?

Yes, there are times that a discovery overturns a huge chunk of what we thought we knew, but the reason those stand out is because they're so infrequent.  (This is the subject of Thomas Kuhn's seminal book The Structure of Scientific Revolutions, which should be required reading for anyone interested in the scientific process.)  Most of the alterations caused by new discoveries are small course changes, not capsizing the entire boat.  Not that they're unimportant -- refining the model is what science is all about.  But refinement doesn't require destroying the superstructure, any more than remodeling your kitchen requires that you tear down your entire house.

It's why I get frustrated with students who say (usually about evolution) "it's just a theory."  "Theory" is a word that is consistently misused by many laypeople, who take it to mean "a wild guess that could just as easily be disproven as proven," when actually what it means is "a complex explanatory model well supported by all of the available evidence."  Yes, it's possible that the theory of evolution could be disproven, but in the same sense that it's possible you could throw a deck of cards into the air and have them land in a stack by number and suit.  It could happen -- but I wouldn't bet on it.

I saw a frustrating example of this phenomenon yesterday in the usually excellent site Science News, apropos of a discovery in South Africa of a rock that may force a revision of our timetable for the tectonic history of the Earth.  Pretty cool, even if the revision isn't that large, in the grand scheme of things -- pushing back the start of tectonic activity from 2.7 to 3.3 billion years ago.  The most interesting thing is that this means tectonic movement started right around the same time as life did, leading to speculation that there may be some kind of causation there.  (Recall that tectonics isn't just responsible for earthquakes and volcanoes, but for recycling large chunks of the Earth's crust.  It may be that this movement of minerals and seawater kicked off the chemical reactions that led to the first living things -- although this is still highly speculative.)

[Image is in the Public Domain]

So the article is cool, but the headline made me cringe: "Drop of Ancient Seawater Rewrites Earth's History."  Yeah, okay, maybe technically that's true, given that the timetable of geological activity has been altered by the discovery.  But don't take away from it that the sequence of eras and periods in every high school earth science text has been trashed, and that geologists are now completely at sea.  The headline is factually correct but gives the wrong gist, way too reminiscent of the "Discovery Makes Scientists Throw Out the Textbooks!" headlines you see in popular media.  It leads to the all-too-common impression of scientists as bumbling around in their labs making wild guesses, and writing paper after paper (and textbook after textbook) that each supersede the previous ones like the fall of a row of dominoes.

The truth is, perhaps, not nearly as sexy, but popular media (and especially science-for-laypeople media like Science News) should try to reflect it.  In this time when our leaders are actively trying to poison our belief in scientific research on climate change, pollution, and ecology, it is incumbent on media of all type to be as careful as they can about being accurate not only in denotation but in connotation.  As a group, scientists are extremely cautious about publishing until their conclusions are supported by a wealth of evidence, and the impression fostered by many elected officials -- that scientific research is biased, tentative, and inaccurate -- is simply false.

So I wish the people who write about research for popular consumption would take this to heart.  We can't afford any more blows to our confidence in the experts.  Without them, we'd be left with only the politicians to rely on -- and given the choice, I'm trusting the scientists.

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This week's Skeptophilia book recommendation is sheer brilliance -- Jenny Lawson's autobiographical Let's Pretend This Never Happened.  It's an account of her struggles with depression and anxiety, and far from being a downer, it's one of the funniest books I've ever read.  Lawson -- best known from her brilliant blog The Blogess -- has a brutally honest, rather frenetic style of writing, and her book is sometimes poignant and often hilarious.  She draws a clear picture of what it's like to live with crippling social anxiety, an illness that has landed Lawson (as a professional author) in some pretty awkward situations.  She looks at her own difficulties (and those of her long-suffering husband) through the lens of humor, and you'll come away with a better understanding of those of us who deal day-to-day with mental illness, and also with a bellyache from laughing.

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

The forest primeval

One of the reasons I'm so fascinated with paleontology is that it induces me to picture what the Earth looked like a loooooooong time ago -- and to consider a planet that was nothing at all like it is now.

I remember when I first realized something about the three earliest periods of Earth's history -- the Precambrian, Cambrian, and Ordovician -- from a kids' book on prehistory, when I was maybe ten years old.  There was a casual statement that during these periods, there was no life on land.  Every living thing there was lived in the water.

And I thought, "Wait, that can't mean what it sounds like."

But it does.  During those three periods -- which together comprise 90% of the history of the Earth -- the land masses were completely barren.  Rock, sand, dust, dirt (with no organic matter whatsoever), stretching over entire continents.

You think the Sahara is a vast wasteland.  Every square kilometer of the early Earth looked like that, without even the occasional palm tree or camel to break the monotony.

Strange to think of an Earth so unlike what we see around us today.  Even after life colonized the land -- starting with plants living around the margins of bodies of water, in the early Silurian -- it would still have looked pretty foreign, and I'm not just talking about dinosaurs, here.  During the Carboniferous Period there were dragonflies with three-foot wingspans, and centipedes almost big enough to ride.  The Devonian, one step earlier, had some fish called placoderms that look like they're wearing poorly-fitting plate armor.

[Image licensed under the Creative Commons, Nobu Tamura (http://spinops.blogspot.com), Dunkleosteus BW, CC BY 3.0]

In fact, it was a discovery dating to the Devonian that spurred me to write this post.  Last week a paper appeared in Current Biology about a fossilized forest in Xinhang, China that spreads over 250,000 square meters.

Quite a significant find.

Don't, however, picture your typical forest here.  These weren't oaks and maples and pines, they were lycopsids, a group now represented only by club mosses, small and generally unassuming plants you'll find in moist forest understories.  But in the Devonian, they got big.  The largest were over seven meters tall, or about the size of your average dogwood or crabapple tree.

But they didn't look anything like modern trees.  More like something Doctor Seuss would have drawn.

[Image licensed under the Creative Commons Tim Bertelink, Lepidodendron, CC BY-SA 4.0]

Imagine a whole forest of these short, skinny trees and you've got the idea.

"The large density as well as the small size of the trees could make the Xinhang forest very similar to a sugarcane field, although the plants in Xinhang forest are distributed in patches," said Deming Wang, a professor in the School of Earth and Space Sciences at Beijing University, who co-authored the study.  "It might also be that the Xinhang lycopsid forest was much like the mangroves along the coast, since they occur in a similar environment and play comparable ecologic roles."

So our picture of this odd world, when fish were the dominant life-form and the only land animals were primitive amphibians, insects, and arachnids, is becoming more complete.  Think about that next time you go for a walk in the woods.  You might not only ponder what the land you're walking on looked like 400 million years ago, but how different it might look like 400 million years from now -- during which evolution will have had plenty of time to generate, as Darwin put it, "endless forms most beautiful and most wonderful."

***********************************

This week's Skeptophilia book recommendation is sheer brilliance -- Jenny Lawson's autobiographical Let's Pretend This Never Happened.  It's an account of her struggles with depression and anxiety, and far from being a downer, it's one of the funniest books I've ever read.  Lawson -- best known from her brilliant blog The Blogess -- has a brutally honest, rather frenetic style of writing, and her book is sometimes poignant and often hilarious.  She draws a clear picture of what it's like to live with crippling social anxiety, an illness that has landed Lawson (as a professional author) in some pretty awkward situations.  She looks at her own difficulties (and those of her long-suffering husband) through the lens of humor, and you'll come away with a better understanding of those of us who deal day-to-day with mental illness, and also with a bellyache from laughing.

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

Doubling down on error

Is it just me, or is the defining hallmark of discourse these days a steadfast refusal to admit when you're wrong?

Surprisingly enough I'm not referring here to Donald Trump, who has raised a casual disdain for the truth to near-mythic proportions.  What's even more astonishing, though, is his followers' determination to believe everything he says, even when it contradicts what he just said.  Trump could say, "The sky is green!  It is also purple-and-orange plaid!  And I didn't say either of those things!  Also, I am not here!" and his devotees would just nod and smile and comment on what an honest and godly man he is and how great America is now that we've been abandoned by all our allies and the national debt is a record 22 trillion dollars.

In this case, though, I'm referring to two Republican policy wonks who apparently wouldn't believe climate change was happening if the entire continent spontaneously burst into flame.  The first was Matt Schlapp, head of the American Conservative Union, who was pissed off by Bernie Sanders publicly calling Trump an idiot for not accepting climate change, and responded in a tweet, "They can’t even predict if it will rain on tues but we are certain about the weather 12 yrs from now."

This is such an egregious straw man that it's almost a work of art.  In 21 words, we find the following:

• Weather ≠ climate.  For fuck's sake.  We've been through this how many times before?
• Meteorologists are, actually, quite good at predicting when and where it will rain.  Weather is a complex affair, so they don't always get it right, but if the evening weather report says your annual family picnic tomorrow is going to get a drenching, you should probably pay attention.
• Knowing the climatic trends tells you exactly nothing about "the weather twelve years from now."  Cf. my earlier comment about how weather ≠ climate.
• Predictions and trends don't imply certainty.  Ever.  But if 99% of working climatologists believe that anthropogenic climate change is happening, and that it's going to have drastic negative effects not only on the environment but ourselves, I'm gonna listen to them rather than to a guy whose main occupation seems to be sneering at people he disagrees with.

Then there was writer and pontificator Dinesh d'Souza, who posted a video of kangaroos hopping about in the snow with the caption, "Global warming comes to Australia.  Unless you want to believe your lying eyes!"

Unsurprisingly, within minutes d'Souza was excoriated by hundreds of people letting him know that (1) the Earth is spherical, implying that (2) there are these things called "hemispheres," which (3) cause the seasons, and (4) since Australia is in the opposite one than North America, they're experiencing winter right now.  Also, he was informed more than once that the largest mountain range in Australia is named "the Snowy Mountains," and it's for an analogous reason that the Rocky Mountains got their name by virtue of being composed largely of rocks.

A grove of native trees in New South Wales, Australia.  They're called "snow gums."  Guess why?  [Image licensed under the Creative Commons Thennicke, Snow gums, Dead Horse Gap NSW Australia, CC BY-SA 4.0]

What gets me about this is not that two laypeople made a mistake about science.  That is gonna happen because (let's face it) science can be hard.  What I find astonishing is that when confronted with multitudes of fact-based objections, neither man said, "Wow, that sure was a dumb statement!  What a goober I am."  Both of them took the strategy of "Death Before Backing Down," and I can nearly guarantee that this incident will not change their minds one iota, and that (given the opportunity) they will make equally idiotic statements next time.

Look, I'm not claiming I'm infallible.  Far from it.  But what I will say is that if I'm wrong, I'll admit it -- and if it's in print (as here at Skeptophilia) I'll post a correction or retraction, or (if the error was egregious enough) delete the post entirely.  I've done so more than once over the nine years I've had this blog, and although admitting you're mistaken is never pleasant, it's absolutely critical to honest... everything.

But that seems to be a lost art lately.  The attitude these days is, "If someone proves you're wrong, keep saying the same thing, only be more strident."  Evidently truth these days isn't about who has the stronger evidence, but who yells the loudest.  It's no wonder the American citizenry is, as a whole, so misinformed, especially on scientific matters -- in science the touchstone is not volume but factual support.

And that seems to be the last thing any of these people are looking at.

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This week's Skeptophilia book recommendation is sheer brilliance -- Jenny Lawson's autobiographical Let's Pretend This Never Happened.  It's an account of her struggles with depression and anxiety, and far from being a downer, it's one of the funniest books I've ever read.  Lawson -- best known from her brilliant blog The Blogess -- has a brutally honest, rather frenetic style of writing, and her book is sometimes poignant and often hilarious.  She draws a clear picture of what it's like to live with crippling social anxiety, an illness that has landed Lawson (as a professional author) in some pretty awkward situations.  She looks at her own difficulties (and those of her long-suffering husband) through the lens of humor, and you'll come away with a better understanding of those of us who deal day-to-day with mental illness, and also with a bellyache from laughing.

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