Paradoxes within paradoxes

Sometimes the simplest, most innocuous-seeming questions can lead toward mind-blowingly profound answers.

I remember distinctly running into one of these when I was in -- I think -- eighth grade science class.  It was certainly pre-high-school; whether it was from Mrs. Guerin at Paul Breaux Junior High School, or another of my teachers, is a memory that has been lost in the sands of time and middle-aged forgetfulness.

What I have never forgotten is the sudden, pulled-up-short response I had to what has been nicknamed Olbers's Paradox, named after 18th century German astronomer Heinrich Wilhelm Matthias Olbers, who first thought to ask the question -- if the universe is infinite, as it certainly seems to be, why isn't the night sky uniformly and dazzlingly bright?

I mean, think about it.  If the universe really is infinite, then no matter what direction you look, your line of sight is bound to intersect with a star eventually.  So there should be light coming from every direction at once, and the night sky shouldn't be dark.  Why isn't it?

The first thought was that there was something absorptive in the way -- cosmic dust, microscopic or submicroscopic debris left behind by stars and blown outward by stellar wind.  The problem is, there doesn't seem to be enough of it.  The average density of cosmic dust in interstellar space is less than a millionth of a gram per cubic meter.

When the answer was discovered, it was nothing short of mind-boggling.  It turns out Olbers's paradox isn't a paradox at all, because there is light coming at us from all directions, and the night sky is uniformly bright -- it's just that it's shining in a region of the spectrum our eyes can't detect.  It's called the three-degree cosmic microwave background radiation, and it appears to be pretty well isotropic (at equal intensities no matter where you look). It's one of the most persuasive arguments for the Big Bang model, and in fact what scientists have theorized about the conditions in the early universe added to what we know about the phenomenon of red-shifting (the stretching of wavelengths of light if the space in between the source and the detector is expanding) gives a number that is precisely what we see -- light peaking at a wavelength of around one millimeter (putting it in the microwave region of the spectrum) coming from all directions.

[Image licensed under the Creative Commons Original: Drbogdan Vector: Yinweichen, History of the Universe, CC BY-SA 3.0]

So, okay.  Olbers's paradox isn't a paradox, and its explanation led to powerful support for the Big Bang model.  But in science, one thing leads to another, and the resolution of Olbers's paradox led to another paradox -- the horizon problem.

The horizon problem hinges on Einstein's discovery that nothing, including information, can travel faster than the speed of light.  So if two objects are separated by a distance so great that there hasn't been time for light to travel from one to the other, then they are causally disconnected -- they can't have had any contact with each other, ever.

The problem is, we know lots of such pairs of objects.  There are quasars that are ten billion light years away -- and other quasars ten billion light years away in the opposite direction.  Therefore, those quasars are twenty billion light years from each other, so light hasn't had time to travel from one to the other in the 13.8 billion years since they were created.

Okay, so what?  They can't talk to each other.  But it runs deeper than that.  When the aforementioned cosmic microwave background radiation formed, on the order of 300,000 years after the Big Bang, those objects were already causally disconnected.  And the process that produced the radiation is thought to have been essentially random (it's called decoupling, and it occurred when the average temperature of the universe decreased enough to free photons from the plasma and send them streaming across space).

The key here is the word average.  Just as a microwaved cup of coffee could have an average temperature of 80 C but have spots that are cooler and spots that are hotter, the fact that the average temperature of the universe had cooled sufficiently to release photons doesn't mean it happened everywhere simultaneously, leaving everything at exactly the same temperature.  In fact, the great likelihood is that it wouldn't.  And since at that point there were already causally disconnected regions of space, there is no possible way they could interact in such a way as to smooth out the temperature distribution -- sort of like what happens when you stir a cup of coffee.

And yet one of the most striking things about the cosmic microwave background radiation is that it is very nearly isotropic.  The horizon problem points out how astronomically unlikely that is (pun intended) if our current understanding is correct.

One possible explanation is called cosmic inflation -- that a spectacularly huge expansion, in the first fraction of a second after the Big Bang, smoothed out any irregularities so much that everywhere did pretty much decouple at the same time.  The problem is, we still don't know if inflation happened, although work by Alan Guth (M.I.T.), Andrei Linde (Stanford), and Paul Steinhardt (Princeton) has certainly added a great deal to its credibility.

So as is so often the case with science, solving one question just led to several other, bigger questions.  But that's what's cool about it.  If you're interested in the way the universe works, you'll never run out of things to learn -- and ways to blow your mind.

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Getting into the spirit

So it's Black Friday, wherein we Americans follow up a day set aside to give thanks for everything we have with a day set aside to trample each other to death trying to save money on overhyped garbage we really don't need.

Me, I stay right the hell away from stores on Black Friday.  I hate shopping in any case, and the rabid crowds only make it worse.  Plus, today marks the first day of the Little Drummer Boy Challenge, a yearly contest in which participants see how long they can make it into the Christmas season without hearing "The Little Drummer Boy," which ranks right up there with "Frosty the Snowman" and "Santa Claus is Comin' to Town" as the most annoying Christmas carol ever written.  This song not only is irritating as hell, it also has what must be the most ridiculous plot line ever dreamed up, involving a kid who comes up to a pair of new parents with a peacefully sleeping newborn baby, and the kid thinks, "You know what these people need?  A drum solo."

Frankly, I'm surprised Joseph didn't smack him.  Pah-rum-puh-pum-POW, you odious little twerp.

I've participated in this contest for nine years, and haven't made it to Christmas Day undefeated yet.  My most ignominious loss occurred a few years ago, when I was taken out of the competition by a clerk in a hardware store who didn't even know all of the freakin' words, and kept having to la-la bits of it:

Come they LA LA pah-rum-puh-pum-pum
A newborn LA LA LA pah-rum-puh-pum-pum
Our LA LA gifts we bring pah-rum-puh-pum-pum
LA LA before the king pah-rum-puh-pum-pum, rum-puh-pum-pum, rum-puh-pum-pum

And so on and so forth.  He was singing it with hearty good cheer, so I felt kind of guilty when I realized that he'd knocked me out of the game and blurted out, "Are you fucking kidding me?" a little louder than I intended, eliciting a shocked look from the clerk and a significant diminishment in the general Christmas spirit amongst those around me.

Thomas Couture, The Drummer Boy (1857) [Image is in the Public Domain]

And of course, the Christmas season wouldn't be complete without the Fox News types ramping up the whole imaginary War on Christmas thing.  We atheists have allegedly been waging this war for what, now... twenty years?  Twenty-five?  And yet if you'll look around you, just like the Grinch's attempt at banishing Christmas from Whoville, the holiday season still goes right on, pretty much exactly as it did before.

Oops!  Shouldn't say "holiday," because that's part of the War on Christmas, too, even though the word "holiday" comes from "holy day" and therefore is also religious.  This is a point that seems to escape a lot of the Fox News and Newsmax commentators and their ilk, but to be fair, "grip on reality" has never been their forte anyhow.  This year, for example, the rage-of-the-season has been triggered by we Godless Liberal Democratic Unpatriotic Snowflakes somehow inducing Starbucks to put out holiday cups that have designs of hearts and stars instead of having Christmas trees or presents or whatnot, a decision which apparently is Very Naughty In God's Sight.  One furious ex-customer shrieked, "Starbucks REMOVED CHRISTMAS from their cups because they hate Jesus!!!", because apparently all it takes to defeat their all-powerful and omnipotent God is to change the design on some disposable paper cups.

What is wryly amusing about all of this is that I'm one of the aforementioned liberal atheists, and I love the holidays.  We had a nice turkey-and-stuffing dinner yesterday with my brother-in-law and his family for Thanksgiving, and I'm already putting together some gifts for friends and family for Christmas and looking forward to putting up a tree.  So it might come as a surprise to Fox News et al. that in December I tell people "Merry Christmas" at least as often as I say "Happy Holidays." Basically, if someone says "Merry Christmas" to me, I say it back to them; if they say, "Happy Holidays," I say that.  Likewise "Happy Hanukkah," "Happy Kwanzaa," "Blessed Solstice," "Merry Festivus," or "Have A Nice Day."

You know why?  If people speak kindly to me, I reciprocate, because I may be a liberal and an atheist, but I am not an asshole.  So I guess that's three ways in which I differ from the commentators over at Fox News.

Basically, be nice to me, I'll be nice to you.  Unless you're singing "The Little Drummer Boy."  I'm sorry, but my tolerance does have its limits.

In any case, mostly what I plan to do today is to sit around recovering from the food-and-wine-induced coma in which I spent most of yesterday evening.  So however you choose to observe the day and the season, I hope you enjoy it, whether you get into the spirit of it or pretty much ignore the whole thing.

Pah-rum-puh-pum-pum.

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Dreaming the past

My novel In the Midst of Lions opens with a character named Mary Hansard -- an ordinary forty-something high school physics teacher -- suddenly realizing she can see the future.

More than that, really; she now has no reliable way of telling the future from the past.  She "remembers" both of them, and if she has no external context by which to decide, she can't tell if what's in her mind occurred in the past or will occur in the future.  Eventually, she realizes that the division of the passage of time she'd always considered real and inviolable has changed.  Instead of past, present, and future, there are now only two divisions: present and not-present.  Here's how she comes to see things:

In the past two months, it felt like the universe had changed shape.  The linear slow march of time was clean gone, and what was left was a block that was unalterable, the people and events in it frozen in place like butterflies in amber.  Her own position in it had become as observer rather than participant.  She could see a wedge of the block, extending back into her distant past and forward into her all-too-short future.  Anything outside that wedge was invisible...  She found that it completely dissolved her anxiety about what might happen next.  Being not-present, the future couldn’t hurt her.  If pain lay ahead of her, it was as removed from her as her memories of a broken arm when she was twelve.  Neither one had any impact on the present as it slowly glided along, a moving flashlight beam following her footsteps through the wrecked cityscape.

 I found myself thinking about Mary and her peculiar forwards-and-backwards perception while I was reading physicist Sean Carroll's wonderful and mind-blowing book From Eternity to Here: A Quest for the Ultimate Theory of Time, which looks at the puzzling conundrum of what physicists call time's arrow -- why, when virtually all physical laws are time-reversible, there is a clear directionality to our perceptions of the universe.  A classic example is the motion of billiard balls on a table.  Each ball's individual motion is completely time-reversible (at least if you discount friction with the table); if you filmed a ball rolling and bouncing off a bumper, then ran the recording backwards, it would be impossible to tell which was the original video and which was the reversed one.  The laws of motion make no differentiation between time running forward and time running backward.

But.

If you played a video of the initial break of the balls at the beginning of the game, then ran the recording backwards -- showing the balls rolling around and after a moment, assembling themselves back into a perfect triangle -- it would be blatantly obvious which was the reversed video.  The difference, Carroll explains, is entropy, which is a measure of the number of possible ways a system can exist and be indistinguishable on the macro level.  What I mean by this is that the racked balls are in a low-entropy state; there aren't that many ways you can assemble fifteen balls into a perfect equilateral triangle.  On the other hand, after the break, with the balls scattered around the table seemingly at random -- there are nearly an infinite number of ways you can have the balls arranged that would be more or less indistinguishable, in the sense that any of them would be equally likely to occur following the break.  Given photographs of thousands of different positions, not even Commander Data could determine which one was the pic taken immediately after the balls stopped moving.

Sure, it's possible you could get all the balls rolling in such a way that they would come to rest reassembled into a perfect triangle.  It's just extremely unlikely.  The increase in entropy, it seems, is based on what will probably happen.  There are so many high-entropy states and so few low-entropy states that if you start with a low-entropy arrangement, the chances are it will evolve over time into a high-entropy one.  The result is that it is (very) strongly statistically favored that entropy increases over time.  

The Arrow of Time by artist benpva16 [Image licensed under the Creative Commons Creative Commons BY-NC-ND 3.0 license: creativecommons.org/licenses/b…]

The part of the book that I am still trying to parse is chapter nine, "Information and Life," where he ties the physical arrow of time (an example of which I described above) with the psychological arrow of time.  Why can't we all do what Mary Hansard can do -- see the past and future both -- if the only thing that keeps us knowing which way is forward and which way is backward is the probability of a state's evolution?  After all, there are plenty of cases where entropy can locally go down; a seed growing into a tree, for example.  (This only occurs because of a constant input of energy; contrary to what creationists would have you believe, the Second Law of Thermodynamics doesn't disprove evolution, because living things are open systems and require an energy source.  Turn off the Sun, and entropy would increase fast.)

So if entropy actually explains the psychological arrow of time, why can I remember events where entropy went down -- such as yesterday, when I took a lump of clay and fashioned it into a sculpture?

Carroll's explanation kind of made my mind blow up.  He says that our memories themselves aren't real reflections of the past; they're a state of objects in our environment and neural firings in our brain in the present that we then assemble into a picture of what we think the past was, based on our assumption that entropy was lower in the past than it is now.  He writes:

So let's imagine you have in your possession something you think of as a reliable record of the past: for example, a photograph taken of your tenth birthday party.  You might say to yourself, "I can be confident that I was wearing a red shirt at my tenth birthday party, because this photograph of that event shows me wearing a red shirt."...

[Is] the present macrostate including the photo... enough to conclude with confidence that we were really wearing a red shirt at our tenth birthday party?

Not even close.  We tend to think that [it is], without really worrying about the details too much as we get through our lives.  Roughly speaking, we figure that a photograph like that is a highly specific arrangement of its constituent molecules.  (Likewise for a memory in our brain of the same event.)  It's not as if those molecules are just going to randomly assemble themselves into the form of that particular photo -- that's astronomically unlikely.  If, however, there really was an event in the past corresponding to the image portrayed in the photo, and someone was there with a camera, then the existence of the photo becomes relatively likely.  It's therefore very reasonable to conclude that the birthday party really did happen in the way seen in the photo.

All of those statements are reasonable, but the problem is that they are not nearly enough to justify the final conclusion...  Yes, the photograph is a very specific and unlikely arrangement of molecules.  However, the story we are telling to "explain" it -- an elaborate reconstruction of the past, involving birthday parties and cameras and photographs surviving essentially undisturbed to the present day -- is even less likely than the photo all by itself...

Think of it this way: You would never think to appeal to some elaborate story in the future to explain the existence of a particular artifact in the present.  If we ask about the future of our birthday photo, we might have some plans to frame it or whatnot, but we'll have to admit to a great deal of uncertainty -- we could lose it, it could fall into a puddle and decay, or it could burn in a fire.  Those are all perfectly plausible extrapolations of the present state into the future, even with the specific anchor point provided by the photo here in the present.  So why are we so confident about what the photo implies concerning the past?

The answer, he says, is that we're relying on probability and the likelihood that the past had lower entropy -- in other words, that the photo didn't come from some random collision of molecules, just as our surmise about the billiard balls' past came from the fact that a perfect triangular arrangement is way less likely than a random one.  All we have, Carroll says, is our knowledge of the present; everything else is an inference.  In every present moment, our reconstruction of the past is a dream, pieced together using whatever we're experiencing at the time.

So maybe we're not as different from Mary Hansard, with her moving flashlight beam gliding along and spotlighting the present, as I'd thought.

Mind = blown.

I'm still not completely convinced I'm understanding all the subtleties in Carroll's arguments, but I get enough of it that I've been thinking about it ever since I put the book down.  But in any case, I'd better wrap this up, because...

... I'm running short on time.

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The phantom touch illusion

It seems like every time researchers look further into our sensory-perceptive systems, we have another hole punched in our certainty that what we think we're perceiving is actually real.

We've looked at optical illusions -- and the fact that dogs fall for 'em, too.  We've considered two kinds of auditory illusions, the postdictive effect and the McGurk effect.  Sometimes we see patterns of motion in still objects -- and illusory "impossible" motion that our brains just can't figure out.  A rather simple protocol convinced test subjects their hands had turned to stone.  Stimulating a particular clump of neurons in the brain made patients see the doctor's face as melting.  We can even be tricked into feeling like we're controlling a second body, that just happens to be invisible.

As eminent astrophysicist Neil deGrasse Tyson put it, "The human brain is rife with ways of getting it wrong."  Honestly, at this point it's a wonder we trust anything we perceive -- and yet you still hear people say "I saw it with my own eyes" as if that somehow carried any weight at all.  Add to that all the problems with the reliability of memory, and you have to ask why eyewitness accounts are still considered the gold standard of evidence.

If you needed more proof of this, take a look at some research that came out last week from Ruhr-Universität Bochum into what happens when a person watches a virtual-reality avatar of their own body.  Participants were suited up in VR gear, and after a period of acclimation -- during which they got used to their avatar's arms and hands moving as their own did -- they were instructed to use a virtual representation of a stick to touch their avatar's hand.  Nearly all of the subjects reported feeling a sensation of touch, or at least a tingling, at the spot the virtual stick appeared to touch.

[Image licensed under the Creative Commons Samuel Zeller samuelzeller, VR (Unsplash VK284NKoAVU), CC0 1.0]

The researchers decided to check and see if the sensation occurred simply by drawing awareness to the hand, so they did the same thing only using a virtual laser pointer -- and no feeling of touch occurred.

Apparently all it took was convincing the subjects they were being touched to stimulate the sensation itself.

"The phantom touch illusion also occurs when the subjects touched parts of their bodies that were not visible in virtual reality," said study co-author Marita Metzler.  "This suggests that human perception and body sensation are not only based on vision, but on a complex combination of many sensory perceptions and the internal representation of our body."

The whole thing brings to mind a conversation I had with an acquaintance, a Ph.D. in philosophy, some years ago about the impossibility of proving materialism.  I'd always considered myself a hard-nosed materialist, but her stance was that no one could prove the external world was real.  I shot back with a snarky, "Well, that works until someone throws a rock at your head.  Hard to deny the rock isn't real after that."  She patiently responded, "No.  What is real are the sensations you experience -- the shock, the pain, the adrenaline rush.  Possibly a period of loss of consciousness.  You're still locked inside your own skull, and the only thing you have access to are your own thoughts and feelings.  Those are all you can be certain are real experiences -- and even those might well be false or misleading."

Well, it was a fair knockout (pun intended), and I still haven't really come up with a rejoinder.  Not that this is surprising; philosophers have been discussing the whole materialism vs. idealism thing for centuries, and haven't really settled it to anyone's satisfaction.  And since the time of that argument, I've found more and more evidence that we experience through our sensory-perceptive apparatus only the barest fraction of what's out there -- what neuroscientist David Eagleman calls our umwelt -- and even that part, we see inaccurately.

Kind of humbling, isn't it?  Think about that next time someone starts acting so all-fired certain about their own perceptions, memories, experiences, and opinions.  The more you know, they more you should realize that none of us should be sure of anything.

But after all, doubt isn't a bad place to start.  I'll end as I did yesterday, with a quote from the brilliant physicist Richard Feynman: "The first principle is that you must not fool yourself; and you are the easiest person to fool."

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A light into shadow

I think my love of science comes from the joy of unlocking one at a time the pieces of the universe that were mysteries.  It's why I'm such a dilettante -- someone who, as an acquaintance once described me, has knowledge a light year across and an inch deep.  I find it all fascinating.  I was never able to focus on one thing long enough to really become an expert.  I'd start in one direction, but in short order I'd say, "Oh, look, something shiny!" and take off on some unrelated tangent.

I may not have much in the way of academic credentials, but it makes me a force to be reckoned with when playing Trivial Pursuit.

It's okay, really.  I enjoy the fact that my brain makes up for in breadth what it lacks in depth.  Which is why last week we had posts about astronomy, geology, glaciology, paleontology, and cosmology, and today we're on to archaeology.

Because of my love of mysteries, I've always been drawn to trying to understand civilizations whose relics are scanty or poorly-understood.  The Incas, Aztecs, and Mayas.  The ancestors of the First Nations of North America.  The Songhai Empire and the kingdoms of Benin, Congo, and Aksum in Africa.  The ancient history of Southeast Asia and Australia.  And while European history is generally considered to be well-studied and accessible, that's because most of the focus is on the Romans, Greeks, and Norse, who left extensive written records.  The Celts, Slavs, and the southern Germanic tribes, for whom we have far fewer extant records (and many of those were penned by conquering cultures which took few pains to represent them fairly or accurately), have an ancient history that is largely lost to the shadows of time.

Or... maybe not entirely lost.

Archaeologists are now using sophisticated technological tools to discern traces of long-gone settlements, recovering traces of civilizations that have been up till now complete ciphers.  The reason this comes up is a study by a team from University College Dublin, working with colleagues in Serbia and Slovenia, which used aerial photography to piece together the remnants of 3,500 year old settlements in the southern Carpathian Basin -- and found that the area was as thickly-settled as many of the far better known cultures who were at their height around the same time.

"Some of the largest sites, we call these mega-forts, have been known for a few years now, such as Gradište Iđoš, Csanádpalota, Sântana or the mind-blowing Corneşti Iarcuri enclosed by thirty-three kilometers of ditches and eclipsing in size the contemporary citadels and fortifications of the Hittites, Mycenaeans or Egyptians,” said UCD archaeologist Barry Molloy, who led the study.  "What is new, however, is finding that these massive sites did not stand alone, they were part of a dense network of closely related and codependent communities.  At their peak, the people living within this lower Pannonian network of sites must have numbered into the tens of thousands...  Uniquely for prehistoric Europe, we are able to do more than identify the location of a few sites using satellite imagery but have been able to define an entire settled landscape, complete with maps of the size and layout of sites, even down to the locations of people’s homes within them. This really gives an unprecedented view of how these Bronze Age people lived with each other and their many neighbors."

One of the circular hill-forts discovered through analysis of aerial photographs

Of course, this sets the imagination running.  Like the Australian fossilized bird footprints we looked at yesterday, these remnants only tell you so much, in this case tantalizing clues about how their cities were laid out, coupled with hypothesizing the purposes of buildings for which we only have traces of foundations.  But deeper information about the societies who lived there, their political and social structure, religious beliefs, and languages -- the relics we have are silent on all of that.  Who these people were, we can only speculate.

Still, it's a remarkable achievement.  "1200 BC was a striking turning point in Old World prehistory, with kingdoms, empires, cities, and whole societies collapsing within a few decades throughout a vast area of southwest Asia, north Africa, and southern Europe," Molloy said.  "It is fascinating to discover these new polities and to see how they were related to well-known influential societies yet sobering to see how they ultimately suffered a similar fate in wave of crises that struck this wider region."

And for me, looking at it from the outside, it's wonderful to cast some light into the shadows of a culture that heretofore was completely mysterious.  Knowing them, even if only a little, is thrilling.  I'll end with a quote from the inimitable Richard Feynman, from his book The Pleasure of Finding Things Out:

Fall in love with some activity, and do it!  Nobody ever figures out what life is all about, and it doesn’t matter.  Explore the world.  Nearly everything is really interesting if you go into it deeply enough.  Work as hard and as much as you want to on the things you like to do the best.  Don’t think about what you want to be, but what you want to do.

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Birds down under

I've been an avid birdwatcher for many years, and have been fortunate enough to travel to some amazingly cool places in search of avifauna.  Besides exploring my own country, I've been to Canada (several times), Belize (twice), Ecuador (twice), Iceland (twice), England (twice), Scotland, Sweden, Finland, Denmark, Russia, Spain, Portugal, and Malaysia.

One place I've never been, though, is Australia, which is a shame because it's got some incredible animals.  And despite a pretty well-deserved reputation for having far more than their fair share of wildlife that's actively trying to kill you, most tourists come back from trips to Australia alive and with all their limbs still attached in the right places.

The main reason for Australia's unique ecosystems is that it's been isolated for a very long time.  During the breakup of Pangaea, the northern part (Laurasia, made up of what is now Europe, North America, and most of Asia) separated from the southern part (Gondwanaland, made up of what is now Africa, South America, Antarctica, Australia, and India), something on the order of 180 million years ago.  The other pieces gradually pulled apart as rifting occured, but Australia remained attached to Antarctica until around thirty million years ago.  At that point, the whole thing had a fairly temperate climate, but when the Tasman Gateway opened up during the Oligocene Period, it allowed the formation of the Antarctic Circumpolar Current, isolating and cooling Antarctica and resulting in the extinction of nearly all of its native species.  Australia, now separate, began to drift northward, gradually warming as it went, and carrying with it a completely unique suite of animals and plants.

The reason all this comes up is a sharp-eyed Australian loyal reader of Skeptophilia, who sent me a link to a news story about a recent discovery by a dedicated amateur fossil hunter and birdwatcher, Melissa Lowery, who was looking for fossils on the Bass Coast of Victoria and stumbled upon something extraordinary -- some 125 million year old bird footprints.

Lowery's bird footprints [Image by photographer Rob French, Museums Victoria]

At that point, the separation of Australia and Antarctica was some 65 million years in the future, the sauropod dinosaurs were still the dominant animal group, and Victoria itself was somewhere near the South Pole.  Lowery's find led to a full-scale scientific investigation of the area, and uncovered a great many more bird tracks, including some with ten-centimeter-long toes.  Also in the area were the footprints of dozens of kinds of non-avian dinosaurs.

"Most of the bird tracks and body fossils dating back to the Early Cretaceous are from the Northern Hemisphere, particularly from Asia," said Anthony Martin, of Emory University, who led the study.  "Our discovery shows that there were many birds, and a variety of them, near the South Pole about 125 million years ago."

Of course, being a birdwatcher, I'm intensely curious as to what these birds looked like, but there's only so much you can tell from a footprint, or even fossilized bones.  It's simultaneously intriguing and frustrating to think about the fact that these animals -- and all the other animals and plants that lived alongside them -- had every bit of the diversity, all the curious and wonderful and beautiful adaptations and behaviors, that our modern wildlife does.

Imagine what it would be like to transport yourself back to Australia in the early Cretaceous, and witness all of that with your own eyes and ears.  (With, of course, a guarantee of coming back alive and with all your limbs still attached in the right places.  Back then, Australia was a rougher place than it is now.)

So thanks to the reader who sent me the link -- it's renewed my desire to visit Australia.  If I can't see the amazing birds they had 125 million years ago, at least I can have a look through my binoculars at some of the ones they have today.

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Strange new worlds

Since the discovery of the first exoplanet in January of 1992, astronomers have identified over 5,500 of them, with nearly a thousand of the systems analyzed having more than one detected planet.  It now appears that at least one of the variables in the Drake equation -- f_p, the fraction of stars that have planets -- is far higher than anyone might have expected. 

What has come as an additional surprise is how varied these worlds are.  Having grown up on a steady diet of Lost in Space, Star Trek, and Star Wars, I kind of had exoplanets pictured as mostly Earth-like, with lots of big rocks and maybe an odd-colored sky:

The truth is, every new one we find holds some sort of surprise.  Some of the odder ones are:

• TrES-2b, which holds the record as the least-reflective planet yet discovered.  It's darker than a charcoal briquet.  This led some people to conclude that it's made of dark matter, something I dealt with here at Skeptophilia a while back.  (tl:dr -- it's not.)
• CoRoT-7b, one of the hottest exoplanets known.  Its composition and size are thought to be fairly Earth-like, but it orbits its star so closely that it has a twenty-day orbital period and surface temperatures around 3000 C.  This means that it is likely to be completely liquid, and experience rain made of molten iron and magnesium.
• 55 Cancri e, nicknamed the "diamond planet."  Another "hot super-Earth," this one is thought to be carbon rich, and that because of the heat and pressure, much of the carbon could be in the form of diamonds.  (Don't tell Dr. Smith.)
• PSR J1719−1438, a planet orbiting a pulsar (the collapsed, rapidly rotating core of a giant star).  It has one of the fastest rates of revolution of any orbiting object known, circling its host star in only 2.17 hours.
• V1400 Centauri, a planet with rings that are two hundred times wider than the rings of Saturn.  In fact, they dwarf the planet itself -- the whole thing looks a bit like a pea in the middle of a dinner plate.

The reason all this comes up is that we just had a new addition to the "weird exoplanet" list thanks to the James Webb Space Telescope.  It's called WASP-107b, and it has a number of bizarre characteristics.  First, it is "fluffy" -- that's actually how the astronomers describe it -- having one of the lowest overall densities of any exoplanet known.  It has about the mass of Neptune, but a diameter closer to that of Jupiter.

Second, it has a retrograde orbit -- it moves the opposite direction from the rotation of its host star and the revolution of the rest of the planets in the system.  Its orbit is highly eccentric (elliptical), and is actually tipped 118 degrees away from the ecliptic (the plane of revolution of the rest of the system).  Astrophysicists believe that it got this way because of interaction with the much more massive WASP-107c, but the truth is, they've never seen anything like it, so that's a surmise.

The atmosphere has high quantities of water vapor -- kept gaseous by the high temperatures (the upper atmosphere has an average temperature of 500 C) -- and sulfur dioxide.  A bigger surprise was that the "highly dynamic atmosphere" (scientist-speak for "wind speeds that would blow your ass into the middle of next week") creates clouds of superheated silicate sand.  The overall result is that being on WASP-107b would be like living inside a permanent pyroclastic flow.

"The fact that we see these sand clouds high up in the atmosphere must mean that the sand rain droplets evaporate in deeper, very hot layers and the resulting silicate vapor is efficiently moved back up, where they recondense to form silicate clouds once more," said study co-author Michiel Min.  "This is very similar to the water vapor and cloud cycle on our own Earth but with droplets made of sand."

"JWST enables a deep atmospheric characterization of an exoplanet that does not have any counterpart in our Solar System," added study lead author Achrène Dyrek.  "We are unravelling new worlds."

What's shocking is how bizarre some of these new worlds are.  It was natural enough to look at the planets in our own Solar System and assume that they kind of ran the gamut of planetary types -- thus the predominance of rocky worlds and gas giants with zillions of moons that you find in early science fiction.  What continues to astonish is just how wrong that was.  Wherever we look, we see an incredible variety of planets and star systems, and the great likelihood is that despite how many we've found, we've only scratched the surface.

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