The rain of fire

On the morning of October 24, 79 C.E., Mount Vesuvius erupted in one of the deadliest volcanic events in recorded history.

The nearby towns of Pompeii, Herculaneum, Stabiae, and Oplontis had warnings.  There was a series of earthquakes during the lead-up to the eruption, which got a few people to leave the area -- everyone remembered that there'd been a powerful earthquake in February of 62 that had destroyed a number of buildings, and the skittish thought that something similar might be about to happen again -- but by and large, the residents just shrugged their shoulders.  Pliny the Younger, who wrote the only extant eyewitness account of the eruption (he was safely in Misenum, thirty kilometers away across the Bay of Naples, when it happened), said that the earthquakes that preceded the eruption "were not particularly alarming because they are frequent in Campania," and thus the majority of people in the area ignored them and stayed home.

This turned out to be a mistake.

The morning of October 24 dawned clear and bright, but there was already a plume of steam coming from the summit of the mountain that loomed over the four cities.  This, too, was nothing unusual; it's doubtful many people even noticed.  But at around midday, there was a sudden jolt, and the entire peak exploded, sending a column of ash, rock, and superheated steam an estimated thirty kilometers high, blasting out material at a rate of 1.5 million tons per second.  Rocks and ash rained down on the cities, but worse was to come; by evening, the pressure forcing the column upward dropped suddenly and the entire column collapsed, causing a pyroclastic surge with an estimated temperature of six hundred degrees Celsius pouring downhill at about a hundred kilometers an hour.  Anything or anyone left that hadn't been killed by asphyxiation or roofs collapsing died instantly, and the ash flow blanketed the region.  The greatest quantity of ash landed in Herculaneum, which was buried under a layer twenty meters thick.

But all four cities were completely obliterated, to the point that within a hundred years, most people forgot that they'd ever existed.  References to Pompeii, Herculaneum, Stabiae, and Oplontis, four prosperous towns that had been wiped out by the wrath of the gods, were considered fanciful legends -- a little like Plato's mention of the mythical land of Atlantis sinking beneath the waves.

Then, in 1709, a farmer was plowing his field, and the plow hit the edge of a buried wall.  It turned out to be a surviving piece of masonry from Herculaneum.  Something similar happened in Pompeii in 1748.  Archaeologists were called in, and gradually, the work started that is still ongoing -- clearing away meters-thick layers of welded ash to uncover what is left of the four cities.

Today it's a strange, somber place.  Wandering around its cobblestone streets, and looking at the snaggletoothed silhouette of Vesuvius in the distance -- the mountain lost almost half of its original height in the eruption -- was chilling despite the bright warmth of the sun.  We looked at remnants of homes, shops, temples, baths, the central forum, and even a brothel (each room decorated with highly explicit paintings of what services you could expect within).

We got to see some of the casts of the people who died during the eruption, their names long forgotten, their bodies entombed in fused hot ash, then burned and decayed away to leave a cavity that archaeologists filled with plaster to reveal their ghostly forms.

Many of the 1,044 molds of human victims were found with their hands over their faces, futilely trying to shield themselves from the choking, scalding ash.

Today, around three million people live in the shadow of Vesuvius, most of them in the city of Naples and the nearby towns of Pozzuoli, Bagnoli, San Giorgio a Cremano, and Portici.  Our guide said there were two reasons for this, and for the number of people living in other volcanic areas, such as Indonesia, Japan, Costa Rica, Cameroon, and Ecuador -- (1) volcanic soil is wonderfully fertile for agriculture, and (2) people have short memories.  But now that we have a better understanding of plate tectonics and geology, you have to wonder why people are willing to accept the risk.  A man we talked to in Rome had an explanation for that, too.  "Those people down in Naples," he said, shaking his head, "they're crazy."

Today Pompeii is seemingly at peace, its ruins as quiet as the cemetery it in fact is.  Flowers grow in profusion in every grassy spot.

But not far beneath the surface, the magma is still moving.  The processes that destroyed the region in the first century C.E. are haven't stopped, and the tranquil scene up above is very much an illusion.  After seeing the city, we hiked up to the summit of Vesuvius and looked down into the crater, the hole blasted out of the center of the mountain.

The whole thing was enough to make me feel very small and very powerless.  We flatter ourselves to think we can control the forces of nature, but in reality, we're still at their mercy -- no different from the residents of Pompeii on October 23, who knew the mountain was rumbling but figured there was nothing to worry about.  The rain of fire that was to come only twenty-four hours later was unstoppable.  Although now we can predict volcanic eruptions better than the first-century Romans, we still are at the mercy of a natural world that cares little for our lives.

But there's nothing wrong with being reminded of this periodically.  A bit of humility is good for the mind.

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Southern European retrospective

Greetings, loyal readers, I'm back a couple of days earlier than anticipated from a two-and-a-half week's trip to Europe, still a bit jet-lagged but otherwise unscathed.  We visited Italy, Croatia, Greece, France, and Spain, so only got a touch of each place (Italy is the place we got to explore the most thoroughly), but it was still, overall, a wonderful trip.

Flying, not so much.  Unlike certain other trips I can recall, it was mishap-free -- no missed connections or lost luggage, and not so much as a delay -- but flying in general has become a fairly miserable experience.  Witness our flight from Paris back to New York, wherein a passenger in the seat in front of my wife reclined her seat so far that Carol had about six cubic centimeters of space left in front of her.  She couldn't even bend over to get anything from underneath the seat.  It was tempting for her to recline her own seat, but she resisted, not only out of consideration and compassion for the passenger behind her, but for fear of triggering the dreaded Reclining Seat Chain Reaction, which continues like a row of human dominoes until you get to the row in the very back where the seats don't recline, and the last person ends up getting compressed into a vaguely human-shaped splat mark against the rear bulkhead.

But, honestly, these are clearly First World Problems, and we were privileged to get to travel and see some amazing places.  Here are a few high points, and some photos I took of cool spots, in the order we visited them.

First off, Rome.  Oh, my goodness, Rome.  The sense of antiquity there is palpable, almost everywhere you go.  So is the sense that you're taking your life into your own hands when you step into the street.  Roman drivers are flat-out insane.  They use their horns to communicate three things: (1) buongiorno!; (2) get out of the damn way, you idiot tourist; and (3) my car has a horn.  Lane markings are considered merely suggestions.  If you're on a motorcycle, lane markings are considered imaginary.  But we escaped without being run down, and got to see places like Palatine Hill:

Palatine Hill is where Augustus and Livia had their home.  Yes, that Augustus and Livia.  The foundation of their house still exists, in fact, which I find astonishing given that Augustus died in the year 14 C.E.  Then there's the Forum:

And the abso-freakin-lutely huge second-century temple of the emperor Antoninus Pius:

And the Fontana degli Dioscuri:

The last-mentioned is one of many giant statues we saw featuring extremely attractive naked people, which was a popular subject of sculpture back in ancient Rome and a tradition I definitely think we should bring back.

From Rome, our next stop was the lovely city of Dubrovnik, Croatia.  Here I parted ways with the rest of our group (Carol and I were traveling with four friends) and went on a boat ride through a wetland nature preserve north of the city.  The coastline of Croatia is stunningly beautiful -- one of the prettiest places I saw on the entire trip.

After Croatia, we had a day on the lovely island of Corfu.  Coastal Greece has the clearest water I've ever seen -- unfortunately, it was still a little cool to go for a swim.  The following photo is unretouched -- no filters, nothing.  That's actually the color of the water.

We got to do some tasting of local food and drink -- something that became a bit of a theme on the trip -- and were treated to Greek limoncello (much better than the Italian variety, we were told by the proprietor), various olives and olive oils (with freshly-baked bread), honeys, jams, and marmalades.

After Corfu we were supposed to go to Malta, long a fascination of mine for its role in the Crusades, but the weather turned very windy and the ship was unable to dock.  So, unfortunately, we had a day at sea instead -- Malta will have to wait for another time, I suppose.

The next stop was the island of Sicily, where we got to take a cooking class in the town of Taormina.  Here's a picture from near the restaurant.  That's Mount Etna in the background.

We learned how to make traditional hand-made pasta and pizza and then got to lunch on the results -- accompanied, of course, with large quantities of amazingly good wine.

At the end of the meal, we had a digestif of limoncello, which the proprietors assured us was much better than the Greek variety.

At this point we were in volcano-and-earthquake territory, which long-time readers of Skeptophilia will know is a major fascination of mine.  The 1908 earthquake in Messina, our guide told us, killed eighty thousand people and flattened nearly the entire city; most of the casualties, she said, died within a span of thirty-seven seconds as the ground lurched and buildings collapsed.  The Messina-Taormina fault, which lies just offshore of the east coast of the island, is still very much active, and as you saw, Mount Etna looms over the town of Taormina.  As we were sailing away that evening, we got a light show from the pretty well constantly-erupting island of Stromboli, which has been nicknamed "The Lighthouse of the Mediterranean."

Speaking of volcanoes, we next went to Naples, which sits in the shadow of Vesuvius -- in fact, a magmatic system underlies the entire region, leading to its nickname of the "Campi Flegrei" ("burning fields") about which I've written before.  We visited the ruins of Pompeii, which was an overwhelming enough experience that I'm planning an entire post devoted just to that, so you'll have to wait for photos and commentary.  But here's a photo of the city of Naples taken from the slopes of Vesuvius, just to give you an idea of how many people live in the bullseye.

After Naples we docked in the rather unattractive industrial port town of Livorno, and took a bus into Florence.  Florence, as you undoubtedly know, is famous for its art and architecture, including the Duomo -- the city cathedral -- which is truly incredible.

We also got to see David -- not the David, but a replica that is out in the square near the Accademia Gallery, home of the original.  Even the replica was suitably amazing.

As an amateur sculptor, I was gobsmacked by the beauty of the human figure, and the incredible detail Michelangelo was able to work into the musculature.  That man was a true genius.

It rained just about the entire time we were in Florence, so we went to the Galileo Museum, which is very much worth a visit if you're a science nerd.  The museum has a fine collection of early scientific devices, including this amazing armillary sphere that stands about eight feet tall:

And a hand-cranked glass lathe used for making lenses for telescopes and microscopes:

After Florence, we had a quick stop in coastal France.  This was the place I most felt shortchanged about, time-wise; we only had time to take a quick run in from our port (Cannes) to the charming little village of St. Paul de Vence.  It was still raining, but it's a lovely place, and one I wish I'd been able to spend more time exploring.  I also would have loved to go farther north; my father's family comes from only about two hundred kilometers north of there, up in the high Alps.  Once again -- like Malta -- that'll have to wait for another trip.

After Cannes, we went to the island of Ibiza.  Ibiza is one of two islands in the Balearic Archipelago, east of Spain, that we got to visit.  When a friend found out we were going to Ibiza, he said he'd been there, and that it was famous for sun, swimming, sex, and alcohol, and because of the last-mentioned he didn't remember much about the other three.  But true to form, we did something extremely nerdy instead and went to visit an organic farm, where we got to make our own herbal liqueur (which, amazingly enough, we were able to successfully transport home without the bottles breaking).

I didn't get any good photos of the farm, but here's an evening shot of the Ibiza lighthouse:

After Ibiza we went to another island in the Balearics, Mallorca, and while there we took a taxi up to Bellver Castle (which overlooks the city of Palma) and hiked our way back down, stopping along the way for some truly amazing cappuccino.

We finished up the trip in the city of Barcelona, where we got to visit the Sagrada Familia (again, which will be the subject of another post), and the wild, Dr.-Seussian Park Güell, conceived by the astonishingly creative mind of the Catalan architect Antoni Gaudí:

From there, it was a quick flight to Paris, a long flight to New York City, a quick flight to Rochester, and a drive back home, where we got in at two AM.  Then had to get up at seven to go pick up the dogs from the kennel.  So I think I'll be fighting the dregs of jet lag for a couple more days.

It was a whirlwind tour but an opportunity to visit some amazing places, have some awesome food and wine (and limoncello, about which I will not be pinned down to rank by any Greek or Italian partisans in the audience).  But it's nice to be home as well, where spring has finally set in and the garden is ready to plant.

So goodbye for now, southern Europe.  With luck, I'll be back someday.

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In the dark

Dear Readers:

After today's post, I'm going to be taking a long-overdue break from Skeptophilia.  My intent -- lord willin' an' the creek don't rise, as my grandma used to say -- is that my next post will be Monday, May 13.  See you then!

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To further investigate our general topic of people giving woo-woo explanations to damn near everything, today we investigate: The Dark.

First, a brief physics lesson.

Things are generally called "dark" for one of two reasons.  First, there are objects whose chemical makeup results in their absorbing most of the light that falls on them.  Second, there are things that don't interact with light much at all, so they neither absorb nor reflect light -- light passes right through them.  An example of the first would be a charcoal briquet.  An example of the second would be interstellar space, which is sort of dark-by-default.

This whole thing comes up because of an extrasolar planet with the mellifluous name TrES-2b.  TrES-2b orbits the even more charmingly named GSC 03549-02811, a star about 718 light years away.  More interestingly, it has the distinction of being the darkest extrasolar planet yet discovered.  David Kipping, of the Harvard-Smithsonian Center for Astrophysics, stated, "TrES-2b is considerably less reflective than black acrylic paint, so it is truly an alien world."

Artist's conception of TrES-2b  [Image is in the Public Domain courtesy of NASA/JPL-Caltech]

That was all it took.  Whereas my reaction was, "Huh!  A Jupiter-sized charcoal briquet!  That's kinda cool," the woo-woos just couldn't resist wooing all over this story.  We now have the following speculations, all from websites owned by people who probably shouldn't be allowed outside unsupervised:

• TrES-2b is made of antimatter, and we shouldn't go there because it (and we) would blow up.  We know it's antimatter because antimatter has the opposite properties to matter, so it's dark.
• TrES-2b is made of "dark matter," and yes, they're not just talking about stuff that's black, they're talking about the physicists' "dark matter," about which I'll have more to say in a moment.
• TrES-2b is dark because it's being hidden by aliens who are currently on their way to Earth to take over.  Lucky for us we spotted it in time!
• TrES-2b is hell.  No, I'm not making this up.

Well.  You just opened the floodgates, now didn't you, Dr. Kipping?

The first two explanations left me with a giant bruise on my forehead from doing a faceplant while reading.  At the risk of insulting my readers' intelligence, let me just say quickly that (1) antimatter's "opposite properties" have nothing to do with regular matter being light and antimatter being dark, because if it did, the next time a kindergartner pulled a black crayon out of the box, he would explode in a burst of gamma rays; and (2) "dark matter" is called "dark" because of the second reason, that it doesn't interact with much of anything, including light, so the idea of a planet made of it is a little ridiculous, and in any case physicists haven't even proved that it exists, so if some astrophysicist found a whole freakin' planet made of it it would KIND OF MAKE HEADLINES ALL OVER THE FUCKING WORLD, YOU KNOW?

*brief pause to do some nice, slow deep breathing*

Sorry for getting carried away, there.  But I will reiterate something I have said more than once, in this blog; if you're going to start blathering on about science, for cryin' in the sink at least get the science right.  Even the least scientific woo-woo out there can read the Wikipedia page for "Dark Matter," for example, wherein we find in the first paragraph the sentence, "The name refers to the fact that it does not emit or interact with electromagnetic radiation, such as light, and is thus invisible to the entire electromagnetic spectrum." (Italics mine, and put in so that any of the aforementioned woo-woos who are reading this post will focus on the important part.)

And I won't even address the "secret alien base" and "hell" theories regarding TrES-2b, except to say that it should come as a relief that the evil aliens or Satan (depending on which version you went for) are safely 718 light years away.  To put this in perspective, this means that if they were heading here in the fastest spacecraft humans have ever created, Voyager 1, which travels at about 16 kilometers per second, it would still take them eleven million years to get here.

In any case, I guess it's all a matter of how you view what's around you.  I find the universe, and therefore science, endlessly fascinating, because what scientists have uncovered is weird, wonderful, and counterintuitive.  I don't need to start attaching all sorts of anti-scientific bunk to their discoveries -- nature is cool enough as it is.

Okay, thus endeth today's rant.  I will simply end with an admonishment to be careful next time you barbecue.  I hear those charcoal briquets can be made of antimatter, which could make your next cook-out a dicey affair.  You might want to wear gloves while you handle them.  Better safe than sorry!

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The titan

One thing science teaches us is that just about everything is interesting if you look at it carefully enough.  Still, there's an ingrained human tendency to be overawed by superlatives -- the biggest, the heaviest, the brightest, the strongest, the most powerful.

It's why a recent fossil discovery from Somerset, England has made the headlines.  The rocks in Somerset, in the southwest of England, are mostly of Triassic age; it's not far from the famous "Jurassic Coast," which begins around Exmouth with Triassic sedimentary rocks that gradually become younger as you head west.  It's the site that the brilliant nineteenth century paleontologist Mary Anning studied -- becoming one of a very long list of talented women scientists who struggled for recognition by their male peers with tragically little success.

Somerset, which is a bit north from there, is also a great site for Mesozoic fossils, and some amateur fossil hunters recently found a doozy.  Father-and-daughter team Justin and Ruby Reynolds were searching along the north Somerset coast and saw what turned out to be a fossilized jawbone...

... of a creature which is estimated to have been twenty-five meters long.  (For my fellow Americans, twenty-five meters is about 130 bananas long.)

The animal was a type of ichthyosaur, a group that reached their height of diversity in the late Triassic Period.  We've known for a long time that ichthyosaurs were bizarre animals.  They were streamlined predators that look remarkably like dolphins, although they are only distantly related (making the two groups a great example of convergent evolution).  A number of them had an even stranger feature, which is the largest eye-diameter-to-body-size ratio of any animal known -- the well-named Ophthalmosaurus (Greek for "eye lizard") was six meters long and had eyes the size of basketballs.

But this new species could have eaten an Ophthalmosaurus as an appetizer and still had plenty of room for the entrée.  It's been dubbed Ichthyotitan severnensis -- more or less, "gigantic fish-thing from the Severn."  The fossil dates to about 202 million years ago.

[Image credit: artist Sergey Krasovskiy]

"I was highly impressed that Ruby and Justin correctly identified the discovery as another enormous jawbone from an ichthyosaur," said Dean Lomax, paleontologist at the University of Manchester, who verified the find and helped to classify it, in an interview with Science Daily.  "They recognized that it matched the one we described in 2018. I asked them whether they would like to join my team to study and describe this fossil, including naming it.  They jumped at the chance.  For Ruby, especially, she is now a published scientist who not only found but also helped to name a type of gigantic prehistoric reptile.  There are probably not many fifteen-year-olds who can say that!  A Mary Anning in the making, perhaps."

The Ichthyotitan, though, was one of the last of its kind; it, and a great many other species, were victims of the Late Triassic Mass Extinction, a poorly-understood extinction event that occurred around 201 million years ago and was only slightly smaller than the much better-known Cretaceous-Tertiary Extinction that would happen 135 million years later.  The most likely explanation of the Late Triassic event is volcanism and outgassing from the Central Atlantic Magmatic Province, the mantle upwelling from which would ultimately split up Pangaea and open the Atlantic Ocean, but that point is still being argued over by geologists and paleontologists.

Whether this particular Ichthyotitan was killed during the extinction event itself is, of course, impossible to tell, but the fossil dates to almost exactly the right time.  Its discovery also ramps up the search for more fossils along the north Somerset coast.  "It is quite remarkable to think that gigantic, blue whale-sized ichthyosaurs were swimming in the oceans around what was the UK during the Triassic Period," Lomax said.  "These jawbones provide tantalizing evidence that perhaps one day a complete skull or skeleton of one of these giants might be found.  You never know."

It's a hell of a find -- a bone from a creature in contention for the largest animal known.  I don't know about you, but it's hard even to imagine a predator that big.  The late Triassic must have been an impressive-looking place...

... observed, of course, from a safe distance.

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Flat space, Hawking radiation, and warm spots

Ever wonder if the universe is flat?

No, I haven't taken Wingnut Pills and decided that the Flat Earthers make sense.  This is an honest-to-Einstein problem in physics, one that not only raises eyebrows about the supposed "fine-tuning" of the universe but has a huge effect on its ultimate fate.

By this time most people who are reasonably scientifically literate (or at least watch Star Trek) know about curved space -- that the presence of mass warps space-time, a little like the way a heavy weight on a trampoline stretches and deforms the flexible sheet it's sitting on.  The trampoline analogy isn't a bad one; if you have a bowling ball in the middle of a trampoline, and you roll a marble on the surface, the marble's path will be deflected in such a way that it appears the bowling ball is attracting the marble.  In reality, however, there's no attraction involved; the bowling ball has warped the space around it, and the marble is only following the contours of the space it's traveling through.

Bump up the number of dimensions by one, and you've got an idea of how curved space-time works.  The trampoline is a 2-D surface warped into a third dimension; where you're sitting right now is a 3-D space warped into a fourth dimension.  (In fact, the effects of that curvature are what you are experiencing as a downward pull toward the Earth's surface right now.)

The "flatness problem" asks a seemingly simple question; okay, matter deforms space locally, but what's the shape of space as a whole?  In our trampoline analogy, you can visualize that although the bowling ball deflects the surface near it, as a whole the trampoline is flat.  Harder to picture, perhaps, is that the trampoline could be a different shape; the surface of the entire trampoline could be spherical, for example, and still have indentations on the surface corresponding to places where massive objects are located.

That, in a nutshell, is the flatness problem.  The key is the matter/energy density of the entire universe.  If the universe is flat as a whole, the matter/energy density is exactly right for the outward expansion from the Big Bang to slow down, asymptotically approaching zero, but never quite getting there (and never reversing direction).  A universe with a higher matter/energy density than the critical value would eventually halt, then fall inward again, resulting in a "Big Crunch" as all the stuff in the universe collapses back to a singularity.  (This is sometimes called a "spherical universe" because space-time would be warped into a four-dimensional hypersphere.  If you can't picture this, don't worry, neither can anyone else.)  If the matter/energy density is lower than the critical value, the universe would continue to expand forever, getting thinner and more spread out, eventually reaching the point where any particular cubic light year of space would have very little chance of having even a single atom in it somewhere.  (This is known as a "hyperbolic universe," for analogous reasons to the "spherical universe" mentioned above, but even harder to visualize.)

[Image is in the Public Domain courtesy of NASA]

So, which is it?

There doesn't seem to be a good reason, argued from first principles, that the universe has to be any particular one of the three.  When I first ran into this concept, in high school physics class, I was rooting for the spherical universe solution; ending the universe with an enormous collapse seemed (and still seems) preferable to the gradual attenuation of matter and energy that would occur with the other two.  Plus, it also raised the possibility of a rebounding second Big Bang and a new start, which was kind of hopeful-sounding even if nothing much would survive intact through the cusp.

Because there seemed to be no reason to expect the value of the matter-energy density -- known to physicists as Ω -- to be constrained, figuring out what it actually is occupied a great deal of time and effort by the astrophysicists.  It was a matter of some shock when by their best measurements, the value of Ω was:

1.00000000000000000000000000000000000000000000000000000000000000

To save you the trouble, that's exactly one, out to the 62nd decimal place.

So in other words, the universe is flat, or so close to it that we can't tell the difference.

This engenders more than a few other problems.  For one thing, why is Ω exactly 1?  Like I said earlier, nothing from the basic laws of physics seems to require it.  This brings up the issue of cosmological fine-tuning, which understandably makes us science-types a little twitchy.  Then there's the problem that the outer reaches of the universe that we can see -- so places farther away in space, and further back in time -- are moving away from us a lot faster than they should if the universe was flat.  This has given rise to a hypothesized repulsive "dark energy" to account for this, but what exactly dark energy is turns out to be even more problematic than the "dark matter" that appears to comprise over a quarter of the overall mass/energy of the universe even though we haven't been able to detect it other than by its gravitational bending of space-time.

The reason this warped topic comes up is research by the groundbreaking and often controversial Nobel laureate Roger Penrose, who published a paper in Monthly Notices of the Royal Astronomical Society that identified six "warm spots" that had been detected in the background radiation of the universe, and which Penrose believes are "Hawking points" -- places where a black hole evaporated due to its "Hawking radiation" eventually bleeding off mass (a topic I dealt with in a little more detail last year).  The problem is, the evaporation of a black hole by Hawking radiation generates theoretical lifetimes for your average black hole of many times the current age of the universe, so the presence of six of them indicates something funny must be going on.

What that funny business is, Penrose claims, is that we're seeing the ghosts of black holes that evaporated before the Big Bang that formed our universe.

In other words, in a previous universe.

"The Big Bang was not the beginning," Penrose said in an interview with Sarah Knapton in The Telegraph.  "There was something before the Big Bang and that something is what we will have in our future.  We have a universe that expands and expands, and all mass decays away, and in this crazy theory of mine, that remote future becomes the Big Bang of another aeon.  So our Big Bang began with something which was the remote future of a previous aeon."

So he's not talking about a spherical universe, collapsing in on itself; Penrose thinks that even if the universe is flat or hyperbolic, eventually random quantum fluctuations will generate an expansion that will start it all over again.  This may seem a little like the example my thermodynamics teacher used about random motion -- yes, it's possible that all the molecules in your cup of coffee will by chance jitter in the same direction at the same time, and your coffee will fountain up out of the cup.  He had us calculate the odds, though, and it turns out it's so remote that it's virtually certain it has never happened anywhere in the universe, during its entire thirteen-odd billion year existence.

But if you consider that a flat universe would have an essentially infinitely long time span, all it takes is the coffee to jitter in the right direction once, and you generate a new Big Bang.

Metaphorically speaking.

Whether Penrose is right about this remains to be seen, but it must be pointed out that he's had ideas before that have seemed "out there" and have turned out to be correct.  Martin Rees, Astronomer Royal and Fellow of Trinity College at the University of Cambridge and no faint light himself, said, "There would, I think, be a consensus that Penrose and Hawking are the two individuals who have done more than anyone else since Einstein to deepen our knowledge of gravity."

So I'm disinclined to shrug my shoulders at anything Penrose says, however odd it may sound.  And it brings me back to the hopes for an oscillating universe I first held when I was seventeen years old.  If Penrose is right, there was something that existed before our current universe, and likely something will exist afterward.  Even if those are in the impossibly remote past and future, it still seems preferable to the miserable demise of a standard flat or hyperbolic universe.

So the issue is far from settled.  Which is the way of science, after all.  Every problem you solve brings up two more new ones.  Meaning we should have enough to keep us occupied until the next Big Bang -- and maybe even beyond.

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The sound of thunder

Last Sunday (April 14) we had a series of thunderstorms roll through the region, kind of unusual for upstate New York at this time of year.  We're not particularly stormy in general, but most of the thunder and lightning we do get comes in the heat of midsummer.  On Sunday, though, a warm front brought in turbulent, moist air, and we got some decent storms and rain for most of the day.

At 11:51 AM (EDT), though, something odd happened.  There was a deep, shuddering rumble that repeated three times within the span of about two or three minutes.  (The first was the strongest.)  I grew up in the Deep South, where thunder is a frequent occurrence, and to my ears this didn't feel or sound like thunder.  Immediately I thought of a mild earthquake -- primed, of course, by the April 6 quake, centered in New Jersey, which was felt over large regions of New York and the neighboring states.

The rumble we experienced preceded the arrival of the strongest of the storms; because of that, and the fact that it "sounded wrong," I was convinced that we'd experienced an earthquake.  That conviction intensified when reports began to pour in that the same noise had been heard at the same time -- in locations separated by fifty kilometers or more.  (Thunder ordinarily can only be heard about fifteen kilometers from the source.)  

My wife, on the other hand, was absolutely sure it was thunder, albeit rather powerful and deep-pitched.

Well, let it never be said that I won't admit it when I'm wrong.

I started to doubt myself when the Paleontological Research Institution in Ithaca (only ten miles from my home) reported on Monday morning that despite numerous people calling in to report noise and shaking, their seismometer had not recorded an earthquake.  That seemed pretty unequivocal -- and after all, there had been storms in the area, even though at the time we heard the rumble, the center of the front wouldn't arrive for over an hour.  But if it had been thunder, how had a single thunderclap (or three in rapid succession) been heard over such a great distance?

The answer turns out to be a temperature inversion.  Ordinarily, temperature decreases as you go up in altitude; but this effect competes with the fact that cool air is denser and tends to sink.  (This is why in winter, the greatest risk of frost damage to plants is in isolated valleys.)  So sometimes, a wedge of warm air gets forced up and over a blob of cooler air, meaning that for a while, the temperature rises as you go up in altitude.

This is exactly what happens in a warm front; the warm air, which carries more moisture, rises and forms clouds (and if there's enough moisture and a high enough temperature gradient, thunderclouds).  But this has another effect that is less well known -- at least, by me.

The difference in density of warm and cool air means that they have different indices of refraction -- a measure of how fast a wave can travel in the medium.  A common example of different indices of refraction is the bending of light at the boundary between air and water, which is why a pencil leaning in a glass of water looks kinked at the boundary.  At a shallow enough angle, the wave doesn't cross the boundary at all, but reflects off the surface layer; this causes the heat shimmer you see on hot road surfaces, as light bounces off the layer of hot air right above the asphalt.

Sound waves can also refract, although the effect is less obvious.  But that's exactly what happened on Sunday.  A powerful lightning strike created a roll of thunder, and the sound waves propagated outward at about 343 meters per second; but when they struck the undersurface of the temperature inversion, instead of dispersing upward into the upper atmosphere, they reflected back downward.  This not only drastically increased the distance over which the sound was heard, but amplified it, changing the quality of the sound from the usual booming roll we associate with thunder to something more like an explosion -- or an earthquake.

So despite the jolt and the odd (and startlingly loud) sound, we didn't have an earthquake on Sunday.  I'm kind of disappointed, actually.  I didn't feel the one on April 6 -- although some folks in the area did -- and despite having lived in a tectonically-active part of the country (Seattle, Washington) for ten years, I've never experienced an earthquake.  I'd rather not have my house fall down, or anything, but given that the pinnacle of excitement around here is when the farmer across the road bales his hay, a mild jolt would have been kind of entertaining.

But I guess I can't check that box quite yet.  Thunder, combined with a temperature inversion, was all it was.

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Dream songs

Last night I dreamed that our local mall had been converted into a giant used book store.  (Something I would entirely approve of.)  We were going to to go shopping ("we" being my wife, me, and our younger son, who lives in Houston but was apparently up for a visit) but we realized that a bunch of other family members were unexpectedly going to descend upon us, and for some reason we knew they were going to walk into our house without knocking, which our dogs would not appreciate, so we had to get home fast.  But while trying to get out of the mall we were hindered by a bunch of science-fiction cosplayers wearing silver body paint.

After that, it got kind of weird.

Dreams are a very peculiar thing, but they (and the REM sleep stage during which they occur) are ubiquitous in the brainier species of animals.  In fact, as I'm writing this, my puppy Jethro is curled up in his bed by my desk dreaming about something, because his paws are twitching and every once in a while he makes a very cute little "oof" noise.  But what would a puppy dream about?  Presumably the things that make up his waking life -- playing, chasing squirrels, swimming in our pond, eating his dinner.

You have to wonder if sometimes dogs, like humans, have weird dreams, and what they might make of them.

The function of dreaming is unknown, but what's certain is that it's necessary.  Suppress REM and dreaming, and the results are hallucinations and psychosis.  Aficionados of Star Trek: The Next Generation will no doubt remember the chilling scene in the episode "Night Terrors," where something is preventing the crew from experiencing REM sleep, and Dr. Crusher is in the makeshift morgue where the victims of a massacre are being examined -- and when she turns around, all the dead bodies are sitting up, still shrouded in their sheets.  She closes her eyes -- exhibiting far more bravery than I would have -- and says, "This is not real," and when she opens them, they're all lying back down again.

*shudder*

In any case, what brings up this topic today is far cheerier; a fascinating piece of research out of the University of Buenos Aires that looked at dreams in an animal we usually don't associate with them -- birds.  A team led by Gabriel Mindlin looked at a species of bird called the Great Kiskadee (Pitangus sulphuratus), a brightly-colored and vocal flycatcher found in much of Central and South America.  

Mindlin is one of the foremost experts in the physiology of bird song.  Birds have a unique apparatus called the syrinx that allows them to make some of the most complex vocalizations of any group of animals; not only can some (such as many wrens and thrushes) produce two or more tones at the same time, birds like parrots, mynahs, lyrebirds, and starlings are brilliant mimics and can imitate a variety of other sounds, including human speech.  (A lyrebird in a park in Australia learned to convincingly imitate a chainsaw, a car alarm, various cellphone ringtones, and a camera shutter.)

What Mindlin and his team did was to implant electrodes in the obliquus ventralis muscle, the main muscle birds use to control pitch and volume in vocalization, and also outfit some Great Kiskadees with devices to monitor their brain waves.  When the birds went into REM sleep, the researchers found that the OV muscle was contracting in exactly the way it does when the birds vocalize while awake.

The birds were singing silently in their sleep!

Singing in birds generally serves two purposes; mate attraction and territorial defense.  (As one of my AP Biology students put it, "they sing when they're mad or horny.")  It's more complicated than that -- science generally is -- but as a broad-brush explanation, it'll do.  Many species have different songs and calls for different purposes, each associated with a specific pattern of contractions and relaxation of the muscles in the syrinx.  Mindlin and his team used software capable of taking the muscle movements the electrodes detected and decoding them, determining what song the bird would have been producing if it was awake.  What they found was that the song their test subjects were dream-singing was one associated with marking out territories. 

"I felt great empathy imagining that solitary bird recreating a territorial dispute in its dream," Mindlin said.  "We have more in common with other species that we usually recognize."

So birds dream, and the content of their dreams is apparently -- just like Jethro -- taken from their own umwelt, the slice of sensory experience they engage with while they're awake.  (I wrote in more detail about the umwelt a while back, if you're curious.)  

On the other hand, how this accounts for my dream of silver-body-painted cosplayers in a mall filled with old books, I have no idea.

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