Cocktail Party Physics

the unbearable lightness of LEGO

Is there anything LEGO can't build? Jen-Luc Piquant is positively giddy over a recent find while trawling Twitter. It seems science journalist Adam Rutherford (who once visited us here in Los Angeles and got to be all fabulous, attending film premieres and all) and some pals have put together a behind-the-scenes video of a guy who built a working replica of the famed (in certain circles) Antikythera Mechanism -- entirely out of LEGOs.

Allow me to plagiarize one of my own earlier posts to give you a bit of background. In 1900, a Greek sponge diver named Elias Stadiatis discovered the wreck of an ancient cargo ship off the coast of Antikythera island in Greece. He and other divers recovered all kinds of artifacts from the ship. A year later, an archaeologist was studying what he thought was just a piece of rock recovered from the shipwreck, and noticed there was a gear wheel embedded in it. It turned out to be an ancient mechanical device -- perhaps the earliest example of a geared device -- now known as the Antikythera mechanism and housed in the Bronze Collection of the National Archaeological Museum of Athens. The device was originally housed in a wooden box roughly the size of a shoebox, with dials on the outside and containing a complex assembly of gear wheels within. Its very existence offers strong evidence that such technology existed as early as 150-100 BC but the knowledge was subsequently lost. Similar machines with equivalent complexity didn't appear again until the 18th century.

It took decades just to clean it off, and in 1951, a British science historian named Derek J. de Solla Price began his life's work investigating the theoretical workings of the device. Based on X-ray photographs of the fragments, he published a handful of minor papers before the first major paper appeared in Scientific American in June 1959.

Entitled "An Ancient Greek Computer," the article detailed Price's hypothesis that the mechanism had been used to calculate the motions of stars and planets -- making it the first known analog computer.  A November 30, 2006, article in Nature included a new reconstruction of the device based on the high-resolution X-ray tomography conducted by the study. Based on the new discoveries, the mechanism has been pretty much confirmed to be an astronomical computer used to predict the positions of heavenly bodies in the sky.

And here's where the LEGO comes in, because now that the Antikythera Mechanism has been cleaned off, x-rayed, and reconstructed (at least on paper), those "blueprints" could be used to build a real working model with moving parts and everything. Out of plastic building blocks. The ancient Greeks didn't have LEGOs, otherwise I'm sure they would have done exactly what Andy Carol did. Per the Small Mammals blog:

This is a 2000-year-old analog computing device reconstructed out of Lego. It predicts solar and lunar eclipses, accurate to within two hours — all using plastic gears. Andy Carol, its designer, builds mechanical computers out of Lego as a hobby. He made this device basically because Adam Rutherford, an editor and producer at Nature, dared him to. When Adam heard that Andy had actually built the device, he called me and said, “Well, clearly we have to make some sort of film about this thing now.”

That was almost a year ago.

Read on to find out exactly how they did it. A year they spent on this -- just the film part! -- and the painstaking effort and professionalism definitely shows. This is so many kinds of win, I really have nothing much to say about it, other than to go all Keanu on you: "Whoa. Duuuudes....." Adam et al., you are my heroes.

the ones that got away: science through cross-disciplinary eyes

There's a song by Bruce Cockburn called "The Trouble With Normal" that has stuck with me for years since I first heard it in graduate school. The line in its entirety goes "The trouble with normal is it only gets worse," an observation that applies to so many facets of life: political leaders, repressive regimes, pollution, war, gas prices, age—you name it. It seems to take humans a surprisingly short time to adjust to new conditions, no matter how bad they are. Worse, it seems to take us an equally short time to forget what things used to be like. We dismiss the reminiscing of old folks as just that: dreams of a golden age edited by memory.

This is one reason why studying history is so important. You know: those who forget history are doomed to repeat it, and all that. But history, the kind practiced by historians rather than paleontologists, can also give us a glimpse of what's wrong with our environment, or at least how drastically it's changed in some cases. This is the basis of at least part of the newish discipline of climate study, and some branches of archaeology. Turns out it's also providing a picture of what human predation has done to the size and quantity of ocean fauna.

The History of Marine Animal Populations (HMAP) and its ongoing Census of Marine Life (CoML) project is using records as diverse as old ship logs, literary texts (literary texts! Yay!), tax accounts, newly translated legal documents and even mounted trophies, to track historical sizes, abundance and distribution. Some of the images that are coming to light are, in a word, boggling, but it delights me to no end to see this kind of cross-disciplinary approach. Specialization is a necessity in science, but for big pictures, it always helps to stand back and switch your filters. Dusty stuff like old whaling ships' logs and other documents, for instance, are usually the domain of historians, but they've offered a resource to calculate the pre-whaling whale population with 95% statistical certainty. The decline in population in the very short time that whaling was practiced world-wide is appalling. For example, researchers calculate that southern right whales alone numbered between 22,000 and 32,000 in the early 1800s, declining rapidly once whaling began. By 1925, perhaps as few as 25 reproductive females survived. That's not just predation. It's slaughter on the scale of the buffalo.

We're not used to thinking about whale populations in terms of tens of thousands. As Jennifer pointed out when I first posted the link to this particular study on Facebook, that phenomenon is something that biologist-turned filmmaker Randy Olson calls "shifting baselines," and those shifting baselines can be deeply deceiving. Andy Rosenberg, of the University of New Hampshire, points out that appraising modern marine life through the narrow window of observations during recent decades "skews perceptions" of "natural" marine life sizes, abundance, habitats and vulnerability. Put another way, we're pleased when whale populations climb back to a few thousand or so, but the real baseline to measure their progress against is much larger. When you know that, you realize the poor whales still have a long way to go and their population gains seem far more fragile and worthy of further protections. Having the correct baseline, this one provided by historical documents not current scientific census data, can help form the correct international policy to protect them.

Then there's that size issue.

Fishermen, God love 'em, always talk about the one that got away, and it's inevitably a huge beauty that no one believes actually existed. Fish just don't get that big, unless you're fishing for the big guys like marlin or grouper, right? The photo at right (courtesy of HMAP/CoML) illustrates the decline in size, species diversity and abundance of gamefish in the Florida Keys between 1956 and 2007. There are some real beauties any fisherman would brag about in the top, earliest photo that make the recent catches in the bottom photo look puny-ass by comparison. The study found that from 1956 to 1960, large groupers and other large predatory fish dominated the catches, including sharks that averaged nearly two meters long. By contrast, small snappers with an average length of 34.4 cm dominated catches in 2007. Just today, in one of my cooking magazines touting the wonders of summer trout, was a photo of a guy holding a wee little fishie that barely spanned both palms, something I would have been told to throw back as a kid. Overfishing makes the catch amounts and individual sizes smaller simply because fish aren't allowed to fully mature before they're caught and eaten. You don't grow a 500 lb. grouper overnight. It takes, in fact, about 30 years. An 800 lb. grouper may be as much as 50 years old. I'm glad my middle age spread isn't that drastic. Freshwater fish grow more rapidly, but they still take time to mature into the three-foot-long pike my uncle pulled from the lake 40 years ago.

This drop in average fish weight isn't a modern phenomenon. Once humans started fishing with nets or weirs, the fish were in trouble. The Romans apparently were fishing with nets quite early on, but it wasn't until the middle ages that evidence of reduced sizes in the fish themselves begin to be recorded. That's when improvements in boat design and equipment allowed fishermen to start dragging those nets farther from shore, rather than just casting them and hauling them up, as in the picture above, from an 11th century Byzantine manuscript (International Journal of Nautical Archaeology/CoML). But in the course of this study, researchers determined that the human impact on the oceans began much earlier than previously thought, as early as the Middle Stone Age: 300,000 to 30,000 years ago, which is 10 times earlier than previously believed.

This is where I get really tickled about this kind of study. Where does the evidence come from? Not just archaeology. That can only find physical evidence of the fishing methods and tools, and if you're lucky, fish bones in the midden heaps. Nope, the evidence about how small the fish have gotten comes from literary texts. Latin and Greek verse written in the 2nd century CE was used to determine that the Romans were even then learning to trawl in a limited way and finding that, over time, it reduced the size of the fish they caught. Old logbooks and collections of sea lore were also studied for comparison purposes. Even old restaurant menus were scrutinized. Researchers also cited a text written in Sicily in 1153 that describes the seas of the North Atlantic as having "animals of such great size that the inhabitants of the islands use their bones and vertebrae in place of wood to build houses. They make hammers, arrows, spears, knives, seats, steps, and in general every sort of thing elsewhere made of wood."

Our biggest problem with this kind of literary evidence is that we find it hard to believe, in view of our own experiences. It's like the hillbilly who, when a giraffe was shown to him, declared, "There ain't no sich animal!" Krakens? Yeah, right. But we know that deep sea (and polar ocean) critters often exhibit an inordinate gigantism we didn't expect and can't fully explain, like the giant isopods found on the deep sea floor (imagine a foot-long pill bug). And there really are giant squids, though one big enough to pull down a ship hasn't yet been found. And to be fair, there's a great deal of exaggeration and sheer make-believe in the early histories. Look at Isidore of Seville's Etymologies, which describes the Blemmyes, who were an actual African tribe, as having their faces on their chests because they had no heads. To be fair, he stole it from Pliny the Elder, whose Naturalis Historia was the first encyclopedia and model for those that followed, at least in format if not veracity.

So how do you tell the fact from fiction in old sources? Statistical analysis and confirmation from other sources. In addition to the literary sources, researchers used photographs of previous catches, legal documents, tax accounts, whalebone buttons, paintings, old pavements, isotopes, and ice cores to develop backcasts. This cross-disciplinary approach gives a much broader picture than just observations of what's currently in existence. It's studies like this that help us inot just magine but undertstand, for instance, what Manhattan might have looked like when Henry Hudson sailed into the harbor or what the world might look like without us.

Apparently, a lot bigger, with a lot more in it. At any rate, it's good to remember that our "normal" isn't necessarily the norm.

standing stones in the (inland) sea

Though I don't like to admit it, I grew up in Michigan a quarter mile from Lake Huron. I also have thing for shipwrecks and stone circles like Stonehenge and Avebury. So what do the three factoids have in common? Water. The Great Lakes, shared by Minnesota (barely), Wisconsin, Illinois, Indiana, Ohio, Michigan, Pennsylvania, New York State and the provinces of Ontario and Quebec, are five of the top twelve largest bodies of freshwater in the world, and hold something like 22% of the world's fresh water. They're a little boggling to land-locked folks; you can't see across them in most places and they act more like seas than lakes, but without the daily tides and the salt; 350 million years ago, they were seas that left fossilized coral colonies called Petoskey stones. What you see now, though, is the remnant of glaciers that covered most of North America 10,000 years ago and gouged out those lake beds before filling them with meltwater.

The Great Lakes are deceptively deep and each has a personality of its own. Huron, the one I lived on, is a known ship swallower of oceanic proportions. Of the approximately 4,700 known shipwrecks (with an estimated six to ten thousand total) in the Great Lakes, more than a thousand ships, from ocean-going iron ore freighters to pleasure boats (and airplanes), have been documented as sunk in Lake Huron alone, a large number in the area known as Thunder Bay, just to the north of where I grew up. Lake Michigan, though, gets some of the fiercest storms. It's estimated that 3,000 ships lie in the sands of Lake Michigan.

But ships aren't the only things the waters of the Great Lakes have drowned. The lakes' mean levels rise and fall (PDF) in an approximately 20-year cycle that has to do more with annual snowfall than gravity, so houses and docks and boathouses have a tendency to disappear cyclically as well. Shoreline appears and disappears, is reshaped and eroded and built back up again; wetlands come and go. And as the glaciers pulled away, the lakes rose even more drastically than during this cycle until they reached their present levels, leaving being a number of isolated islands.

One of these islands is Big Beaver Island in Lake Michigan, home to Michigan's very own stone circle. Now there may be another, this one discovered underwater by Dr. Mark W. Holley of Northwestern Michigan College in Traverse City during the course of surveying the shipwrecks and other debris in Grand Traverse Bay. Ah, see? It all comes together: Michigan, shipwrecks, stone circles. Maybe I should clarify before you take a look at the photo of it at right. Don't expected Stonehenge, capital S. It's as much a stone alignment as a henge, which are circular or oval in nature. But standing stone arrangements come in numerous configurations, most of which seemed to have some kind of astronomical significance. Many, like the familiar Stonehenge near Salisbury, UK, were both grave sites and astronomical markers. One acoustics scientist, Rupert Till,has discovered that Stonehenge, at least, reflects music almost perfectly, "making the stone circle an ideal setting for listening to repetitive trance rhythms," as the Discovery News article points out. Rave on, Dude! Of course, whether that's actually what went on there is impossible to tell.

(That circle in the middle of the sonar photo above is an artifact of the imaging tool, a Kongsberg-Mesotech MS 1000 sonar, which produces some eerily vivid images of underwater objects (including a very spooky image of a downed plane on their home page) by pinging soundwaves off them. From watching old  submarine movies, I'm used to seeing a sweeping green line with little blips on it as sonar images, not something this high-def. That high definition is, of course, thanks to software processing programs rather more sophisticated than the echolocation sonar used in WWII subs. Unlike the side-scanning sonar that's towed behind a surface vessel or sub that can give wide, sweeping views of the seafloor, this is a more or less stationary sonar dropped overboard to scan a circular area. Sound waves blanket an area and the time they take to bounce back to the transmitter/receiver tells you how high off the surface the objects returning the sound are, as well as how dense they are, since different materials absorb and reflect sound differently. The software is calibrated for the type of surface that's being pinged, so harder objects, like stones, form clearer pictures than the background sand, for instance.)

Just what function North American stone circles had is still up for grabs; there are very few of them. What there are a lot of is medicine wheels, which may have served a similar function but have a very different design. What you're seeing here looks very similar to the remains of other medicine wheels across the Great Plains (left). What's doubly interesting about this particular set of standing stones is that one appears to have a picture of a mastodon with a spear in its side carved into it. Mastodon remains have not previously been found that far north, so this could be a significant find. There's some question about whether the stone really shows a mastodon, and it's hard to verify the fact since it's in 40 feet of water and covered in algae.

The truly mystifying thing about most stone circles is how the heck they got where they are. North American stone structures are generally made of rocks that could easily be carried by hand from the surrounding area, but European megaliths often weigh from several hundred pounds to several tons, and some of the stones were quarried hundreds of miles away. It's cases like this that really show up human ingenuity and give the lie to the idea that people in history were less sophisticated or dumber than we are. First, they've chipped this slab of bluestone (which describes the color more than denoting a particular type of stone in this case) out of a quarry 250 miles away in Wales. What now? Using gravity, bits of wood, and some rope, a former construction worker in Flint, Michigan shows you how to move two ton rocks with your bare hands:

This isn't exactly an unknown technique; the Egyptians probably used something like it to erect their obelisks, like the one now residing in London, or the one in New York's Central Park. When the Vatican wanted one moved from behind the sacristy of St. Peter's to the piazza in front, it took "900 men, 75 horses and untold numbers of pulleys and lengths of rope," and a lot of scaffolding. So Wally Wallington's feat is pretty impressive. The stones he's moving weight as much as a minivan. Of course, you could just go directly to the minivan itself.

I shudder to think what future archaeologists might make of Carhenge. Maybe it'll wind up underwater too, with a little luck, and rust can take its course. In the mean time, I wonder how a rave there might sound?

[h/t to Geoff Manaugh at BLDGBLOG]

what lies beneath

Since we're dallying at the science/art interface this week, here's some breaking news via AIP's Physics News Update: a group of Italian and German scientists have used nuclear magnetic resonance -- the underlying physics behind MRI machines -- to non-invasively map out the layers of historical fine paintings, and announced their results in the July 21 issue of Applied Physics Letters. Apparently this is known as "stratigraphy." Who knew? (Hint: not me! We live and we learn.) That includes any preparatory layers, under-drawings, the actual layers of paint, and in many cases, a layer of varnish.

The rationale for doing this at all is that this sort of precise analysis helps establish age, origin and authenticity of works of art, in much the same as geologists learn about the Earth's history by studying the various geological strata. The new technique does much the same thing for paintings as it does for the human body, except instead of using x-rays, detectors, and cutting-edge computers to provide information about soft tissue and the possible presence of tumors, it provides information about the binding agents used in the painted layers. Those agents were often made of things like egg yolk or oil.

How good is the technique? Well, just knowing the nature of the binding agent can usually distinguish between a naturally-aged painting and one that has been artificially aged (a polite euphemism for "forged"). It's non-invasive, and the magnet used in single-sided, unlike MRI magnets which have to surround the patient (and/or limb) for imaging. So scientists can bring the scanner right up to the painting without ever touching the surface. Ease of use counts for a lot when it comes to marketable applications! Furthermore, the technique can determine the thickness of various paint layers, too, and while it can't definitively "date" each layer, it can tell which ones are older than others. It's easy to see why this might be a useful tool for art historians.

There's a strong tradition in science already of using x-ray imaging to study art, ancient manuscripts, even archaeological objects, although these don't penetrate to the same depths as the new MRI technique. I've blogged about that approach previously here. For about a year, scientists at the University of San Diego have been collaborating with an Italian engineer named Maurizio Seracini to analyze 500-year-old bricks from a wall in Florence's Palazzo Vecchio.

They're looking specifically for a lost fresco by Leonardo da Vinci called the "Battle of Anghiari" that was never completed and -- until recently -- presumed to have been destroyed. Leonardo began the project to commemorate the 15th century Florentine victory over Milan at Anghiari in Tuscany, but he left the following year without completing the mural. And they're bringing all the ammo they can muster to the task: laser scanners, thermal imaging, radar, and neutron beams, among other techniques

About 30 years ago, Seracini noticed a cryptic message on another fresco in the hall by another 16th century artist, Giorgio Vasari: "Cerca, trova," or "Seek, and you shall find." (The image above is a scene from Vasari's fresco entitled "The Castration of Venus by Saturn." Truly an edifying image, or at least one guaranteed to strike the fear of god into the hearts of men.) This made him suspect that Vasari preserved Leonardo's unfinished fresco rather than destroying it. He also found bricks and stonework in a storeroom that were once part of the enormous hall, the Salone del Cinquecento ("Hall of the 1500s) in the Palazzo Vecchio. With the permission of Culture Minister Francesco Rutelli, he shipped off the bricks to UCSD so that scientists could analyze their structure and composition.

Just a few years ago, they used radar and x-ray scans to locate a cavity behind Vasari's fresco, indicating a space between walls, and last November they used a laser scanner to construct a 3D model of Vasari's wall. Since then, they've been working on chemical analysis of Vasari's paint pigments, and thermal imaging to better delineate the wall structure. This will give them a better understanding of what might lie behind that wall in preparation for the final step: sending a flux of neutrons through the entire structure. Everything they've learned about the pigments and walls can be subtracted from the overall neutron analysis, thereby establishing the composition of the wall Leonardo worked on. If it's there, Seracini thinks the mural should be found right on top of the original stone wall of the hall. He could be wrong -- there might not be a lost Leonardo there at all. But at least art restoration can benefit from all these snazzy cutting-edge technologies.

And just a couple of weeks ago that a team of European scientists have used synchrotron radiation to reconstruct the portrait of a peasant woman painted by Vincent van Gogh that the artist had then painted over when he created 1887's "Patch of Grass." It lay there, dormant, for 121 years until we finally had the technology to nondestructively analyze the painting and reproduce the hidden image. And we owe it all to the Deutches Elektronen-Synchrotron (mercifully known by the acronym DESY) in Hamburg, Germany.   

Synchrotron radiation is a bit different from conventional x-rays; it's a thin beam of very high-intensity x-rays generated within a particle accelerator. The Cliff's Notes version of how it works is this: You fire electrons into a linear accelerator (linac), boost their speeds in a small synchrotron and inject them into a storage ring, where they zoom through at near-light-speed. A series of magnets bend and focus the electrons, and in the process, they give off x-rays, which can then be focused down beamlines. This is useful for imaging purposes, and for analyzing structure, because in general, the shorter the wavelength used (and the higher the energy of the light), the finer the details one can image and/or analyze.

Someone already used conventional x-rays to reveal the rough outlines of the underlying portrait, but that technique just wasn't sufficient to distinguish between the many layers of paint. Also, pigments made from heavy metals tended to obscure the colors derived from other elements, resulting in what Joris Dik, a materials scientist and art historian at the Technical University of Delft in the Netherlands, described as "a very partial, fragmentary, color-blind view."

Dik and his colleagues took "Patch of Grass" to DESY and exposed the painting to the x-ray beams. The radiation excited the atoms on the canvas, which then emitted x-rays of their own, picked up a fluorescence detector. Each element in the painting had its own x-ray signature, so they were able to identify the distribution of metals in the many layers of paint, construct a 3D model, and then peel off the layers one by one in the virtual image until what lay beneath was finally revealed. Per the Los Angeles Times: "The top layer consisted of paints made with zinc, barium, sulfur, and other elements. Behind that they found a uniform distribution of lead, which was used as a primer to hide the portrait and prepare the canvas for a new painting. Once that was removed, they combined the distributions of two more elements -- mercury and antimony -- to produce the outlines of the hidden portrait."

They found the remains of a portrait of a woman bearing a striking resemblance to the model van Gogh used while composing his famous "The Potato Eaters" in 1885, and used computer software to recreate the painting using their own version of a "paint-by-numbers" technique. Van Gogh, apparently, was known to recycle his canvases, which was quite thrifty and environmentally correct of him. Clearly, a man ahead of his time. In fact, some art experts think that as many as one-third of his earlier paintings have older ones underneath them; many of these might find there way to Germany for synchrotron analysis over the next few years, as funds permit. (I'm guessing time on a major synchrotron facility ain't cheap!)

It's nice to see new uses emerging for the big machines of science -- especially when those new uses span across traditional disciplinary boundaries. Synchrotron light is a burgeoning research area, finding use in physics, chemistry, materials science, medicine, geological and environmental science, structural genomics, and (as we have seen) archaeology. No wonder various European countries are collaborating on building a brand-new fourth-generation synchrotron light source at DESY, called the X-Ray Free-Electron Laser (FXEL).

Alas, the Synchrotron Radiation Source (SRS) based at the Daresbury Laboratory in Warrington, UK, was switched off earlier this week. But fear not! Its good work will continue at a shiny new facility: the Diamond synchrotron in Oxfordshire, part of a growing number of world-class research facilities in that area. In fact, scientists from the University of Cardiff have already developed a new technique for the Diamond synchrotron for analyzing the hidden content in ancient parchment without having to open them, such as the  original musical scores of Bach, or the Dead Sea Scrolls (some of which are so fragile and badly damaged, they haven't been unrolled yet).

Cardiff's Tim Weiss explained that many manuscripts, such as those in the 12th century, used iron gall ink made from oak apples, but the parchment on which they were written contains collagen (since the parchment was made from the thinly stretched skins of cows, sheep, or goats), and collagen naturally degrades to gelatin. Iron ink speeds up the process. It's a wonder so many parchments survived, frankly.

Anyway, they're using the synchrotron's powerful x-ray beams, to create 3D images of iron-inked documents. Because the inked lettering contains iron, the result is an absorption image, much like how one's bones show up so vividly on a standard x-ray. Rolled parchment works the best with the technique; books are flat and thick, which is a bit more challenging. Apparently, per Weiss, "You really end up with a stencil rather than the lettering," in those cases.

Isn't technology wonderful? I can't wait to see what else science finds lurking beneath the surfaces of other paintings and manuscripts.

the skull beneath the skin

"Webster was much possessed by death
And saw the skull beneath the skin;
And breastless creatures underground
Leaned backward with a lipless grin."
-- T.S. Eliot, "Whispers of Immortality"

Eliot's classic poem alludes to the great Jacobean tragedian, John Webster (of Duchess of Malfi fame), who did indeed have a predilection for the macabre, but the Indiana Jones film series arguably has an element of that as well. The Spousal Unit and I finally went to see Indiana Jones and the Kingdom of the Crystal Skull Sunday night (he was decidedly underwhelmed, I was moderately entertained). All the usual tropes were present: the mystical objects (loosely based on historical artifacts and legend), the drawn-out chase scenes, inventive stunt work, sly witticisms (this installment is less witty than others), attacks by creepy-crawlies, the double-crossing "ally", the power-mad villain(ess), and the almost laughably absurd supernatural climax -- in this case, bringing in shades of The X-Files. (The Spousal Unit bemoaned the silliness of the ending; it was silly, but not any sillier than any of the previous three installments.) Of course, there's also loads of mucking about underground in ancient archaeological sites, strewn with dusty cobwebs, booby traps, and lots and lots of decaying corpses grossing out delighted filmgoers with their "lipless grins."

Admittedly, the film suffers from a formula that's getting a wee bit tired, and what appears to be laziness on the part of the filmmakers in terms of character development, dialogue, and pacing. Everyone's in such a hurry to get to the next stunt or special effect, hurtling towards the climax, that they forget to let the audience savor those little throw-away moments that made the first and most successful Indy film so much fun. The cheesy props don't help matters -- could the crystal skull of the title look any sillier? paging CGI! -- but really, when has Indiana Jones ever been about anything except far-out fun? Cue my usual mantra about how it's unrealistic to expect film and television to be very true to life when it comes to facts about science, history, blah, blah, blah. (NOTE: There may be a few unintentional spoilers below for those who haven't yet seen the film.)

Except in this case, I'm starting to think the thin line between fiction and reality really might be getting a bit too blurred. Last month the Archaeological Institute of America -- the oldest and largest nonprofit organization in the US devoted to archaeology -- elected actor Harrison Ford to its Board of Directors in recognition of his role in "stimulating the public's interest in archaeological exploration," according to AIA president Brian Rose. I'm happy for Ford, who does seem to have an genuine interest in the field; any celebrities who care to lend their name in support of science get mega-points with me. But, well, Dr. Jones is a pretty glamorized version of your typical archaeologist. The National Science Foundation was sufficiently concerned to issue a special report highlighting the differences and similarities between the worlds of science and Indiana Jones. Per the press release accompanying its release:

NSF-supported archaeologists do discover "lost cities." They try to figure out what happened to "vanished civilizations" and whether what caused their collapse may have relevance to contemporary problems. They seek rare and precious artifacts that tell important stories about the past, even if those artifacts are minute snails and the scrapings of ancient teeth and not golden idols. They "deal with Native peoples," though with respect, as partners in the process of learning about the past, rather than with weapons. And certainly, as jokingly noted in the latest Indiana Jones adventure, teaching is an important part of what they do.

Being tall is also an important part of what archaeologists do, not to mention breaking into song when locating ancient Sumerian artifacts from the 3rd dynasty -- at least according to Monty Python (h/t: Afarensis). Harrison Ford's got the tall part down, at least, even if the NSF report failed to mention it.

Most of the press related to the new film, however, has focused on the legends and myths surrounding the crystal skulls. Yes, Virginia, there really are crystal skulls -- 13 of them, to be exact -- and the film even identifies the most famous one by name: the infamous Mitchell-Hedges skull, a.k.a., "the skull of doom." It was supposedly discovered by 17-year-old Anna Mitchell Hedges and her father in either 1924 or 1927 (they never did get their stories straight on the year) under the altar of a Mayan temple in a ruined city in Belize, although there is documentary evidence that in fact, Anna's father bought the skull at a Sotheby's sale in 1943.  (Anna herself later came up with an "explanation" for that bill of sale.") Her father, a British "adventurer" named F.A. Mitchell-Hedges, claimed the clear quartz crystal skull was "at least 3600 years old, and according to legend was used by the High Priest of the Maya when performing esoteric rites. It is said that when he willed death with the help of the skull, death inevitably followed. It has been described as the embodiment of all evil."

The other skulls include "Max," the "Texas crystal skull," supposedly from Guatemala; "ET", supposedly discovered in 1900 (notable for its pronounced overbite); "Ami," an amethyst crystal skull, supposed to be Mayan; "Sha-na-ra," a clear crystal skull that moonlights as a member of an a capella doo-wop group whose owner claims to have found it in Mexico; the British Museum crystal skull (also mentioned in the film), made of cloudy quartz; the Paris Skull, thought to be Aztec, currently housed in the Musee de l'Homme in Paris; and an Aztec crystal skull anonymously sent to the Smithsonian's Museum of Natural History in 1992, which also had a smaller crystal skull in its possession for many years.

The real crystal skulls look nothing like the hulking prop used in Kingdom of the Crystal Skull. For starters, they're a lot smaller; some of them measure as little as an inch across, most likely having been carved out of authentic pre-Colombian beads in the 19th century, when museums first began collecting crystal skulls. There are exceptions: the one in the British Museum is life-sized, and  the crystal skull mysteriously mailed to the Smithsonian in 1992 weighs a whopping 30 pounds; the anonymous sender claimed it was of Aztec origin.

Not so, sez Jane MacLaren Walsh, a Smithsonian anthropologist who has studied several of the skulls extensively, including the most recent acquisition. In a recent cover story in Archaeology magazine, she insists, "These exotic carvings are usually attributed to pre-Colombian Mesoamerican cultures, but not a single crystal skull in a museum comes from a documented excavation, and they have little stylistic or technical relationship with any genuine pre-Colombian depictions of skulls, which are an important motif in Mesoamerican iconography." (You can find a preliminary report on her study of both the Smithsonian and British Museum crystal skulls here.)

Walsh is featured in an upcoming documentary for the Smithsonian Channel, The Legend of the Crystal Skulls, airing July 10th. (You can see clips/video footage, and find quite a bit of background information about the skulls, here. And if you want to own your very own crystal skull, you can buy one here, although many of the most popular models are currently sold out -- no doubt boosted by the current Indiana Jones craze. They also offer clear stone phalluses, which if nothing else would make for an interesting conversation piece at dinner parties.)

There are some wacky sorts out there who attribute the crystal skulls with special psychic powers, and even some murmurings of possible alien provenance (rumors that started with F.A. Mitchell-Hedges). An art restorer named Frank Dorland claimed to hear ringing bells and the sound of a choir singing and could see images when he gazed into the Mitchell-Hedges skull -- which he studied for about six years, becoming one of its staunchest devotees. Anna claims her skull has been used for healing -- disputing her own father's characterization of the artifact as "the embodiment of evil." The owner of "ET", a smoky crystal skull, believed it healed her brain tumor. These claims have been handily debunked, of course, but certainly the notion that the skulls have special powers captures the imagination: an episode of Stargate SG-1 memorably featured a crystal skull that enabled characters to travel between worlds.

The most popular legend has it that when all 13 of the crystal skulls are brought together in a certain configuration -- and no doubt at a specific place and time, just to make it as unlikely as possible -- they will "divulge their secret and prevent a terrible calamity." LucasFilms Ltd. picked up that premise and ran with it in their latest blockbuster, although they got a bit confused at the end about what calamity, exactly, the skulls were supposed to prevent. (The destruction of an entire Mayan city might strike some as a calamity.)

So where did the skulls come from? The consensus seems to be that they emerged in the late 19th century, part of a wave of pre-Colombian fakes that found their way into various museums around the world. While visiting Mexico City in 1884, the Smithsonian archaeologist W.H. Holmes warned about the burgeoning number of "relic shops" on every street corned filled with fakes, prompting him to write an article for Science on "The Trade in Spurious Mexican Antiquities." One wonders, then, how the Institute was taken in a mere two years later, when, in 1996, the Smithsonian purchased a small crystal skull from a man who had been Emperor Maximilian's secretary in Mexico at the time. In part, museums began collecting rock-crystal skulls at this time because existing knowledge about real artifacts was pretty scarce, making it easy to pass off fakes as the real deal.

Walsh tracked down several of the skulls to one Eugene Boban, a French art dealer in the late 19th century. At least three of the 13 famed crystal skulls can be traced directly back to Boban, who served as the official "archaeologist" in the Mexican court of Maximilian, as well as being a member of the French Scientific Commission in Mexico. After Maximilian's execution by the army of Benito Juarez, Boban found himself back in Paris, where he opened an antiquities shop. Even at the time (1885), one of his second-generation crystal skulls was denounced as a fake when he tried to sell it to Mexico's national museum as a bona fide Aztec artifact. Eventually he found himself in New York City, where he managed to sell the skull at auction to Tiffany's for $950. (This skull is the one that was later sold to the British Museum.)

As scientific knowledge advanced in the 20th century, the crystal skulls lost quite a bit of their mystic luster, and almost all of their credibility as bona fide antiquities. Based on her research, Walsh concludes that "all of the smaller crystal skulls that constitute the first generation of fakes were made in Mexico around the time they were sold, between 1856 and 1880. This 24-year period may represent the output of a single artisan, or perhaps a single workshop."

In the 1950s, a Smithsonian mineralogist named William Foshag realized that the crystal skull it had acquired in the 1800s had been carved with a modern lapidary wheel. From then until it mysteriously disappeared in 1973, the skull was displayed in an exhibit of archaeological fakes.

Using high-end instruments like Scanning Electron Microscopy, Walsh concluded that the Mitchell-Hedges skull, for instance, shows evidence of tool marks, casting serious doubt on claims the skulls are pre-Colombian in origin, since the Maya, Aztecs or other pre-Colombian peoples just didn't have the tools to make those kinds of marks. (Aliens, though, would most certainly have had advanced tools, claim the True Believers.) Heck, even Frank Dorland said that the Mitchell-Hedges skull showed signs of "mechanical grinding on the faces of the teeth," although he was a proponent of the alien origin theory, the better to bolster his delusions about the skull's power. The Paris Skull -- which Walsh believes to be a "transitional piece," larger but similar in style to the first generation of crystal skulls -- will be undergoing extensive scientific testing with such advanced elemental testing techniques as particle induced X-ray emission and Raman spectroscopy, to determine its exact age/composition once and for all.

As for attributing special mystical powers to the crystal skulls -- or any kind of crystal, for that matter -- no doubt True Believers would say that scientists are close-minded and refuse to consider the possibility. Um, nice try, but actually, scientists know a great deal about the properties of crystals. There's an entire field of material physics (crystallography) devoted to studying those properties, and crystals -- unlike, say, soft condensed matter (amorphous solids and the like) -- are among the best understood materials today. Crystals get their properties from their atomic structure; the definition of a crystal is a solid in which the atoms, molecules and/or ions are arranged in regularly ordered, repeating patterns in all three spatial directions. It's a naturally occurring structure, wondrous in and of itself, but that's not enough for crystal aficionados, who feel the need to attribute mystical properties to these materials as well.

According to crystal skull sycophant Frank Dorland, "The crystal stimulates an unknown part of the brain, opening a psychic door to the absolute." It's a common type of argument. For instance, True Believers have been known to cite the natural piezoelectric properties of quartz crystals as evidence of their power. Now, piezoelectricity is pretty nifty: in 1880, Pierre and Jacques Curie discovered that squeezing a quartz crystal produced an electrical charge, which is why quartz is used in watches, those old car lighters, all kinds of sensors, and so forth. Granted, this is energy of a sort, but it's certainly not psychic energy, just plain old electricity. Crystals are very pretty, though, which might explain why there's so much wishful thinking surrounding the issue of whether they have healing or psychic powers.

So there you have it: the lowdown on the real-life crystal skulls, which are nothing like that depicted in Kingdom of the Crystal Skull -- but nonetheless, I think they're still pretty darn cool. And science could offer some useful fodder for future installments in the Indiana Jones saga, should Hollywood decide to build a similar series around Indy's son, Henry Jones III (Shia LeBoeuf). Over at Twisted Physics, I mentioned the use of cosmic ray detectors by archaeologists, using muons to map out archaeological sites and detect hidden tombs or chambers. I think it would make an excellent premise for the first Son of Indy flick. After all, Crystal Skulls takes place in 1957. Luis Alvarez first used cosmic ray detectors to study Egyptian pyramids around 1967, when Indy 2.0 would be around 30 (give or take a couple of years), hopefully having completed some semblance of an education at long last.

Can't you just see Alvarez teaming up with a rebel archaeologist to foil some nefarious plot or another? Ancient Egypt certainly has enough myth, legend, and mystical artifacts to fuel another wacky plotline, and Alvarez really is the sort of physicist who should be better known among the general populace. I think he'd get a kick out it, frankly. So, George Lucas, feel free to use the above suggestion as you see fit -- in exchange for just a teensy percentage of the profits from the inevitable Son of Indy franchise. Then I should be able to keep the Spousal Unit and Resident Feline in the manner to which they would like to become accustomed.

surfin' safari

Many people might not be aware that Mark Twain (a.k.a. Samuel Clemens), beloved author of Tom Sawyer and The Adventures of Huckleberry Finn, was an admirer of surfing, or, as he called it in his essay, Roughing It, "surf-bathing." He admired it enough to try his own hand at it, with predictable results:

"I tried surf-bathing once, but made a failure of it. I got the board placed right, and at the right moment, too; but missed the connection myself. The board struck the shore in three-quarters of a second, without any cargo, and I struck the bottom about the same time with a couple of barrels of water in me. None but the natives ever master the art of surf-bathing thoroughly."

I can empathize with Twain's wipe-out, having done something similar more than once on my very first attempt at surfing, during a recent (mid-December) trip to Kona, Hawaii. Technically, I was there doing book-related research -- research, I tell you! Authors must suffer for their art! -- by visiting the infrasound laboratory of Milton Garces (a.k.a., "the volcano whisperer"), an acoustician with the University of Hawaii whose work has been featured previously at the cocktail party -- and also in more mainstream media outlets like Wired magazine and a segment on Wired Science. (If you're not watching the show, why not? Until the writer's strike is over, everything else is reruns and reality shows. A fine time to catch up on all that quality science programming! Like the two-part NOVA series on Absolute Zero -- Part 2 airs tonight.)

One year later, I found myself driving down the Queen K Highway in my cheap little rental car to check out the lab, which is located right on the water. I'd previously only visited Honolulu, which didn't leave the best impression of our 50th state; it kinda reminded me of a super-mall in Los Angeles, to be honest, only more humid -- granted, I didn't venture very far afield from the downtown area. But Kona is the panoramic Hawaii of Captain Cook and all those surf movies (Endless Summer, Step Into Liquid, and the more soap-opera-like Blue Crush, just to name those I've actually seen). Plus it has volcanoes and fascinating microclimates, making it the perfect location for Garces' varied research, which spans not just volcanoes and breaking ocean waves, but also nuclear monitoring and (the latest twist) passively listening to the whale populations off the shore. Yes, all of those involve some kind of infrasound. The lab also has a killer sound system, capable of taking the roof off that sucka, and had the biggest speaker in the system not been out for repairs, I might have been privy to a demonstration of its acoustic power. Let's just say that Garces and his colleagues would appreciate today's XKCD:

So, I loved the Big Island. Sure, Maui has miles of sandy white beaches, while Kona's shore's are strewn with lava rocks (the entire island is basically the remnants of volcanic eruptions over thousands of years). Personally, I loved the lava rocks, as well as the local version of graffiti (placing white shells against the black rocks to make pictures and spell out the usual graffiti messages). It gives rise to some interesting geological formations. I scrambled over slick lava rocks with Garces to check out one of the island's many "lava tubes" -- the one nearest the lab is awesome, since it routinely gets hammered by the incoming waves, with the occasional shock/explosion propelling water up through the rock to the surface. It's like a geyser, only less predictable.

I also jolted along unpaved "roads" (I use the term loosely, since at one point it was little more than a grassy foot path) to the top of the mountain in Garces' (mercifully) 4-wheel drive vehicle to check out the sensor arrays that form the heart of his infrasound research. Thanks to a recent tropical storm, we ended up walking the last bit of the way. You know someone's doing hard-core field research when you find yourself longing for a machete to hack your way through the undergrowth. (And why, oh why, did I not have the foresight to bring my Tevas, which are perfect sandals for hiking and scrambling over rocks?) Anyway, then Garces insisted on taking me surfing, which pretty much makes him the best host ever -- no other lab I've visited has taken me surfing; that sets the bar pretty high.

There was actually a very good reason for doing so, apart from the fun factor, and the fact that Garces, his wife and daughter, and most of the guys in his lab, are all avid surfers, it being almost a way of life in Hawaii. I haven't been around that many tanned, uber-fit people since my last foray into Santa Monica (except in Hawaii, people look less plastic, because there's less of an obsession with steroids and silicone). Garces insisted that I could observe everything I needed to know about wavefronts by hopping on a surfboard and experiencing the ocean firsthand from that (rather vulnerable) vantage point.

And that's how my pasty-white, city-dwelling self ended up on a borrowed surfboard, gamely paddling out to meet the incoming waves. (I did not, alas, remain pasty-white; by the end of the afternoon, my entire back was bright red, even the soles of my feet. I looked like a haddock that had only been seared on one side. The Spousal Unit, always supportive, suggested when I called that I burn my front side the following day to even things out. Jen-Luc Piquant suspects he may have been a wee bit envious that his research, on the origins of the universe, doesn't call for trips to Hawaii.)

It shouldn't come as a shock to anyone that there's a lot of physics involved in surfing, so you'd think that my grasp of the basic principles, combined with my general fitness, strong swimming skills, and years of martial arts training, would give me a tiny bit of an advantage. And maybe those things helped a little, but  honestly? Surfing is one of those activities that's pretty straightforward in concept, yet very difficult to master -- as Twain found out a century or more ago. Basically, you paddle a decent way out from shore -- being careful to avoid proximity to dangerous rock formations and such -- turn the board around, and wait for a promising wave. (Jen-Luc helpfully points out that at this point, the primary physical mechanisms at work are our friends, gravity and buoyancy. Think Archimedes and his "Eureka!" moment. There is no acceleration, and thus no net force. So it's a pleasant sensation, but hardly exhilarating.) Per the Exploratorium's exhibit on the physics of surfing, you want "a nice roller, moving towards you at a constant speed." Okay then.

This is not an easy call to make; ocean wave dynamics are pretty complex. That's why surf forecasters prefer to rely on real-time meteorological data from satellites to locate the biggest waves. The size and shape of ocean waves depends on three major variables: wind speed, the "fetch" (not as in "That is so fetch!" from Mean Girls, but as in, the distance of open water the wind has been blowing over to form the waves), and how long the wind has been blowing over a given area. The best waves, according to hard-core surfers, are those produced by intense distant storms that generate heavy winds. Those winds blow continuously for several days, creating lots of waves that slam into each other repeatedly to create a "chop." Gradually, all the little waves accumulate into a larger swell. By the time they reach the shores of Hawaii (in this instance), they've become a series of power, large swells.

It was not a big wave day when I had my outing -- good news for me, as a beginner, since the waves were smaller and the waters less crowded with hard-core surfers. Generally, waves are measured according to height (from trough to crest), wavelength (from crest to crest) and period (the interval between the arrival of consecutive crests at a fixed point). Many of them eventually "break" as they move into shallower water (or when two wave systems collide and combine their forces), which is what happens when the wave base can no longer support its top, causing it to collapse. We had the pleasant spilling or rolling version of breaking waves. The plunging variety can break too suddenly, dumping surfers and pushing them to the bottom with a lot more force than one might think. There's a lot of energy in those ocean waves: depending on the size, it can be as much as 5 to 10 tons per square yard. Ouch! Surging waves might not even break, but their powerful undertows can drag unwary swimmers and surfers into deeper, more dangerous waters.

No doubt people who surf a lot, or who study wave dynamics for a living, get pretty adept at eyeballing the incoming waves to identify the most promising for surf purposes (by size, by when they're likely to break, etc) -- and also estimating how fast those waves will be traveling by the time they reach the surfer. But to a novice like me, they all look about the same, and it's tough to predict when they'll crest and break unless you have a lot of experience with ocean wave behavior. I don't, so pretty much relied on the Garces family to let me know when it was time to paddle like crazy. (They were both on hand, tanned and fit and looking perfectly at ease on their much more advanced boards.) Because you've got to get up to the same speed as the incoming wave if you want to catch it, otherwise it just shoots right past you, leaving you bobbing forlornly behind on your surfboard. That was Twain's mistake, I think. 

Or maybe Twain caught the wave, but failed to keep paddling after that first tug. That's Step 2: keep paddling until you're sure you're riding the wave, at which point you attempt to stand. And this, my friends, is where things get tricky, because a moving wave is literally a slippery slope, with constantly shifting  changing forces acting on the surfboard -- not just gravity and buoyancy at this point, but also hydrodynamics forces (exerted by a moving fluid) that push the board forward (along with a certain amount of friction or drag along the bottom of the board). Ergo, you've got to keep shifting your weight back and forth to stay near the board's center of mass as you ride the wave to keep the proper balance of forces (between the downward force of gravity and the upward buoyant force). When they're out of balance, the board torques, or twists. If the nose is too low, you pitch forward; if you shift too far back and the nose is too high, you lose your momentum, the board stops, and you pitch into the water.

Apparently it's easier to maintain that critical balance between opposing forces on a shorter board; the tradeoff is that it's harder to catch the initial waves. So for a beginner, like me, a long board is best, which is indeed what I was using. Garces assured me the board would "catch anything" (or would, with a better surfer wielding it); but it meant it got a bit trickier when I tried to stand up. 

Let's just say I wiped out on a regular basis and swallowed my share of salt water. I never quite got into a full stand, either; the best I could manage was a low crouch. But I have to say, it's pretty darned exhilarating even catching the baby waves and riding them into shore. I managed it maybe three times -- not a great record, compared to the high number of spills, but the successes are what you end up remembering. I'll be spending three months in Santa Barbara beginning in February, as Journalist in Residence at the Kavli Institute of Theoretical Physics. I'm told by CV's Daniel Holz that the surfing around there is pretty good -- provided you have a wet suit (Brrr! the water's cold!). Who knows? This surfing thing might become something of a habit. Maybe I'll even figure out how to turn, which is all about deliberately moving the balance between gravity and buoyancy out of alignment temporarily to exert a torque, and thus execute a turn.

After all that excitement, what, exactly, did I learn from the experience? Well, I learned that a high SPF waterproof sunscreen is pretty much de rigeur in Hawaii, and if I decide to go surfing again, I'll make sure to get the proper gear (although La Famille Garces were amazingly generous with their stuff). And I did come away with more of a firsthand, experiential grasp of wave dynamics (as opposed to mere book-larnin'). After all, from a mathematical viewpoint, it doesn't really matter much if you're talking about a sound wave, a light wave, or a water wave: you can still use many of the same equations in each case, notably, the infamous Fourier Transform devised by Jean-Baptiste Joseph Fourier. (This will be the subject of a future post at some point, when I find the time to write about it.) I wasn't able to find any historical evidence that Fourier, like Twain, tried his hand at surfing. I'm guessing late 18th century France was not so much with the surf-bathing. But if given the opportunity, I'm sure Fourier would have made an excellent surfer -- at least in theory.

asphalt jungle

In 1769, Gaspar Portola, the Spanish governor of Baja California, led an excursion across the Los Angeles River and down what is now Wilshire Boulevard in modern-day La-La Land. According to a journal kept by one of the expedition members -- a priest named Juan Crespi -- the travelers "saw some large marshes of a certain substance like pitch, they were boiling and bubbling... and there is such an abundance of it that would serve to caulk many ships." This is the first recorded sighting of the famed La Brea Tar Pits.

The landscape has changed a bit since then. Okay, it's changed a lot. Shortly after I moved to Los Angeles this past April, we were driving down Wilshire Boulevard en route to the city's high-end shopping mecca, Rodeo Drive, when we passed a sign reading "La Brea Tar Pits." Initially I assumed it was an advertisement, but the Spousal Unit assured me that no, in fact, the tar pits were right there, just off Wilshire, and couldn't I detect that telltale whiff of methane in the air? So one of the most well-known U.S. sites for paleontological fossils is located smack in the middle of suburban sprawl, amid condominium complexes, a Rite-Aid, and various fast food joints like Baja Fresh, Koo Koo Roo and IHoP. You can admire the pretty Pleistocene fossils, then pop on over to LA's Disney-esque shopping complex, The Grove, stopping off at Whole Foods for some organic produce on the way home.

You'd think that with the place so close, and me being such a big science geek and all, it would be one of the first places I'd visit. Alas, you'd be wrong. We didn't get around to visiting the La Brea Tar Pits and accompanying Page Museum until last weekend, when fellow physics blogger Chuck (a.k.a., that lounging Lab Lemming from the Land of Oz) blew through town with his family, on their way to visit relatives elsewhere in the U.S.  We had a great time strolling through the exhibits, admiring the rather seedy (by now) animatronic mammoth, and placing bets on whether the ground sloth or the saber-toothed tiger would win their sculpted pitched battle. True, they are frozen in time in the Page Museum, but I maintain that the tiger is on the verge of victory: its enormous canines are in the perfect position to rip out the sloth's jugular.

Technically, that substance oozing out of the ground in Hancock Park isn't really tar (a byproduct of the distillation of coal or peat); it's asphalt, the lowest grade of crude oil. The bubbling is due to methane gas, a byproduct of the decomposing remains of plants and animals trapped in the pits, which turn into crude oil. Which explains the origins of the large petroleum reservoir, the Salt Lake Oil field, located just below the surface, north of Hancock Park. According to the museum's various informative placards, the oil was formed from marine plankton that found themselves summarily deposited in an ocean basin between 5 and 25 million years ago, and eventually time and pressure converted that organic matter into oil. Beginning some 40,000 years ago, petroleum began seeping to the surface around Hancock Park, forming hundreds of sticky pools of ooze. And the La Brea Tar Pits were born.

Anyway, for tens of thousands of years, animals would come sniffing around the pits -- usually predators and scavengers drawn by animals already trapped in the tar, thinking them easy prey -- and would in turn become trapped in the sticky ooze themselves. They would gradually get sucked down into the pit and asphyxiate, and over time their remains became fossilized as the lighter fractions of the petroleum evaporated, leaving the bones trapped in a more solid substance. And there they stayed, awaiting discovery by modern archaeologists thousands of years later.

The centerpiece of the La Brea grounds is a large Lake Pit outside, where methane gas still bubbles to the surface every few minutes or so, making the whole place smell like freshly laid asphalt. To capture the tragedy of senseless animal deaths, traumatizing young children in the process, the Lake Pit also features a diorama of a mammoth vainly struggling to free itself from the  muck, while what can only assume are its mammoth-y family members look on in helpless horror.

One might be forgiven for thinking, "C'mon, how hard can it be to get out of a tar pit?" After all, Arnold Schwarzenegger fell into the tar pits in Last Action Hero and just swam out and wiped himself clean. The museum knows we're thinking this, and has helpfully set up a terrific hands-on demonstration of just how sticky this gooey stuff really is. We struggled mightily to pull metal plungers of different sizes and weights out of a vat of molten asphalt. Point taken. And the pits have their own form of camouflage, since they're covered by a layer of water, or dirt, or dust. It would be very easy to think you were just strolling through a marshy sort of puddle, and suddenly find, too late, that there's sticky asphalt underneath.

The local Native Americans used the sticky asphalt as a glue and to waterproof their baskets and canoes. When Westerners arrived, they mined the tar and used it as a roofing material. From the beginning, bones were occasionally found in the tar, usually dismissed as belonging to unfortunate cattle who'd become trapped in the pits. It was not until 1875 that the geologist William Denton visited the tar pits and identified the canine tooth of a saber-toothed cat. The rest of the scientific community just ignored his conclusion. Timing is everything, and Denton was too far ahead of the curve. The first bona fide scientific excavation of the pits didn't begin until 1901, when William W. Orcutt, a geologist who was investigating oil resources in the vicinity, noted that the bones in the asphalt seeps belonged to many extinct species.  

And so the pillaging of these priceless artifacts began. Between 1905 and 1915, literally millions of bones were taken out of the ground. In 1913, the landowner, George Alan Hancock, feared that the fossils would be taken from the community and scattered widely. So he granted exclusive rights to excavate the fossil resources to Los Angeles County’s fledgling Natural History Museum—but only for two years. Between 1913 and 1915, museum crews made nearly a hundred excavations, collecting roughly a million bones. The work was messy, and not without its perils: excavators used boiling kerosene to clean the sticky bones, which would sometimes accidentally catch fire and singe the eyebrows of workers. But it was worth it. In all, the species count from the excavations in the early 1900s included 133 birds, 63 insects, 43 mammals, and 29 plants, plus a handful of amphibian, mollusk, reptile, and water flea species.

Surprisingly, there's a lot more fossils of carnivores and predators than there are of herbivores -- roughly 9:1, nowhere near the ratio most likely typical of the animal population living in the area back then. Scientists think it's because of the aforementioned hypothesis that predators and scavengers were drawn to the scent of trapped, rotting corpses and became trapped themselves. That's the prevailing hypothesis among scientists, although predictably, those wacky Young Earth Creationists maintain that the tar pits are evidence of a global flood. Noah's Ark totally happened, dude! Just like in Evan Almighty! By their "logic" (note judicious use of scare quotes to indicate sarcasm), the high ratio of carnivore fossils is due to the fact that theyw ere carried there from somewhere else by a huge flow of water. The fact that the tar pits date back some 40,000 years and are therefore older than the supposed Young Earth by a factor of 4, is considered to be a trifling dating error, or some mischievous test of faith by the Deity. Sigh.

Anyway, the animals didn't seem to learn from their mistakes, which could explain why they eventually became extinct: camels, mammoths, mastodons, long-horned bison, and the saber-toothed cat are no longer found in North America, and Chuck informed me (and the museum exhibit confirmed) that the horse, originally native to the area, died out and was introduced to the region by Spanish settlers. The dire wolf, in particular, seems to have been a bit lacking on the brain trust front: skulls and fossilized remains of the dire wolf are among the most common finds in the La Brea tar pits (over 3000 found to date, and still counting), and the Page Museum has an entire wall displaying nothing but hundreds of dire wolf skulls recovered over the years.

There's one species that is not well represented among the fossilized remains recovered from the tar pits: homo sapiens. You'd never know that from how often the tar pits feature in various thrillers and murder mysteries. For instance, in the forgettable 1990 film Bad Influence, the two men try to cover up a murder committed by a third friend -- why? misplaced guy loyalty, I guess -- by tossing the dead woman into the La Brea tar pits, where she is discovered the following day. In fact, there has been only one human being recovered from the pits, known as La Brea Woman; carbon dating revealed she died some 9000 years ago.

Technically, just her skull and a few other bones were recovered, and even so, the femur was stolen in the 1970s while the remains were in transit from their original home at the Natural History Museum to the newly constructed Page Museum. (Jen-Luc Piquant wonders aloud what kind of sick mind would steal a fossilized femur, and then recalls that her pal El Finster brazenly sports a bona fide human skull on his bookshelf. Authorities might want to check his office for any missing fossilized remains.)

Anyway, scientists believe La Brea Woman didn't end up in the tar by accident: there's strong circumstantial evidence that she was murdered, her skull bashed in with a blunt instrument, most likely with an artifact conveniently found a few inches from where her skull was found. This makes her the first documented murder victim in Los Angeles. They killed her little dog, too: canine bones were also found near her remains. Other than that, very little is known about La Brea Woman; the most extensive discussion I could find was this 2006 article in the Los Angeles Times by Amy Wilentz. That's where I learned that the museum used to have an exhibit devoted entirely to La Brea Woman until just a few years ago, when the curator decided to remove it amid concerns of offending local Native Americans. Like many of the exhibits in this woefully under-funded museum, the original exhibit was a bit archaic, featuring mirrors and spotlights to create a "Pepper's Ghost" kind of illusion: people would see her skeleton, then the special effects would kick in to create a mannequin version of how she might have looked in life.

Wilentz's article also informs us that the skeleton on display wasn't actually La Brea Woman; after all, most of her remains weren't found. Instead, they obtained the body of "a modern Pakistani female" of similar age and height, treated the bones so they looked like the dark bronze color that typifies tar pit bones, shortened the femurs, and attached the original skull. And the artistic depiction of how she would have looked in real life? Not so much with the accuracy. Far from being, in Wilentz's words, "a young, attractive sensuous tanned brunette with long, long hair strategically covering her nipples," La Brea Woman was a bit on the homely side, and probably considered middle-aged by 20 (most "elders" from that period were around 30; life was cheap and very, very short in the Pleistocene). She had an ectopic tooth protruding above her lip -- one of her few remaining teeth -- and an impacted molar in her jaw. Yet her remains have inspired subplots in at least two novels: Michael Connelly's City of Bones, and Robert Masello's The Bestiary. Something about La Brea Woman and her all-too-human fate speaks to us across the ages.

One might assume that after nearly a century of digging, the La Brea Tar Pits would be picked clean by now, but such is not the case. The focus has merely shifted from the large skeletons of mammoths, ground sloths, and saber-toothed tigers, to birds, bone fragments, seeds, pollen, insects, fish, rodents, and other objects so tiny, it's hard to believe the scientists were even able to identify them. The focus of the museum's current excavation activities is Pit 91, measuring 28 square feet and descending about 14 feet into the earth. Every summer, the pit is open for business from June to the beginning of October, so visits can stand in a special observation area and watch local paleontologists and a few lucky volunteers sift through the muck armed with dental picks, trowels, small chisels and brushes, in search of fossilized treasure.

And what a treasure trove the pit continues to be! In 2006 alone, the teams collected over 1000 in two months, ranging from three saber-toothed cat skulls, four dire wolf skulls, bones from sloths, horses, bison, coyotes and birds, insects, and a few plant fossils.  (Since excavation of Pit 91 began in 1915, over 250,000 fossils have been recovered.) After the fossils are removed, the surrounding sediment is placed in screen baskets, then boiled in solvent to remove the asphalt, revealing a mix of sand, pebbles, small pieces of fossils, and microfossils like seeds. I feel for whoever has the thankless task for cleaning, sorting identifying and labeling this flotsam and jetsam.

Okay, I'm being prematurely dismissive: those bits and pieces can actually tell us a lot about the area during the Pleistocene, specifically, the habitats and climate (apparently LA was cooler and moister in the Pleistocene). Most recently, scientists have discovered 200-300 previously unknown species of bacteria, extremophiles who flourish in the harsh conditions of the asphalt pits: no water and very little oxygen, but loads of yummy toxic chemicals! They chomp away at the petroleum, breaking it down with special enzymes (e.g., polychlorinated biphenyls, or PCB) and then releasing the telltale methane that bubbles to the surface. (Technically, the bacteria suffer from gas and post-meal bloating, and no wonder, considering their diet.) A team from University of California, Riverside, led by David Crowley, identified the bacteria by sequencing recovered DNA. They froze the tar with liquid nitrogen and pulverized it into a powder, exposing the bacteria, and thus were able to extract the DNA. It's quite possible that this discovery could lead to new methods for cleaning up oil spills and enhancing oil recovery.

The tar pits have had more than their share of 15 minutes of fame in popular culture, usually in wildly speculative contexts, none so much as in 1997's Volcano, in which a volcano sprouts out of the Lake Pit and spews a river of hot lava down Wilshire Boulevard -- no doubt engulfing loads of unsuspecting well-heeled shoppers. (Young Earth Creationists would most likely attribute this to the avenging hand of a wrathful Deity.) But the reality is haunting in its own quiet way, with no need for exaggerated pyrotechnics. Wilentz describes the museum, for all its noble educational intentions, as "an homage to an oil reserve where millions of creatures died," a structure that has been built "above what can only be described as a mass grave." The La Brea tar pits are LA's very own heart of darkness, the epitome of "Nature, red in tooth and claw." After all, asphalt doesn't much care how many species perish in its sticky depths.

search lights in the sky

We are now well into Day 13 of the search for missing millionaire-cum-adventurer Steve Fossett, whose plane disappeared off the radar -- literally -- somewhere over the vast expanse of the Nevada wilderness. A planned three-hour private excursion turned into a immense manhunt to rescue the missing man. Dozens of aircraft have scoured a whopping 20,000 square miles, with a small army of online volunteers poring over satellite imagery, courtesy of Google and Amazon, and yet Fossett and his single-engine plane remain missing. Searchers have found wreckage from seven prior unrecorded crash sites, however -- a testament to just how difficult it can be to locate small planes in that region, a task made even more difficult by (a) an apparent malfunction in the plane's transponder/emergency locater, and (b) Fossett's failure to file a flight plan. (In fairness, it was supposed to be a very short, routine flight, and Fossett is/was a highly experienced pilot who has survived plenty of harrowing crash landings in the past.)

I don't know if the airborne searchers are employing just conventional  aerial and satellite imaging, or whether they're also making use of more innovative techniques, notably Light Detection and Ranging (LIDAR), but I hope they'll at least consider doing so, just to improve the odds that much more. LIDAR is an optical remote sensing technology that exploits the same basic principle as radar and sonar -- sending out pulses that bounce off objects and analyzing the returning signals to determine an object's distance from the source -- except it uses light wave pulses instead of radio waves. (Yes, I know, radio waves are technically just another form of electromagnetic radiation; in this instance, "light" refers to the visible and near-infrared frequencies in the spectrum.) It's not so much a replacement technology, as a complementary one -- just one more tool in our growing arsenal for remote sensing and mapping, and for finding things like Fossett's downed plane.

A LIDAR instrument transmits pulses of light to a target, and the parts of the spectra that are not absorbed by the target are reflected back (known as backscatter) to the system, which then are detected, stored and analyzed. It's the changes in the properties of the light when it scatters back that enable scientists to measure specific properties of the target.  Bats use ultrasonic pulses to hunt for their prey, emitting a series of pulses that become more frequent the closer it gets to its target, climaxing in a kind of "feeding buzz" as it locks in for the kill. Similarly, the more frequent the light pulses emitted in a LIDAR system, the more information is gathered, and the more accurately a target area can be mapped. For airborne topographical mapping, as many as 33,000 laser pulses can be transmitted every second.

LIDAR has been around for quite a long time, having been invented shortly after the first lasers appeared in 1958. But the technology was a bit ahead of its time, and languished for several decades until a whole bunch of other enabling technologies emerged. Early lasers were too expensive, frankly, and too heavy, too big, and required too much power, to make them practical for airborne applications. When the solid-state diode pumped laser emerged, that changed: they were cheap, rugged, and compact, with comparably low power requirements. Computing technology also needed to advance to the point where it was fast enough, and cheap enough, to perform the kind of advanced data analysis required by a LIDAR system.

Most notably, early LIDAR systems could make accurate measurements in the centimeter range, but only for lasers fixed on the ground. This strictly limited its useful deployment, since once anyone placed a laser on a moving platform, all bets were off. Then came the Global Positioning System (GPS), and suddenly it became perfectly feasible to figure out exactly where a moving object might be in relation to a ground-based coordinate system. And LIDAR was finally dusted off and brought into the marketplace.

For remote sensing applications, the LIDAR system is mounted onto an aircraft equipped with a GPS receiver (de rigeur these days in just about any vehicle) to track its exact location and altitude. It also needs a high-accuracy inertial measurement unit (IMU) to track the pitch and roll of the airplane so that movement can be accounted for in the final analysis.  Basic physics tells us that objects spinning at a very high rate tend to maintain their relative position in space, so an IMU incorporates several spinning gyroscopes. By measuring the angle of tilt as each spins a spherical mass within a gimbal (or cage), and coupling that with an accelerometer to keep track of shifts in velocity, the system can tell us how far, how fast and in what direction a target is moving relative to a given starting point. Usually, all the data collected from the various instruments, when combined, can give an elevation that is accurate to within 6 inches.

Generally speaking, we can usually only image a feature or object roughly the same size as the wavelength of the EM radiation being used, or larger. Radio waves used in typical radar systems are great at detecting things like metallic objects -- which is why they're so useful for military and aviation applications -- but rocks or raindrops might not produce much in the way of detectable reflections at all, making them well nigh invisible to radar. But because the wavelengths used are much shorter than radio waves, LIDAR systems are much better at detecting very small objects, like particles in the atmosphere. In fact, they are already used to study atmospheric conditions, notably the densities of various particles, not to mention all kinds of emerging applications in geology, seismology, and even archeology. Also, lasers use a very narrow beam, so LIDAR allows for mapping of physical features with much higher resolution than conventional radar. It can have a "footprint" of less than 1 meter, making it possible to map the floor underneath a forest canopy, or the urban canyons between tall buildings.

There's more than one kind of LIDAR system, each suited to a specific kind of application. If you just want to measure the distance from your instrument to a solid target, range-finder LIDAR should suit your purposes just fine. If it's a moving target, and you want to figure out how fast it's moving, you'll probably want to use Doppler LIDAR, which -- as its name clearly implies -- relies on the Doppler shift effect  to determine an object's velocity. If you're a meteorologist interested in measuring the specific concentrations of chemicals and such in the atmosphere -- ozone, water vapor, and pollutants -- or if you want to map a shallow river bed underwater, you're better off using differential absorption LIDAR. Underwater imaging in particular can be difficult using infrared  and near-infrared preferred for terrestrial mapping, since water absorbs those wavelengths; only the blue-green end of the visible spectrum can penetrate water, for the most part.

Small wonder so many applications have emerged in the past decade for LIDAR systems. In geology and seismology, they're used to detect faults -- most famously, to locate the fault in Seattle, Washington -- and to measure "uplift"  at Mount St. Helen's in Oregon. (I assume this refers to plumes of ashes that the mountain occasionally burps out from time to time, which is an indication of whether its internal distress is reaching a critical eruption point.) Airborne LIDAR is used to monitor glacial melting and other coastal changes, while in forestry, LIDAR is used to study canopy heights and measure biomass, not to mention making the surveying process that much faster. On a more mundane scale, there are now handheld LIDAR systems for traffic enforcement. Whereas radar relies on Doppler shifts to directly measure speed, LIDAR actually calculates the speed, making it easier to isolate particular vehicles from a heavy stream of traffic. Remember that next time you're tempted to weave in and out of lanes at high speeds.

LIDAR has been used for search and rescue before, most notably in the wake of the terrorist attacks of September 11, 2001. For several days after the World Trade Center fell, a small plane made several passes over Ground Zero in Manhattan (and also over the damaged Pentagon in Washington, DC) taking LIDAR readings of the debris -- courtesy of a company called EarthData, which used the collected data to produce topographical images of the sites. This in turn helped rescue workers navigate the often-treacherous terrain by identifying unstable areas likely to shift or collapse. The maps also enabled building and utility workers to locate foundation-support structures, elevator shafts, basement storage areas, and so forth. As workers moved deeper into the WTC's basement wreckage, LIDAR mapping showed where the integrity of the underground walls might have been compromised, thus making those areas more at risk of flooding. The maps were even able to measure the volume of the debris and how much reach the cranes would need to efficiently remove it.   

In the realm of atmospheric studies, LIDAR systems could bring some relief to frequent fliers who have spent way too many wasted hours in airports with chronic delays (*cough* O'Hare *cough*) because our flights were grounded. Scientists at RL Associates in Pennsylvania presented a paper at the recent meeting of the Optical Society of America on their new near-infrared LIDAR system, now in its prototype phase and slated for testing in about 18 months. According to Mary Ludwig, one of the leading scientists on the project, the system will provide better images in foggy, rainy, or extremely hazy conditions, thereby making it a whole lot easier for pilots to take off an land in those conditions, as well as giving more advance warning of potentially hazardous atmospheric conditions, such as icing. This in turn could help reduce weather-related flight delays .

There are other experimental LIDAR systems for similar purposes, using visible green light to detect different kinds of particles in the atmosphere, but most commercial planes aren't equipped with such systems. Ludwig's team has developed a system that uses a polarized laser light beam, i.e., its electric field points in a specific direction. The system beams this polarized infrared light outwards, and then records the amount of polarization that returns to the sensors. The data is then processed to form an image of the ground. If need it be, it can also be translated into verbal commands. This is especially useful for atmospheric applications because ice crystals, for example, are highly depolarizing, while mere water droplets are not. Hard, manmade objects will depolarize the returning signal less than natural objects, so it's possible to get enhanced images of targets in a obscured or camouflaged environment -- say a small, crashed aircraft hidden in dense underbrush. Ergo, Ludwig et al.'s system is better at detecting different types of atmospheric particles, such as ice, supercooled liquid, or water vapor, plus it can also tell the different between water vapor and other substances (metal, or the human body, for example).

The system also incorporates something called a "range-gated detector" that is only turned on for very short periods of time, rather than continuously -- namely, whenever the return signal is expected. The detector is turned off when the laser pulse is first emitted from the system, so it doesn't pick up all the near-field backscatter from things that might be in the pulse's path to the target -- usually the major source of noise for such a system. This means there's a lot less noise in the resulting data so you get better images, particularly in foggy or hazy conditions. All of which spells welcome news for frequent airline travelers.

Perhaps the niftiest new application of LIDAR is in archeology. In England, Cambridge University is collaborating with the UK Environment Agency in the use of LIDAR imaging to produce terrain maps for large swathes of the countryside. It started out as a way of assessing flood risks, but then an organization called English Heritage contracted with the EA to conduct a LIDAR survey of Stonehenge -- one of the most studied landscapes in all of Europe, and a certified World Heritage Site. See the nifty LIDAR image of Stonehenge below, courtesy of English Heritage? How cool is that? It turns out that LIDAR is terrific for recording terrestrial features that have been leveled by many years of ploughing: the WHS survey revealed several previously unrecorded banks in and around the Stonehenge site.

LIDAR mapping isn't just about mapping positions and elevations anymore (although that's definitely the primary focus); newer systems seek to integrate other aspects of feature recognition to make map production ever more automated. A few years ago, scientists from Sweden and Italy teamed up to use LIDAR to image the various types of stone used in the construction of Lund Cathedral. Located in Sweden, the cathedral is an impressive 12-century edifice that ranks as the largest Romanesque building in northern Europe. (Whether you're impressed probably depends on your fondness for the Romanesque period.) Not only could they "see" the differences between the stone used, but they could also tell, from a distance, which of the walls had moss and lichen growing on them.

As intensity recording is incorporated into LIDAR systems, scientists should be able to improve even further on this type of analysis. Intensity recording not only measures the distance between the LIDAR and the target, but it can determine the features of a landscape based on the strength of returning signals. That's because every reflective surface will absorb some wavelengths and reflect others. A concrete block, for instance, reflects almost every wavelength and absorbs very little, so the returning signal is very strong. Leafy vegetation, however, absorbs quite a bit more of the light, and hence returns a weaker signal. These data can also be turned into a visual image.

So light and lasers are an increasingly important tool in archaeological mapping. And the innovations just keep coming. An article a couple of months ago in the San Francisco Chronicle profiled a retired civil engineer named Ben Kacyra, who invented "a camera-like device that uses lasers to scan three-dimensional objects -- such as archaeological ruins -- to create digital blueprints accurate to within a few millimeters." (You can see many such images taken with the instrument here.) At the heart of his device is a laser that emits light with sufficient power to bounce off a distant object and return to a sensor, capable of timing the intervals between signal and response. In this way, "the laser maps the surface of objects by taking millions of measurements at different angles." Sounds like a LIDAR system to me.

Kacyra's system -- which he sold to Swiss company Leica Geosystems in 2001 -- has been used to study pre-Incan Peruvian ruins, the buried Roman city of Pompeii, and the cliff dwellings of the extinct Anasazi people in southwest Colorado. And once these digital blueprints are created and stored, it becomes so much easier to recreate portions of those sites and edifices in a virtual framework -- perhaps, one day, in Second Life. Kacyra has already created a small reproduction of an ancient frieze that he scanned, using his mapping tool. As the Chronicle article put it, "Think of the archaeological equivalent of a reprint of a famous painting, a chance to hold a piece of history." Indeed. There lies the future of LIDAR.

mummy sings the blues

Jen-Luc Piquant has been on a bit of a mummy craze this past week, ferreting out such online gems as a downloadable Mummy Maze Game; an archived Cyber Mummy; and National Geographic's highly informative How To Make A Mummy. She was inspired after catching a cable rerun of the 1999 blockbuster, The Mummy, which contains a scene where Evelyn (Rachel Weiz) explains to Brendon Fraser's Rick O'Connell exactly how Egyptian mummies are created: something about shoving hot pointy hooks up your nostrils and scrambling your brains around a bit before yanking them out through your nasal passage. Not to mention removing all the vital organs and storing them in decorative canopic jars. Evelyn's assurance that one would be dead when they performed these acts does little to assuage the otherwise alpha-male Rick's distaste for mummification -- a distaste no doubt shared by arch-villain Imhotep's priests, who were all mummified alive as punishment for abetting their master's treachery.

It's a pretty accurate description of the process, actually -- perhaps a bit surprising considering the substantial liberties the film (and its sequel) otherwise took with Egyptian history. Sometimes truth is stranger than fiction. The brain was indeed scrambled with hooks to liquefy the gray matter, then yanked out through the nostrils; the Egyptians didn't consider the brain to be an important asset for the afterlife (!), unlike the rest of the vital organs, which were carefully removed and stored in the aforementioned jars. The head was stuffed with sawdust and various resins, and the body was "embalmed"  by covering the corpse in natron, an inorganic salt common to the region. This dried out the body and prevented decomposition. The corpse was then wrapped in strips of white linen, then in a sheet of canvas before being buried in an entombed coffin, surrounded by various sacred charms and amulets.

There are certain rare cases of natural mummification, too, when the environmental conditions are just right -- extreme cold, for instance. Otzi the Iceman was found frozen in a glacier in the Otztal Alps in 1991, dating back to 3300 BC. Desiccating dryness helped preserve a group of Incan mummies found in Peru. Perhaps the most astonishing example of natural mummification, though, is the so-called Bog People; these "bog bodies" have been found in the UK, Ireland, Germany, the Netherlands, Sweden and Denmark. They are the remains of bodies deposited in sphagnum (peat) bogs, in which the acidity of the water, cold temperature, and lack of oxygen served to essentially tan the body's skin and soft tissue. The skeletons may have disintegrated over the centuries, but the skin and internal organs are so well-preserved, researchers have been able to determine their stomach contents. The details thus preserved can be astonishing. One can see fine facial features, even some stubble, in Tollund Man (shown), who was found with the rope apparently used to hang him. Most of the Bog People appear to have died violently, but it's unclear whether they were part of a ritual sacrifice, or executed for unknown crimes.

Jen-Luc is in good company when it comes to a fascination with mummies. We loves our thousand-year-old dessicated corpses, whether as a reminder of our own mortality, or as hope that some part of us will remain after death, who can say? In the 19th century, mummy heads were sold as souvenirs and proudly displayed in the home. Aristocrats liked to entertain guests by unwrapping purchased mummies for informal observation sessions (causing them to rapidly disintegrate because of the sudden exposure to air).

The corpses were ground up into powder and sold as medicines to stop bleeding, and the wrappings were sometimes used to steep tea. (I'll say it for you: Ewww!) That rascally scamp Mark Twain is credited with spreading an urban myth that mummies were being used as fuel for locomotives. And in the 1830s, a man named Jeremy Bentham died and left a will instructing that his remains (minus his skull) be mummified and displayed, fully dressed in his usual clothing, "seated in a Chair usually occupied by me... when engaged in thought." (How he could be engaged in thought without his skull isn't addressed, but heck, apparently we don't need our brains in the afterlife.)

Even though mummies have been around awhile, there's still a lot to learn about them. In 2001, a couple of organic chemists at the University of Bristol in England --Richard Evershed and Stephen Buckley -- took a closer look at the techniques and materials the Egyptians used in their mummification processes, using a combination of gas chromatography and mass spectrometry. The advantage of their approach is they could work with minuscule samples, minimizing damage to the mummies. They studied 13 mummies ranging across a 2300-year period, from around 1985 BC to AC 395. There's a great online article from National Geographic about their work, but here's the gist:

Sure, you can gut a corpse and douse it with salt until it's dessicated to the nth degree, but that in itself won't 100% ensure proper preservation. The tomb might be humid (yeah, it's in the desert, but still...), causing the body to rehydrate, and let's face it, that kind of moist environment is a veritable playground for decay-inducing microbes. Evershed and Buckley maintain that the Egyptians were extremely knowledgeable about the innate anti-microbial properties of the materials they used in their embalming recipes. In addition to the gutting and stuffing of sawdust and natron into various body cavities, the linen wrappings used to encase the corpse were treated with resins from fir and pine trees, beeswax, myrrh, palm wine, cassia, camphor oil, and other naturally microbe-resistant ingredients. They also might have helped cover up the noxious odors associated with decaying flesh (there's a reason the embalming tents were located far from the city centers).

Today, mummies are sometimes used to calibrate CAT scan machines at radiation levels too high to be safely endured by a living human. It's fitting, since X-rays and CAT scans are the primary means of imaging mummies for further study. (Brief reminder for non-scientists: a CAT scan is just like a standard x-ray, except it uses an x-ray generating device that moves around the entire body to generate cross-sectioned images that are fed into a computer to produce a full 3D image.)

CAT scan images reveal far more detail of things like internal organs than conventional x-ray machines: a CT scan found an arrowhead in the frigid body of poor Otzi the Iceman that archaeologists believe was the cause of death. Famed Egyptian Pharaoh Ramses I had his 3D image taken with a CAT scan. And just this past March, the Carnegie Museum of Natural History collaborated with the University of Pittsburgh Medical Center to scan the mummy of a small child (currently on display at the museum). Child mummies are rare, and this one is smaller than normal, with an oversized head and a slight curvature of the spine. The researchers hope to determine what disorder the child may have suffered from in life to cause those features.

In the case of Tutankhamen -- affectionately known as King Tut, a boy-king who ascended the throne at the ripe old age of 8 -- a series of CT scans taken in 2005 told researchers quite a bit about this relatively minor Egyptian Pharaoh, who died around age 19. The 15-minute scan produced a whopping 1700 images. He was pretty healthy for the most part, although he had a slightly cleft palate and an impacted wisdom tooth. (No word on what Egyptian dentistry prescribed for such things.)

The biggest headlines, of course, had to do with how Tut died. Earlier x-rays seemed to indicate the presence of bone fragments, suggestive of a blow to the head, leading to speculation that Tut had been murdered (a common fate of many Pharaohs). There also was a dense spot at the lower back of the skull, which researchers interpreted as evidence of a subdural hematoma, also consistent with a blow to the head. The 2005 CT scans put the speculation to rest, finding no evidence of foul play. Rather, it seems King Tut died of a broken leg that turned gangrenous, killing the Boy-King within days, possibly even hours. The current prevailing theory is that he fell from his horse -- not nearly as scandalous as being murdered by your trusted priest, who's been having it off with your mistress.

Even more important (to some) than determining Tut's cause of death was solving the Mystery of the Missing Male Member. The team swore they also managed to locate the boy-king's missing penis -- assiduously cataloged in the 1920s along with the rest of his parts, but not seen since. They believe it's mixed in with the sand next to the body, along with lots of other tiny skeletal fragments. (Like thumbs. One hopes, for Tut's sake, that the Royal Equipage would not easily be mistaken for a thumb. Dead at 19 from a broken leg, and under-endowed besides, seems an especially tough cross to bear.)

The 2005 scans marked the first time Tut and been out of his tomb since it was first excavated 82 years ago by an archaeological team led by Howard Carter. I'm old enough (ahem) to remember the big national tour of Tut and his treasures. Along with about 8 million other people, I have some vague memory of viewing the exhibit, highlighted by the famed gold and blue mask, which was apparently pried off the mummy's face with very hot, sharp knives, causing a great deal of damage.

In fact, because the resins used in the mummification process affixed the wrapped corpse to his coffin, Carter's team pretty much dismembered the body to get it out. Really. They chopped off the arms and legs, removed the head, and cut the torso in half, all to recover the gold objects and precious jewels buried with the corpse. Grave robbers or serious scholars? Sometimes it's hard to tell the difference. Also in 2005, three separate teams of scientists (Egyptian, French and American) teamed up to reconstruct a facial likeness for King Tut, working from those sale 1700 3D CT scan images of the Pharaoh's skull. The resulting silicone bust was featured on the cover of Time, but even that proved controversial: some complained about the choice of a medium skin tone. The researchers claimed that because of the wide range of skin tones among the North African population, we may never know for sure Tut's exact skin tone. Or his eye color. They went with their best approximation.

All in all, poor Tut has good reason to be depressed about his afterlife, which might be why the illustrious Chicago songwriter, Michael Smith (not to be confused with the Christian pop musician of the same moniker), penned a catchy little tune dedicated to the Boy-King, "Dead Egyptian Blues" (excerpted below). You should all go out and buy this man's CDs for a taste of American songwriting at its best. I mean, who else could find such a fitting rhyme for "esophagus"?

Oh Mister Tut what good's it do
They love your chair but nobody cares for you
Egyptian nights were never colder
And all your friends are thousands of years older
Whatever happened to that gang down by the Sphinx
Seems they're only forty winks away
Those girls from Cairo with their belly button jewels
Made you play the fool yesterday yesterday
Now you keep in shape with Elmer's glue
Man you're all wrapped up in them dead Egyptian blues

Oh Mister Tut they love the mask
But do they love you honey sweetheart don't ask
Where's those baby browns and that pearly smile
That smile that drove 'em wild by the early Nile
You make one terrific hieroglyphic don't you bro'
Centuries of standing sideways turned you to a pro
Those girls from Cairo who filled your heart with lust
They've all turned to dust yesterday yesterday
And those bandages don't do that much for you
Man you're all wrapped up in them dead Egyptian blues

Oh Mister Tut they dig the tomb
All that gold leaf brightens up a room
But what's the diff when you're stiff what riff they're playing
When your ears have spent five thousand years decaying
What does it matter what possessions you may boast
When you're just a ghost it's only jive clive
Your sarcophagus is glowing but your esophagus is showing
Who cares how rich you are love
When you look like Boris Karloff
And they even named this dog food after you
Man you're all wrapped up in them dead Egyptian blues.