Over the past year, a steady trickle of books, articles, and film proposals has crossed my desk about world-changing events that the ancient Maya are said to have predicted for the date of December 21st, 2012. The latest is a press release for a book claiming that physicists searching for the Higgs boson (the so-called "God Particle") at the giant particle accelerator at CERN, near Geneva, are at risk of triggering "seismic events that could release cataclysms prophesied by the Mayan Calendar 2,000 years ago." Other popular theories involve giant solar flares wreaking havoc on satellite communications, or a "galactic alignment" of the plane of the Milky Way that could bring spiritual enlightenment rather than doomsday. In anticipation of either dire or uplifting events, tourists are flocking to Maya sites in Guatemala, Mexico, and Belize in record numbers.

If you're inclined to suspect that Y12 might be as big a fizzle as Y2K, you may still enjoy a sober look at the evidence for what the ancient Maya actually believed about the cosmos and the calendar. There's no better introduction to that subject than "The End of Time: The Maya Mystery of 2012," a popular book by Anthony Aveni, a pioneering investigator of Maya astronomy. Shot through with characteristic humor and a gift for sharp explanation, Aveni's book presents a clear picture of Maya creation myths and the motivations of their skywatchers. He outlines how the Maya followed three separate calendar cycles that mesh together like gears in a bicycle wheel; the biggest "gear," or cycle, was the "Long Count," which tracked the number of days that had elapsed since a creation date in 3114 BC, far back in their mythological past. If you project the Long Count forward in time, then a sub-cycle known as the baktun, equivalent to roughly 395 solar years, is due to turn over and reset itself, like the numbers in an odometer, on December 21st.

Easter procession
An Easter procession in the highland town of Nebaj, Guatemala. Today's Maya observe ceremonies that are a blend of Christian and pre-Hispanic influences.

So what did the Maya believe about this cycling of their calendar? Since the late 1970s, scholars have made astonishing progress in deciphering Maya writing--the intricate hieroglyphs that they painted on vases or carved into stone monuments between AD 250-900. We now know that many of the inscriptions relate the ancestry of their rulers back to the start of the Long Count or other auspicious events in the deep past. Others concern the political present and give details of accessions, alliances, military conquests, and the overthrow of rival rulers. To see a vivid slice of this evidence, Mark van Stone's "2012: Science and Prophecy of the Ancient Maya" presents a highly accessible pictorial guide to Maya art and hieroglyphs and how they relate to the 2012 question.

The bottom line is that amid all the rich hieroglyphic records kept by Maya scribes, there's total silence about what they actually thought about the future turnover of the baktun. Only two inscriptions even mention the turn of the 13th baktun, which corresponds to December 21st, 2012 in our calendar. One of them was discovered this summer at the Maya site of La Corona in Guatemala by David Stuart, a leading scholar of Maya writing, who says he was stunned when he spotted a text mentioning the 2012 turn of the cycle. Like so many other inscriptions, Stuart says, its context is the politics and history of the 7th century AD, specifically the divine status of one of La Corona's rulers. "The point was to associate the divine king's time on the throne to time on a cosmic scale," he says. To understand more about how the Maya recorded and justified the affairs of their rulers, see Stuart's popular book titled "The Order of Days: Unlocking the Secrets of the Ancient Maya." In his final chapter, Stuart concludes, "No Maya text, ancient, colonial, or modern, ever predicted the end of time or the end of the world."

Today, in the highland villages of Guatemala, traditional Maya calendar cycles are still observed by "Daykeepers," or shamans, although the cycles are no longer geared to the fortunes of powerful kings and queens. The most important of these cycles is a ritual calendar of 260 days, perhaps related to the length of human pregnancy, known as the tzolk'in. The same cycle was widely observed by the Maya 1,000 years ago. One of the Daykeepers' major preoccupations is to perform ceremonies correctly so that the tzolk'in keeps running smoothly, thus ensuring the fertility and health of the community. Allen J. Christenson, an anthropologist who has worked for decades in Guatemala, says that rural Maya villagers had little or no awareness of any kind of apocalypse in December 2012 until they heard about it from outside media sources. But they do believe the world is going to die. As Christenson explained recently in Archaeology magazine, the Maya believe that the world dies each day when the sun sets or crops are harvested. "The world is constantly dying," he says, "and the role of the Daykeeper is to make sure they get things going again." In this perspective, the idea of a single cataclysmic "doomsday" is simply a projection of our own culture.

Lake Atitlan
Lake Atitlan in Guatemala is the focus of traditional creation myths among the Maya. In the lakeside community of Santiago Atitlán, anthropologist Allen J. Christenson apprenticed himself to a Daykeeper to gain insights into Maya beliefs and ritual practices.

While no serious evidence supports the idea that either the ancient Maya or traditional shamans believed in a world-shattering event, the modern mythology of a 2012 apocalypse has taken on a life of its own. Across Latin America, many of today's roughly seven million Maya people are planning events and festivals to celebrate their identity around the upcoming date. Throughout Latin America, the 21st will be an occasion to celebrate the rich heritage of Maya civilization, which science has played a vital part in recovering.

For further reading, see:

Anthony F. Aveni, 2009. "The End of Time: The Maya Mystery of 2012." University of Colorado Press.

Mark Van Stone, 2010. "2012: Science and Prophecy of the Ancient Maya." Tlacaelel Press.

David Stuart, 2011. "The Order of Days: Unlocking the Secrets of the Ancient Maya." Harmony.

Zach Zorich, 2012. "The Maya Sense of Time," in Archaeology magazine, Volume 65 Number 6, November/December.

David Stuart talks briefly about the 2012 apocalypse in a recent episode of WAMC Northeast Public Radio's "The Academic Minute."

The world watched in astonishment last week as NASA delivered its one-ton Curiosity rover to the surface of Mars with astonishing precision, hitting a target area just 12 x 4 miles wide after eight months and 352 million miles in space. While this epic engineering feat was unfolding, I was working on an upcoming NOVA show about another phenomenal achievement involving the precise tracking of objects in space--this one dating back more than 2,000 years. Unlikely as it might seem, a common thread of human ingenuity connects both endeavors.

The Antikythera Mechanism is an intricate ancient Greek astronomical calculating device that has only recently yielded up its secrets. In 1901 AD, a group of sponge divers accidentally discovered it while exploring an ancient shipwreck off the tiny Greek island of Antikythera. All that was left of the Mechanism was an inconspicuous lump of heavily corroded bronze that broke into fragments after it was taken to the National Archaeological Museum in Athens. Traces of carefully cut gearwheels were noted on these fragments, which eventually led to speculation that it was some kind of calculating device. But "decoding" the device has only been possible in the last decade, thanks to state-of-the-art x-ray imaging and digitally enhanced surface photography. In a program scheduled for air on November 21, NOVA presents the unique inside story of how an Anglo-Greek scientific team succeeded in piecing together the exact design and function of all but one of the Mechanism's 30 known bronze gearwheels. Their story is a tour-de-force of scientific detective work.

antikythera.jpg The main fragment of the 2,000 year-old Antikythera Mechanism on display in the National Archaeological Museum, Athens, showing traces of one of the gearwheels.

As reconstructed by the team, the Mechanism was a kind of miniature planetarium, using dials and pointers to show the positions in the sky of the sun, moon, and five major planets. But it was also a computer that predicted the future. By turning a hand crank, the user could read off the date, hour, and even the color of future lunar eclipses, which the Greeks regarded as divine omens. The Athenian navy suffered a calamitous defeat at Syracuse 413 BC when their general interpreted a lunar eclipse as a warning not to put to sea, leading them to be trapped in the harbor by the enemy fleet.

One of the first clues that the Mechanism had something to do with eclipses was when British mathematician Tony Freeth, one of the scientific team, reconstructed a large bronze gearwheel with 223 teeth. That number corresponds to a famous ancient astronomical cycle called the Saros, first recognized by Babylonian sky watchers centuries before the Greeks, and based on a pattern of lunar eclipses that repeats every 223 lunar months. If the eclipse connection seemed obvious, other aspects were baffling, such as an enigmatic pin-and-slot mechanism visible on one of four small gears attached to the big one.

After months of struggling with the problem, Freeth finally realized with a shock that the pin-and-slot mechanism exactly models the ancient Greek theory of the moon's motion, including extremely subtle variations in the moon's position in the sky. By the second century BC, ancient Greek astronomers had calculated these tiny variations with great accuracy, and now Freeth discovered that the Mechanism's engineer had managed to translate them into a complex geared mechanism of equal precision.

The implications are remarkable: the Antikythera Mechanism emerges as the world's first known computer, able to predict eclipses accurately for decades to come. It demonstrates its makers' passion for state-of-the-art astronomical theory and extreme mechanical ingenuity.

Of course, the ancient Greeks didn't get everything right. Since each tooth of the bronze gearwheels had to be cut by hand, the Mechanism's accuracy was limited, while the pattern of eclipses would eventually get out of synch with the Saros cycle. In addition, the Greeks understood the tiny variations they observed in moon's position differently than a modern astronomer. Today, we know these irregularities are due to the moon's complex elliptical orbit around the Earth, while the Greeks explained them with the help of combined circular motions, or "epicycles." It seems likely that the maker of the Mechanism visualized the sun, moon, and planets as revolving on concentric spheres around the fixed Earth.

Yet if that vision of the cosmos was limited, the Antikythera Mechanism is eloquent testimony to qualities the ancient craftsman shared with today's NASA engineers: a drive to impose order on the universe through exact mathematical prediction, reflected in elegant, highly precise, miniaturized design.

Too often, television shows mystify the achievements of ancient technologists by attributing the building of monuments like Stonehenge or the pyramids to lost civilizations or aliens. This denies ancient people their ingenuity and the thread of connection that links our minds to theirs, despite the gulf of thousands of years that separates us.

For more about the Antikythera Mechanism, see:

Edmunds, Mike G., and Freeth, T. 2011. "Using Computation to Decode the First Known Computer," IEEE Computer, July 2011, p. 32.

Freeth, Tony, 2009. "Decoding an Ancient Computer" in Scientific American, December 2009, p. 76.

Marchant, Jo, 2009. Decoding the Heavens, Da Capo Press.

"Ancient Computer" airs on PBS Wednesday, November 21 at 9PM/8C.

Worried about warming but confused about carbon? Try University of Chicago geophysicist David Archer's The Long Thaw, which tells you nearly everything you need to know with down-to-earth clarity and brevity. Archer is known for his studies of "the long tail" - the lifetime of CO2 released by human activities - which he and his colleagues have shown will continue to heat up the planet for thousands of years to come. He calls it "a climate storm" with an impact that will "last longer than Stonehenge." Yet reading The Long Thaw is sobering and enlightening rather than depressing. It's packed with informative, accessible background on past climate cycles and why they are relevant to assessing today's warming. Ultimately, Archer argues, the fate of our climate depends on what we do with earth's vast coal reserves. If we burn all that coal, it has the potential to take us to a hothouse world last seen not long after the demise of the dinosaurs. Yet Archer doesn't preach or waste much space on climate skeptics. His clear-eyed epilog settles quietly on the issue of ethics. Solutions to warming will only work if the nations that have benefited most from fossil fuels take on most of the burden of fixing the problem. The Long Thaw is published by Princeton University Press (2009, $22.95).