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Ancient Maya road ‘frozen’ by volcano (Wonderful! Read the whole story!)

An ancient Maya white road known as a sacbe has been discovered buried under roughly 17 feet of volcanic ash at the archaeological village of Ceren in El Salvador by a University of Colorado Boulder team. The sacbe, shown here with a drainage canal on the left and several corn plants preserved by ash on the right, is roughly 1,400 years old and is the only one ever discovered constructed without stone linings. (Credit: Payson Sheets, University of Colorado)

U. COLORADO-BOULDER (US) — A team excavating a Maya village in El Salvador buried by a volcanic eruption 1,400 years ago has unexpectedly hit an ancient white road that appears to lead to and from the town frozen in time by a blanket of ash.

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The road, known as a “sacbe,” is roughly 6 feet across and is made from white volcanic ash from a previous eruption that was packed down and shored up along its edges by residents living there in roughly A.D. 600, says Payson Sheets, an anthropology professor at the University of Colorado-Boulder who discovered the buried village known as Ceren near the city of San Salvador in 1978.

In Yucatan Maya, the word “sacbe” (SOCK’-bay) literally means “white way” or “white road” and is used to describe elevated ancient roads typically lined with stone and paved with white lime plaster and that sometimes connected temples, plazas and towns.

The sacbe at the buried village of Ceren—which had canals of water running on each side—is the first ever discovered at a Maya archaeology site that was built without bordering paving stones, says Sheets. The road was serendipitously discovered by the team while digging a test pit through 17 feet of volcanic ash in July to analyze agricultural activity on the edges of Ceren, considered the best preserved Maya village in Central America.

“Until our discovery, these roads were only known from the Yucatan area in Mexico and all were built with stone linings, which generally preserved well,” says Sheets. “It took the unusual preservation at Ceren to tell us the Maya also made them without stone. I’d like to say we saw some anomaly in the ground-penetrating radar data that guided us to the Ceren sacbe, but that was not the case. This was a complete surprise.”

Eruption hit during celebration

The sacbe was struck almost dead-on by the excavators of the 3-meter by 3-meter test pit, says Sheets, with the full width of road visible. In order to follow the sacbe, two subsequent test pits were excavated to the north and confirmed the sacbe had a minimum length of at least 148 feet long—about half the length of a football field.

The sacbe appears to be headed toward two Ceren ceremonial structures less than 100 feet away—buildings that were unearthed in Ceren by Sheets and his team in 1991. One structure is believed to have been used by a female shaman. The adjacent community ceremonial structure contained evidence—including the bones of butchered deer, a deer headdress painted red and blue, and a large alligator-shaped pot—that large quantities of food and drink were being prepared and dispensed to villagers in the town plaza during what Sheets believes was a crop-harvesting ceremony.

“We know there was a celebration going on when the eruption hit,” says Sheets. “And we’ve found no evidence of anyone going back to their houses, gathering up valuables, and fleeing, because all the household doors were tied shut. We think people may have left the plaza and run south, possibly on the sacbe, because the danger was to the north.”

Radiocarbon dates from Ceren indicate the eruption occurred in roughly A.D. 630, and Sheets and colleagues have even pinpointed the month and time of day the fiery mass of ash and debris from the Loma Caldera volcano rained down on the town from less than a third of a mile away.

Sheets believes the eruption hit at roughly 7 p.m. on an August evening because of the mature corn stalks preserved in ash casts, the fact that the farming implements had been brought inside, the sleeping mats had not yet been rolled out, meals had been served but the dishes were not yet washed, and corn was set into pots to soak in water overnight.

Emergency route

Sheets says it is logical that the villagers in the plaza might have used the white sacbe as an emergency route to flee the destruction of the volcano in the dark of night.

“How far they might have gotten, I don’t know,” says Sheets. “It would have been a footrace. I think it is very likely we will find bodies as we follow the sacbe southward in future excavations.” To date, no human remains have been found at the village.

Sacbeob, the plural of sacbe, had strong practical, political, and spiritual connotations in the Pre-Columbian Yucatan, said Sheets. Some were fairly long—up to 40 miles—while others stretched less than 50 feet. Because of the high level of preservation at Ceren, the researchers can see hand marks of farmers who were repairing the edges of the sacbe.

While there is speculation the Ceren sacbe may have led to the Maya center of San Andres roughly three miles to the south, there is no evidence of that yet, Sheets says.

Comparisons to Pompeii

While some refer to Ceren as “The New World Pompeii,” Sheets is quick to point out the differences. Pompeii was an affluent Roman resort community with multi-story concrete houses, stone streets and marble statues, while Ceren was a modest farming community.

Because tiny particles of hot, moist ash blanketed Ceren and packed the thatch-roofed structures, gardens, and agricultural fields, the preservation of organic materials is greater than at Pompeii, where dry, pea-sized particles rained down in the Mount Vesuvius eruption of A.D. 79.

Sheets has visited Pompeii, and researchers from Pompeii have visited Ceren, analyzing the similarities and differences at the sites. “When they tell me they wish they had this kind of preservation level at Pompeii, I tell them I wouldn’t mind finding a marble statue or two at Ceren,” says Sheets.

The Ceren preservation is so great that researchers have found marks of finger swipes in ceramic bowls, human footprints in gardens hosting ash casts of plants like corn and manioc, thatched roofs, woven baskets and pots filled with beans. Researchers have found the remains of mice that lived in the thatched roofs of kitchen areas, and entomologists have even been able to discern that two species of ants inhabited the village, Sheets adds.

Thus far 12 buildings at Ceren—which are believed to have been home to about 200 people—have been excavated, including living quarters, storehouses, workshops, kitchens, religious buildings and a community sauna. There are dozens of unexcavated structures and there may even be another undiscovered settlement or two under the ash, which covers an area of roughly two square miles.

While much of the Maya archaeological record points to rigid, top-down societies where the elite made most political and economic decisions, there is evidence of some autonomy at Ceren, including divergent choices by farmers regarding crop cultivation techniques that were discovered this summer, said Sheets. He believes a community building with two large benches in the front room may have hosted village elders when it came time to make community decisions at Ceren.

Researchers from the University of Cincinnati and the Sorbonne in Paris and 23 local Salvadoran workers collaborated on the project. The 2011 field season was funded by the National Science Foundation.

More news from the University of Colorado-Boulder: www.colorado.edu/news/

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via futurity.org

L'éducation à l'environnement investit de plus en plus les bancs de l'école

L'éducation à l'environnement investit de plus en plus les bancs de l'école

Une institutrice et ses élèves à Marseille le 3 septembre 2009 © AFP/Archives Anne-Christine Poujoulat

02/09/2011 11:03 am

PARIS (AFP) - Construire une ville pour 10.000 personnes en respectant l'environnement, trouver comment nourrir 9 milliards de personnes d'ici 2050 ou de gérer durablement les ressources de nos océans: ces thèmes dignes de sommets des Nations unies sont désormais en bonne place à l'école, au collège et au lycée.

"Ce sont des sujets qui rentrent aussi bien dans les sommets de l'Onu que dans les programmes d'enseignement parce que ce sont des questions essentielles du monde contemporain", souligne à l'AFP Jean-Michel Valantin, conseiller pour le développement durable (DD) au ministère de l'Education nationale.

L'éducation à l'environnement et au développement durable (EEDD) a été lancée en 2004 en France. Depuis l'an dernier, une grande partie du programme de géographie et sciences et vie de la Terre des collèges y est consacrée. En seconde au lycée tout le programme de géographie (plus de 44 heures sur l'année) traite des thèmes comme les déséquilibres à venir en matière de démographie, sécurité alimentaire, développement urbain et gestion des ressources.

Les outils pédagogiques pour les enseignants évoluent avec les technologies de communication. Des expositions photos aux jeux vidéo en passant par les extraits de conférences internationales ou des vidéos de témoignages concrets, il n'y a que l'embarras du choix.

"Nous, au lycée agricole, on fait maintenant du compost avec nos déchets qui sert ensuite aux maraîchers près d'ici, et on a un projet de faire nos yaourts et planter nos légumes pour notre cantine", explique Toinon, élève du lycée du Paraclet près d'Amiens dans une vidéo disponible sur le site du pôle national de compétence en matière d'EEDD.

Ce pôle basé à Amiens, véritable mine d'or de ressources pédagogiques aux contenus scientifiques validés, recense entre autres tous les textes réglementaires sur le DD.

Ludique

"Ce dont les enseignants ont surtout besoin, c'est du ludique", précise Florence Clément, chargée de l'information à l'Agence de l'environnement et de la maîtrise de l'énergie (Ademe).

En partenariat ou avec le soutien de l'Education nationale, des ministères de l'Ecologie et de l'Agriculture, nombre d'associations et organismes spécialisés multiplient les outils pour capter l'attention des élèves.

Le jeu vidéo Ecoville, promu par l'Ademe, vise à "construire une ville durable avec un cahier des charges imposé par la mairie et dans un temps imparti", explique Mme Clément. "La première fois, les élèves échouent toujours parce qu'ils font ce qu'on a l'habitude de faire, à savoir créer des tours pour y mettre rapidement le nombre d'habitants fixés par le cahier des charges."

Ils n'ont évidemment pas assuré la capacité énergétique suffisante pour une population brusquement accrue, ont omis le problème de la gestion des déchets et ignoré la solution des bâtiments moins énergivores. Après examen des erreurs, la deuxième tentative tient souvent mieux compte de ces contraintes.

"C'est en formant les enfants qui seront les ingénieurs, architectes ou avocats de demain qu'on va changer les choses", souligne Géraldine Poivert, présidente d'Ecofolio, éco-organisme du papier (collecte, tri et recyclage) et qui a formé plus de 100.000 enfants, notamment par des partenariats avec les rectorats de Corse et Montpellier.

Le réseau Ecole et nature avec Eco-emballages, promeut des éco-parlements des jeunes, initiative soutenue, parmi de nombreuses autres, par le ministère de l'Ecologie dans le cadre des activités extra-scolaires.

"Pour intéresser les jeunes il faut qu'il y ait eu un déclic positif", selon Florence Clément citant une étude récente de l'Ademe, car "beaucoup d'adolescents ne veulent pas porter la responsabilité des erreurs de la génération précédente en matière d'environnement."

© AFP

via goodplanet.info

Bonne nouvelle !

Beyond space-time: Welcome to phase space - space - 08 August 2011 - New Scientist

A theory of reality beyond Einstein's universe is taking shape – and a mysterious cosmic signal could soon fill in the blanks

IT WASN'T so long ago we thought space and time were the absolute and unchanging scaffolding of the universe. Then along came Albert Einstein, who showed that different observers can disagree about the length of objects and the timing of events. His theory of relativity unified space and time into a single entity - space-time. It meant the way we thought about the fabric of reality would never be the same again. "Henceforth space by itself, and time by itself, are doomed to fade into mere shadows," declared mathematician Hermann Minkowski. "Only a kind of union of the two will preserve an independent reality."

But did Einstein's revolution go far enough? Physicist Lee Smolin at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, doesn't think so. He and a trio of colleagues are aiming to take relativity to a whole new level, and they have space-time in their sights. They say we need to forget about the home Einstein invented for us: we live instead in a place called phase space.

If this radical claim is true, it could solve a troubling paradox about black holes that has stumped physicists for decades. What's more, it could set them on the path towards their heart's desire: a "theory of everything" that will finally unite general relativity and quantum mechanics.

So what is phase space? It is a curious eight-dimensional world that merges our familiar four dimensions of space and time and a four-dimensional world called momentum space.

Momentum space isn't as alien as it first sounds. When you look at the world around you, says Smolin, you don't ever observe space or time - instead you see energy and momentum. When you look at your watch, for example, photons bounce off a surface and land on your retina. By detecting the energy and momentum of the photons, your brain reconstructs events in space and time.

The same is true of physics experiments. Inside particle smashers, physicists measure the energy and momentum of particles as they speed toward one another and collide, and the energy and momentum of the debris that comes flying out. Likewise, telescopes measure the energy and momentum of photons streaming in from the far reaches of the universe. "If you go by what we observe, we don't live in space-time," Smolin says. "We live in momentum space."

And just as space-time can be pictured as a coordinate system with time on one axis and space - its three dimensions condensed to one - on the other axis, the same is true of momentum space. In this case energy is on one axis and momentum - which, like space, has three components - is on the other (see diagram).

Simple mathematical transformations exist to translate measurements in this momentum space into measurements in space-time, and the common wisdom is that momentum space is a mere mathematical tool. After all, Einstein showed that space-time is reality's true arena, in which the dramas of the cosmos are played out.

Smolin and his colleagues aren't the first to wonder whether that is the full story. As far back as 1938, the German physicist Max Born noticed that several pivotal equations in quantum mechanics remain the same whether expressed in space-time coordinates or in momentum space coordinates. He wondered whether it might be possible to use this connection to unite the seemingly incompatible theories of general relativity, which deals with space-time, and quantum mechanics, whose particles have momentum and energy. Maybe it could provide the key to the long-sought theory of quantum gravity.

Born's idea that space-time and momentum space should be interchangeable - a theory now known as "Born reciprocity" - had a remarkable consequence: if space-time can be curved by the masses of stars and galaxies, as Einstein's theory showed, then it should be possible to curve momentum space too.

At the time it was not clear what kind of physical entity might curve momentum space, and the mathematics necessary to make such an idea work hadn't even been invented. So Born never fulfilled his dream of putting space-time and momentum space on an equal footing.

That is where Smolin and his colleagues enter the story. Together with Laurent Freidel, also at the Perimeter Institute, Jerzy Kowalski-Glikman at the University of Wroclaw, Poland, and Giovanni Amelino-Camelia at Sapienza University of Rome in Italy, Smolin has been investigating the effects of a curvature of momentum space.

The quartet took the standard mathematical rules for translating between momentum space and space-time and applied them to a curved momentum space. What they discovered is shocking: observers living in a curved momentum space will no longer agree on measurements made in a unified space-time. That goes entirely against the grain of Einstein's relativity. He had shown that while space and time were relative, space-time was the same for everyone. For observers in a curved momentum space, however, even space-time is relative (see diagram).

This mismatch between one observer's space-time measurements and another's grows with distance or over time, which means that while space-time in your immediate vicinity will always be sharply defined, objects and events in the far distance become fuzzier. "The further away you are and the more energy is involved, the larger the event seems to spread out in space-time," says Smolin.

For instance, if you are 10 billion light years from a supernova and the energy of its light is about 10 gigaelectronvolts, then your measurement of its location in space-time would differ from a local observer's by a light second. That may not sound like much, but it amounts to 300,000 kilometres. Neither of you would be wrong - it's just that locations in space-time are relative, a phenomenon the researchers have dubbed "relative locality".

Relative locality would deal a huge blow to our picture of reality. If space-time is no longer an invariant backdrop of the universe on which all observers can agree, in what sense can it be considered the true fabric of reality?

That is a question still to be wrestled with, but relative locality has its benefits, too. For one thing, it could shed light on a stubborn puzzle known as the black hole information-loss paradox. In the 1970s, Stephen Hawking discovered that black holes radiate away their mass, eventually evaporating and disappearing altogether. That posed an intriguing question: what happens to all the stuff that fell into the black hole in the first place?

Relativity prevents anything that falls into a black hole from escaping, because it would have to travel faster than light to do so - a cosmic speed limit that is strictly enforced. But quantum mechanics enforces its own strict law: things, or more precisely the information that they contain, cannot simply vanish from reality. Black hole evaporation put physicists between a rock and a hard place.

According to Smolin, relative locality saves the day. Let's say you were patient enough to wait around while a black hole evaporated, a process that could take billions of years. Once it had vanished, you could ask what happened to, say, an elephant that once succumbed to its gravitational grip. But as you look back to the time at which you thought the elephant had fallen in, you would find that locations in space-time had grown so fuzzy and uncertain that there would be no way to tell whether the elephant actually fell into the black hole or narrowly missed it. The information-loss paradox dissolves.

Big questions still remain. For instance, how can we know if momentum space is really curved? To find the answer, the team has proposed several experiments.

One idea is to look at light arriving at the Earth from distant gamma-ray bursts. If momentum space is curved in a particular way that mathematicians refer to as "non-metric", then a high-energy photon in the gamma-ray burst should arrive at our telescope a little later than a lower-energy photon from the same burst, despite the two being emitted at the same time.

Just that phenomenon has already been seen, starting with some unusual observations made by a telescope in the Canary Islands in 2005 (New Scientist, 15 August 2009, p 29)Movie Camera. The effect has since been confirmed by NASA's Fermi gamma-ray space telescope, which has been collecting light from cosmic explosions since it launched in 2008. "The Fermi data show that it is an undeniable experimental fact that there is a correlation between arrival time and energy - high-energy photons arrive later than low-energy photons," says Amelino-Camelia.

Still, he is not popping the champagne just yet. It is not clear whether the observed delays are true signatures of curved momentum space, or whether they are down to "unknown properties of the explosions themselves", as Amelino-Camelia puts it. Calculations of gamma-ray bursts idealise the explosions as instantaneous, but in reality they last for several seconds. While there is no obvious reason to think so, it is possible that the bursts occur in such a way that they emit lower-energy photons a second or two before higher-energy photons, which would account for the observed delays.

In order to disentangle the properties of the explosions from properties of relative locality, we need a large sample of gamma-ray bursts taking place at various known distances (arxiv.org/abs/1103.5626). If the delay is a property of the explosion, its length will not depend on how far away the burst is from our telescope; if it is a sign of relative locality, it will. Amelino-Camelia and the rest of Smolin's team are now anxiously awaiting more data from Fermi.

The questions don't end there, however. Even if Fermi's observations confirm that momentum space is curved, they still won't tell us what is doing the curving. In general relativity, it is momentum and energy in the form of mass that warp space-time. In a world in which momentum space is fundamental, could space and time somehow be responsible for curving momentum space?

Work by Shahn Majid, a mathematical physicist at Queen Mary University of London, might hold some clues. In the 1990s, he showed that curved momentum space is equivalent to what's known as a noncommutative space-time. In familiar space-time, coordinates commute - that is, if we want to reach the point with coordinates (x,y), it doesn't matter whether we take x steps to the right and then y steps forward, or if we travel y steps forward followed by x steps to the right. But mathematicians can construct space-times in which this order no longer holds, leaving space-time with an inherent fuzziness.

In a sense, such fuzziness is exactly what you might expect once quantum effects take hold. What makes quantum mechanics different from ordinary mechanics is Heisenberg's uncertainty principle: when you fix a particle's momentum - by measuring it, for example - then its position becomes completely uncertain, and vice versa. The order in which you measure position and momentum determines their values; in other words, these properties do not commute. This, Majid says, implies that curved momentum space is just quantum space-time in another guise.

What's more, Majid suspects that this relationship between curvature and quantum uncertainty works two ways: the curvature of space-time - a manifestation of gravity in Einstein's relativity - implies that momentum space is also quantum. Smolin and colleagues' model does not yet include gravity, but once it does, Majid says, observers will not agree on measurements in momentum space either. So if both space-time and momentum space are relative, where does objective reality lie? What is the true fabric of reality?

Smolin's hunch is that we will find ourselves in a place where space-time and momentum space meet: an eight-dimensional phase space that represents all possible values of position, time, energy and momentum. In relativity, what one observer views as space, another views as time and vice versa, because ultimately they are two sides of a single coin - a unified space-time. Likewise, in Smolin's picture of quantum gravity, what one observer sees as space-time another sees as momentum space, and the two are unified in a higher-dimensional phase space that is absolute and invariant to all observers. With relativity bumped up another level, it will be goodbye to both space-time and momentum space, and hello phase space.

"It has been obvious for a long time that the separation between space-time and energy-momentum is misleading when dealing with quantum gravity," says physicist João Magueijo of Imperial College London. In ordinary physics, it is easy enough to treat space-time and momentum space as separate things, he explains, "but quantum gravity may require their complete entanglement". Once we figure out how the puzzle pieces of space-time and momentum space fit together, Born's dream will finally be realised and the true scaffolding of reality will be revealed.

Bibliography

  1. The principle of relative locality by Giovanni Amelino-Camelia and others (arxiv.org/abs/1101.0931)

Amanda Gefter is a consultant for New Scientist based in Boston

via newscientist.com