Why Desalination Doesn't Work (Yet)

Source: World Bank, 2007. The Most Arid Region in the World. With an average of only 1,383 cubic meters of renewable water resources per person per year in 2006, the MENA region falls far below the global average of 8,462. Environmental problems resulting from water issues cost MENA countries between 0.5 and 2.5 percent of GDP every year. People and economies also suffer from the consequences of droughts, floods and water-related public health issues. The region has responded to these water challenges with some of the best hydraulic engineers in the world, who have pioneered sophisticated irrigation and drainage systems as well as cutting edge desalinization technologies.



Why Desalination Doesn't Work (Yet)

By Michael Schirber, Special to LiveScience
livescience.com
posted: 25 June 2007 08:49 am ET

With water fast becoming a hot commodity, especially in drought-prone regions with burgeoning populations, an obvious solution is to take the salt out of seawater. Desalination technology has been around for thousands of years, after all. Even Aristotle worked on the problem.

Tantalizing as desalinated water might sound, the energy costs have made it rather unpalatable.

"Until recently, seawater desalination was a very expensive water source solution," said Gary Crisp, an engineer for the Water Corporation of Western Australia.

Drinking seawater straight is a bad idea because your body must expel the salt by urinating more water than it actually gains. Seawater contains roughly 130 grams of salt per gallon. Desalination can reduce salt levels to below 2 grams per gallon, which is the limit for safe human consumption.

Currently, between 10 and 13 billion gallons of water are desalinated worldwide per day. That's only about 0.2 percent of global water consumption, but the number is increasing.

"There is significant growth in desalination capacity throughout the world, and it is anticipated to continue for sometime," says Stephen Gray of Victoria University.

Gray has been chosen to lead a new research program in Australia—where many regions lack fresh water supplies—to improve the efficiency of desalination plants.

Aristotle's efforts

Back in the 4th century B.C., Aristotle imagined using successive filters to remove the salt from seawater.

But the first actual practice of desalination involved collecting the freshwater steam from boiling saltwater. Around 200 A.D., sailors began desalinating seawater with simple boilers on their ships.

The energy required for this distillation process today makes it prohibitively expensive on a large scale. A lot of the current market for so-called "thermal desalination" has therefore been in oil-rich, water-poor countries in the Middle East.

Since the 1950s, researchers have been developing membranes that could filter out salt, similar to what Aristotle originally envisioned. Presently, this membrane technique, sometimes called "reverse osmosis," requires one-fourth of the energy and costs half of the price of distilling saltwater.

"In the last ten years, seawater reverse-osmosis has matured into a viable alternative to thermal desalination," Crisp says.

Energy is key

But even with membranes, large amounts of energy are needed to generate the high pressure that forces the water through the filter. Current methods require about 14 kilowatt-hours of energy to produce 1,000 gallons of desalinated seawater.

A typical American uses 80 to 100 gallons of water a day, according to the U.S. Geological Survey. The entire country consumes about 323 billion gallons per day of surface water and another 84.5 billion gallons of ground water.

If half of this water came from desalination, the United States would need more than 100 extra electric power plants, each with a gigawatt of capacity.

Depending on local energy prices, 1,000 gallons of desalinated seawater can cost around $3 or $4. Although that might not seem like much, it is still cheaper in many places to pump water out of the ground or import it from somewhere else.

But the price difference will undoubtedly narrow, especially in regions that could experience more intense droughts owing to climate change.

Water use has been growing twice as fast as population growth, causing more and more communities to suffer water shortages. The demand for freshwater supplies will drive prices higher, making desalination increasingly attractive.

Brainstorming on membranes

The number of desalination plants worldwide has grown to more than 15,000, and efforts continue to make them more affordable.

Last month, Australia's largest scientific research agency joined with nine major universities in a membrane research program to reduce desalination energy costs, as well as maintenance costs associated with gunk sticking to membranes and fouling them up.

"Lowering the energy required for desalination and the fouling propensity of membranes are the two biggest challenges facing desalination," Gray says.

A team of diverse researchers will try to tackle these problems by developing new types of membrane materials. The goal is to cut in half the energy required for desalination.

"We would hope to have something available within the next 10 years," Gray said.

Global Warming: How Do Scientists Know They're Not Wrong?

image: undispatch.com

Global Warming: How Do Scientists Know They're Not Wrong?

By Andrea Thompson, LiveScience Staff Writer
posted: 16 July 2007 09:34 am ET

From catastrophic sea level rise to jarring changes in local weather, humanity faces a potentially dangerous threat from the changes our own pollution has wrought on Earth’s climate. But since nothing in science can ever be proven with 100 percent certainty, how is it that scientists can be so sure that we are the cause of global warming?

For years, there has been clear scientific consensus that Earth’s climate is heating up and that humans are the culprits behind the trend, says Naomi Oreskes, a historian of science at the University of California, San Diego.

A few years ago, she evaluated 928 scientific papers that dealt with global climate change and found that none disagreed about human-generated global warming. The results of her analysis were published in a 2004 essay in the journal Science.

And the Intergovernmental Panel on Climate Change (IPCC), the National Academy of Sciences and numerous other noted scientific organizations have issued statements that unequivocally endorse the idea of global warming and attribute it to human activities.

“We’re confident about what’s going on,” said climate scientist Gavin Schmidt of NASA’s Goddard Institute of Space Science in New York.

But even if there is a consensus, how can scientists be so confident about a trend playing out over dozens of years in the grand scheme of the Earth's existence? How do they know they didn’t miss something, or that there is not some other explanation for the world’s warming? After all, there was once a scientific consensus that the Earth was flat. How can scientists prove their position?

Best predictor wins

Contrary to popular parlance, science can never truly “prove” a theory. Science simply arrives at the best explanation of how the world works. Global warming can no more be “proven” than the theory of continental drift, the theory of evolution or the concept that germs carry diseases.

“All science is fallible,” Oreskes told LiveScience. “Climate science shouldn’t be expected to stand up to some fantasy standard that no science can live up to.”

Instead, a variety of methods and standards are used to evaluate the viability of different scientific explanations and theories. One such standard is how well a theory predicts the outcome of an event, and climate change theory has proven to be a strong predictor.

The effects of putting massive amounts of carbon dioxide in the air were predicted as long ago as the early 20th century by Swedish chemist Svante Arrhenius.

Noted oceanographer Roger Revelle’s 1957 predictions that carbon dioxide would build up in the atmosphere and cause noticeable changes by the year 2000 have been borne out by numerous studies, as has Princeton climatologist Suki Manabe’s 1980 prediction that the Earth’s poles would be first to see the effects of global warming.

Also in the 1980s, NASA climatologist James Hansen predicted with high accuracy what the global average temperature would be in 30 years time (now the present day).

Hansen's model predictions are “a shining example of a successful prediction in climate science,” said climatologist Michael Mann of Pennsylvania State University.

Schmidt says that predictions by those who doubted global warming have failed to come true.

“Why don’t you trust a psychic? Because their predictions are wrong,” he told LiveScience. “The credibility goes to the side that gets these predictions right.”

Mounting evidence

Besides their successful predictions, climate scientists have been assembling a “body of evidence that has been growing significantly with each year,” Mann said.

Data from tree rings, ice cores and coral reefs taken with instrumental observations of air and ocean temperatures, sea ice melt and greenhouse gas concentrations have all emerged in support of climate change theory.

“There are 20 different lines of evidence that the planet is warming,” and the same goes for evidence that greenhouse gases are increasing in the atmosphere, Schmidt said. “All of these things are very incontrovertible.”

But skeptics have often raised the question of whether these observations and effects attributed to global warming may in fact be explained by natural variation or changes in solar radiation hitting the Earth.

Hurricane expert William Gray, of Colorado State University, told Discover magazine in a 2005 interview, "I'm not disputing that there has been global warming. There was a lot of global warming in the 1930s and '40s, and then there was a slight global cooling from the middle '40s to the early '70s. And there has been warming since the middle '70s, especially in the last 10 years. But this is natural, due to ocean circulation changes and other factors. It is not human induced.”

Isaac Newton had something to say about all this: In his seminal “Principia Mathematica,” he noted that if separate data sets are best explained by one theory or idea, that explanation is most likely the true explanation.

And studies have overwhelmingly shown that climate change scenarios in which greenhouse gases emitted from human activities cause global warming best explain the observed changes in Earth’s climate, Mann said—models that use only natural variation can’t account for the significant warming that has occurred in the last few decades.

Mythic ice age

One argument commonly used to cast doubt on the idea of global warming is the supposed predictions of an impending ice age by scientists in the 1970s. One might say: First the Earth was supposed to be getting colder; now scientists say it’s getting hotter—how can we trust scientists if they’re predictions are so wishy-washy?

Because the first prediction was never actually made. Rather, it’s something of an urban climate myth.

Mann says that this myth started from a “tiny grain of truth around which so much distortion and misinformation has been placed.”

Scientists were well aware of the warming that could be caused by increasing greenhouse gases, both Mann and Schmidt explained, but in the decades preceding the 1970s, aerosols, or air pollution, had been steadily increasing. These tiny particles tended to have a cooling effect in the atmosphere, and at the time, scientists were unsure who would win the climate-changing battle, aerosols or greenhouse gases.

“It was unclear what direction the climate was going,” Mann said.

But several popular media, such as Newsweek, ran articles that exaggerated what scientists had said about the potential of aerosols to cool the Earth.

But the battle is now over, and greenhouse gases have won.

“Human society has made a clear decision as to which direction [the climate] is going to go,” Mann said.

Future predictions

One of the remaining skeptics, is MIT meteorologist Richard Lindzen. While he acknowledges the trends of rising temperatures and greenhouse gases, Lindzen expressed his doubt on man’s culpability in the case and casts doubt on the dire predictions made by some climate models, in an April 2006 editorial for The Wall Street Journal.

“What the public fails to grasp is that the claims neither constitute support for alarm nor establish man's responsibility for the small amount of warming that has occurred,” Lindzen wrote.

To be sure, there is a certain degree of uncertainty involved in modeling and predicting future changes in the climate, but “you don’t need to have a climate model to know that climate change is a problem,” Oreskes said.

Climate scientists have clearly met the burden of proof with the mounting evidence they’ve assembled and the strong predictive power of global warming theory, Oreskes said-- global warming is something to pay attention to.

Schmidt agrees. “All of these little things just reinforce the big picture,” he said. “And the big picture is very worrying.”

Water Discovered to Flow Like Molasses

Water Discovered to Flow Like Molasses

By Ben Mauk, Special to LiveScience
livescience.com
posted: 11 May 2007 08:58 am ET

The Taoist poet Lao Tse famously wrote that water exemplifies the highest good, benefiting all and flowing easily without effort. While this makes for a lovely metaphor, there's more to H20 than is dreamt of in Lao Tse's philosophies.

Researchers at Georgia Institute of Technology have found that, at the molecular level, water exhibits viscous, even solid-like properties.

When molecules of water are forced to move through a small gap between two solid surfaces, the substance's viscosity increases by a factor of 1,000 to 10,000, approaching that of molasses.

"In this small space between surfaces, the water, which is usually very fluid, organizes itself into a new state in which well-defined layers of molecules form," said Uzi Landmann, director of the Center for Computational Materials Science at Georgia Tech, in a phone interview with Live Science.

Layering refers to a structural phenomenon in which molecules form strata between which there is very little molecular exchange. Water molecules can move about fluidly within a single layer, but not between layers. This vertical structure resembles that found in solid substances.

Landmann directed the team of physicists that simulated the experiment and predicted the layering effect. Georgia Tech experimental physicist Elisa Riedo led the team that performed the actual experiments. Together they found that the simulation predictions matched the experimental results.

The experiment observed the properties visualized in the simulation by measuring the force required to push the solid walls together. Riedo found that the force oscillates predictably, becoming largest at the point when a layer of particles is squeezed out.

Riedo and Landmann's results stand at odds with long-held beliefs about water.

"The literature almost uniformly said that water doesn't layer," said Landmann. "Without direct evidence it was inferred that water would behave differently from those liquids that do."

Previously, experiments had not measured the force directly but rather had deduced it from other properties, since techniques at the time did not allow scientists to probe the one nanometer region required to observe the effect.

The layering phenomenon has been known for about 25 years. Hexadecanes (molecule chains of 16 carbon atoms) exhibit layering properties. These are featured in many common liquids, but not in water.

Applications for the findings can be found in fields ranging from pharmaceuticals to nanotechnology. The newfound viscosity of water suggests a cheap method for lubricating very narrow regions. Water was long thought too fluid to be useful for this purpose.

But it is not merely a matter of application, insists Landmann. "The question of the nature of materials on the small scale is itself fascinating."

On that point even Lao Tse agrees: "Magnify the small, increase the few."

Scientists Make Water Run Uphill

By Corey Binns, Special to LiveScience
livescience.com
posted: 29 March 2006 06:46 am ET

Toss water on a hot pan and it sizzles and evaporates. Toss water on a really hot pan, and the water beads up and starts roaming around.

Now, turn your hot pan into a hot small staircase and watch the water climb the stairs.

Researchers did just that, taking an everyday sighting in the kitchen to a new level in the lab.

How it works

If a pan's really hot, the water starts to evaporate before it even touches the surface. The evaporating water, in the airy form of a water-vapor cushion, holds the droplet above the pan. With moves as smooth as Fred Astaire, the droplet glides around on air.

When scientists heated a piece of brass with saw-tooth ridges-a thing that looks like a ratchet-water drops traveled quickly and in one direction: up.

[See the video. Credit: Heiner Linke, University of Oregon]

"The drop rides along on the vapor like a boat on a river," said physicist Heiner Linke from the University of Oregon. "The vapor is generated between the droplet and the ratchet's surface in a narrow gap, about the width of a human hair. The vapor needs a way to get out of there, and it's going to take the easiest way out. There's always going to be one direction in which it's easier to get out."

Video Watch the Full Video A liquid drop placed on a hot ratchet moves uphill. Credit: Heiner Linke, University of Oregon

The escaping vapor pulls the droplet along in the same direction.

The research is scheduled to be published in the April 14 issue of the journal Physical Review Letters.

Potential use

The traveling drops could prove helpful in cases where scientists need to cool something down with water or another liquid. Tiny air conditioners are used to cook microchips in laptop computers. But the cooling system itself requires extra energy, which creates more heat.

With the newfound trick, drops could potentially pump themselves, using heat that's already there. "Pumps that don't use moving parts are simpler to make, cheaper and live longer," Linke pointed out.

If the droplet pumps prove strong enough, Linke said they could be cooling computers in about six years.

In the meantime, schoolteachers have a new trick for the classroom.

Timeline: The Frightening Future of Earth

Timeline: The Frightening Future of Earth

By Andrea Thompson, and Ker Than
livescience.com
posted: 19 April 2007 08:32 am ET

Our planet's prospects for environmental stability are bleaker than ever with the approach of this year's Earth Day, April 22. Global warming is widely accepted as a reality by scientists and even by previously doubtful government and industrial leaders. And according to a recent report by the Intergovernmental Panel on Climate Change (IPCC), there is a 90 percent likelihood that humans are contributing to the change.

The international panel of scientists predicts the global average temperature could increase by 2 to 11 degrees Fahrenheit by 2100 and that sea levels could rise by up to 2 feet.

Scientists have even speculated that a slight increase in Earth's rotation rate could result, along with other changes. Glaciers, already receding, will disappear. Epic floods will hit some areas while intense drought will strike others. Humans will face widespread water shortages. Famine and disease will increase. Earth's landscape will transform radically, with a quarter of plants and animals at risk of extinction.

While putting specific dates on these traumatic potential events is challenging, this timeline paints the big picture and details Earth's future based on several recent studies and the longer scientific version of the IPCC report, which was made available to LiveScience.

2007

More of the world's population now lives in cities than in rural areas, changing patterns of land use. The world population surpasses 6.6 billion. (Peter Crane, Royal Botanic Gardens, UK, Science; UN World Urbanization Prospectus: The 2003 Revision; U.S. Census Bureau)

2008

Global oil production peaks sometime between 2008 and 2018, according to a model by one Swedish physicist. Others say this turning point, known as "Hubbert's Peak," won't occur until after 2020. Once Hubbert's Peak is reached, global oil production will begin an irreversible decline, possibly triggering a global recession, food shortages and conflict between nations over dwindling oil supplies. (doctoral dissertation of Frederik Robelius, University of Uppsala, Sweden; report by Robert Hirsch of the Science Applications International Corporation)

2020

Flash floods will very likely increase across all parts of Europe. (IPCC)

Less rainfall could reduce agriculture yields by up to 50 percent in some parts of the world. (IPCC)

World population will reach 7.6 billion people. (U.S. Census Bureau)

2030

Diarrhea-related diseases will likely increase by up to 5 percent in low-income parts of the world. (IPCC)

Up to 18 percent of the world's coral reefs will likely be lost as a result of climate change and other environmental stresses. In Asian coastal waters, the coral loss could reach 30 percent. (IPCC)

World population will reach 8.3 billion people. (U.S. Census Bureau)

Warming temperatures will cause temperate glaciers on equatorial mountains in Africa to disappear. (Richard Taylor, University College London, Geophysical Research Letters:)

In developing countries, the urban population will more than double to about 4 billion people, packing more people onto a given city's land area. The urban populations of developed countries may also increase by as much as 20 percent. (World Bank: The Dynamics of Global Urban Expansion)

2040

The Arctic Sea could be ice-free in the summer, and winter ice depth may shrink drastically. Other scientists say the region will still have summer ice up to 2060 and 2105. (Marika Holland, NCAR, Geophysical Research Letters)

2050

Small alpine glaciers will very likely disappear completely, and large glaciers will shrink by 30 to 70 percent. Austrian scientist Roland Psenner of the University of Innsbruck says this is a conservative estimate, and the small alpine glaciers could be gone as soon as 2037. (IPCC)

In Australia, there will likely be an additional 3,200 to 5,200 heat-related deaths per year. The hardest hit will be people over the age of 65. An extra 500 to 1,000 people will die of heat-related deaths in New York City per year. In the United Kingdom, the opposite will occur, and cold-related deaths will outpace heat-related ones. (IPCC)

World population reaches 9.4 billion people. (U.S. Census Bureau)

Crop yields could increase by up to 20 percent in East and Southeast Asia, while decreasing by up to 30 percent in Central and South Asia. Similar shifts in crop yields could occur on other continents. (IPCC)

As biodiversity hotspots are more threatened, a quarter of the world's plant and vertebrate animal species could face extinction. (Jay Malcolm, University of Toronto, Conservation Biology)

2070

As glaciers disappear and areas affected by drought increase, electricity production for the world's existing hydropower stations will decrease. Hardest hit will be Europe, where hydropower potential is expected to decline on average by 6 percent; around the Mediterranean, the decrease could be up to 50 percent. (IPCC)

Warmer, drier conditions will lead to more frequent and longer droughts, as well as longer fire-seasons, increased fire risks, and more frequent heat waves, especially in Mediterranean regions. (IPCC)

2080

While some parts of the world dry out, others will be inundated. Scientists predict up to 20 percent of the world's populations live in river basins likely to be affected by increased flood hazards. Up to 100 million people could experience coastal flooding each year. Most at risk are densely populated and low-lying areas that are less able to adapt to rising sea levels and areas which already face other challenges such as tropical storms. (IPCC)

Coastal population could balloon to 5 billion people, up from 1.2 billion in 1990. (IPCC)

Between 1.1 and 3.2 billion people will experience water shortages and up to 600 million will go hungry. (IPCC)

Sea levels could rise around New York City by more than three feet, potentially flooding the Rockaways, Coney Island, much of southern Brooklyn and Queens, portions of Long Island City, Astoria, Flushing Meadows-Corona Park, Queens, lower Manhattan and eastern Staten Island from Great Kills Harbor north to the Verrazano-Narrows Bridge. (NASA GISS)

2085

The risk of dengue fever from climate change is estimated to increase to 3.5 billion people. (IPCC)

2100

A combination of global warming and other factors will push many ecosystems to the limit, forcing them to exceed their natural ability to adapt to climate change. (IPCC)

Atmospheric carbon dioxide levels will be much higher than anytime during the past 650,000 years. (IPCC)

Ocean pH levels will very likely decrease by as much as 0.5 pH units, the lowest it's been in the last 20 million years. The ability of marine organisms such as corals, crabs and oysters to form shells or exoskeletons could be impaired. (IPCC)

Thawing permafrost and other factors will make Earth's land a net source of carbon emissions, meaning it will emit more carbon dioxide into the atmosphere than it absorbs. (IPCC)

Roughly 20 to 30 percent of species assessed as of 2007 could be extinct by 2100 if global mean temperatures exceed 2 to 3 degrees of pre-industrial levels. (IPCC)

New climate zones appear on up to 39 percent of the world's land surface, radically transforming the planet. (Jack Williams, University of Wisconsin-Madison, Proceedings of the National Academy of Sciences)

A quarter of all species of plants and land animals-more than a million total-could be driven to extinction. The IPCC reports warn that current "conservation practices are generally ill-prepared for climate change and effective adaptation responses are likely to be costly to implement." (IPCC)

Increased droughts could significantly reduce moisture levels in the American Southwest, northern Mexico and possibly parts of Europe, Africa and the Middle East, effectively recreating the "Dust Bowl" environments of the 1930s in the United States. (Richard Seager, Lamont Doherty Earth Observatory, Science)

2200

An Earth day will be 0.12 milliseconds shorter, as rising temperatures cause oceans to expand away from the equator and toward the poles, one model predicts. One reason water will be shifted toward the poles is most of the expansion will take place in the North Atlantic Ocean, near the North Pole. The poles are closer to the Earth's axis of rotation, so having more mass there should speed up the planet's rotation. (Felix Landerer, Max Planck Institute for Meteorology, Geophysical Research Letters)

Fossil Hunter Condemns Lucy Tour of U.S.

The framed hominid fossil "Lucy," is seen at a exhibition at the Ethiopian Natural History Museum in the Ethiopian capital of Addis Ababa, Tuesday, Oct. 24, 2006. The 3.2 million-year-old Lucy skeleton has left Ethiopia for a tour of the United States _ a trip that some say is simply too risky for one of the world's most famous fossils. Credit: AP Photo/Les Neuhaus



Fossil Hunter Condemns Lucy Tour of U.S.

By Khaled Kazziha, Associated Press
livescience.com
posted: 11 August 2007 01:35 pm ET


NAIROBI, Kenya (AP) -- One of the world's leading paleontologists denounced Ethiopia's decision to send the Lucy skeleton on a six-year tour of the United States, warning Friday that the 3.2 million-year-old fossil will likely be damaged no matter how careful its handlers are.
The skeleton was quietly flown out of Ethiopia earlier this week for the U.S. tour.
Paleontologist Richard Leakey joined other experts in criticizing what some see as a gamble with one of the world's most famous fossils. The Smithsonian Institution also has objected to the tour, and the secretive manner in which the remains were sent abroad has raised eyebrows in Ethiopia, where Lucy has been displayed to the public only twice.
"It's a form of prostitution, it's gross exploitation of the ancestors of humanity and it should not be permitted,'' Leakey told The Associated Press in an interview at his office in Nairobi.
Ethiopian officials could not immediately be reached for comment, but have said proceeds from the tour would be used to upgrade museums in one of the world's poorest countries.
Dirk Van Tuerenhout, the curator of anthropology at the Houston Museum of Natural Science, where Lucy will be on display from Aug. 31 to April 20, said his museum would treat the relic with "the greatest respect and sense of protection -- something we in the museum world do all the time.''
"On the one hand, I would say we definitely share the concern that people have to safeguard fossils like Lucy, or for that matter any other fossils,'' Van Tuerenhout said. "Where we part company, in a sense, is the decision that was made to allow her to travel.''
He emphasized the decision to allow Lucy to travel abroad was made by the Ethiopian government, and that Houston was honored by its selection.
Van Tuerenhout also noted the exhibit's story line was broader than just Lucy and offers other educational aspects.
"We are definitely going to be able, with Lucy's presence, to tell the story of Ethiopia -- not only the prehistoric part, but also the historic part,'' he said. "This is one of those exhibits that covers quite a lot of history.''
Lucy, the fossilized partial skeleton of what was once a 3 1/2-foot-tall adult of an ape-man species, was discovered in 1974 in the remote, desert-like Afar region in northeastern Ethiopia. Lucy is classified as an Australopithecus afarensis, which lived in Africa between about 3 million to 4 million years ago, and is the earliest known hominid.
The State Department approved the exhibit for temporary importation into the U.S., saying that display of Lucy and the other artifacts is in the national interest because of their "cultural significance.''
Stops beyond Houston have yet to be finalized, but Ethiopian officials have said they include New York, Denver and Chicago.
Leakey said the skeleton will almost certainly get damaged.
"These specimens will get damaged no matter how careful you are and every time she is moved there is a risk,'' he said. "A specimen that is that precious and unique shouldn't be exposed to the threats of damage by travel.''
He also said keeping Lucy in Ethiopia would lure tourists to the country.
"The point is, what is the benefit of taking one of the most iconic examples of the human story from Africa to parade it around in second-level museums in the United States?'' he said.
Leakey is one of the world's most renowned paleontologists. His team unearthed the bones of Turkana Boy -- the most complete skeleton of a prehistoric human ever found -- in the desolate, far northern reaches of Kenya in 1984.
He is also a conservationist credited with helping end the slaughter of elephants in Kenya during the 1980s.

Associated Press Writer John Peretto contributed to this story from Houston.

Glimpse of Time Before Big Bang Possible

Glimpse of Time Before Big Bang Possible

By Charles Q. Choi, Special to LiveScience
livescience.com
posted: 01 July 2007 01:15 pm ET

It may be possible to glimpse before the supposed beginning of time into the universe prior to the Big Bang, researchers now say.

Unfortunately, any such picture will always be fuzzy at best due to a kind of "cosmic forgetfulness."

The Big Bang is often thought as the start of everything, including time, making any questions about what happened during it or beforehand nonsensical. Recently scientists have instead suggested the Big Bang might have just been the explosive beginning of the current era of the universe, hinting at a mysterious past.

To see how far into history one might gaze, theoretical physicist Martin Bojowald at Pennsylvania State University ran calculations based on loop quantum gravity, one of a number of competing theories seeking to explain how the underlying structure of the universe works.

Past research suggested the Big Bang was preceded by infinite energies and space-time warping where existing scientific theories break down, making it impossible to peer beforehand. The new findings suggest that although the levels of energy and space-time warping before the Big Bang were both incredibly high, they were finite.

Scientists could spot clues in the present day of what the cosmos looked like previously. If evidence of the past persisted after the Big Bang, its influence could be spotted in astronomical observations and computational models, Bojowald explained.

However, Bojowald also figures some knowledge of the past was irrevocably lost. For instance, the sheer size of the present universe would suppress precise knowledge of how the universe changed in size before the Big Bang, he said.

"It came as a big surprise that some properties of the universe before the Big Bang may have only such a weak influence on current observations that they are practically undetermined," Bojowald said of findings detailed online July 1 in the journal Nature Physics.

One implication of this "cosmic forgetfulness," as Bojowald calls it, is that history does not repeat itself-the fundamental properties of the current era of the universe are different from the last, Bojowald explained. "It's as if the universe forgot some of its properties and acquired new properties independent of what it had before," he told SPACE.com.

"The eternal recurrence of absolutely identical universes would seem to be prevented by the apparent existence of an intrinsic cosmic forgetfulness," he added.

These findings differ from a cyclic model of the cosmos from cosmologist Paul Steinhardt at Princeton and theoretical physicist Neil Turok at Cambridge, which envisions an infinite series of Big Bangs preceding our universe caused by additional membranes or "branes" of reality perpetually colliding and bouncing off each other. Steinhardt said he felt Bojowald's calculations were concrete, but needed further elaboration to include the interplay of different kinds of matter and radiation.

Cosmologist Carlo Rovelli at the Center of Theoretical Physics in Marseilles, France, found it "remarkable" that the new work could delve past the Big Bang. He added the work had to lead to predictions that could be compared to cosmological observations "in order to become credible."

Puzzle of Hot Young Stars Solved

The Taurus Molecular Cloud in the infrared, revealing the vast star-forming regions nearest to Earth. The cloud contains over 400 young stars. Credits: Five College Radio Astronomy Observatory/Gopal Narayanan/Mark Heyer



Puzzle of Hot Young Stars Solved

By Dave Mosher, Staff Writer
livescience.com
posted: 14 August 2007 06:05 am ET


Most newborn stars are gluttons, feeding on afterbirth of dust and gas long after igniting.
Although this accreting activity doubles stellar surface temperatures by burning up the material, it mysteriously softens the emission of high-energy X-rays.
"Accreting stars have three times less X-ray emission than non-accreting stars, which seems unusual," said Kevin Briggs, an astrophysicist at the Swiss Federal Institute of Technology in Zurich, Switzerland.
Now Briggs and several teams of researchers have discovered why some stars' X-ray profiles are so thin: The nebulous surroundings of a young star absorb the extra energy produced by falling into it.
The discovery gives astronomers a better glimpse into the early stages of stellar life.
Burning filters
Briggs explained that dust and gas surrounding young stars act like light filters on a camera, where gas absorbs X-rays and dust absorbs visible light.
Yet if both materials surrounding energetic young stars are very dense--and soak up most of the energy they create--Briggs said the team wondered why the stars weren't fainter.
The filters, it turns out, burn.
"The dust is heated so much by the radiation from the star, that it is vaporized before it can fall on the star," said Manuel Guedel, also an astrophysicist at the Swiss Federal Institute of Technology.
As the dust and gas still waiting to be eaten by the young stars vaporizes, Briggs explained, they glow like hot plasma and mimic the appearance of a star's surface.
Shocking creation
Briggs said repetitive "shocks" of energy create young stars' X-rays, and that there are two recipes to make them.
The first type of shock is produced when gas and dust falls into a star and slams into its surface at nearly 671,000 mph (1,080,000 kph). "The impact against the star's surface can produce the high-energy shock," Briggs said.
The second type of X-ray shock in young stars is produced by gas and dust jettisoned away from a star's poles.
"It happens when fast-moving material catches up to slow-moving material and collides," Briggs said. But nature leans toward variety with its shocking young stars. "What we actually see is both types in these stars," he said.
Because stellar meals of gas and dust absorb most young stars' X-ray outputs, the teams think the few X-rays that can be detected originate from shocks emitted from the stars' jets.
"This emission must come from outside the accretion streams," Guedel said. The teams looked at 400 young stars in the constellation Taurus to uncover their findings, which are detailed in a recent issue of the journal Astronomy and Astrophysics.