Plants are extremely efficient converters of light into energy, more or less setting the bar for researchers creating photovoltaic cells that convert sunlight into electricity. As such, researchers are constantly trying to mimic the tricks that millions of years of evolution and development have taught to plant biology. Now, a team of MIT scientists believe they've done it, creating a synthetic, self-assembling chloroplast that can be broken down and reassembled repeatedly, restoring solar cells that are damaged by the sun.

While the leaves on a tree appear to be as static as the PV cells on a solar panel, they're not; sunlight is actually quite destructive, and to counter this effect leaves rapidly recycle their proteins as often as every 45 minutes when in direct summer sunlight. This rapid repair mechanism allows plants to take full advantage of the sun's bountiful energy without losing efficiency over time.

To recreate this unique regenerative ability, the MIT team devised a novel set of self-assembling molecules that use photons to shake electrons loose in the form of electricity. The system contains seven different compounds, including carbon nanotubes that provide structure and a means to conduct the electricity away from the cells, synthetic phospholipids that form discs that also provide structural support, and other molecules that self-assemble into "reaction centers" that actually interact with the incoming photons to release electrons.

Under certain conditions, the compounds assemble themselves into uniform structures suitable for harvesting solar energy. But in the presence of a surfactant (similar to the stuff used to disperse oil during oil spills) the structures break down into a solution of nanotubes, phospholipids, and other constituent molecules. By pushing the solution through a membrane to remove the surfactant, the elements once again assemble into working, rejuvenated solar cells undamaged by their prior exposure to the sun.

The cells are work at 40 percent efficiency, and researchers think with some tweaks they could push that efficiency much higher. And because they don't degrade over time - just give ‘em a quick shake with the surfactant and they're essentially brand new - the tech could be the next big step forward for solar technology.

[Eurekalert]

A particularly mind-bending (and controversial) physics paper surfaced in the past week that should make you feel pretty special. It seems the laws of physics can change after all, and it just so happens they're uniquely suited for us right here, right now.

The paper, recently submitted to Physical Review Letters and posted to the physics arXiv, suggests the fine structure constant is not actually constant at all. This could mean that if we were in a different place or time period, atoms would not stay together and nothing - neither planets nor people - could exist.

A team led by John Webb at the University of New South Wales, Australia, has been studying whether the fine structure constant, otherwise known as alpha, changes over time. Alpha is a special number that essentially describes the strength of the electromagnetic force. The famous physicist Richard Feynman called its value "one of the greatest damn mysteries of physics." If it is not 1/137.036, things fall apart.

If alpha was different in the past, the universe might have looked different, too, which could be determined by looking at distant interstellar gases and how they absorb light. Observations by Webb and others at the Keck Observatory in Hawaii suggest that this is exactly the case - over time, alpha has changed ever so slightly.

Competing studies did not find the same result, however, so this is still a controversial idea. But it's a fair bet Webb's follow-up is even more tendentious: He says alpha also changes over space. According to his theory, we're smack in the Goldilocks zone, where alpha is exactly the right value to make matter possible.

This paper happened because Webb and his team wanted to reexamine their Keck findings, which suggested alpha was a tiny bit smaller about 9 billion years in the past. They went to the Very Large Observatory in Chile to check it out, and were shocked by what they saw: the further they looked, the bigger alpha got. The discrepancy is even stranger given the two telescopes' positions: they are in two different hemispheres, so they look in two different directions.

So, to recap: in one direction, alpha was once smaller; in exactly the opposite direction, it was once bigger. This implies that alpha continuously varies throughout space. As Technology Review's physics blog puts it, that's a mind-blowing result. If it's true and can be verified, it could mean the universe is much larger than what we can see, and that the laws of physics vary within it.

It would not be possible for our type of life to exist in a place where alpha were any different. So here's to here and now.

[The Economist]

The father of evolution apparently played God with a tropical ecosystem 160 years ago, and the results could inform future experiments to terraform Mars, botanists say.

The BBC recounts how Charles Darwin helped build an artificial forest on Ascension Island, one of his subjects of study from his trips on the HMS Beagle. Today, the island is home to species of plants that would not naturally co-exist. Darwin and his friends put them there, and nearly two centuries later, their grand experiment is living proof that we can transform natural environments.

Originally used as an outpost to keep an eye on Napoleon in exile, Ascension Island, between South America and Africa, was a busy Atlantic waystation in Darwin's day. It had meager fresh water supplies, however, so Darwin and his botanist friend, Joseph Hooker, set out to change things.

The BBC interviews Darwin biographer David Catling, a professor at the University of Washington-Seattle, who says he believes Darwin decided to build a lush "Little England" on the volcanic island after visiting it in 1836.

Darwin's friend Hooker explored Ascension a few years later, and in 1847, Darwin convinced Hooker to get his father -- director of the Kew Gardens -- to send trees, hoping they would capture rain, prevent erosion and reduce evaporation.

Beginning in 1850 and continuing each year, ships brought an assortment of plants from botanical gardens in Europe, South Africa and Argentina, the BBC says. By the late 1870s, eucalyptus, Norfolk Island pine, bamboo, and banana had taken hold.

Today, Ascension is home to a cloud forest that would have taken millions of years to evolve naturally, according to Dave Wilkinson, an ecologist at Liverpool John Moores University in the UK.

It's proof that humans can build a fully functioning ecosystem simply through trial and error, he said. As the BBC reports, the same principle could be used in future Mars colonies: "Rather than trying to improve an environment by force, the best approach might be to work with life to help it find its own way."

Intelligent design, indeed.

East Coast residents are bracing for this monster, headed their way with 125-mph winds, as a fleet of NASA satellites and airplanes monitors its evolution.

As of Wednesday morning, Hurricane Earl was a Category 3 storm, but an especially large one. Storm-force winds extend 200 miles from its eye, seen above in a photo snapped from the International Space Station.

NASA scientists are flying airplanes into this swirling mass, measuring the hurricane's wind speeds, precipitation and more. As part of NASA's GRIP program - Genesis and Rapid Intensification Processes - a NASA DC-8 flew through Earl's eye six times as the hurricane intensified from a Category 2 to a Category 4 storm.

Meanwhile, an ISS crew member used a digital camera with a 50mm lens to take the above photo, from a much safer distance.

Apparently, some tigers can change their stripes -- especially if they have books to sell. One of our favorite climate villains, the Danish economist Bjørn Lomborg, has apparently warmed to the idea of climate change, and now says it's a problem on which the world ought to spend $100 billion annually.

Lomborg's forthcoming book, Smart Solutions to Climate Change, declares that global warming is "undoubtedly one of the chief concerns facing the world today." He examines eight methods to reduce or stop it, including wave, wind, solar and nuclear power, as well as geoengineering, and advocates a carbon emissions tax to finance investment.

As the British media points out, it's a nice U-turn from a man whom the UN climate chief once compared to Adolf Hitler. In a great example of climate politics making strange bedfellows, the same UN chief, Rajendra Pachauri, provides a book-jacket endorsement: "This book provides not only a reservoir of information on the reality of human-induced climate change, but raises vital questions and examines viable options on what can be done."

In an interview with the Guardian, Lomborg explains that he reached his conclusions like any good economist: By studying the numbers. In 2004, economists at Lomborg's Copenhagen Consensus think tank were asked how they'd spend $50 billion to solve the world's problems. They ranked climate change near the bottom of the priority list, below issues like HIV and malaria. But four years later, economists tackled the question again, and interest in climate change had risen like the polar temperatures. Lomborg said this prompted him to consider new climate change policies, so global warming wouldn't languish at the bottom of the list.

Earlier this summer, we ripped Lomborg for railing against programs and treaties that aim to lessen or halt anthropogenic climate change. Now that he says it should be a top priority, we'll take him off our villain list. And give him credit for his media savvy -- the guy knows how to sell books.

[the Guardian]

Is everything in the universe made up of vibrating one-dimensional strings? For the first time, scientists think they can concretely test string theory, the mind-blowing "theory of everything" that has dominated physics for the past two decades. It turns out that string theory predicts the behavior of entangled quantum particles, which can be tested in a lab - therefore testing string theory.

String theory elegantly reconciles the otherwise competing rules of quantum mechanics and general relativity. It's the most widely accepted unified field theory, but it remains controversial. It basically posits that electrons and quarks are not objects, but one-dimensional strings, whose oscillation gives them their observed qualities. The most fun element of string theory is the requirement that the universe has about a dozen dimensions, rather than the usual four (length, width, height and time).

M-theory, the dominant version of string theory, holds that the universe is made up of unfathomably small slices of a 2-dimensional membrane, wriggling in 11-dimensional space.

These bizarre ideas are widely accepted by many theoretical physicists, but the problem is that they can't be tested - how do you examine an 11th dimension? The field has suffered a backlash in recent years partly for this reason, as some scientists say a theory is not a theory if its predictions can't be studied in a lab.

Well, now they can, according to professor Mike Duff of the theoretical physics department at Imperial College London. He is lead author of a paper to be published tomorrow in Physical Review Letters, which explains how string theory math can be used to predict quantum entanglement.

Duff said he was at a conference in Tasmania when a colleague presented some mathematical formulas describing entanglement of multiple quantum bits. The equations looked familiar. Upon returning home, Duff checked his notebooks from a few years earlier, and realized the formulas were the same as those he developed to use string theory to describe black holes.

This is completely unexpected, he said. There is no obvious reason why the insanely complex mathematics underlying string theory can also be used to predict the behavior of entangled quantum systems.

"This may be telling us something very deep about the world we live in, or it may be no more than a quirky coincidence," he said.

Either way, it's useful, he added. Using string theory math, Duff predicted the pattern that would occur when four quantum bits are entangled with each other. This can be measured in a lab, and the results will demonstrate whether string theory actually works.

Right now, the best hope for string theory tests comes from CERN's Large Hadron Collider, which is designed to find the tiniest elementary particles that make up matter. It's theoretically possible that LHC experiments will uncover supersymmetric particles - one element of string theory - or bounce a graviton into a higher dimension, which could help prove M-theory. But testing the fuzzy math that predicts these behaviors will be much easier.

The European Space Agency has released a series of new images of Orcus Patera, a long crater near Mars's Mons Olympus whose rim rises some 6,000 feet. But the images, taken by the Mars Express craft, only deepen the mystery of the crater's origin.

The ESA says "the most likely explanation is that it was made in an oblique impact, when a small body struck the surface at a very shallow angle." Sounds almost definitely like aliens.

[ESA]

Water, water everywhere, but in the developing world or in areas ravaged by natural disasters - like the ongoing flooding in Pakistan, for instance - there's often not a clean, purified drop to be found. Water is usually made potable in such places via filters that physically trap bacteria as water flows through, but researchers at Stanford have shown devised a high-speed filter composed of nothing but plain cotton cloth and nanotubes that can quickly filter nearly all bacteria from dirty water using less power than slower conventional water purifiers.

Most water filters simply trap living bacteria as it passes through a series of tiny pores, a method that is effective but prone to a variety of problems. For one, they are painfully slow, and in disaster situations that can lead to critical shortages as thirsty populations wait for the water to trickle through.

Further, the water must be driven through the filters with pumps, which themselves require a decent amount of electricity - a resource that can be in short supply in remote regions or at disaster sites. Such filters are also susceptible to biofouling, in which trapped bacteria form a film that clogs the pores of the filter.

The Stanford team's filter circumvents most of these problems by simply letting the bacteria pass freely through, zapping them with fatal doses of voltage as they go. By dipping plain cotton cloth procured at Wal-Mart into a solution of carbon nanotubes and silver nanowires, the team created a filter that can kill 98 percent of Escherichia coli bacteria in water with a mere 20 volts of electricity, less than is required to operate the pumps on conventional filters.

Addressing the problems with conventional filters noted above, the team knew that carbon nanotubes are efficient conductors of electricity and that silver has bacteria-killing chemical properties. So they went about figuring out how to get all these ingredients into a single, inexpensive filter (the amount of silver used is so small that it's negligible). The cotton simply serves as an inexpensive platform on which to lay their nanotube/nanowire structure.

Plugged into a couple of 12-volt batteries or a hand cranked generator, the filter can run until the energy runs out, its larger pores letting vast volumes of water pass quickly, and cleanly, through. No pump is needed because the pores are large enough that gravity does the trick.

The next step is trying the filter on various other bacteria to see how universal the silver-carbon combo really is. One filter can kill 98 percent of the Escherichia coli in water, but a compound filter with layers of different materials might be able to push that number even closer to 100 percent for a variety of bacteria known to cause water-borne illnesses.

[Eurekalert]

In what could be a major blow to health research, the National Institutes of Health on Monday ordered an immediate shutdown of NIH experiments involving human embryonic stem cells.

The move, reported in ScienceInsider, comes on the heels of a ruling last week that blocked the use of federal funds to study new embryonic stem cell lines. A judge said President Obama's 2009 executive order violates a federal law barring the use of federal funds to destroy embryos.

Scientists are seething over today's ruling, announced in a memo from NIH intramural research chief Michael Gottesman. According to ScienceInsider, Gottesman said: "The injunction ... is applicable to the use of human embryonic stem cells in intramural research projects. In light of this determination, effective today, intramural scientists who use human ES cell lines should initiate procedures to terminate these projects. Procedures that will conserve and protect the research resources should be followed."

So far, outside labs are unaffected -- intramural means researchers in labs on the NIH campus, while extramural refers to researchers at other institutions who receive NIH grants.

The agency has eight research projects that use human embryonic stem cells, most if not all of which use lines approved under the Bush Administration back in 2001.

Under Obama's rules, federal money could be used for research on cell lines in addition to the ones Bush greenlighted nine years ago. After the injunction, scientists were hopeful they could still use the original cell lines -- but now the future looks murky.

ScienceInsider says the Department of Justice might ask the courts to delay the injunction, which could allow experiments to continue uninterrupted.

[ScienceInsider/AAAS]