Seeing light in a new light: Scientists create never-before-seen form of matter

Sep. 25, 2013 — Harvard and MIT scientists are challenging the conventional wisdom about light, and they didn’t need to go to a galaxy far, far away to do it.

Working with colleagues at the Harvard-MIT Center for Ultracold Atoms, a group led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic have managed to coax photons into binding together to form molecules — a state of matter that, until recently, had been purely theoretical. The work is described in a September 25 paper in Nature.

The discovery, Lukin said, runs contrary to decades of accepted wisdom about the nature of light. Photons have long been described as massless particles which don’t interact with each other — shine two laser beams at each other, he said, and they simply pass through one another.

“Photonic molecules,” however, behave less like traditional lasers and more like something you might find in science fiction — the light saber.

“Most of the properties of light we know about originate from the fact that photons are massless, and that they do not interact with each other,” Lukin said. “What we have done is create a special type of medium in which photons interact with each other so strongly that they begin to act as though they have mass, and they bind together to form molecules. This type of photonic bound state has been discussed theoretically for quite a while, but until now it hadn’t been observed.

“It’s not an in-apt analogy to compare this to light sabers,” Lukin added. “When these photons interact with each other, they’re pushing against and deflect each other. The physics of what’s happening in these molecules is similar to what we see in the movies.”

Continue reading @ Seeing light in a new light: Scientists create never-before-seen form of matter.


Strength Of Gravity Shifts, And This Time It’s Serious!


The resulting value for G is 240 parts per million bigger than the official one, set in 2010. James Faller of the University of Colorado at Boulder, who tested G in 2010, is holding out for an error: “Errors are like violets in the springtime: they can spring up in any group’s experiment,” he says. “Logically, either some of the experiments are wrong, or G isn’t constant,” says Mark Kasevich of Stanford University.

Continue reading @ Strength Of Gravity Shifts And This Time It’s Serious.

Earth and others lose status as Goldilocks worlds

Bad news for Kepler-22b. Once deemed the most habitable world outside our solar system, it no longer looks life-friendly. More strangely, Earth’s habitability rating has also taken a hit. Both results are thanks to a redefinition of the habitable zone – the region around a star in which liquid water can theoretically exist.

Also known as the Goldilocks zone, because temperatures are “just right” for life there, the habitable zone is the main tool that exoplanet hunters have to rank their finds. But researchers are still using a definition coined in 1993. “Those habitable zones have not been updated in the last 20 years,” says Ravi Kopparapu of Penn State University.

He and his colleagues have a new definition. The zone’s boundaries have always depended on the star’s temperature, plus estimates of how well the atmospheres of any planets would absorb heat from their star. But in recent years, lab experiments have turned up new figures for how water and carbon dioxide absorb light from different types of stars. The redefinition is based on these figures – and pushes the zone further from the star than the old definition.

Now, many planets, including supposedly balmy Kepler-22b, look too hot. However, the redefinition should also bring into the habitable fold planets that were thought to be too cold.

No ultimate judge

Shockingly, Earth – which used to be smack-bang in the middle of our sun’s habitable zone – is now a scant million kilometres away from the warm edge, so almost too hot for liquid water. Of course, we know Earth is robustly life-friendly – the mismatch is probably because neither definition accounts for clouds, which reflect sunlight away from Earth.

As Earth shows, the Goldilocks zone is no ultimate judge of habitability, something exoplanet researchers have known for years. As well as clouds, volcanic activity or the location of other moons or planets in the solar system, may be important for life to develop on planets like Earth.

For now, however, with clouds not visible on an exoplanet, and many other details unknown about alien solar systems, the habitable zone is the best guide we’ve got – and thanks to Kopparapu’s team, it just got a bit better.

“I think this is going to be the new gold standard for the habitable zone,” says Rory Barnes of the University of Washington in Seattle, who was not involved in the new work. “But I think we should always look at planets in the habitable zone and say, maybe. It’s not that planets in the habitable zone are inhabited, it just means we can’t rule them out yet.”

Journal reference:

via Earth and others lose status as Goldilocks worlds – space – 30 January 2013 – New Scientist.

The World’s Tiniest Clock Is Made From Just One Atom

We’ve gotten pretty good at clocks. The nuclear clocks that exist right now are super accurate, so what more could you ask for? Something simpler. How about a clock that’s just one, single atom? That’s exactly what researchers just figured out how to make…

Continue reading @ The World’s Tiniest Clock Is Made From Just One Atom.

Has Curiosity Made an ‘Earth-Shaking’ Discovery?

The Mars Science Laboratory team has hinted that they might have some big news to share soon. But like good scientists, they are waiting until they verify their results before saying anything definitive. In an interview on NPR today, MSL Principal Investigator John Grotzinger said a recent soil sample test in the SAM instrument Sample Analysis at Mars shows something ‘earthshaking.’

“This data is gonna be one for the history books,” he said. “It’s looking really good. ”What could it be?

SAM is designed to investigate the chemical and isotopic composition of the Martian atmosphere and soil. In particular, SAM is looking for organic molecules, which is important in the search for life on Mars. Life as we know it cannot exist without organic molecules; however they can exist without life. SAM will be able to detect lower concentrations of a wider variety of organic molecules than any other instrument yet sent to Mars.

As many scientists have said, both the presence and the absence of organic molecules would be important science results, as both would provide important information about the environmental conditions of Gale Crater on Mars.But something ‘Earthshaking’ or “really good” probably wouldn’t be a nil result.Already, the team has found evidence for huge amounts of flowing water in Gale Crater.

Continue reading @ Has Curiosity Made an ‘Earth-Shaking’ Discovery?.

Bioengineers introduce Bi-Fi | The biological Internet

Bioengineers introduce Bi-Fi -- The biological Internet

If you were a bacterium, the virus M13 might seem innocuous enough. It insinuates more than it invades, setting up shop like a freeloading houseguest, not a killer. Once inside it makes itself at home, eating your food, texting indiscriminately. Recently, however, bioengineers at Stanford University have given M13 a bit of a makeover.

The researchers, Monica Ortiz, a doctoral candidate in bioengineering, and Drew Endy, PhD, an assistant professor of bioengineering, have parasitized the parasite and harnessed M13’s key attributes — its non-lethality and its ability to package and broadcast arbitrary DNA strands — to create what might be termed the biological Internet, or “Bi-Fi.” Their findings were published online Sept. 7 in the Journal of Biological Engineering.

Using the virus, Ortiz and Endy have created a biological mechanism to send genetic messages from cell to cell. The system greatly increases the complexity and amount of data that can be communicated between cells and could lead to greater control of biological functions within cell communities. The advance could prove a boon to bioengineers looking to create complex, multicellular communities that work in concert to accomplish important biological functions…

Continue @ Bioengineers introduce Bi-Fi — The biological Internet.

Delivering drugs via nanoparticles to target mitochondria

Researchers at the University of Georgia have refined the nanoparticle drug delivery process further by using nanoparticles to deliver drugs to a specific organelle within cells.

By targeting mitochondria, “the powerhouse of cells,” the researchers increased the effectiveness of mitochondria-acting therapeutics used to treat cancer, Alzheimer’s disease and obesity in studies conducted with cultured cells.

“The mitochondrion is a complex organelle that is very difficult to reach, but these nanoparticles are engineered so that they do the right job in the right place,” said senior author Shanta Dhar, an assistant professor of chemistry in the UGA Franklin College of Arts and Sciences.

Dhar and her co-author, doctoral student Sean Marrache, used a biodegradable, FDA-approved polymer to fabricate their nanoparticles and then used the particles to encapsulate and test drugs that treat a variety of conditions. Their results were published this week in early edition of the journal Proceedings of the National Academy of Sciences.

Continue reading @ Delivering drugs via nanoparticles to target mitochondria | KurzweilAI.

Moving plane exchanges quantum keys with Earth

AN AEROPLANE has beamed quantum encryption keys to a station on the ground, paving the way for an ultra-secure global communications network.

Quantum key distribution (QKD) uses photons polarised in two different ways to encode the 0s and 1s of an encryption key. The laws of quantum mechanics ensure the transmission is secure, as any attempt to intercept the key disturbs the polarisation – a tip-off to the receiver that the key has been seen and should be discarded.

Quantum keys had previously been exchanged between two land-based stations. Now Sebastian Nauerth at the Ludwig Maximilian University of Munich, Germany, and colleagues have extended the feat to an aircraft, a stepping stone to QKD via satellite, which could allow secure messages to be transmitted around the world.

Flying at a height of 20 kilometres and a speed of nearly 300 km per hour, the challenge was to tightly align the infrared laser pulses transmitted by the aircraft with the receiving station on the ground. Any deviation would limit the number of photons reaching the target.

The researchers kept the laser on track using moving mirrors both in the aircraft and on the ground. Performing the experiment shortly after sunset avoided interference from sunlight. The transmission lasted for 10 minutes, amounting to a key long enough to encrypt 10 kilobytes of data. The team presented the work at the QCrypt conference in Singapore on 12 September.

“It is a very challenging experiment,” says John Rarity, an optical engineer at the University of Bristol, UK, who was not involved in the work. He adds that aligning the laser with a satellite will be even more difficult. In the meantime, he suggests that solar-powered planes, which can stay aloft for weeks at a time, could enable QKD to be used in military surveillance, for example.

Back on the ground, researchers at the European Space Agency’s Optical Ground Station in Spain’s Canary Islands broke the distance record for quantum teleportation, which uses quantum entanglement to make message transmission more secure (Nature, They teleported quantum states over 143 km, breaking a record of 97 km reported earlier this year.

via Moving plane exchanges quantum keys with Earth – tech – 16 September 2012 – New Scientist.

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