Tuesday, July 1, 2014

A perfect negative crystal floating in space - 01 July 2014 - New Scientist

A perfect negative crystal floating in space - 01 July 2014 - New Scientist: The octahedron is the outline of a space, and what looks at first like the sides of a solid crystal are actually the walls of a void inside a bigger lump of crystal.

Monday, June 30, 2014

Study helps unlock mystery of high-temp superconductors

Study helps unlock mystery of high-temp superconductors: "Evidence has been accumulating that this phase supports an exotic density wave state that may be key to its existence...". A density wave forms in a metal if the fluid electrons themselves crystalize.
Using a scanning tunneling microscope (STM) to visualize the electronic structure of the oxygen sites within a superconductor, the team found a density wave with a d-orbital structure. (The electron density near each copper atom looks a bit like a daisy in the crystallized pattern.) That's especially surprising because most density waves have an s-orbital structure; their electron density is isotropic. "It's not the pattern you would expect," Lawler says.
In this research, Lawler and his colleagues focused on a member of the cuprate class of superconductors called bismuth strontium calcium copper oxide (BSCCO). "We now believe these density waves exist in all cuprates," says Lawler, a theorist whose contribution to the research involved subtle uses of the Fourier transform, a mathematical analysis that's useful when examining amplitude patterns in waves.

Muscle-powered bio-bots walk on command | News Bureau | University of Illinois

Muscle-powered bio-bots walk on command | News Bureau | University of Illinois: The new bio-bots are powered by a strip of skeletal muscle cells that can be triggered by an electric pulse...

“Skeletal muscles cells are very attractive because you can pace them using external signals,” Bashir said. “For example, you would use skeletal muscle when designing a device that you wanted to start functioning when it senses a chemical or when it received a certain signal. To us, it’s part of a design toolbox. We want to have different options that could be used by engineers to design these things.”

The design is inspired by the muscle-tendon-bone complex found in nature. There is a backbone of 3-D printed hydrogel, strong enough to give the bio-bot structure but flexible enough to bend like a joint. Two posts serve to anchor a strip of muscle to the backbone, like tendons attach muscle to bone, but the posts also act as feet for the bio-bot.


Sunday, June 29, 2014

Single-pixel 'multiplex' captures elusive terahertz images

Single-pixel 'multiplex' captures elusive terahertz images: The team reports it developed a "multiplex" tunable spatial light modulator (SLM) that uses a series of filter-like "masks" to retrieve multiple samples of a terahertz (THz) scene, which are reassembled by a single-pixel detector...

Data obtained from these encoded measurements are used to computationally reconstruct the images as much as six times faster than traditional raster scan THz devices, the team reports.

Thursday, June 26, 2014

Is time moving forward or backward? Computers learn to spot the difference | Science/AAAS | News

Is time moving forward or backward? Computers learn to spot the difference | Science/AAAS | News: To find out, she and her collaborators broke down 180 YouTube videos into square patches of a few hundred pixels, which they further divided into four-by-four grids. Combining standard techniques for discovering objects in still photographs with motion detection algorithms, the researchers identified 4000 typical patterns of motion, or “flow words,” across a grid’s 16 cells. The gentle downward drifting of snowflakes, for example, would be one flow word. From those patterns, the team created flow word descriptions of each video along with three other versions—a time-reversed version, a mirror-image version, and a mirror-image and time-reversed version. Then, they made a computer program watch 120 of these clips, training it to identify which flow words best revealed whether a video ran forward or backward.

When they tested their program on the remaining 60 videos, the trained computers could correctly determine whether a video ran forward or backward 80% of the time...  A closer analysis found that flow words associated with divergence (water splashing outward as someone dives into a pool) or dissipation (a steam train’s exhaust spreading out in air) were especially good indicators of the direction in which time was moving.


Cambridge team breaks superconductor world record

Cambridge team breaks superconductor world record: The Cambridge researchers managed to 'trap' a magnetic field with a strength of 17.6 Tesla - roughly 100 times stronger than the field generated by a typical fridge magnet - in a high temperature gadolinium barium copper oxide (GdBCO) superconductor, beating the previous record by 0.4 Tesla...

In order to hold in, or trap, the magnetic field, the researchers had to modify both the microstructure of GdBCO to increase its current carrying and thermal performance, and reinforce it with a stainless steel ring, which was used to 'shrink-wrap' the single grain samples. "This was an important step in achieving this result..."

...by engineering the bulk microstructure, the field is retained in the sample by so-called 'flux pinning centres' distributed throughout the material...

Wednesday, June 25, 2014

Embrace the lumpiverse: How mess kills dark energy - physics-math - 25 June 2014 - New Scientist

Embrace the lumpiverse: How mess kills dark energy - physics-math - 25 June 2014 - New Scientist: Wiltshire takes issue with the last of the motions used to make the dipole anisotropy disappear: a movement at a speed of 635 kilometres per second of the entire Local Group towards a "great attractor" somewhere in the distant Hydra-Centaurus supercluster of galaxies...

They claim the galaxies' movements make most sense if the Local Group isn't moving at all. Instead, the greater density of matter towards Hydra-Centaurus is slowing the universe's expansion along our line of sight, giving us the impression of such a movement. A comparative void in the other direction, meanwhile, is producing the opposite effect, causing an area of faster expansion behind us. The effects of the inhomogeneities along this axis are comparatively local, occurring on scales up to about 300 million light years, and only alter the universe's expansion rate by some 0.5 per cent. But they are sufficient to account for nearly all of the dipole anisotropy – and so colour our view of the entire universe...

This suggests that the age of the universe could be as much as 18.6 billion years in places where a low density of matter means the clock has ticked particularly fast. Our own smaller estimate of the universe's age is a natural consequence of sitting in an area of unusually high density: a galaxy.

Monday, June 23, 2014

First Evidence Of A Correction To The Speed of Light — The Physics arXiv Blog — Medium

First Evidence Of A Correction To The Speed of Light — The Physics arXiv Blog — Medium: Because all previous speed-of-light calculations have relied only on general relativity, they do not take into account the tiny effects of quantum mechanics. But these effects are significant over such long distances and through such a large mass as the Milky Way, says Franson...

Franson’s idea is that the gravitational potential must influence the electron-positron pair because they have mass. “Roughly speaking, the gravitational potential changes the energy of a virtual electron-positron pair, which in turn produces a small change in the energy of a photon,” he says. “This results in a small correction to the angular frequency of a photon and thus its velocity.”

Clingy dark matter may slow the spin of corpse stars - physics-math - 23 June 2014 - New Scientist

Clingy dark matter may slow the spin of corpse stars - physics-math - 23 June 2014 - New Scientist: Their strong magnetic fields gradually slow their spin, but over the past 15 years, astronomers have noticed that many pulsars are slowing more than we would expect.

Chris Kouvaris at the University of Southern Denmark thinks a form of dark matter with a tiny electric charge may be putting on the brakes.

Equations reveal the rebellious rhythms at the heart of nature

Equations reveal the rebellious rhythms at the heart of nature: Physicists Dmytro Iatsenko , Professor Peter McClintock, and Professor Aneta Stefanovska, have reported a far more general solution of the Kuramoto equations than anyone has achieved previously, with some quite unexpected results.

One surprise is that the oscillators can form "glassy" states, where they adjust the tempos of their rhythms but otherwise remain uncoordinated with each other, thus giving birth to some kind of "synchronous disorder" rather like the disordered molecular structure of window glass. Furthermore and even more astonishingly, under certain circumstances the oscillators can behave in a totally independent manner despite being tightly coupled together, the phenomenon the authors call "super-relaxation".

Friday, June 20, 2014

New test may provide 'smoking gun' for modified gravity

New test may provide 'smoking gun' for modified gravity: Now in a new paper published in Physical Review Letters, Wojciech A. Hellwing, et al., have proposed a new test of modified gravity that is based on measuring the tendency of well-separated galaxies to approach each other. This movement is called the galaxy pairwise velocity.
The physicists show that the galaxy pairwise velocity distribution of many galaxies with a wide range of masses is expected to deviate from the predictions of general relativity by significant amounts: between 5 and 10 standard deviations or higher, depending on the model. Due to these large deviations, this proposed test could potentially offer the strongest evidence in support of modified gravity to date.

Sound sieve lets you choose what to levitate - tech - 20 June 2014 - New Scientist

Sound sieve lets you choose what to levitate - tech - 20 June 2014 - New Scientist: The team etched a thin brass plate with rectangular strips and suspended it in a tank of water. Ultrasound blasted from above sends acoustic waves through the water that cause the plate to resonate with the bottom of the tank. The resulting sound pressure lifts objects placed below the plate according to size and density.

The team sorted small glass beads from larger ones and pulled glass beads away from tin beads of the same size...

Elastic invisibility cloak hides materials from touch sense

Elastic invisibility cloak hides materials from touch sense: The metamaterial is a crystalline material structured with sub-micrometer accuracy. It consists of needle-shaped cones, whose tips meet. The size of the contact points is calculated precisely to reach the mechanical properties desired. In this way, a structure results, through which a finger or a measurement instrument cannot feel its way.

In the invisibility cloak produced, a hard cylinder is inserted into the bottom layer. Any objects to be hidden can be put into its cavity. If a light foam or many layers of cotton would be placed above the hard cylinder, the cylinder would be more difficult to touch, but could still be felt as a form. The metamaterial structure directs the forces of the touching finger such that the cylinder is hidden completely...

Thursday, June 19, 2014

Quantum Method Closes in on Gravitational Constant - Scientific American

Quantum Method Closes in on Gravitational Constant - Scientific American; Researchers have been unable to identify the source of errors causing the disagreement in the conventional measurements. The set-up of the latest measurement is unlikely to contain the same errors as the torque method...

In the experiment described by Tino’s team, pulses of laser light tickle a cloud of rubidium atoms cooled to nearly absolute zero, driving the atoms to rise and fall like a fountain under the influence of gravity. The pulses split the 'matter wave' associated with each atom into a superposition of two energy states, each of which has a different velocity and reaches a different height — 60 or 90 centimeters — before falling back. The matter wave that rises farthest has a greater separation from the tungsten cylinders, and thus senses a slightly different gravitational pull. The difference in force imparts a measurable shift in the final state of the two matter waves when they recombine, creating an interference pattern.

Big Bang breakthrough team back-pedals on major result - physics-math - 19 June 2014 - New Scientist

Big Bang breakthrough team back-pedals on major result - physics-math - 19 June 2014 - New Scientist: The paper published today is significant because it is the first time the researchers themselves have dialled back on their original claims...

"It seems that real data from Planck is indicating that these dust models are under-estimates," says Pryke. "The prior knowledge of dust at these latitudes in our field of view has gone up and so the confidence in the gravitational wave component has gone down."

New ultrastiff, ultralight material developed | MIT News Office

New ultrastiff, ultralight material developed | MIT News Office: The actual production of such materials is made possible by a high-precision 3-D printing process called projection microstereolithography...

“We found that for a material as light and sparse as aerogel [a kind of glass foam], we see a mechanical stiffness that’s comparable to that of solid rubber, and 400 times stronger than a counterpart of similar density. Such samples can easily withstand a load of more than 160,000 times their own weight,” says Fang...

Wednesday, June 18, 2014

Human brain's ultimate barrier to open for first time - health - 18 June 2014 - New Scientist

Human brain's ultimate barrier to open for first time - health - 18 June 2014 - New Scientist: Next is a treatment called high-intensity focused ultrasound. The volunteers will wear a cap that contains an array of transducers that direct ultrasound waves into their brain. Just as the sun's rays can be focused by a magnifying glass, ultrasound waves can be concentrated inside the body to get the microbubbles to vibrate.

The vibrating bubbles will expand and contract about 200,000 times a second, which will force apart the endothelial cells that form the BBB. The idea is that this will allow the chemotherapy drug in the bloodstream to sneak through the gaps in the barrier and into any nearby tumour cells...

If Spacetime Were a Superfluid, Would It Unify Physics—or Is the Theory All Wet? - Scientific American

If Spacetime Were a Superfluid, Would It Unify Physics—or Is the Theory All Wet? - Scientific American: If it is true that spacetime is a superfluid and that photons of different energies travel at different speeds or dissipate over time, that means relativity does not hold in all situations. One of the main tenets of relativity, the Lorentz invariance, states that the speed of light is unchanging, regardless of an observer’s frame of reference. “The possibility that spacetime as we know it emerges from something that violates relativity is a fairly radical one,” Jacobson says. It does, however, clear a potential pathway toward rectifying some of the problems that arise when trying to combine relativity and quantum mechanics. “Violating relativity would open up the possibility of eliminating infinite quantities that arise in present theory and which seem to some unlikely to be physically correct.”

Monday, June 16, 2014

Quantum biology: Algae evolved to switch quantum coherence on and off

Quantum biology: Algae evolved to switch quantum coherence on and off: "Most cryptophytes have a light-harvesting system where quantum coherence is present. But we have found a class of cryptophytes where it is switched off because of a genetic mutation that alters the shape of a light-harvesting protein.
"This is a very exciting find. It means we will be able to uncover the role of quantum coherence in photosynthesis by comparing organisms with the two different types of proteins."

Quantum theory reveals puzzling pattern in how people respond to some surveys

Quantum theory reveals puzzling pattern in how people respond to some surveys: The survey changed the order in which these questions were asked between respondents and, as expected, there were question-order effects found. When respondents were asked about Clinton first, 49 percent said that both Clinton and Gore were trustworthy. But when respondents were asked about Gore first, 56 percent said that both were trustworthy.

The pattern that quantum theory predicted – and that the researchers found – was that the number of people who switch from "yes-yes" to "no-no" when the question order is reversed must be offset by the number of people who switch in the opposite direction...

The researchers called this phenomenon "quantum question equality." They found it in every one of the surveys studied.

First Movie Of An Entire Brain’s Neuronal Activity — The Physics arXiv Blog — Medium

First Movie Of An Entire Brain’s Neuronal Activity — The Physics arXiv Blog — Medium: ...Schrödel, Prevedel and co developed a way to ensure that the genes only fluoresce in the nucleus of each neuron. That makes active neurons much easier to tell apart...

...light sculpting. This works by bouncing the spot of laser light off a grating that stretches it out. This creates a disc of light that images an area of the brain in one go rather than a single point. In affect, it produces a cross-sectional image of brain activtiy.

The advantage is that the light disc need only be scanned in one direction to capture the whole volume of the brain. And this can be done at a rate that allows the team to film the neuronal activity of the entire brain at a rate of 80 frames per second.

Sunday, June 15, 2014

Create the ultimate world clock with a quantum link - physics-math - 15 June 2014 - New Scientist

Create the ultimate world clock with a quantum link - physics-math - 15 June 2014 - New Scientist: Timekeeping institutes around the world each have their own caesium clocks. They submit their time signal measurements to the International Bureau of Weights and Measures in Paris, France, which averages them and publishes a monthly newsletter that sets Coordinated Universal Time (UTC). But that means there is no real-time measure of a universally agreed standard time...

...The team calculates that a global quantum clock network would be about 100 times more precise than any individual clock...


Friday, June 13, 2014

Ultrasonic imaging at 1,000 times times higher resolution | KurzweilAI

Ultrasonic imaging at 1,000 times times higher resolution | KurzweilAI: The researchers used a combination of subpicosecond laser pulses and unique nanostructures to produce acoustic phonons... at a frequency of 10 gigahertz (10 billion cycles per second).

By comparison, medical ultrasounds devices today typically reach a frequency of only about 20 megahertz...

“To generate 10 GHz acoustic frequencies in our plasmonic nanostructures we use a technique known as picosecond ultrasonics,” said author are Kevin O’Brien. “Sub-picosecond pulses of laser light excite plasmons which dissipate their energy as heat. The nanostructure rapidly expands and generates coherent acoustic phonons. This process transduces photons from the laser into coherent phonons.”

Thursday, June 12, 2014

Could wireless replace wearables? | MIT News Office

Could wireless replace wearables? | MIT News Office: As described in an earlier MIT News story, the system works by transmitting a low-power wireless signal and using its reflections to track moving humans. It can do so even if the humans are in closed rooms or hiding behind a wall.

As the signal is transmitted at a wall, a portion of the signal penetrates through, reflecting off a person on the other side. However, due to all the signal interference from other objects, the team had to create technology to cancel out irrelevant reflections.

In order to monitor breathing, the technology needed to be precise: The researchers created a complex metric that approximates the subject’s volume, and then observed and amplified its changes to distinguish the breathing.

Long-range tunneling of quantum particles

Long-range tunneling of quantum particles: Experimental physicists in Innsbruck, Austria, have now directly observed quantum particles transmitting through a whole series of up to five potential barriers under conditions where a single particle could not do the move.

Synchronized brain waves enable rapid learning | MIT News Office

Synchronized brain waves enable rapid learning | MIT News Office:  Brain waves known as “beta bands,” produced independently by the prefrontal cortex and the striatum, began to synchronize with each other. This suggests that a communication circuit is forming between the two regions, Miller says.

“There is some unknown mechanism that allows these resonance patterns to form, and these circuits start humming together,” he says. “That humming may then foster subsequent long-term plasticity changes in the brain, so real anatomical circuits can form. But the first thing that happens is they start humming together..."

Previous studies have shown that during cognitively demanding tasks, there is increased synchrony between the frontal cortex and visual cortex, but Miller’s lab is the first to show specific patterns of synchrony linked to specific thoughts.

Friday, June 6, 2014

Researchers build optical invisibility cloak for a diffusive medium

Researchers build optical invisibility cloak for a diffusive medium: ...The tank was filled with a white, turbid liquid. Objects inside cast a visible shadow onto the tank wall. Simple metal cylinders or spheres of a few centimeters in diameter were used as test objects... To pass the light around the object, the researchers applied a thin shell made of the transparent silicon material PDMS, to which a certain concentration of light-scattering melamine microparticles was added. The silicon/melamine shell caused a quicker diffusion than in the environment and, thus, passed the light around the objects...

"Ideal optical invisibility cloaks in air have a drawback... They violate Albert Einstein's theory of relativity that prescribes an upper limit for the speed of light.  In diffuse media, in which light is scattered several times, however, the effective speed of light is reduced. Here, ideal invisibility cloaks can be realized."

Thursday, June 5, 2014

Continuous terahertz sources demonstrated at room temperature

Continuous terahertz sources demonstrated at room temperature: They have developed the first room-temperature, compact, continuous terahertz radiation source, and it's six times more efficient than previous systems...

The team generated terahertz radiation through nonlinear frequency mixing of two mid-infrared wavelengths at 8.8 microns and 9.8 microns from a single QCL chip. Room temperature, continuous terahertz emission with 3 microwatts is realized in a monolithic nonlinear QCL device with a tiny packaging dimension (as small as 2x5x8 mm3). This is achieved by improving the thermal conductance with epilayer-down bonding and a buried ridge waveguide, as well as by decreasing the optical loss with a buried composite grating for stable, single mode operation.

Wednesday, June 4, 2014

Mathematician unleashes 'a wave of new results' in geometric analysis

Mathematician unleashes 'a wave of new results' in geometric analysis: "If you drive into a parking garage and go up a level, that spiral ramp is part of a helicoid," he says. "And one of the things we were able to show was that every embedded minimal surface could be built out of these things. So the minimal surface either looks like a nice flat thing where the area is bounded, or it looks exactly like one of these double spiral staircases..."

They have been able to prove, he says, that of the infinite number of singularities that could possibly affect a surface through this curvature flow, only two types are stable enough to survive in reality. "If you were to wiggle your surface ever so slightly, in fact only two are stable of the infinitely many that are possible," Minicozzi says. "So if you are trying to understand [mean curvature flow] and you have to deal with all of these cases, it's much better to have to deal with two cases than an infinite number."

Tuesday, June 3, 2014

Proteins 'ring like bells'

Proteins 'ring like bells': Using modern laser spectroscopy, the scientists have been able to measure the vibrational spectrum of the enzyme lysozyme, a protein that fights off bacteria. They discovered that this enzyme rings like a bell with a frequency of a few terahertz or a million-million hertz. Most remarkably, the ringing involves the entire protein, meaning the ringing motion could be responsible for the transfer of energy across proteins.

The experiments show that the ringing motion lasts for only a picosecond or one millionth of a millionth of a second. Biochemical reactions take place on a picosecond timescale and the scientists believe that evolution has optimised enzymes to ring for just the right amount of time. Any shorter, and biochemical reactions would become inefficient as energy is drained from the system too quickly. Any longer and the enzyme would simple oscillate forever: react, unreact, react, unreact, etc...


Friday, May 30, 2014

Researchers design a new structure that absorbs all sound

Researchers design a new structure that absorbs all sound: In their work, the researchers have demonstrated how the designed structure achieves extraordinary sound absorption using an apparently contradictory strategy: the sound attenuation increases when the quantity of absorbent material is reduced. This way, a totally reflective surface becomes a perfect absorbent despite the fact that, for the most part, there is no material that absorbs sound.

Tuesday, May 27, 2014

Unbelievable Display Technology Uses Levitating Particles as Pixels

Unbelievable Display Technology Uses Levitating Particles as Pixels: Researchers actually figured out how to levitate objects using nothing but sound years ago, but to date it's really only been with single particles. This new research, from Yoichi Ochiai, Takayuki Hoshi, and Jun Rekimoto, presented at the annual Siggraph conference, involves hundreds of tiny specks, all strategically arranged in real-time to form images, and even moving animations.

The Flaw Lurking In Every Deep Neural Net

The Flaw Lurking In Every Deep Neural Net: "For all the networks we studied, for each sample, we always manage to generate very close, visually indistinguishable, adversarial examples that are misclassified by the original network."
To be clear, the adversarial examples looked to a human like the original, but the network misclassified them. You can have two photos that look not only like a cat but the same cat, indeed the same photo, to a human, but the machine gets one right and the other wrong.

Make Your Own World With Programmable Matter - IEEE Spectrum

Make Your Own World With Programmable Matter - IEEE Spectrum: Goldstein and his colleagues think that an efficient way to produce shape changes might be to fill the initial blob of catoms with lots of little voids and then shift them around to achieve the right contours. Small local movements of adjacent catoms would be sufficient to shift the cavities, and if they are allowed to bubble to the surface, the overall volume would shrink. Conversely, the material could expand by opening up pockets at the surface and engulfing them.

Monday, May 26, 2014

The Major Blunders That Held Back Progress in Modern Astronomy� — The Physics arXiv Blog — Medium

The Major Blunders That Held Back Progress in Modern Astronomy� — The Physics arXiv Blog — Medium: “A very common flaw of astronomers is to believe that they know the truth even when data is scarce,” says Loeb...

In 1952, the Russian-American astronomer Otto Struve suggested that close-in planets may exist and would be easy to spot but his paper was ignored because of exactly the same prejudices.


Researchers develop three-step process for building fractal nanostructures

Researchers develop three-step process for building fractal nanostructures: Greer's group has developed a three-step process for building such complex structures very precisely. They first use a direct laser writing method called two-photon lithography to "write" a three-dimensional pattern in a polymer, allowing a laser beam to crosslink and harden the polymer wherever it is focused. At the end of the patterning step, the parts of the polymer that were exposed to the laser remain intact while the rest is dissolved away, revealing a three-dimensional scaffold. Next, the scientists coat the polymer scaffold with a continuous, very thin layer of a material—it can be a ceramic, metal, metallic glass, semiconductor, "just about anything," Greer says. In this case, they used alumina, or aluminum oxide, which is a brittle ceramic, to coat the scaffold. In the final step they etch out the polymer from within the structure, leaving a hollow architecture.

Thursday, May 22, 2014

Are Black Holes All Shaped Like Doughnuts?

Are Black Holes All Shaped Like Doughnuts?: Black holes appear to have several different kinds of shapes. The unified model posits that the reasoning behind this is not that they are shaped differently, but that the perspective we're seeing them from shifts.

Wednesday, May 21, 2014

New method for propulsion in fluids | MIT News Office

New method for propulsion in fluids | MIT News Office: The effect itself is surprisingly simple, Peacock explains: “By virtue of heating or cooling the surface of an object, you change the density of any fluid next to that surface.” In the valley winds previously considered, the object was either a glacier or a valley wall heated by the sun, and the fluid was the air passing over it; in this case, it’s the solid wedge and its surrounding water.
The changed density of the fluid generates a flow over the surface, Peacock says, adding, “That flow then creates unbalanced forces, with lower pressure on one side, and higher on the other” — an imbalance that propels the object from the higher pressure toward the lower.

Backlash to Big Bang Discovery Gathers Steam - Scientific American

Backlash to Big Bang Discovery Gathers Steam - Scientific American: Spergel also says the BICEP2 team evidently failed to factor in contamination from the cosmic infrared background radiation that comes from distant, dusty galaxies. “When you do that,” Spergel says, “it’s probably enough to account for the entire signal they’re seeing.

Tuesday, May 20, 2014

Particles near absolute zero do not break the laws of physics after all

Particles near absolute zero do not break the laws of physics after all: The authors focused on a model system favored by thermodynamics experts that consists of a free particle strongly coupled to a heat bath, representing the effect of its environment... Previous theoretical predictions suggested that, under certain circumstances, the specific heat can decrease below zero at a temperature of strictly zero (−273.15°C)...

...In fact, a real particle will always be confined to a finite volume—even if that volume may be extremely large. Therefore, they discovered that previous studies need to be modified in order to account for a spatial confinement of the particle...

Sunday, May 18, 2014

Scientists discover how to turn light into matter after 80-year quest

Scientists discover how to turn light into matter after 80-year quest: The collider experiment that the scientists have proposed involves two key steps. First, the scientists would use an extremely powerful high-intensity laser to speed up electrons to just below the speed of light. They would then fire these electrons into a slab of gold to create a beam of photons a billion times more energetic than visible light.
The next stage of the experiment involves a tiny gold can called a hohlraum (German for 'empty room'). Scientists would fire a high-energy laser at the inner surface of this gold can, to create a thermal radiation field, generating light similar to the light emitted by stars.
They would then direct the photon beam from the first stage of the experiment through the centre of the can, causing the photons from the two sources to collide and form electrons and positrons. It would then be possible to detect the formation of the electrons and positrons when they exited the can.

Friday, May 16, 2014

New Double Helix Visualization Revises What We Know About DNA

New Double Helix Visualization Revises What We Know About DNA: Results reaffirmed the structure first suggested by Watson and Crick in 1953. But surprisingly, the single-molecule images showed major variations in the depths and grooves in the double helix structure.

Glasses-free 3-D projector (w/ Video)

Glasses-free 3-D projector (w/ Video): The MIT researchers—research scientist Gordon Wetzstein, graduate student Matthew Hirsch, and Ramesh Raskar, the NEC Career Development Associate Professor of Media Arts and Sciences and head of the Camera Culture group—built a prototype of their system using off-the-shelf components. The heart of the projector is a pair of liquid-crystal modulators—which are like tiny liquid-crystal displays (LCDs)—positioned between the light source and the lens. Patterns of light and dark on the first modulator effectively turn it into a bank of slightly angled light emitters—that is, light passing through it reaches the second modulator only at particular angles. The combinations of the patterns displayed by the two modulators thus ensure that the viewer will see slightly different images from different angles.

Thursday, May 15, 2014

‘Hyperbolic metamaterials’ closer to reality | KurzweilAI

‘Hyperbolic metamaterials’ closer to reality | KurzweilAI: The hyperbolic metamaterial behaves as a metal when light is passing through it in one direction and like a dielectric in the perpendicular direction. This “extreme anisotropy” leads to “hyperbolic dispersion” of light and the ability to extract many more photons from devices than otherwise possible, resulting in high performance...

The list of possible applications for metamaterials includes a “planar hyperlens” that could make optical microscopes 10 times more powerful and able to see objects as small as DNA, advanced sensors, more efficient solar collectors, and quantum computing.

Monday, May 12, 2014

Blockbuster Big Bang Result May Fizzle, Rumor Suggests | Science/AAAS | News

Blockbuster Big Bang Result May Fizzle, Rumor Suggests | Science/AAAS | News: To subtract the galactic foreground, BICEP researchers relied on a particular map of it generated by the European Space Agency's spacecraft Planck, which mapped the CMB across the entire sky from 2009 until last year. However, the BICEP team apparently interpreted the map as showing only the galactic emissions. In reality, it may also contain the largely unpolarized hazy glow from other galaxies, which has the effect of making the galactic microwaves coming from any particular point of the sky look less thoroughly polarized than they actually are. So using the map to strip out the galactic foreground may actually leave some of that foreground in the data where it could produce a spurious signal, Falkowski explains.

Friday, May 9, 2014

A Tractor Beam Made Of Sound Waves | Popular Science

A Tractor Beam Made Of Sound Waves | Popular Science: The device consists of about a thousand ultrasound emitters, placed underwater. When turned on, scientists used it to tug along centimeter-sized objects (roughly half and inch), such as a small hollow triangular shape. Normally the effect of sending acoustic beams at something would tend to push it away. But the scientists found that by precisely controlling the angle of sound waves, they can create a low pressure zone in front of the object, thus pulling it closer.

Quantum Random Number Generator Created Using A Smartphone Camera� — The Physics arXiv Blog — Medium

Quantum Random Number Generator Created Using A Smartphone Camera� — The Physics arXiv Blog — Medium:  It’s straightforward to calculate the average number of electrons this process should produce, given the probabilistic nature of photon emission. But the actual number of electrons should differ by a number that is random. That produces a single random digit. And since a light-sensitive array consists of many pixels working in parallel, it is possible to generate a large quantity of random digits from each image...

So the process of generating random numbers consists of pointing the camera at a green LED that evenly illuminates all the pixels and pressing the shutter button. A simple program then extracts the random digits.

Thursday, May 8, 2014

Scientists May Have Decoded One of the Secrets to Superconductors | Science | WIRED

Scientists May Have Decoded One of the Secrets to Superconductors | Science | WIRED: ...ripples of electrons inside the superconductors that are called charge density waves. The fine-grained structure of the waves, reported in two new papers by independent groups of researchers, suggests that they may be driven by the same force as superconductivity. Davis and his colleagues directly visualized the waves in a study posted online in April...

It seemed possible that if the force shaping electrons into charge density waves could be suppressed, its rival, the force that forms superconducting pairs, would flourish. But some researchers argued that the ripples of electrons were merely a surface anomaly and irrelevant to superconductivity.

The community remained divided until 2012, when two groups using a technique called resonant X-ray scattering managed to detect charge density waves deep inside cuprates, cementing the importance of the waves...


Wednesday, May 7, 2014

Fabrication technique brings metamaterial applications a step closer

Fabrication technique brings metamaterial applications a step closer: The second approach is to pattern a sacrificial substrate and then deposit repeated layers onto it. This 'pattern-first' process suffers from its own difficulties, the most important of which is that the total thickness of the final fishnet material is typically limited to tens of nanometers or less...

Zhou and colleagues were able to increase the total thickness of pattern-first fishnet films to around 300 nanometers, allowing five bilayers of film to be deposited and resulting in a strong characteristic resonance and pronounced metamaterial behavior. To achieve this, they adopted a technique called trilayer lift-off, which is commonly used in industry but seldom applied in research laboratories. It involves patterning a sacrificial layer of a photoresist resting on a layer of silicon dioxide under which lies a second photoresist layer...