Glasses-free 3-D TV looks nearer (w/ Video)

A new glasses-free 3-D video system uses three layered LCD panels displaying bizarre patterns (top three images) that collectively produce a coherent, high-resolution, multiperspective 3-D image. The bottom image illustrates, roughly, the composite image that would reach one eye at one viewing angle. Images courtesy of the Camera Culture group

Despite impressive recent advances, holographic television, which would present images that vary with varying perspectives, probably remains some distance in the future. But in a new paper featured as a research highlight at this summer’s Siggraph computer-graphics conference, the MIT Media Lab’s Camera Culture group offers a new approach to multiple-perspective, glasses-free 3-D that could prove much more practical in the short term.

Instead of the complex hardware required to produce holograms, the Media Lab system, dubbed a Tensor Display, uses several layers of liquid-crystal displays (LCDs), the technology currently found in most flat-panel TVs. To produce a convincing 3-D illusion, the LCDs would need to refresh at a rate of about 360 times a second, or 360 hertz. Such displays may not be far off: LCD TVs that boast 240-hertz refresh rates have already appeared on the market, just a few years after 120-hertz TVs made their debut.

“Holography works, it’s beautiful, nothing can touch its quality,” says Douglas Lanman, a postdoc at the Media Lab and one of the new paper’s co-authors. “The problem, of course, is that holograms don’t move. To make them move, you need to create a hologram in real time, and to do that, you need … little tiny pixels, smaller than anything we can build at large volume at low cost. So the question is, what do we have now? We have LCDs. They’re incredibly mature, and they’re cheap.”

Dark galaxies of the early Universe spotted for the first time

New nanodevice builds electricity from tiny pieces

Dark matter underpinnings of cosmic web found

THE skeleton of dark matter that undergirds the cosmic web of matter in the universe has been clearly detected for first time.

We know that matter in the cosmos forms a web, with galaxies and clusterslinked by filaments across mostly empty space. Filaments are made of normal matter and dark matter - the unseen stuff that makes up about 85 per cent of the universe's mass. Recent observations have seen the normal matter in such filaments.

Now Jörg Dietrich at the University Observatory in Munich, Germany, and his team have detected the dark matter component in a filament in a supercluster about 2.7 billion light years from us, called Abell 222/223.

The massive filament's gravity focuses the light travelling towards Earth from more distant background galaxies. The team used this light to calculate the filament's mass and shape. X-rays from the hot gas of normal matter in the vicinity showed that this matter lined up with the filament but made up only about 10 per cent of its mass. The rest must be dark matter (Nature, DOI: 10.1038/nature11224). This shows that the filament is "part of a network of dark matter that connects galaxy clusters throughout the universe", says Dietrich.

 source   NEW SCIENTIST

Confirmed: the Higgs boson does exist

A Rare Look at Quantum Mechanics in Action

In a world where seeing is believing, one of the chief disadvantages of quantum physics, unlike Newtonian physics, is that it’s largely invisible. The wonderfully bizarre rules that allow a vanishingly small particle to exist in two places simultaneously, or two seemingly isolated particles to influence each other across space—what Einstein called spooky action at distance—usually apply at scales too small to be seen by the naked eye. But not always. Here, physicist Boaz Almog of Israeli’s Tel Aviv University gives audience members of the 5th Annual World Science Festival Gala Celebration—and now the rest of us—a rare macroscopic view of the magical properties of quantum mechanics. Sharing the stage with fellow physicist Brian Green, Almog conducts the first public demonstration of an ethereal phenomenon he calls quantum levitation, sending a thin wafer super-chilled below -301 degrees F zipping around a circular track like a miniature flying saucer. Boaz also makes the wafer hover in midair, frozen as though trapped in a vat of invisible glue. How? Watch as Greene explains.

            


source  world science festival

Is Death An Illusion? Evidence Suggests Death Isn’t the End

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Switchable Nano Magnets May Revolutionize Data Storage: Magnetism of Individual Molecules Switched

Breaking the limits of classical physics

Graphene on boron nitride work may lead to breakthrough in microchip technology

 Graphene is the wonder material that could solve the problem of making ever faster computers and smaller mobile devices when current silicon microchip technology hits an inevitable wall. Graphene, a single layer of carbon atoms in a tight hexagonal arrangement, has been highly researched because of its incredible electronic properties, with theoretical speeds 100 times greater than silicon. But putting the material into a microchip that could outperform current silicon technology has proven difficult.

The answer may lie in new nanoscale systems based on ultrathin layers of materials with exotic properties. Called two-dimensional layered materials, these systems could be important for microelectronics, various types of hypersensitive sensors, catalysis,tissue engineering and energy storage. Researchers at Penn State have applied one such 2D layered material, a combination of graphene and hexagonal boron nitride, to produce improved transistor performance at an industrially relevant scale.

“Other groups have shown that graphene on boron nitride can improve performance two to three times, but not in a way that could be scaled up. For the first time, we have been able to take this material and apply it to make transistors at wafer scale,” said Joshua Robinson, assistant professor of materials science and engineering at Penn State and the corresponding author on a paper reporting their work in the online version of the journal ACS Nano.

In the article, the Penn State team describes a method for integrating a thin layer of graphene only one or two atoms thick, with a second layer of hexagonal boron nitride (hBN) with a thickness of a few atoms up to several hundred atoms. The resulting bilayer material constitutes the next step in creating functional graphene field effect transistors for high frequency electronic and optoelectronic devices.

Previous research by other groups has shown that a common material called hexagonal boron nitride (hBN), a synthetic mixture of boron and nitrogen that is used as an industrial lubricant and is found in many cosmetics, is a potential replacement for silicon dioxide and other high-performance dielectrics that have failed to integrate well with graphene. Because boron sits next to carbon on the periodic table, and hexagonal boron nitride has a similar arrangement of atoms as graphene, the two materials match up well electronically. In fact, hBN is often referred to as white graphene. To be of more than academic interest in the lab, however, the hBN-graphene bilayer had to be grown at wafer scale – from around 3 inches (75 mm) to almost 12 inches (300 mm).

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How the Universe escaped its 'dark ages'

Silicene: substitute for graphene

 

AFTER only a few years basking in the limelight, wonder material graphene has a competitor in the shape of silicene. For the first time, silicon has been turned into a sheet just one atom thick. Silicene is thought to have similar electronic properties to graphene but ought to be more compatible with silicon-based electronic devices.

Patrick Vogt of Berlin's Technical University in Germany, and colleagues at Aix-Marseille University in France created silicene by condensing silicon vapour onto a silver plate to form a single layer of atoms. They then measured the optical, chemical and electronic properties of the layer, showing it closely matched those predicted by theory (Physical Review Letters, DOI: 10.1103/PhysRevLett.108.155501).

Silicene may turn out to be a better bet than graphene for smaller and cheaper electronic devices because it can be integrated more easily into silicon chip production lines.

In 2010, another Aix-Marseille group led by Bernard Aufray attempted create silicene using a similar approach but failed to present convincing evidence that it was present. Michel Houssa of the Catholic University of Leuven (KUL) in Belgium, who was not involved in the new work, says: "In my opinion, this is the first compelling evidence that silicene can be grown on silver."

He says an important challenge now will be to grow silicene on insulating substrates to learn more about its electrical properties and understand how they can be exploited to build future electronic devices.

Einstein was right, neutrino researchers admit

 

Self Sculpting Sand

Research currently underway at MIT’s Distributed Robotic Laboratory (DRL) could lead to an innovative replicative manufacturing technique with the disruptive potential equal to that of 3D printing. Imagine a sand-like material that could autonomously assemble itself into a replica of any object encased within. Incredible though this may sound, the DRL researchers have already managed to build a large scale proof-of-concept, with 10-mm cubes acting as the grains.

Before we go into how these cubes - or "smart pebbles" - work, let’s sketch out the general concept. The idea is to create objects using a subtractive method, where excess material is removed just like when carving in stone. Each grain of smart sand would be a self-contained micro computer. These tiny machines would use an elaborate algorithm to communicate with the neighboring particles in order to establish the exact position and shape of the input object so that it can be replicated.

The already mentioned smart pebbles demonstrate this principle in a more easily understandable 2D setting. First the pebbles establish which of them border on the perimeter of the object to be replicated. Once identified, these particles pass on a message to their neighbors, and effectively specific particles selected by the algorithm are notified that an identical (or scaled) arrangement should be recreated a safe distance away, so that the two shapes do not overlap.Once the perimeter of the copy is identified, the pebbles within that area bond to each other, while the redundant material simply falls away. The resultant object would be solid, but it could be easily deconstructed simply by putting it back into the heap of smart sand. The constituent grains would detach from each other and the whole process could be repeated with an entirely new shape.

Each smart pebble cube used for testing was equipped with a set of electro-permanent magnets on four sides. The magnetic properties of such magnets can be switched on and off using electrical impulses, but unlike electromagnets, they do not require electricity to sustain these properties over time. With each particle neighboring on eight other particles in a 2D scenario, the magnets allow for selective bonding with any of the neighbors. However, the magnets also play a role in communication and power sharing.

Each smart pebble was also fitted with a rudimentary microprocessor capable of storing 32 kilobytes of code and boasting two kilobytes of working memory. With such limited processing power at the disposal of a single unit, the main computational heft had to fall on the distributed intelligence algorithm that constitutes the core of the current DRL endeavors.
"How do you develop efficient algorithms that do not waste any information at the level of communication and at the level of storage?" asks Daniela Rus, a computer science and engineering professor at MIT. The answer to that question is likely to be found in a paper that Rus co-authored with her student, Kyle Gilpin, and which is going to be presented in May at the IEEE International Conference on Robotics and Automation.

The algorithms developed at DRL have already been shown to work robustly with 3D scenarios, where the bed of smart sand would be divided into layers, each constituting a separate 2D grid. Now the only thing that stops smart sand from joining 3D printing in revolutionizing the world of rapid manufacturing is getting the scale right.

But according to Robert Wood, an associate professor of electrical engineering at Harvard University, this is not an issue. Wood reckons recreating the functionalities of the smart pebbles in smaller scale is feasible. Yes, it would require quite a lot of engineering, but the goal is well defined and reachable. “That’s a well-posed but very difficult set of engineering challenges that they could continue to address in the future.”, he says. If Wood is right, the future of subtractive manufacturing is bright.

Watch the video below to find out more about the algorithm behind smart pebbles.

Source: MIT

Hawking's 'Escher-verse' could be theory of everything

Stephen Hawking has come up with a way to describe the universe that suggests it may have the same geometry as mind-boggling images by M. C. Escher

THE universe may have the same surreal geometry as some of art's most mind-boggling images. That's the upshot of a study by the world's most famous living scientist, Stephen Hawking of the University of Cambridge.

The finding may delight fans of Dutch artist M. C. Escher, but Hawking's team claim that their study provides a way to square the geometric demands of string theory, a still-hypothetical "theory of everything", with the universe we observe.

Their calculations rely on a mathematical twist that was previously considered impossible. If it stands up, it could explain how the universe emerged from the big bang and unite gravity and quantum mechanics.

"We have a new route towards constructing string theory models of our world," says Hawking's colleague Thomas Hertog of the Institute for Theoretical Physics at the Catholic University of Leuven (KUL) in Belgium.

On the face of it, the idea that Escher's images can describe the layout of the universe seems to contradict what we know about it.

The images in question are tessellations, arrangements of repeated shapes, such as the images of interlocking bats and angels seen in Circle Limit IV. Although these are flat, they serve as "projections" of an alternative geometry called hyperbolic space, rather like a flat map of the world is a projection of a globe. For example, although the bats in the flat projection appear to shrink at an exponential rate at the edges, in hyperbolic space they are all the same size. These distortions in the projection arise because hyperbolic space cannot lie flat. Instead, it resembles a twisting, wiggly landscape of saddle-like hills.

That is not what our universe seems to look like. Measurements of the cosmic microwave background - the echo of the big bang - and distances to supernovae have revealed that our universe is flat, not twisted.

It is also expanding at an accelerating rate, because of a mysterious entity known as dark energy. We don't know what dark energy is or where it came from, but the mathematical language provided by Einstein's theory of general relativity has a way to describe this accelerated expansion. Sticking a constant - known as the cosmological constant - into the general-relativity equations keeps the universe expanding forever, but only if the constant has a positive sign. Until now, saying we live in an ever-expanding universe has been the same as saying our universe has a positive cosmological constant.

There are some outstanding problems, however. General relativity covers this aspect of the universe, but it can't describe the big bang. Nor can it unite gravity, which works on large scales, with quantum mechanics, which works on very small scales. "That means you cannot predict why we live in the universe that we live in," Hertog says.

String theory, in the meantime, offers a beautifully complete picture of the universe's history and connects gravity to quantum mechanics - but is most comfortable in a universe with a negatively curved, Escher-like geometry and with a negative cosmological constant.

This left physicists with a deep chasm to cross: on one side is a universe that works but lacks a complete theory, and on the other is a complete theory that doesn't describe the actual universe.

Now, Hawking, Hertog and James Hartle of the University of California, Santa Barbara, are proposing a bridge. They have found a way to produce expanding, accelerating universes using a negative cosmological constant. This means that string theory may, after all, describe the universe that we observe. The proposal grew from an idea that Hawking and Hartle had in the 1980s to get around general relativity's shortcomings by looking for a quantum picture of cosmology.

In quantum mechanics, a single equation called the wave function describes all the possible states that a quantum object can be in, and assigns each of them a certain probability. Hawking and Hartle sought a similar wave function that can generate the probability of various universes arising from the big bang. It would describe all the possible universes that could have been - including ones in which the solar system never formed, or in which life might have evolved very differently.

Over the past 30 years, Hawking and Hartle have been forcing a positive cosmological constant into their wave function, because that was considered necessary. But that meant sacrificing precision: they just couldn't get these universes to be anything more than clunky approximations of reality.

Tip the balanceString theorists had also been struggling with universes with positive cosmological constants, which tend to be unstable. Building them is a bit like trying to balance a pencil on its tip: it might work for a while, but the pencil's most energetically stable state is lying flat on the table, and eventually it will fall over. The most successful versions of string theory would rather live in the Escher-verse.

"String theory with a negative cosmological constant just goes much better," Hertog says.

But Hawking's latest work suggests that this supposed flaw may actually be the thing that knits string theory back to reality. In a paper posted online, Hawking and colleagues describe how they produced a plethora of universes from wave functions with negative cosmological constants, some of which are expanding and accelerating (arxiv.org/abs/1205.3807).

"Some of those universes are accelerating, just like our universe," Hertog says. "It turns out the quantum state includes both kinds of universes, automatically." For a certain wave function, these accelerating and expanding universes even turn out to be the most likely ones.

The key to this insight was recognising that the universes generated by the team's wave function could evolve to look a lot like a particular formulation of string theory, produced by Juan Maldacena of the Institute for Advanced Study in Princeton, New Jersey in 1997 (arxiv.org/abs/hep-th/9711200). "There was a mathematical connection, a very elegant connection," Hertog says.

Once they had spotted its connection to their wave function, Hawking's team decided to try to stitch the two together by writing a new wave function with a negative cosmological constant. They reasoned that this would allow them to borrow the beautifully complete mathematical picture of the universe provided by string theory and produce universes that accelerate outwards.

What about the observations suggesting that our universe is flat? Similar to how Newton's laws of motion work for everyday objects but give way to the more comprehensive laws of Einstein on cosmological scales, Hawking's team thinks that the universe's apparent flatness may describe it well as far as we can see but ultimately gives way to an underlying Escher-like geometry.

It is too soon to declare the universe solved. Maldacena says the Hawking team's model leaves out aspects of complete versions of string theory, such as provisions for the stability of some particles. "It would be wonderful if it was all we need to do," he says. "But I think it's too simplified. It's hard to see how it can be expanded to a more complete theory."

Hertog agrees that their work isn't finished - but thinks that the negative cosmological constant will eventually lead to a complete, description of the universe we observe. "It's an avenue that is opening up now," he says, "not something we have yet."