NEWS : TECH (NFPC)

Light Powers Levitating Magnets

Magnetic levitation is old hat these days, with maglev trains operating in China and planned systems taking shape in other countries. But they run by manipulating the train, which is "floating" on a magnetic field, with electricity. Now a team of researchers in Japan have found a way to manipulate magnetically levitating objects using light. The technique could lead to new forms of powered maglev transportation systems and could make solar-powered generators more efficient.

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To make the levitating graphite device, Masayuki Kobayashi and professor Jiro Abe of Aoyama Gakuin University in Kanagawa arranged a set of magnets made of neodymium, iron and boron in a grid. They then put a piece of graphite on top of the grid. When exposed to an external magnetic field, graphite -- specifically an artificial type called pyrolitic graphite -- generates its own field that repels the external one, a property called diamagnetism. That makes graphite levitate when it's placed on top of permanent magnets.

The researchers then hit the graphite with a laser. The laser heated up part of the graphite and changed its susceptibility to the surrounding magnetic field. Hitting the graphite in the center made it sink, as the heating was more even. Aiming the laser at the edge made it move in the direction of the beam.

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Next, they put the graphite on top of a tower of cylindrical magnets and hit the edge of it with the laser beam. The result was a little graphite disc spinning at up to 200 rpm when it was exposed to the laser -- or sunlight.

The researchers published the results of their study in the Journal of the American Chemical Society.

Being able to generate useful mechanical motion this way could change the way solar power setups are made. A spinning disk could run a generator directly rather than extracting the energy in several steps such as converting the DC current from a photovoltaic cell or using solar power to make steam.

Via Physorg, Journal of the American Chemical Society

Credit: Masayuki Kobayashi and Jiro Abe

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Sonic 'Bullets' Could Destroy Tumors Better

Ultrasound is often used to destroy cancerous cells. The sound waves emitted from an ultrasonic device raise the temperature of diseased cells, causing them to die. But there's a limit to how intense the sound wave can be -- too much and they'll damage the surrounding healthy tissue.

Now scientists at the California Institute of Technology are experimenting with sound "bullets" that could improve cancer treatments by better focussing the waves on precise areas. The technique could also improve sonar, which is used to create images of objects underwater.

At a recent gathering of the American Physical Society in San Diego, a team of researchers led by Chiara Daraio described their experiments with shaping sound energy into focused bullets. 

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Ordinary ultrasound sends sound waves into a material. Those waves bounce back to the source, where a computer analyzes the signal and creates an image. But the images can be fuzzy, since the waves are traveling back and forth through a material and getting dispersed. Sonar is similar. A submarine typically uses it to "ping" its surrounding. But again, the sound waves get dispersed through the water and may be scattered further by particles or small fish suspended in it. It's similar to how headlights scatter in the rain, making it more difficult to see.

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The Cal Tech team devised a technique that overcomes the challenges of dispersal and provides sharper images. Their innovation works in a way similar to the Newton's Cradle toy, in which a row of metal balls hang from strings. If you pull back on a ball at one end and allow it to swing and collide with the row of balls, the energy passes through all of the balls and gets transferred to the one on the opposite end, causing it to swing up.

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In the case of the Cal Tech's innovation, rows of tiny steel spheres are arranged rows and columns to form a cube shape. The sound waves travel through the balls, emerging as a pulse at the end of the array. The pulse of sound is concentrated and therefore has more power than the conventional ultrasound, which emits sound waves in a continous flow. More power results in a higher resolution image.

Daraio told Discovery News that because it's possible to control the sound energy this way, it's possible to make a kind of ultrasound machine that wouldn't suffer from the scattering and wave diffraction problems that ordinary ultrasound does. The same is true of sonar. Because the pulse of sound is short, rather than continuous, sending a high-power pulse through tissue would be safer to do. When treating tumors this way, more energy could be sent at one time, with tighter focus.

The next step is to refine the experiments and see if they work for real imaging.

Credit: California Institute of Technology

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Seafloor Platform 'Cloaks' Big Ocean Waves

Floating offshore oil drilling platforms, offshore wind farms and buoys are vulnerable to waves, especially those from storm swells. But a team of engineers has found a way to make those ocean-faring structures invisible to waves. The technique could help protect marine structures from damage when big storms hit.

Mohammed-Reza Alam, assistant professor of mechanical engineering at the University of California, Berkeley, have designed a rippled platform that sits on the seafloor directly below an ocean-faring structure. The ripples in the platform influence the the behavior of the water all the way up to the surface -- ultimately reducing the size of damaging surface waves. Alam calls his technique a "cloak" because it makes the ocean structure invisible to the surrounding waves. He presented the work Monday at an American Physical Society conference in San Diego.

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The seafloor influences the beahavior of surface waves because of the unique structure of deep water. The top is heated by the sun, making the surface less dense as the heat expands it. Meanwhile, at the bottom, the water is cold and dense with more salt in it. The place where the two layers meet and where the temperature and density changes is called the thermocline. 

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In that layer are "internal" waves. If one could pull off the top layer of ocean, the internal waves would look a lot like ordinary surface waves, except they would probably be longer (lower frequency) and taller (higher amplitude) than the ones on the surface. They happen because the waves on the surface are transmitting energy to the sea floor. Just as the energy from wind makes waves on the surface, the energy is transferred to the thermocline, where it make the internal waves.

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Meanwhile, the seafloor isn't perfectly smooth. The shape of it can affect the motion of deep water as it flows over it and some of that energy can get transferred all the way back to surface waves.

Alam found that if he used a rippled sheet of material, one that had a specific set of heights and lengths, and put it on the oceanfloor, the energy from deep water would make the internal waves in the thermocline more energentic, but cancel out surface waves. That makes for calm water on the surface.

An Invisibility Cloak For Heat

Alam told Discovery News that if one were building a working version -- something several years away at least -- it would only need to face in one direction, since you only need to cancel the waves out when they are approaching. Waves also tend to come from one side -- they don't often go from shore to sea, for instance.

He added that there is a lot of interest in this kind of work for another reason: underwater acoustics. Understanding how sound transmits through water is crucial for designing better sonar. The interface between warm and cold water can affect what a sonar system "sees" and better understanding that layer could improve sonar systems.

Beyond building something to protect floating structures, this kind of work could also help engineers decide where to put them. The "cloaking" effect sometimes occurs because the seafloor isn't level; there are areas of calm water as a result. Putting an oil drilling platform in a place where big waves are less likely to happen at all would make the whole operation safer.

Credit: Mick Roessler/Corbis

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Deadly Tesla Lightning Battle: Gotta-See Video

Superheroes like Iron Man make their way to being super through technology, and now we have some of those powers today.

This video shows two people battling it out using electricity. They're throwing lightning bolts at each other while doused in red and blue lights. The whole choreographed show took place on the streets of Belfast, Ireland and though the fun starts at about 1:40, these guys are workin' it the whole time.

Tesla coils at high amperage allow electrical current to jump through the air through conductive material. Human bodies DO conduct electricity but these performers are wearing special suits to protect their fragile human forms.

If only science gladiators could battle it out like this...via dVice

Want to recommend a video? Tweet it to @Discovery_News with the hashtag #GottaSeeVideos.

Don't miss today's Must-Read DNews Nuggets and you can watch Discovery Curiosity video here.

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Lab Gamifies Einstein's Relativity

Relativity is a hard concept to grasp. So to make it easier to understand, researchers from the Massachusetts Institute of Technology's Game Lab decided to turn it into a game. The developed "A Slower Speed of Light." The game itself is really simple: run around a landscape and collect multicolored orbs until you acquire 100 of them.

But it's the world of the game that gets interesting: as you collect more orbs, the speed of light slows down. The player sees more extreme effects of this as she walks around.

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What are some of these effects? For one thing, you'd be able to see beyond visible light into the infrared and ultraviolet spectrum. This is because as an observer moves forward, the light waves she sees coming toward her from other objects get compressed -- they get shorter. Anything producing infrared light will become visible. Eventually it would possible to see radio waves.

Meanwhile, the light waves from any objects she is passing by will stretch out, making the objects look redder. As she looks behind her, the visible light will all eventually move to the infrared. Eventually, even gamma and X-rays would become visible. The phenomenon is known as the Doppler effect.

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Another consequence of relativity is concentrating the light from objects in front of you -- and to the sides. It's called relativistic aberration. Objects on either side start to enter the field of view in the front, and the world starts to look like it does through a fish-eye lens. It also means anything in front of you looks brighter. Move backwards, and the world seems to go darker as the light waves you can see come from a narrower and narrower field.

The game also adds in time dilation and altering the length of space dimensions in the direction of motion. As one approaches the speed of light, time slows down –- the observer's clock moves more slowly than a stationary one. This is the source of the "twin paradox" in which one twin who travels near the speed of light for years ages more slowly than her sister on Earth, though the slowly aging twin doesn't notice until she returns to her now-older sisiter. (It's also a common plot device in science fiction novels, notably Joe Haldeman's The Forever War).

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Less well-known is the shortening of length dimensions -– a moving object looks shorter in its direction of motion, so a person running by at near light speed would look as though they had been flattened to an outside observer. The runner wouldn't see any difference.

The result is a world where everything bends and other objects seem to slow down, and it becomes difficult not to overshoot targets.

The game might be too simple for some people but it doesn't have to stay that way: the code is open source, so anyone who wants to design a game in the world governed by relativity will be able to do so.

Photo: The world at about 25 percent lightspeed. Credit: MIT Game Lab

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Quantum Teleportation Race Heats Up

Whether it's Captain Kirk's iconic "Beam me up, Scotty" or Mike Teavee whizzing through the air in a million little pieces compliments of Wonkavision, teleportation has always occupied a fascinating seat within the grandstands of pop culture.

Science has not yet caught up to the fiction of beaming a person or object between two places, however, quantum teleportation is no fantasy. In fact, it's been proven so many times that an international space race to develop quantum teleportation in currently underway.

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In the past year, a team of Chinese researchers and another group from Austria set new records for beaming bits of subatomic information and particles. Both teams used a laser to transport photons through the air over 60 and 89 miles, respectively.

Considering the previous record, set in 2012 by the Chinese team, was 10 miles, such exponential growth in such a short time has scientists and space agencies reaching for the stars.

"There’s basically a race going on to get into space first with a quantum satellite," Thomas Jennewein, a physicist at the University of Waterloo in Ontario, Canada, told Wired.

The Chinese space agency has plans to launch a satellite with quantum teleporation capabilities in 2016. European, Japanese and Canadian space agencies also have plans to launch similar projects in the coming years.

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Bringing up the rear in race is the U.S., whose quantum communication programs have stumbled in recent years, largely due to bureaucratic reshuffling that left research projects without government support in 2008.

"There's been a four-year gap and the world doesn't stand still," said physicist Richard Hughes of the Alamos National Laboratory in New Mexico. "It's interesting how strong China has become in the last four or five years in the international science scene -- they've really come along fast."

via Wired

Credit: VICTOR HABBICK VISIONS/Science Photo Library/Corbis

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Internet Billionaire Sweetens Pot: DNews Nugget

Internet Billionaire Sweetens Pot: Two months ago, tech investor Yuri Milner awarded $27 million to nine winners of his first Fundamental Physics Prize. The cash prizes dwarfed all other scientific awards, notably the money given to Nobel Prize winners. Today, Milner’s foundation announced yet another award, the Physics Frontiers Prize, which will place three individuals in the running for a $3 million prize. Runners up will receive $300,000. Three Physics Frontiers Prize laureates will be announced by the end of the year. These scientists will become eligible for the multimillion-dollar Fundamental Physics Prize, which will be awarded in 2013. via Nature News

GET MORE MUST-READ NUGGETS HERE!

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A Dry Run For Fusion Power

The reality of fusion power the same energy that powers the sun remains outside of our reach. Although scientists have figured out how to split atoms and attain nuclear reactions, they have yet to find an efficient way to fuse atoms. So far, techniques require more energy than what's produced.

But at Sandia labs, researchers are getting closer. Recent experiments led by plasma physicist Ryan McBride show that it's possible to reach a "break even" point, where the energy that goes into running a fusion reactor is equal to energy produced. That's a big step toward an alternative energy that produces emission-free energy without the nuclear waste.

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The fusion method at Sandia is called magnetized inertial fusion. Doing it requires a system of coils at each end of a beryllium cylinder just under seven millimeters across. Inside the cylinder is a small amount of deuterium, which is an abundant molecule in the ocean made of hydrogen with an extra neutron.

Here's how the reactor works: First the two coils generate a magnetic field. A few milliseconds later, an accelerator called the Z machine fires a 25-million-ampere current. That current generates a magnetic field that crushes the cylinder in 100 billionths of a second. In that short space of time a laser fires at the cylinder, heating the deuterium gas inside and turning it into a plasma. The two coils at the end, meanwhile, are generating a magnetic field that contains the plasma to allow it to fuse.

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In this experiment, the compression part of that system was tested. The current was run through the coils and the beryllium cylinder was compressed, and retained its shape. This is important because if the cylinder deforms too much, there isn't enough pressure on the whole sample deuterium to initiate fusion.

One of the factors that Sandia labs was trying to determine was how thick and large the cylinder should be. Too big, and the magnetic fields can't crush it. Too small and the electrical current will simply vaporize it completely before it can crush the plasma inside. They found the optimum proportion seems to be a cylinder with a wall about one sixth the radius.   

The experiment is an extension of simulations performed in March. The next step is to try pre-heating the deuterium with the laser, and after that -- possibly some time in late 2013 -- testing it with nuclear fuel inside. The fuel will be deuterium, and it won't be powerful enough to get past the "break even" point and produce energy. But McBride told Discovery News that the output should tell the researhers whether or not using tritium -- hydrogen with two neutrons -- will work when mixed with deuterium.

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So will this lead directly to fusion reactors? Not really, because the amount of current needed to get to "high gain" fusion -- which would mean energy output more than 1,000 times that applied to the fuel -- is more than twice what the Z machine can produce, some 60 million amperes. That said, if the proof-of-concept works, then there isn't any technical barrier to building such a machine. 

The experiment will be presented in an upcoming issue of Physical Review Letters.

Top Photo: Sandia researcher Ryan McBride pays close attention to the tiny central beryllium liner to be imploded by the powerful magnetic field generated by Sandia’s Z machine. The larger cylinders forming a circle on the exterior of the base plate measure Z’s load current by picking up the generated magnetic field.

Image: Sandia National Laboratories

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'Magic Carpet' Predicts Falls

Magic carpets aren't just for flying; they're now for falling. A team of researchers at the University of Manchester in England has developed a carpet embedded with optical fibers that can sense and map walking patterns in real time. The fibers send the information to a tiny electronics at the edge of the carpet that analyze the movement of the walker, identifying changes that may indicate a sudden fall or trip.

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But the computer can monitor the walking pattern over time, too, and recognize if a person's gait is unsteady. That information could be send to a healthcare aid as a warning that the person may fall.

Falls among older people are fairly common. As many as 30 percent to 40 percent of elderly people who live in community housing fall each year. And 50 percent of hospital admissions of people over age 65 are due to injuries from falls.

Smart carpets such as this one could be used in homes to help monitor the mobility of an elderly person or could be used by therapists to improve a patient's balance.

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In a press release, one of the researchers, Dr. Patricia Sully of the University of Manchester’s Photon Science Institute said, “The carpet can be retrofitted at low cost, to allow living space to adapt as the occupiers’ needs evolve – particularly relevant with an aging population and for those with long term disabilities – and incorporated non-intrusively into any living space or furniture surface such as a mattress or wall that a patient interacts with.”

The team presented their magic carpet innovation at this year's Photon 12 conference in Durham, U.K.

Credits: Andrew Bret Wallis (top); University of Manchester (bottom)

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Quantum Computing Closer with Lasers

In the future, computers will be faster than the fastest supercomputers of today, they'll be able crack any code, analyze gobs of data and know immediately if they're being infiltrated by hackers. The computers able to do that will be based on quantum physics, a mysterious and paradoxical area of physics that scientists are still trying to figure out. It requires, at its foundation, the ability to control a single photon.

But now, an international team of physicists and computer scientists from the Massachusetts Institute of Technology and led by Thibault Peyronel has built a device that turns a laser beam into a stream of single photons that can be turned on and off. That capability could lead to a quantum transistor. Transistors in conventional computers are turned on and off by electrical current.

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"What you have is individual photons controlling the switch," Thad Walker, professor of physics at the University of Wisconsin, told Discovery News. Walker was not connected with the research.

To get single photons, Peyronel and the team used two laser beams. The first one they at a cloud of rubidium atoms that were chilled to a temperature that was just hair above absolute zero. Next, the fired a second laser beam, called a control beam.

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Ordinarily, rubidium atoms are opaque. But after being hit with the second laser beam, they became transparent. In that state, photons were able to pass through the atoms, albeit slowly.

The photon didn't just slow down, either. Because the the rubidium atoms were in such an excited state, only one photon at a time was able to pass through the atom. When another photon entered the cloud of atoms, the rubidium becames opaque and the photon was unable to pass through.

Turning off the control beam also rendered the rubidium atom opaque, blocking any photons from passing through. That means the apparatus is an optically controlled switch, one that works on single photons.

The effect also implies that one could build a kind of quantum transistor. A rubidium chamber emitting single photons could be placed next to another just like it. The single photons would go to the second chamber. The first ones to get there could be let through while later ones would be stopped. Turn off the first chamber for a moment and the second one "opens" again.

That is essentially how transistors in conventional computers work, only those are controlled by electric current.

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The ability to send single photons also means it's possible to build a true quantum communications system. Quantum communications can't be eavesdropped upon, because doing so alters the state of the bits being transmitted. That's a dead giveaway to the person receiving the transmission.

This isn't the only group that managed to control single photons. At Georgia Tech, Alex Kuzmich and Yaroslav Dudin used a similar technique to produce single-photon emissions.

Walker noted these experiments also open the way to a lot of fundamental physics research. Ordinarily when a quantum state is measured, the photon is destroyed. The ability to control the transmission of one photon at a time also means one can measure the quantum state of the incoming photon without actually "touching" it.

The MIT research appeared in the journal Nature on July 25.

Image: MIT / Ofer Firstenberg and Yoav Sterman.

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