Tag: india

Metallic hydrogen, once theory, becomes reality

Metallic hydrogen, once theory, becomes reality

Image of diamond anvils compressing molecular hydrogen. At higher pressure the sample converts to atomic hydrogen, as shown on the right. Credit: R. Dias and I.F. Silvera

Nearly a century after it was theorized, Harvard scientists have succeeded in creating the rarest – and potentially one of the most valuable – materials on the planet.

The material – atomic  – was created by Thomas D. Cabot Professor of the Natural Sciences Isaac Silvera and post-doctoral fellow Ranga Dias. In addition to helping scientists answer fundamental questions about the nature of matter, the material is theorized to have a wide range of applications, including as a . The creation of the rare material is described in a January 26 paper published in Science.

“This is the holy grail of high-pressure physics,” Silvera said. “It’s the first-ever sample of metallic hydrogen on Earth, so when you’re looking at it, you’re looking at something that’s never existed before.”

To create it, Silvera and Dias squeezed a tiny hydrogen sample at 495 gigapascal, or more than 71.7 million pounds-per-square inch – greater than the pressure at the center of the Earth. At those extreme pressures, Silvera explained, solid molecular hydrogen -which consists of molecules on the lattice sites of the solid – breaks down, and the tightly bound molecules dissociate to transforms into , which is a metal.

While the work offers an important new window into understanding the general properties of hydrogen, it also offers tantalizing hints at potentially revolutionary new .

“One prediction that’s very important is metallic hydrogen is predicted to be meta-stable,” Silvera said. “That means if you take the pressure off, it will stay metallic, similar to the way diamonds form from graphite under intense heat and pressure, but remains a diamond when that pressure and heat is removed.”

Understanding whether the material is stable is important, Silvera said, because predictions suggest metallic hydrogen could act as a superconductor at room temperatures.

“That would be revolutionary,” he said. “As much as 15 percent of energy is lost to dissipation during transmission, so if you could make wires from this material and use them in the electrical grid, it could change that story.”

Among the holy grails of physics, a room temperature superconductor, Dias said, could radically change our transportation system, making magnetic levitation of high-speed trains possible, as well as making electric cars more efficient and improving the performance of many electronic devices.

The material could also provide major improvements in energy production and storage – because superconductors have zero resistance energy could be stored by maintaining currents in superconducting coils, and then be used when needed.

Metallic hydrogen, once theory, becomes reality
Photos of compressed hydrogen transitioning with increasing pressure from transparent molecular to black molecular to atomic metallic hydrogen. The sketches below show a molecular solid being compressed and then dissociated to atomic hydrogen. Credit: R. Dias and I.F. Silvera

Though it has the potential to transform life on Earth, metallic hydrogen could also play a key role in helping humans explore the far reaches of space, as the most powerful rocket propellant yet discovered.

“It takes a tremendous amount of energy to make metallic hydrogen,” Silvera explained. “And if you convert it back to molecular hydrogen, all that energy is released, so it would make it the most powerful rocket propellant known to man, and could revolutionize rocketry.”

The most powerful fuels in use today are characterized by a “specific impulse” – a measure, in seconds, of how fast a propellant is fired from the back of a rocket – of 450 seconds. The specific impulse for metallic hydrogen, by comparison, is theorized to be 1,700 seconds.

“That would easily allow you to explore the outer planets,” Silvera said. “We would be able to put rockets into orbit with only one stage, versus two, and could send up larger payloads, so it could be very important.”

To create the new material, Silvera and Dias turned to one of the hardest materials on Earth – diamond.

But rather than natural diamond, Silvera and Dias used two small pieces of carefully polished synthetic diamond which were then treated to make them even tougher and then mounted opposite each other in a device known as a .

“Diamonds are polished with diamond powder, and that can gouge out carbon from the surface,” Silvera said. “When we looked at the diamond using atomic force microscopy, we found defects, which could cause it to weaken and break.”

The solution, he said, was to use a reactive ion etching process to shave a tiny layer – just five microns thick, or about one-tenth of a human hair – from the diamond’s surface. The diamonds were then coated with a thin layer of alumina to prevent the hydrogen from diffusing into their crystal structure and embrittling them.

After more than four decades of work on metallic hydrogen, and nearly a century after it was first theorized, seeing the material for the first time, Silvera said, was thrilling.

“It was really exciting,” he said. “Ranga was running the experiment, and we thought we might get there, but when he called me and said, ‘The sample is shining,’ I went running down there, and it was metallic hydrogen.

“I immediately said we have to make the measurements to confirm it, so we rearranged the lab…and that’s what we did,” he said. “It’s a tremendous achievement, and even if it only exists in this diamond anvil cell at high pressure, it’s a very fundamental and transformative discovery.”

Advertisements

Probe for nanofibers has atom-scale sensitivity

Probe for nanofibers has atom-scale sensitivity

Graphic depicting nanofiber evanescent light (red) entering probe fiber (larger glass cylinder). Credit: E. Edwards

Optical fibers are the backbone of modern communications, shuttling information from A to B through thin glass filaments as pulses of light. They are used extensively in telecommunications, allowing information to travel at near the speed of light virtually without loss.

These days, biologists, physicists and other scientists regularly use optical fibers to pipe light around inside their labs. In one recent application, quantum research labs have been reshaping optical fibers, stretching them into tiny tapers (see Nanofibers and designer light traps). For these nanometer-scale tapers, or nanofibers, the injected light still makes its way from A to B, but some of it is forced to travel outside the fiber’s exterior surface. The exterior light, or evanescent field, can capture atoms and then carry information about that light-matter interaction to a detector.

Fine-tuning such evanescent light fields is tricky and requires tools for characterizing both the fiber and the light. To this end, researchers from JQI and the Army Research Laboratory (ARL) have developed a novel method to measure how light propagates through a nanofiber, allowing them to determine the nanofiber’s thickness to a precision less than the width of an atom. The technique, described in the January 20, 2017 issue of the journal Optica , is direct, fast and, unlike the standard imaging method, preserves the integrity of the fiber. As a result, the probe can be used in-situ with the nanofiber fabrication equipment, which will streamline implementation in quantum optics and quantum information experiments. Developing reliable and precise tools for this platform may enable nanofiber technology for sensing and metrology applications.

Light waves have a characteristic size called the wavelength. For visible light, the wavelength is roughly 100 times smaller than a human hair. Light can also have the appearance of different shapes, such a solid circle, ring, clover and more (see image below). Fibers restrict the way light waves can travel and twisting or bending a fiber will alter the light’s characteristics. Nanofibers are made by reshaping a normal fiber into an hourglass-like design, which further affects the guided light waves.

Probe for nanofibers has atom-scale sensitivity
Examples of light shapes. Each panel shows a 3D (top) and 2D (bottom) intensity profile. The red (blue) areas indicate more (less) light intensity. The effect of the fiber appears in the 3D images as a sharp cutout; in 2D the fiber interface looks like a ring-shaped edge. Credit: P. Solano and L. Orozco

In this experiment, researchers inject a combination of light shapes into a nanofiber. The light passes down a thinning taper, squeezes through a narrow waist, and then exits out the other side of the taper. The changing fiber size distorts the , and multiple patterns emerge from the interfering light shapes (See JQI News on Collecting lost light). This is analogous to musical notes, or sound waves, beating together to form a complex chord.

The researchers make direct measurements of the interference patterns (beats). To do this, they employ a second micron-sized fiber that acts as a non-invasive sensor. The nanofiber is on a moving stage and crosses the probe fiber at an oblique angle. At the touching point, a tiny fraction of nanofiber light evanescently enters the second fiber and travels to a detector. As they scan the probe along the length of the nanofiber, the probe detector collects information about the evolving patterns of nanofiber light. The researchers simultaneously monitor the light transmitting through the  to ensure that the probe process is harmless.

The team can achieve a high level of precision with this technique because they are not imaging the fiber with a camera, which would have a spatial resolution limited by the collected light’s wavelength. UMD graduate student Pablo Solano explains, “We are actually seeing the different light modes mix together and that sets the limits on determining the fiber waist—in this case sub-angstrom.” A standard tool known as scanning electron microscopy (SEM) can also measure fiber dimensions with nanoscale resolution. This, however, has a comparative disadvantage, says Eliot Fenton, a UMD undergraduate student working on the project, “With our new method, we can avoid using SEM, which destroys the fiber with imaging chemicals and heating.” Other techniques involve collecting randomly scattered light from the fiber, which is less direct and susceptible to errors. Solano summarizes how researchers can benefit from this new tool, “By directly and sensitively measuring the interference (beating) of  without destroying the fiber, we can know exactly the kind of electromagnetic field that we would apply to atoms.”

Hubble ‘cranes’ in for a closer look at a galaxy

Hubble 'cranes' in for a closer look at a galaxy

IC 5201 sits over 40 million light-years away from us. As with two thirds of all the spirals we see in the universe — including the Milky Way, the galaxy has a bar of stars slicing through its center. Credit: ESA/Hubble & NASA

In 1900, astronomer Joseph Lunt made a discovery: Peering through a telescope at Cape Town Observatory, the British-South African scientist spotted this beautiful sight in the southern constellation of Grus (The Crane): a barred spiral galaxy now named IC 5201.

Over a century later, the galaxy is still of interest to astronomers. For this image, the NASA/ESA Hubble Space Telescope used its Advanced Camera for Surveys (ACS) to produce a beautiful and intricate image of the galaxy. Hubble’s ACS can resolve individual stars within other galaxies, making it an invaluable tool to explore how various populations of stars sprang to life, evolved, and died throughout the cosmos.

IC 5201 sits over 40 million light-years away from us. As with two thirds of all the spirals we see in the Universe—including the Milky Way—the galaxy has a bar of stars slicing through its center.

New instrument could search for signatures of life on Mars

New instrument could search for signatures of life on Mars

This artist’s rendition shows how a proposed laser-fluorescence instrument could operate on Mars.

A sensing technique that the U.S. military currently uses to remotely monitor the air to detect potentially life-threatening chemicals, toxins, and pathogens has inspired a new instrument that could “sniff” for life on Mars and other targets in the solar system—the Bio-Indicator Lidar Instrument, or BILI.

Branimir Blagojevic, a NASA technologist at the Goddard Space Flight Center in Greenbelt, Maryland, formerly worked for a company that developed the sensor. He has applied the technology to create an instrument prototype, proving in testing that the same remote-sensing technology used to identify bio-hazards in public places also could be effective at detecting organic bio-signatures on Mars.

BILI is a fluorescence-based lidar, a type of remote-sensing instrument similar to radar in principle and operation. Instead of using radio waves, however, lidar instruments use light to detect and ultimately analyze the composition of particles in the atmosphere.

Although NASA has used fluorescence instruments to detect chemicals in Earth’s atmosphere as part of its climate-studies research, the agency so far hasn’t employed the technique in planetary studies. “NASA has never used it before for planetary ground level exploration. If the agency develops it, it will be the first of a kind,” Blagojevic said.

A Rover’s ‘Sense of Smell’

As a planetary-exploration tool, Blagojevic and his team, Goddard scientists Melissa Trainer and Alexander Pavlov, envision BILI as primarily “a rover’s sense of smell.”

Positioned on a rover’s mast, BILI would first scan the terrain looking for dust plumes. Once detected, the instrument, then would command its two ultraviolet lasers to pulse light at the dust. The illumination would cause the particles inside these dust clouds to resonate or fluoresce. By analyzing the fluorescence, scientists could determine if the dust contained organic particles created relatively recently or in the past. The data also would reveal the particles’ size.

“If the bio-signatures are there, it could be detected in the dust,” Blagojevic said

BILI’s Beauty

The beauty of BILI, Blagojevic added, is its ability to detect in real-time small levels of complex organic materials from a distance of several hundred meters. Therefore, it could autonomously search for bio-signatures in plumes above recurring slopes—areas not easily traversed by a rover carrying a variety of in-situ instruments for detailed chemical and biological analysis. Furthermore, because it could do a ground-level aerosol analysis from afar, BILI reduces the risk of sample contamination that could skew the results.

“This makes our instrument an excellent complementary organic-detection instrument, which we could use in tandem with more sensitive, point sensor-type mass spectrometers that can only measure a small amount of material at once,” Blagojevic said. “BILI’s measurements do not require consumables other than electrical power and can be conducted quickly over a broad area. This is a survey instrument, with a nose for certain molecules.”

With such a tool, which also could be installed on an orbiting spacecraft, NASA could dramatically increase the probability of finding bio-signatures in the solar system, he added. “We are ready to integrate and test this novel instrument, which would be capable of detecting a number organic bio-signatures,” Blagojevic said. “Our goal is increasing the likelihood of their discovery.”

Long Heritage

Blagojevic hopes to further advance BILI by ruggedizing the design, reducing its size, and confirming that it can detect tiny concentrations of a broad range of organic molecules, particularly in aerosols that would be found at the ground level on Mars.

“This sensing technique is a product of two decades of research,” Blagojevic said, referring to the technology created by his former employer, Science and Engineering Services, LLC..

Blagojevic and his team used NASA’s Center Innovation Fund, or CIF, to advance the technology. CIF stimulates and encourages creativity and innovation within NASA, targeting less mature, yet promising new technologies.

India’s budget mini space shuttle blasts off 

image

India successfully launched its first mini space shuttle on Monday as New Delhi’s famously frugal space agency joined the global race to make rockets as reusable as airplanes.

The shuttle was reportedly developed on a budget of just one billion rupees ($14 million), a fraction of the billions of dollars spent by other nations’ space programmes.

The Reusable Launch Vehicle, or RLV-TD, which is around the size of a minibus, hurtled into a blue sky over southeast India after its 7:00am (0130 GMT) lift off.

After reaching an altitude of about 70 kilometres (43 miles), it glided back down to Earth, splashing into the Bay of Bengal 10 minutes later.

The test mission was a small but crucial step towards eventually developing a full-size, reusable version of the shuttle to make space travel easier and cheaper in the future.

“We have successfully accomplished the RLV mission as a technology demonstrator,” Indian Space Research Organisation (ISRO) spokesman Devi Prasad Karnik told AFP.

The worldwide race for reuseable rockets intensified after NASA retired its space shuttle programme in 2011.

They are seen as key to cutting costs and waste in the space industry, which currently loses millions of dollars in jettisoned machinery after each launch.

Internet tycoon Elon Musk’s SpaceX and Blue Origin of Amazon owner Jeff Bezos have already successfully carried out their own test launches.

Musk told reporters in April that it currently costs about $300,000 to fuel a rocket and about $60 million to build one.

SpaceX first landed its powerful Falcon 9 rocket in December while Blue Origin’s New Shepard successfully completed a third launch and vertical landing in April this year.

But ISRO hopes to develop its own version, primarily to cash in on the huge and lucrative demand from other countries to send up their satellites.

Mission to Mars

The Indian space agency is no stranger to stellar achievements on a shoestring budget.

It made global headlines in 2013 after sending an unmanned rocket to orbit Mars at a cost of just $73 million. NASA’s Maven Mars mission had a $671 million price tag.

The launch and its low cost were a source of immense pride in India, which beat rival China in becoming the first Asian country to reach the Red Planet.

K. Sivan, a scientist involved in the latest project, said the seven-metre (23-foot) long shuttle survived the test flight, and scientists hope subsequent models six times as big, to be built over the next decade, will glide safely back to land.

“We have located the place where the vehicle is floating. The landing was soft and the vehicle did not break,” Sivan told AFP.

“The mission went off as planned and data from the experiment showed that we have achieved its objectives and demonstrated the RLV technology.”

Prime Minister Narendra Modi praised the “industrious efforts” of ISRO scientists.

“Dynamism & dedication with which our scientists & @isro have worked over the years is exceptional and very inspiring,” Modi said on Twitter.

Modi has often hailed India’s budget space technology, quipping in 2014 that a local rocket that launched four foreign satellites into orbit had cost less to make than Hollywood film “Gravity”.

Sea-level rise claims five islands in Solomons

image

Five islands have disappeared in the Pacific’s Solomon Islands due to rising sea levels and coastal erosion, according to an Australian study that could provide valuable insights for future research.

A further six reef islands have been severely eroded in the remote area of the Solomons, the study said, with one experiencing some 10 houses being swept into the sea between 2011 and 2014.

“At least 11 islands across the northern Solomon Islands have either totally disappeared over recent decades or are currently experiencing severe erosion,” the study published in Environmental Research Letters said.

“Shoreline recession at two sites has destroyed villages that have existed since at least 1935, leading to community relocations.”

The scientists said the five that had vanished were all vegetated reef islands up to five hectares (12 acres) that were occasionally used by fishermen but not populated.

“They were not just little sand islands,” leader author Simon Albert told AFP.

It is feared that the rise in sea levels will cause widespread erosion and inundation of low-lying atolls in the Pacific.

Albert, a senior research fellow at the University of Queensland, said the Solomons was considered asea-level hotspot because rises there are almost three times higher than the global average.

The researchers looked at 33 islands using aerial and satellite imagery from 1947 to 2014, combined with historical insight from local knowledge.

They found that rates of shoreline recession were substantially higher in areas exposed to high wave energy, indicating a “synergistic interaction” between sea-level rise and waves, which Albert said could prove useful for future study.

Those islands which were exposed to higher wave energy—in addition to sea-level rise—were found to have a greatly accelerated loss compared with the more sheltered islands.

“This provides a bit of an insight into the future,” he said.

“There’s these global trends that are happening but the local responses can be very, very localised.”

For now, some communities in the Solomons are already adapting to the changed conditions.

“In addition to these village relocations, Taro, the capital of Choiseul Province is set to become the first provincial capital globally to relocate residents and services due to the threat of sea-level rise,” the study said.

Physicists abuzz about possible new particle as CERN revs up

image

Scientists around the globe are revved up with excitement as the world’s biggest atom smasher—best known for revealing the Higgs boson four years ago—starts whirring again to churn out data that may confirm cautious hints of an entirely new particle.

Such a discovery would all but upend the most basic understanding of physics, experts say.

The European Center for Nuclear Research, or CERN by its French-language acronym, has in recent months given more oomph to the machinery in a 27-kilometer (17-mile) underground circuit along the French-Swiss border known as the Large Hadron Collider.

In a surprise development in December, two separate LHC detectors each turned up faint signs that could indicate a new particle, and since then theorizing has been rife.

“It’s a hint at a possible discovery,” said theoretical physicist Csaba Csaki, who isn’t involved in the experiments. “If this is really true, then it would possibly be the most exciting thing that I have seen in particle physics in my career—more exciting than the discovery of the Higgs itself.”

After a wintertime break, the Large Hadron Collider, or LHC, reopened on March 25 to prepare for a restart in early May. CERN scientists are doing safety tests and scrubbing clean the pipes before slamming together large bundles of particles in hopes of producing enough data to clear up that mystery. Firm answers aren’t expected for weeks, if not until an August conference of physicists in Chicago known as ICHEP.

On Friday, the LHC was temporarily immobilized by a weasel, which invaded a transformer that helps power the machine and set off an electrical outage. CERN says it was one of a few small glitches that will delay by a few days plans to start the data collection at the $4.4 billion collider.

The 2012 confirmation of the Higgs boson, dubbed the “God particle” by some laypeople, culminated a theory first floated decades earlier. The “Higgs” rounded out the Standard Model of physics, which aims to explain how the universe is structured at the infinitesimal level.

The LHC’s Atlas and Compact Muon Solenoid particle detectors in December turned up preliminary readings that suggested a particle not accounted for by the Standard Model might exist at 750 Giga electron Volts. This mystery particle would be nearly four times more massive than the top quark, the most massive particle in the model, and six times more massive than the Higgs, CERN officials say.

The Standard Model has worked well, but has gaps notably about dark matter, which is believed to make up one-quarter of the mass of the universe. Theorists say the December results, if confirmed, could help elucidate that enigma; or it could signal a graviton—a theorized first particle with gravity—or another boson, even hint of a new dimension.

More data is needed to iron those possibilities out, and even then, the December results could just be a blip. But with so much still unexplained, physicists say discoveries of new particles—whether this year or later—may be inevitable as colliders get more and more powerful.

Dave Charlton, who heads the Atlas team, said the December results could just be a “fluctuation” and “in that case, really for science, there’s not really any consequence … At this point, you won’t find any experimentalist who will put any weight on this: We are all very largely expecting it to go away again.”

“But if it stays around, it’s almost a new ball game,” said Charlton, an experimental physicist at the University of Birmingham in Britain.

The unprecedented power of the LHC has turned physics on its head in recent years. Whereas theorists once predicted behaviors that experimentalists would test in the lab, the vast energy being pumped into CERN’s collider means scientists are now seeing results for which there isn’t yet a theoretical explanation.

“This particle—if it’s real—it would be something totally unexpected that tells us we’re missing something interesting,” he said.

Whatever happens, experimentalists and theorists agree that 2016 promises to be exciting because of the sheer amount of data pumped out from the high-intensity collisions at record-high energy of 13 Tera electron Volts, a level first reached on a smaller scale last year, and up from 8 TeVs previously. (CERN likens 1 TeV to the energy generated by a flying mosquito: That may not sound like much, but it’s being generated at a scale a trillion times smaller.)

In energy, the LHC will be nearly at full throttle—its maximum is 14 TeV—and over 2,700 bunches of particles will be in beams that collide at the speed of light, which is “nearly the maximum,” CERN spokesman Arnaud Marsollier said. He said the aim is to produce six times more collisions this year than in 2015.

“When you open up the energies, you open up possibilities to find new particles,” he said. “The window that we’re opening at 13 TeV is very significant. If something exists between 8 and 13 TeV, we’re going to find it.”

Still, both branches of physics are trying to stay skeptical despite the buzz that’s been growing since December.

Csaki, a theorist at Cornell University in Ithaca, New York, stressed that the preliminary results don’t qualify as a discovery yet and there’s a good chance they may turn out not to be true. The Higgs boson had been predicted by physicists for a long time before it was finally confirmed, he noted.

“Right now it’s a statistical game, but the good thing is that there will be a lot of new data coming in this year and hopefully by this summer we will know if this is real or not,” Csaki said, alluding to the Chicago conference. “No vacation in August.”