Slashdot Mirror
Domain: aps.org
Stories and comments across the archive that link to aps.org.
Stories · 125
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Imprisoned Physicist Honored For Refusing To Work On Iran's Nuclear Program
New submitter I3MOUNTAINS writes "Omid Kokabee, a University of Texas graduate student who has been imprisoned in Iran for more than two years, received the American Physical Society's Andrei Sakharov human rights prize for refusing to collaborate on the country's nuclear program. In May, an Iranian court sentenced him to ten years in prison for 'communicating with a hostile government' and receiving 'illegal earnings.' The so-called 'illegal earnings' were the student loans he received while in Texas." -
First Particle Comprising Four Quarks Discovered
ananyo writes "Physicists have resurrected a particle that may have existed in the first hot moments after the Big Bang. Arcanely called Zc(3900), it is the first confirmed particle made of four quarks, the building blocks of much of the Universe's matter (abstract one, abstract two). Until now, observed particles made of quarks have contained only three quarks (such as protons and neutrons) or two quarks (such as the pions and kaons found in cosmic rays)." -
First Particle Comprising Four Quarks Discovered
ananyo writes "Physicists have resurrected a particle that may have existed in the first hot moments after the Big Bang. Arcanely called Zc(3900), it is the first confirmed particle made of four quarks, the building blocks of much of the Universe's matter (abstract one, abstract two). Until now, observed particles made of quarks have contained only three quarks (such as protons and neutrons) or two quarks (such as the pions and kaons found in cosmic rays)." -
Small Black Holes: Cloudy With a Chance of Better Visibility
Rambo Tribble writes "As reported by the BBC, astronomers are hoping to reap a black-hole-hunting windfall when a giant gas cloud passes through an area within our galaxy thought to contain numerous small black holes (abstract). When the cloud interacts with the black holes, the resultant emission of X-rays should allow scientists to finally confirm their existence. 'The idea is that as the cloud speeds past these small black holes — some slightly more massive than our Sun but just a few tens of km across — gas will spiral around them faster and faster, heating up to millions of degrees and emitting X-ray light. It is a bit like allowing a giant sink to empty through thousands of tiny drains and looking for any evidence of swirling water.'" -
A Snapshot of the Inside of an Atom
sciencehabit writes "Physicists have, for the first time, been able to image the quantum workings of electrons in hydrogen atoms, an advance that could open the door to a deeper understanding of the quantum world (abstract). Building on a 1981 proposal by three Russian theorists and more recent work that brought that proposal into the realm of possibility, the team first fired two lasers at hydrogen atoms inside a chamber, kicking off electrons at speeds and directions that depended on their underlying wave functions. A strong electric field inside the chamber guided the electrons to positions on a planar detector that depended on their initial velocities rather than on their initial positions. So the distribution of electrons striking the detector matched the wave function the electrons had at the moment they left their hydrogen nuclei behind. There may be practical applications in the future—a commentary accompanying the paper suggests that the method could aid in the development of technologies such as molecular wires, atom-thick conductors that could help shrink electronic devices—but that their result concerns 'extremely fundamental' physics that might be just as valuable for developing quantum intuition in the next generation of physicists." -
A Snapshot of the Inside of an Atom
sciencehabit writes "Physicists have, for the first time, been able to image the quantum workings of electrons in hydrogen atoms, an advance that could open the door to a deeper understanding of the quantum world (abstract). Building on a 1981 proposal by three Russian theorists and more recent work that brought that proposal into the realm of possibility, the team first fired two lasers at hydrogen atoms inside a chamber, kicking off electrons at speeds and directions that depended on their underlying wave functions. A strong electric field inside the chamber guided the electrons to positions on a planar detector that depended on their initial velocities rather than on their initial positions. So the distribution of electrons striking the detector matched the wave function the electrons had at the moment they left their hydrogen nuclei behind. There may be practical applications in the future—a commentary accompanying the paper suggests that the method could aid in the development of technologies such as molecular wires, atom-thick conductors that could help shrink electronic devices—but that their result concerns 'extremely fundamental' physics that might be just as valuable for developing quantum intuition in the next generation of physicists." -
Electricity Gives Bubbles Super Strength
sciencehabit writes "Left to its own devices, a bubble will weaken and pop as the fluid sandwiched between two thin layers of soap succumbs to gravity and drains toward the floor. But when researchers trapped a bubble between two platinum electrodes and cranked up the voltage, the fluid reversed direction and actually flowed up, against the force of gravity. The newly strong and stable bubbles could live for hours, and even visibly change colors as their walls grew fatter. Because soap film is naturally only nanometers thick, this whimsical experiment could help scientists create more efficient labs-on-chips, the mazes of nanotunnels that can diagnose disease based on the movements of a miniscule drop of blood." -
Manipulating Heat Like Light
An anonymous reader writes "A new technique allows allows 'thermocrystals' to be created that can manipulate heat (a vibration of the atomic lattice of a material). Predicted manipulations include the ability to selectively transmit, reflect or concentrate heat much like light waves can be manipulated by lenses and mirrors. 'Heat differs from sound, he explains, in the frequency of its vibrations: Sound waves consist of lower frequencies (up to the kilohertz range, or thousands of vibrations per second), while heat arises from higher frequencies (in the terahertz range, or trillions of vibrations per second).' Applications range from better thermoelectric devices to switchable heat insulating/transmitting materials (abstract). Perhaps this will result in better cooling/heating mechanisms or more efficient engines." -
What 'Negative Temperature' Really Means
On Friday we discussed news of researchers getting a quantum gas to go below absolute zero. There was confusion about exactly what that meant, and several commenters pointed out that negative temperatures have been achieved before. Now, Rutgers physics grad student Aatish Bhatia has written a comprehensible post for the layman about how negative temperatures work, and why they're not actually "colder" than absolute zero. Quoting: "...you first need to engineer a system that has an upper limit to its energy. This is a very rare thing – normal, everyday stuff that we interact with has kinetic energy of motion, and there is no upper bound to how much kinetic energy it can have. Systems with an upper bound in energy don’t want to be in that highest energy state. ...these systems have low entropy in (i.e. low probability of being in) their high energy state. You have to experimentally ‘trick’ the system into getting here. This was first done in an ingenious experiment by Purcell and Pound in 1951, where they managed to trick the spins of nuclei in a crystal of Lithium Fluoride into entering just such an unlikely high energy state. In that experiment, they maintained a negative temperature for a few minutes. Since then, negative temperatures have been realized in many experiments, and most recently established in a completely different realm, of ultracold atoms of a quantum gas trapped in a laser." -
Particle Physicists Confirm Arrow of Time Using B Meson Measurements
ananyo writes with bad news for John Titor. From the article: "Four years after its closure, researchers working with data from the Stanford Linear Accelerator Center's particle physics experiment BaBar have used the data to make the first direct measurement confirming that time does not run the same forwards as backwards — at least for the B mesons that the experiment produced during its heyday. The application of quantum mechanics to fundamental particles rests on a symmetry known as CPT, for charge-parity-time, which states that fundamental processes remain unchanged when particles are replaced by their antimatter counterparts (C), left and right are reversed (P), and time runs in the reverse direction (T). Violations of C and P alone were first seen in radioactive decays in the 1950s, and BaBar was used to confirm violations of CP in B meson decays in 2001. To keep CPT intact, that implies that time reversal is also violated, but finding ways to compare processes running forward and backward in time has proven tricky. Theoretical physicists at the Universityof Valencia in Spain worked with researchers on BaBar to exploit the fact that the experiment had generated entangled quantum states of the meson Bzero and its antimatter counterpart Bzero-bar, which then evolved through several different decay chains. By comparing the rates of decay in chains in which one type of decay happened before another, with others in which the order was reversed, the researchers were able to compare processes that were effectively time reversed version of each other. They report in Physical Review Letters today that they see a violation of time reversal at an extremely high level of statistical significance." -
Electronic Tweezers Grab Nanoparticles
MTorrice writes "A beam of electrons can pick up and carry nanoparticles, according to a new study (abstract). The so-called electronic tweezers could help scientists in diverse tasks, such as building up new materials nanoparticle-by-nanoparticle, and measuring the forces between nanoparticles and living cells, the researchers say. In the past, scientists have manipulated microsized particles, including single cells, using a beam of laser light called optical tweezers. But the force required to trap a particle with optical tweezers increases as the particle gets smaller, making grappling with nanoparticles difficult. Researchers at Lawrence Berkeley National Laboratory developed an alternative to optical tweezers by modifying a transmission electron microscope, which produces images by passing a stream of electrons through a sample." Reader Sven-Erik adds news of a tractor beam generated with laser light that can pull microscopic particles over distances of 30 micrometers (abstract). -
Physicists Propose "Perpetual Motion" Time Crystals
First time accepted submitter b30w0lf writes "It is commonly understood that crystals exist in a state of matter that is periodic in space. Meanwhile, relativistic physics tells us that we should think of time as being a physical dimension, given similar status to the other spacial dimensions. The combination of these two ideas has lead researchers at the University of Kentucky and MIT to propose special manifestations of matter which would be periodic in both space and time, dubbed 'time crystals.' Time crystals would continually transition between a set of physical states in a kind of perpetual motion. Note: the articles stress that this kind of perpetual motion in no way violates the established laws of thermodynamics. While time crystals remain theoretical, methods have been proposed for creating them. The most obvious application of time crystals is the creation of very precise clocks; however, other applications to time crystals have been proposed, ranging from quantum computing to helping us understand certain cosmological models." -
Gamma-Ray Photon Observations Indicate Space-Time Is Smooth
eldavojohn writes "Seven billion light years away (seven billion years ago), a gamma-ray burst occurred. The observation of four Fermi-detected gamma-ray bursts (GRBs) has led physicists to speculate that space-time is indeed smooth (abstract and a pre-publication PDF both available). A trio of photons were observed to arrive very close together, and the observers believe that these are from the same burst, which means there was nothing diffracting their paths from the gamma-ray burst to Earth. This observation doesn't prove that space-time is infinitesimally smooth like Einstein predicted, but does indicate it's smooth for a range of parameters. Before we can totally discount the theory that space-time is comprised of Planck-scale pixels, we must now establish that the proposed pixels don't disrupt the photons in ways independent of their wavelengths. For example, this observation did not disprove the possibility that the pixels exert a subtler 'quadratic' influence over the photons, nor could it determine the presence of birefringence — an effect that depends on the polarization of the light particles." -
Bessel Beam 'Tractor Beam' Concept Theoretically Demonstrated
cylonlover writes "Last year, NASA revealed it was evaluating three potential 'tractor beam' technologies to deliver planetary or atmospheric particles to a robotic rover or orbiting spacecraft. At the time, the third of these, which involved the use of a Bessel beam, only existed on paper. Researchers at Singapore's Agency for Science, Technology and Research (A*STAR) have now proven the theory behind the concept, demonstrating how a tractor beam can be realized in the real world – albeit on a very small scale (abstract)." -
Iranian Physics Student From UT Gets 10 Years In Jail For Spying
scibri writes "Omid Kokabee, a laser physics graduate student from the University of Texas who has been imprisoned in Tehran for the past 15 months, was sentenced to 10 years in jail on Sunday for allegedly conspiring with foreign countries against Iran. Kokabee was arrested in February 2011 while on a trip home, and charged with 'communicating with a hostile government' (i.e. Israel) and 'illegal earnings.' He has consistently denied the charges, and refused to speak at his trial, where no evidence against him was presented. Several international science groups, including the American Physical Society, have spoken up in his defense, and an online petition has been set up in support." -
Silicene Discovered: Single-layer Silicon That Could Beat Graphene To Market
MrSeb writes "Numerous research groups around the world are reporting that they have created silicene, a one-atom-thick hexagonal mesh of silicon atoms — the silicon equivalent of graphene. You will have heard a lot about graphene, especially with regard to its truly wondrous electrical properties, but it has one rather major problem: It doesn't have a bandgap, which makes it very hard to integrate into existing semiconductor processes. Silicene, on the other hand, is theorized to have excellent electrical properties, while still being compatible with silicon-based electronics (abstract). For now, silicene has only been observed (with a scanning tunneling electron microscope), but the next step is to grow a silicene film on an insulating substrate so that its properties can be properly investigated." -
Checking the Positional Invariance of Planck's Consant Using GPS
gzipped_tar writes "Whether the fundamental constants really stay the same is always a question worth asking. In particular, the constancy of Planck's Constant is something that cannot be simply ignored, owing to its universal importance in linking the quantum and classical pictures of our world. Using publicly available GPS data and terrestrial clocks, researchers form the California State University were able to verify that the value of h indeed stays the same across different positions in the vicinity of our Earth. Their result says the local position invariance of h is satisfied within a limit of 0.007. The paper is published in the journal Physical Review Letters (abstract), and a free-to-read preprint is available on arXiv. In short: by the well-known formula E = h * f, a hypothetical variation on h induces changes in f, the transition frequency that keeps the time in atomic clocks, both on earth and aboard the satellites. When taking account of other time variations, such as general relativistic time dilation, and assuming the invariance of E (atomic transition energy) on physical grounds, we can figure out an upper bound on the variation of h reflected in the measured variation in f." -
Checking the Positional Invariance of Planck's Consant Using GPS
gzipped_tar writes "Whether the fundamental constants really stay the same is always a question worth asking. In particular, the constancy of Planck's Constant is something that cannot be simply ignored, owing to its universal importance in linking the quantum and classical pictures of our world. Using publicly available GPS data and terrestrial clocks, researchers form the California State University were able to verify that the value of h indeed stays the same across different positions in the vicinity of our Earth. Their result says the local position invariance of h is satisfied within a limit of 0.007. The paper is published in the journal Physical Review Letters (abstract), and a free-to-read preprint is available on arXiv. In short: by the well-known formula E = h * f, a hypothetical variation on h induces changes in f, the transition frequency that keeps the time in atomic clocks, both on earth and aboard the satellites. When taking account of other time variations, such as general relativistic time dilation, and assuming the invariance of E (atomic transition energy) on physical grounds, we can figure out an upper bound on the variation of h reflected in the measured variation in f." -
LED's Efficiency Exceeds 100%
New submitter Paul Fernhout writes "Physicists from MIT claim to have demonstrated that an LED can emit more optical power than the electrical power it consumes. Researchers suggest this LED acts like a heat pump somehow (abstract). Is it true that 230% efficient LEDs seem to violate first law of thermodynamics?" -
Physics Is (NP-)Hard
An anonymous reader writes "New research at the boundary of physics and computer science shows that determining the dynamical equations of a system from observations of its behavior is NP-hard. From the abstract: 'The behavior of any physical system is governed by its underlying dynamical equations. Much of physics is concerned with discovering these dynamical equations and understanding their consequences. In this work, we show that, remarkably, identifying the underlying dynamical equation from any amount of experimental data, however precise, is a provably computationally hard problem (it is NP-hard), both for classical and quantum mechanical systems.'" -
Water Droplets In Orbit On the International Space Station
BuzzSkyline writes "Astronaut Don Pettit, who is aboard the International Space Station right now, puts charged water droplets into wild orbits around a knitting needle in the microgravity environment of the ISS. A video he made of the droplets is the first in a series of freefall physics experiments that he will be posting in coming months." -
Fine Structure Constant May Not Be So Constant
BuzzSkyline writes "According to a post at Physics Buzz, 'Just weeks after speeding neutrinos seem to have broken the speed of light, another universal law, the fine structure constant might be about to crumble.' Astronomical observations seem to indicate that the constant, which controls the strength of electromagnetic interactions, is different in distant parts of the universe. Among other things, the paper may explain why the laws of physics in our corner of the universe seem to be finely tuned to support life. The research (abstract) is so controversial that it took over a year to go from submission to publication in Physical Review Letters, rather than the weeks typical of most other papers appearing in the peer-reviewed journal." -
Pumping Fluid With No Moving Parts
RogerRoast writes "In a study published in Physical Review B (abstract; full version is paywalled), researchers demonstrate for the first time an approach that allows ferrofluids to be pumped by magnetic fields alone. The invention could lead to new applications for this mysterious material. Though numerous industrial, commercial, and biomedical applications for ferrofluids have since been created, the original goal — to pump liquids with no machinery — remained elusive, until now. The ferrohydrodynamic pump method works when electrodes wound around a pipe force magnetic nanoparticles within the ferrofluids to rotate at varying speeds. Those particles closest to the electrodes spin faster, and it is this spatial variation in rotation speed that propels the ferrofluid forward." -
Alloy Could Produce Hydrogen Fuel Using Sunlight
intellitech writes "Using state-of-the-art theoretical computations, a University of Kentucky-University of Louisville team demonstrated that an alloy formed by a 2 percent substitution of antimony (Sb) in gallium nitride (GaN) has the right electrical properties to enable solar light energy to split water molecules into hydrogen and oxygen, a process known as photoelectrochemical (PEC) water splitting. When the alloy is immersed in water and exposed to sunlight, the chemical bond between the hydrogen and oxygen molecules in water is broken (abstract). Because pure hydrogen gas is not found in free abundance on Earth, it must be manufactured by unlocking it from other compounds. Thus, hydrogen is not considered an energy source, but rather an 'energy carrier.' Currently, it takes a large amount of electricity to generate hydrogen by water splitting. As a consequence, most of the hydrogen manufactured today is derived from non-renewable sources such as coal and natural gas. The team says the GaN-Sb alloy has the potential to convert solar energy into an economical, carbon-free source for hydrogen." -
Imaging the Molecular Orbitals of Pentacene
eparker05 writes "Researchers at University of Liverpool have used a scanning tunneling microscope to image the aromatic molecule pentacene (Abstract). Not unexpectedly, the resulting images showed an astonishingly close correlation to the theoretically predicted molecular orbitals. This incredible set of images reminds me of the group that imaged a single carbon atom in 2009." -
Scientists Discover Tipping Point for the Spread of Ideas
An anonymous reader writes "Scientists at Rensselaer Polytechnic Institute have found that when just 10 percent of the population holds an unshakable belief, their belief will always be adopted by the majority of the society. 'When the number of committed opinion holders is below 10 percent, there is no visible progress in the spread of ideas. It would literally take the amount of time comparable to the age of the universe for this size group to reach the majority,' said SCNARC Director Boleslaw Szymanski. 'Once that number grows above 10 percent, the idea spreads like flame.' The findings were published in the July 22, 2011, early online edition of the journal Physical Review E." -
Breakthrough Toward Quantum Computing
redwolfe7707 writes "Qubit registers have been a hard thing to construct; this looks to be a substantial advance in the multiple entanglements required for their use. Quoting: 'Olivier Pfister, a professor of physics in the University of Virginia's College of Arts & Sciences, has just published findings in the journal Physical Review Letters demonstrating a breakthrough in the creation of massive numbers of entangled qubits, more precisely a multilevel variant thereof called Qmodes. ... Pfister and researchers in his lab used sophisticated lasers to engineer 15 groups of four entangled Qmodes each, for a total of 60 measurable Qmodes, the most ever created. They believe they may have created as many as 150 groups, or 600 Qmodes, but could measure only 60 with the techniques they used.'" In related news, research published in the New Journal of Physics (abstract) shows "how quantum and classical data can be interlaced in a real-world fiber optics network, taking a step toward distributing quantum information to the home, and with it a quantum internet." -
Acoustic Stealth Technology Finally Created
smitty777 writes "An idea for acoustic stealth technology proposed in 2008 was finally put into practice. The abstract describes taking advantage of the 'transformation acoustics and linear coordinate transformations that result in shells which are homogeneous, broadband, and compact. The required material parameters are highly anisotropic; however, we show that they are easily achievable in practice in metamaterials made of perforated plastic plates.' It is thought this technology might be useful for shielding ships from sonar or creating soundproof rooms." -
Researcher Claims Magnets Can Affect Blood Viscosity
BuzzSkyline writes "A few minutes in a high magnetic field (1.3 Tesla) is enough to thin blood by 30%, potentially leading to a new drug-free therapy to prevent heart attacks. The powerful field causes blood cells to line up in chains that flow much more easily than randomly-scattered individual cells, according to research scheduled to appear this month in the journal Physical Review E." I can't help thinking of Penn & Teller's look at magnets-as-medicine, though at least the idea here described sounds testable and doesn't rely on the power of suggestion. -
Nano-Viewing Record Broken
smitty777 writes "Wired magazine reports on a new nanoviewing lens that is capable of viewing objects less than 100 nm across. Rather than attempting to use a 'perfect' lens, this technology uses a porous surface that actually scatters the light. By measuring how it is scattered and setting up lasers to compensate, they're able to 'steer' the light back to the right spot. The abstract from the Physical Review Letters reads: 'The smallest structures that conventional lenses are able to optically resolve are of the order of 200 nm. We introduce a new type of lens that exploits multiple scattering of light to generate a scanning nanosized optical focus. With an experimental realization of this lens in gallium phosphide we imaged gold nanoparticles at 97 nm optical resolution. Our work is the first lens that provides a resolution better than 100 nm at visible wavelengths.'" -
One-Way Sound Walls Proven Possible
disco_tracy writes "Imagine a room where a band is playing. Neighbors can't hear the music, but if someone outside the room is talking, the musicians can hear it. The concept — a kind of one-way mirror for sound — seems imaginary, but two Italian scientists recently pushed this kind of sound manipulating technology closer to reality (abstract)." -
Frictionless Superfluid Found In Neutron Star Core
intellitech writes "NASA's Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star (abstract). Superfluids created in laboratories on Earth exhibit remarkable properties, such as the ability to climb upward and escape airtight containers. The finding has important implications for understanding nuclear interactions in matter at the highest known densities." -
Frictionless Superfluid Found In Neutron Star Core
intellitech writes "NASA's Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star (abstract). Superfluids created in laboratories on Earth exhibit remarkable properties, such as the ability to climb upward and escape airtight containers. The finding has important implications for understanding nuclear interactions in matter at the highest known densities." -
Fermilab Confirms Evidence of 4th Flavor Neutrino
eldavojohn writes "We've only had evidence for three kinds of neutrinos so far, but a recent test at Fermilab involving an antineutrino beam has reinforced a Michigan researcher's earlier experiment suggesting a fourth flavor. What's really odd about this is that a prior neutrino test (carried out as part of project MiniBooNE) did not result in indications of such strange oscillations. According to the researcher, 'The simplest explanation involves adding new neutrino-like particles, or sterile neutrinos, which do not have the normal weak interactions.' But this could also be an unknown or misunderstood effect. A Los Alamos National Laboratory scientist added that an explanation of this strange anomaly could result in understanding 'matter asymmetry of the universe, or why the universe is primarily composed of matter, rather than antimatter.' The results are published in the Physical Review Letters." -
One Step Closer To Speedier, Bootless Computers
CWmike writes "Physicists at the University of California at Riverside have made a breakthrough in developing a 'spin computer,' which would combine logic with nonvolatile memory, bypassing the need for computers to boot up. The advance could also lead to super-fast chips. The new transistor technology, which one lead scientist believes could become a reality in about five years, would reduce power consumption to the point where eventually computers, mobile phones and other electronic devices could remain on all the time. The breakthrough came when scientists at UC Riverside successfully injected a spinning electron into a resistor material called graphene, which is essentially a very thin layer of graphite. The graphene in this case is one-atom thick. The process is known as 'tunneling spin injection.' A lead scientist for the project said the clock speeds of chips made using tunneling spin injection would be 'thousands of times' faster than today's processors. He describes the tech as a totally new concept that 'will essentially give memory some brains.'" -
Levitating Graphene Is Fastest-Spinning Object
techbeat writes "A flake of exotic carbon a few atoms thick has claimed a record: the speck has been spun faster than any other object, at a clip of 60 million rotations per minute. Previously, micrometre-sized crystals have been spun at up to 30,000 rpm using an optical trap. It is thanks to graphene's amazing strength that the flakes are not pulled apart by the much higher spinning rate, says Bruce Kane at the University of Maryland in College Park. Spinning could be a way to probe the properties of graphene, or manipulate it in new ways." -
The Futurama of Physics
MasaMuneCyrus writes "I was surprised to notice an article about Futurama in my latest American Physical Society news. Titled, 'Profiles in Versatility: The Futurama of Physics with David X. Cohen,' Cohen talks a little bit about his life and his love for physics, and he goes on to describe how he regularly injects graduate-level physics jokes into the script of Futurama. He also talks a little bit about the upcoming season of Futurama: 'In the 10th episode of the upcoming season, tentatively entitled "The Prisoner of Benda," a theorem based on group theory was specifically written (and proven!) by staffer/PhD mathematician Ken Keeler to explain a plot twist.'" -
New Bounds On the Higgs Boson Mass
As the LHC continues to run at half power for the next year+, the US-based Tevatron continues to crank out results. Reader hweimer writes "Three new papers in Physical Review Letters present the latest results for the Higgs boson mass coming from Fermilab's Tevatron. The new data mandates that the Higgs boson mass within the standard model lies between 115 and 150 GeV." A year back we discussed the Tevatron's previous shrinking of the search space for the Higgs "God particle." -
The Weird Science of Tossing Stones Into a Lake
Interoperable writes "Researchers in Spain and the Netherlands add another piece to a centuries-old puzzle in physics: the dynamics of an object falling into water. This common occurrence has a complex anatomy that includes a thin 'crown splash' around the perimeter of the impact, a deep cavity of air following the impactor, and a high, narrow jet of water that results from the collapse of the cavity. The new research, recently published in Physical Review Letters, demonstrates that airflow through the neck of the collapsing cavity reaches supersonic speeds despite low relative pressures between the air in the cavity and ambient pressure. Such an effect has no analogue in aerospace engineering or other sciences because of the highly dynamic nature of the collapsing nozzle structure." It's funny that the APS wants to charge non-subscribers $25 to download what is available for free on the arXiv. -
Online "Guilds" Mirror Real Life Gangs
j-beda writes "In June 2009, Dr. Neil Johnson published a paper titled 'Human group formation in online guilds and offline gangs driven by a common team dynamic' in Physical Review E that found the way in which WoW 'guilds' form can be described by a mathematical model that can also be applied to an unrelated group of people: street gangs in Los Angeles. Since 'Any group that satisfies these fairly autonomous, competitive criteria would also (fit the model),' said Dr. Johnson, the findings are of interest to those combating international as well as local terrorist cells." -
Element 114 Verified
ExRex writes "A team at Lawrence Berkeley National Laboratory has observed the production of superheavy element 114, confirming the results of researchers at the Joint Institute for Nuclear Research in Dubna, Russia. Those researchers first reported producing element 114 in 1999. Such independent verification is important, particularly given the evidence of fabricated results for other superheavy elements. If you're a subscriber to Physical Review Letters, you can download the full article." -
The Ultimate Limit of Moore's Law
BuzzSkyline writes "Physicists have found that there is an ultimate limit to the speed of calculations, regardless of any improvements in technology. According to the researchers who found the computation limit, the bound 'poses an absolute law of nature, just like the speed of light.' While many experts expect technological limits to kick in eventually, engineers always seem to find ways around such roadblocks. If the physicists are right, though, no technology could ever beat the ultimate limit they've calculated — which is about 10^16 times faster than today's fastest machines. At the current Moore's Law pace, computational speeds will hit the wall in 75 to 80 years. A paper describing the analysis, which relies on thermodynamics, quantum mechanics, and information theory, appeared in a recent issue of Physical Review Letters (abstract here)." -
The Best Approach For Avoiding Zombies
BuzzSkyline writes "Last month, math students published a model of a zombie infestation that explained how the disease might spread. A new physics paper offers help for the more immediate problem — how to avoid being eaten. The paper, which recently appeared in the journal Physical Review E, considers where best to hide when being pursued by zombie-like predatory 'random walkers.' Although the researchers weren't thinking of zombies when they wrote the paper, the abstract describes the research as focusing on 'the survival probability of immobile targets annihilated by a population of random walkers.' (Sounds like a zombie movie premise to me.) The bottom line is you're better off the more labyrinth-like your hiding place is. So take a lesson from Dawn of the Dead, and hunker down in the mall, not in a farmhouse (as in Night of the Living Dead)." -
Lego Blocks Simulate Microfluidic Filters
BuzzSkyline writes "Researchers at Johns Hopkins University are playing with Lego blocks to discover how arrays of nanoscopic obstacles could sort cells and other tiny particles by size. Ball bearings dropped through an array of Lego pieces submerged in glycerin serve as an analogue of the tiny systems, with bearings of different sizes taking different paths through the array. An academic paper describing the Lego research recently appeared in the journal Physical Review Letters (subscription required)." -
Obstacles Near Emergency Exits Speed Evacuation
BuzzSkyline writes "Despite fire codes that require emergency exits be clear of obstacles, some types of obstacles actually speed evacuation. The counterintuitive conclusion resulted from a series of experiments performed at a TV studio in Japan. Researchers from the University of Tokyo asked 50 volunteers to exit the studio through a narrow door. Video tapes of the experiments show that people made it out quickest when a pole was placed about 30 degrees to one side of the exit. The lead researcher believes an obstacle reduces jamming and friction among people in crowds by decreasing conflicts as the crowd presses toward the exit. A paper describing the research is scheduled to appear in the journal Physical Review E in September, but a preprint is available on the Physics Arxiv." -
Rude Drivers Reduce Traffic Jams
BuzzSkyline writes "Traffic jams are minimized if a significant fraction of drivers break the rules by doing things like passing on the wrong side or changing lanes too close to an intersection. The insight comes from a cellular automata study published this month in the journal Physical Review E. In effect, people who disregard the rules help to break up the groups that form as rule-followers clump together. The risk of jamming is lower if all people obey the rules than if they all disobey them, according to the analysis, but jamming risk is lowest when about 40 percent of people drive like jerks." -
Electricity From Salty Water
BuzzSkyline writes "It's possible to produce energy by simply mixing fresh and salty water. Although chemists and physicists have long known about the untapped energy available where fresh water rivers pour into salty oceans — it's equivalent to 'each river in the world ending at its mouth in a waterfall 225 meters [739 feet] high' — the technology for exploiting the effect has been lacking. An Italian physicist seems to have solved the problem with the experimental demonstration of a 'salination cell' that creates power given nothing more than input sources of salty and fresh water. The researcher believes that this renewable, environmentally friendly energy source could be deployed in coastal areas and could provide another addition to the green-tech roster. A paper describing the technology is due to be published in an upcoming issue of the journal Physical Review Letters." -
Tiniest Lamp Spans Quantum, Classical Physics
Urchin writes "Physicists in California have made the smallest ever incandescent lamp using a carbon nanotube as the filament. The nanotube is so small it behaves as a quantum mechanical system but it's just large enough that the classical physics rules of thermodynamics should apply. Analyzing the light emitted from the tiny light will give the team a better picture of what happens in the twilight zone between the quantum and classical worlds." The New Scientist article doesn't mention the researchers' surprise, as the abstract does: "Remarkably, the heat equation and Planck's law together give a precise, quantitative description of the light intensity as a function of input power, even though the nanotube's small size places it outside the thermodynamic limit." -
Transistor Made From Bose-Einstein Condensate
holy_calamity writes "US researchers have made a transistor from a Bose-Einstein condensate. They claim it to be the first step towards 'atomic circuits' that run with atoms instead of electrons. 'A small number of atoms can be used to control the flow of a large number of atoms, in much the same way that an FET uses a gate voltage to control a large electric current,' says lead research Alex Zozulya. The abstract of their paper is freely available." -
Dark Matter — "Alternative Gravity" Team Responds
An anonymous reader writes, "Following previous results, an international team of astronomers answers, defending the case for a modification of the theory of gravity. This article presents an alternative to dark matter and states constraints on the neutrino mass. In short, dark matter is still not a necessity, provided that neutrinos weigh 2eV. This is allowed by what we currently know and should be tested in the KATRIN experiment in 2009."