Physicists check whether neutrinos really can travel faster than light | Science According to Einstein's theory of special relativity nothing – not even neutrinos – can travel faster than the speed of light in a vacuum. Photograph: Cine Text/Allstar The scientists who last month appeared to have found that certain subatomic particles can travel faster than light have fine-tuned their experiment to check whether the remarkable discovery is correct. Their modified experiments – which are the result of suggestions from other physicists about potential flaws in their research – should be completed before the end of the year. The original experiment, reported last month, involved firing beams of neutrinos through the ground from Cern near Geneva to the Gran Sasso lab in Italy 720 kilometres (450 miles) away. The finding sent the physics world into a frenzy because it appeared to go against Albert Einstein's theory of special relativity. First time around, the Cern scientists fired pulses of neutrinos lasting around 10 microseconds each through the rock to Gran Sasso.
Finding a direction of time in exotic particle transformations Unlike our daily experience, the world of elementary particle physics is mostly symmetrical in time. Run the clock backward on your day and it won't work; run the clock backward on a process in particle physics and things are just fine. However, to preserve certain fundamental aspects of space-time the Standard Model predicts that certain reversible events nevertheless have different probabilities, depending on which way they go. This time-reversal asymmetry is remarkably hard to observe in practice since it involves measurements of highly unstable particles. New results from the BaBar detector at the Stanford Linear Accelerator Center (SLAC) have uncovered this asymmetry in time. Researchers measured transformations of entangled pairs of particles, including the rates at which these transformations occurred. A direct consequence of relativity in particle physics is the presence of three related symmetries, known as CPT: charge, parity, and time.
Leading Light: What Would Faster-Than-Light Neutrinos Mean for Physics? The stunning recent announcement of neutrinos apparently exceeding the speed of light was greeted with startled wonderment followed by widespread disbelief. Although virtually every scientist on record expects this discovery to vanish once more detailed analysis takes place, dozens of researchers are exploring the question whose answer could shake the foundations of physics: What if this anomaly is real? Neutrinos are ghostly particles that only weakly interact with normal matter; trillions of neutrinos stream through our bodies every second. Last month researchers from the European OPERA (Oscillation Project with Emulsion-tRacking Apparatus) collaboration reported clocking pulses of neutrinos moving at speeds that appeared to be a smidgen faster than light-speed. The credibility of the OPERA scientists who made the supposed discovery of superluminal neutrinos is not in doubt.
Baryon A baryon is a composite subatomic particle made up of three quarks (as distinct from mesons, which comprise one quark and one antiquark). Baryons and mesons belong to the hadron family, which are the quark-based particles. The name "baryon" comes from the Greek word for "heavy" (βαρύς, barys), because, at the time of their naming, most known elementary particles had lower masses than the baryons. As quark-based particles, baryons participate in the strong interaction, whereas leptons, which are not quark-based, do not. The most familiar baryons are the protons and neutrons that make up most of the mass of the visible matter in the universe. Background[edit] Baryons are strongly interacting fermions — that is, they experience the strong nuclear force and are described by Fermi−Dirac statistics, which apply to all particles obeying the Pauli exclusion principle. Baryons, along with mesons, are hadrons, meaning they are particles composed of quarks. Baryonic matter[edit] Baryogenesis[edit]
Neutrinos: faster than the speed of light? By Frank Close To readers of Neutrino, rest assured: there is no need yet for a rewrite based on news that neutrinos might travel faster than light. I have already advertised my caution in The Observer, and a month later nothing has changed. If anything, concerns about the result have increased. The response to my article created some waves. I already mentioned some of the problems with the experiment – how it measures the time and the distance involved at huge accuracy, and then takes the ratio to get a speed. This aspect of my personal mystery typifies the problems that the actual experimenters have. A neutrino is detected in Italy, 500 miles from CERN, and the time is recorded. More theoretical perhaps, but from a Nobel Laureate, Sheldon Glashow, comes evidence of an inconsistency in the evidence for super-luminal neutrinos. Ultimately though, as I said in The Observer article, it is experiment that decides and it doesn’t matter how many theorists say nay.
Trapping flying qubits in a crystal (and getting them back out) Quantum computers come in many different shapes and forms, but the granddaddy of them all is based on light. This is because it is very easy to create the basic computational unit, called a qubit, from light. The big problem is the memory unit. Light has a pesky habit of traveling quite fast, so by the time you are ready to use your carefully prepared qubit, it is halfway to the Moon, never to return. A pair of research groups, working independently, showed an effective and reliable memory for light-based qubits. There are three key elements that make a quantum computer special: superposition, coherence, and entanglement. If we limit ourselves to light, there are still many possible ways to encode a qubit on a photon. Why was memory so difficult? But memory is a problem. Unfortunately, it's not as simple as sticking a bit of material in the path of the photon and hoping that the photon will be absorbed. No, to store the quantum state, one needs to carefully prepare the material.
Bussard ramjet Artist's conception of a Bussard ramjet. The heart of an actual ramjet—a miles-wide electromagnetic field—is invisible. Bussard proposed a ramjet variant of a fusion rocket capable of reasonable interstellar spaceflight, using enormous electromagnetic fields (ranging from kilometers to many thousands of kilometers in diameter) as a ram scoop to collect and compress hydrogen from the interstellar medium. High speeds force the reactive mass into a progressively constricted magnetic field, compressing it until thermonuclear fusion occurs. The magnetic field then directs the energy as rocket exhaust opposite to the intended direction of travel, thereby accelerating the vessel. Design discussion[edit] An object's velocity can be calculated by summing over time the acceleration supplied (ignoring the effects of special relativity, which would quickly become significant at useful interstellar accelerations). The top speed of a ramjet-driven spaceship depends on five things: Feasibility[edit]
New chemical reaction could explain how stars form, evolve, and eventually die University of North Dakota scientist Mark Hoffmann's version of Star Search goes a long way -- a very long way -- out into the universe. Hoffmann, a computational chemist, and his colleagues Tryve Helgaker, a well-known Norwegian scientist, and co-authors E.I. Tellgren and K. That discovery, it turns out, may redefine how science views chemical compound formation. "We discovered a new type of chemical bonding," said Hoffmann, known globally for his pioneering work in the theory and computer modeling of chemical compound formation. "That's a pretty bold statement, but I'm not kidding you! Hoffmann and his colleagues have rewritten the chemical rule book for assessing what happens in the night sky. Their work also provides the secret for how some compounds form in the distant universe. "Our discovery addresses one of the mysteries in astrophysics about the spectrum of white dwarf stars," Hoffmann said. So how did they do it? The team's computer model supported their theory.
icists extend entanglement in Einstein experiment (Phys.org)—Using a photon fission process, physicists have split a single photon into a pair of daughter photons and then split one of the daughter photons into a pair of granddaughters to create a total of three photons. All three photons, the scientists showed, share quantum correlations between their energies (corresponding to their momentums) and between their emission times (corresponding to their positions). The study marks the first experimental demonstration of energy-time entanglement of three or more individual particles, building on the original two-particle version proposed by Einstein, Podolsky, and Rosen (EPR) 77 years ago. The physicists, from the University of Waterloo and the University of Calgary, have published their paper on three-photon energy-time entanglement in a recent issue of Nature Physics. "The original arguments made by EPR in 1935 were designed to show that quantum mechanics, by itself, is not sufficient to describe reality," Shalm said.
Earthworm guts become factory for nanoparticles Quantum dots are nanoscale-sized pieces of semiconductor. Their small size ensures that quantum effects, like the Pauli exclusion principle, influence the behavior of electrons within them. This gives the dots properties that a bulk material with the same composition lacks, and it makes them appealing candidates for things like tiny lasers, photovoltaic materials, and LEDs. Another area where they've shown promise is medical imaging. Some researchers have started to look towards making the dots in biological systems, figuring that the output would necessarily be biocompatible. The authors were interested in creating CdTe quantum dots. For earthworms, that means an organ called the chloragogenous tissue, which surrounds the digestive tract (conveniently labeled in the paper in a figure entitled "Schematics of the earthworm used"). The authors of the paper therefore spiked some soil with CdCl2 and Na2TeO3, and left earthworms in it for 11 days.
Goodbye keyboards: Wristband recognizes words you write in the air | Gadgets Ask any writer, and there’s a good chance he or she will tell you how great it feels to physically write words on a piece of paper. While typing is much faster, and a lot more efficient, something just feels so good when putting pen to paper. In the case of tablets — which tend to have keyboards too wide for dual thumbs, yet too small to type on like a full-sized keyboard — handwriting recognition can be the most efficient way to jot down some words, somewhat satiating that pen-to-paper desire. Unfortunately, handwriting recognition isn’t exactly the peak of refined technology at the moment, and it generally isn’t precise enough to pick up everyone’s wildly different handwriting styles with any real accuracy. Scientists at the Karlsruhe Institute of Technology (KIT) might have found a different solution — a band that detects the motions and gestures of the wrist, and can translate that into writing. Old and busted
Bone conduction A consumer stereo bone conduction headset. The two transducers fit slightly in front of the ears. Bone conduction is the conduction of sound to the inner ear through the bones of the skull. Bone conduction transmission can be used with individuals with normal or impaired hearing. Overview[edit] Bone conduction is one reason why a person's voice sounds different to him/her when it is recorded and played back. Hearing aids[edit] Some hearing aids employ bone conduction, achieving an effect equivalent to hearing directly by means of the ears. At the Chalmers University of Technology in December 2012, surgeons performed an inaugural operation as part of a clinical study that involves a new bone-conduction hearing implant. Products[edit] Bone conduction products are usually categorized into three groups: Ordinary products, such as hands-free headsets or headphonesHearing aids and assistive listening devicesSpecialized communication products (e.g. for underwater or high-noise environments)