Beyond 'absolute zero' temperatures get hotter It sounds like a contradiction in terms but scientists have reached temperatures that go beyond absolute zero in a lab, and get hotter as they do so. Whereas we’re all aware of what happens when temperatures hit negative temperatures on the Fahrenheit and Celsius scales (hint: it gets really cold), the Kelvin scale is an absolute temperature scale in physics where it is not possible to go beyond 0 degrees Kelvin. Therefore, the lowest point that any temperature can reach is 0 K or −460 °F (−273.15 °C); at least that’s what scientists thought until till now. When they cooled an atomic gas to extreme lows, known as ‘ultracooling’, physicists at the Ludwig-Maximilians University Munich and the Max Planck Institute of Quantum Optics in Germany created a gas that went beyond absolute zero. They found that the atoms in the ultracooled gas attract each other and give rise to a negative pressure. Instead of standing still when they go beyond 0 K, the gas becomes hotter.
Is dark energy static or dynamic? (Phys.org)—While hypothesized dark energy can explain observations of the universe expanding at an accelerating rate, the specific properties of dark energy are still an enigma. Scientists think that dark energy could take one of two forms: a static cosmological constant that is homogenous over time and space, or a dynamical entity whose energy density changes in time and space. By examining data from a variety of experiments, scientists in a new study have developed a model that provides tantalizing hints that dark energy may be dynamic. The scientists, Gong-Bo Zhao of the University of Portsmouth in the UK and the Chinese Academy of Science in Beijing; Robert G. Crittenden of the University of Portsmouth; Levon Pogosian of Simon Fraser University in Burnaby, British Columbia, and the University of Portsmouth; and Xinmin Zhang of the Chinese Academy of Science, have published their paper on the evidence for dynamical dark energy in a recent issue of Physical Review Letters.
New phase of water could dominate the interiors of Uranus and Neptune (Phys.org) —While everyone is familiar with water in the liquid, ice, and gas phases, water can also exist in many other phases over a vast range of temperature and pressure conditions. One lesser known phase of water is the superionic phase, which is considered an "ice" but exists somewhere between a solid and a liquid: while the oxygen atoms occupy fixed lattice positions as in a solid, the hydrogen atoms migrate through the lattice as in a fluid. Until now, scientists have thought that there was only one phase of superionic ice, but scientists in a new study have discovered a second phase that is more stable than the original. The new phase of superionic ice could make up a large component of the interiors of giant icy planets such as Uranus and Neptune. The scientists, Hugh F. Exotic water As the scientists explain, water has an unusually rich phase diagram, with 15 crystalline phases observed in laboratory experiments and eight additional phases predicted theoretically.
Exclusive: Pioneering scientists turn fresh air into petrol in massive boost in fight against energy crisis - Home News - UK Air Fuel Synthesis in Stockton-on-Tees has produced five litres of petrol since August when it switched on a small refinery that manufactures gasoline from carbon dioxide and water vapour. The company hopes that within two years it will build a larger, commercial-scale plant capable of producing a ton of petrol a day. It also plans to produce green aviation fuel to make airline travel more carbon-neutral. Tim Fox, head of energy and the environment at the Institution of Mechanical Engineers in London, said: "It sounds too good to be true, but it is true. Although the process is still in the early developmental stages and needs to take electricity from the national grid to work, the company believes it will eventually be possible to use power from renewable sources such as wind farms or tidal barrages. "There's nobody else doing it in this country or indeed overseas as far as we know. "We ought to be aiming for a refinery-scale operation within the next 15 years.
Taming mavericks: Researchers use synthetic magnetism to control light (Phys.org)—Stanford researchers in physics and engineering have demonstrated a device that produces a synthetic magnetism to exert virtual force on photons similar to the effect of magnets on electrons. The advance could yield a new class of nanoscale applications that use light instead of electricity. Magnetically speaking, photons are the mavericks of the engineering world. Lacking electrical charge, they are free to run even in the most intense magnetic fields. The process breaks a key law of physics known as the time-reversal symmetry of light and could yield an entirely new class of devices that use light instead of electricity for applications ranging from accelerators and microscopes to speedier on-chip communications. "This is a fundamentally new way to manipulate light flow. The ability to use magnetic fields to redirect electrons is a founding principle of electronics, but a corollary for photons had not previously existed.
A new probe for spintronics The spin Hall effect (SHE) enables us to create spin current in non-magnetic materials without using ferromagnetic materials. It is a crucial element in the central idea behind spintronics, that of manipulating currents of spin instead of currents of charge. Since the first experimental report on the SHE in semiconductors in 2004, the phenomenon and its mechanism have been intensively studied to find out more efficient and economical methods of generation of the spin current, both in semiconductors and metals. The inverse process of SHE (ISHE) is similarly recognized as a key step to be mastered in order to convert the spin current back into a charge current. So while both the SHE and its inverse are important for the potential applications, there are few examples of their use as an electrical detector of more fundamental properties of condensed matter. Explore further: Information storage for the next generation of plastic computers
Surface structure controls liquid spreading Researchers at Aalto University have developed a purely geometric surface structure that is able to stop and control the spreading of liquids on different types of surfaces. The structure has an undercut edge that works for all types of liquids, irrespective of their surface tension. By using the edges, liquid droplets can be confined and patterned on the surface in defined forms, such as circles. 'Patterning liquids into well-controlled circles is essential in applications such as the production of lenses that begin in liquid form and are then cured. According to the method developed by researchers, the effect of the edge structure on controlling liquids is based purely on geometry. Like an aqueduct without walls With the help of the structure, liquid can also be guided by the edges in a desired direction on the surface. 'These kinds of measurements often involve the guidance of very small fluid flows in microchannels.
Negative friction surprises researchers If you press your finger gently on a table and slide it across the surface, you will find that it glides fairly easily. If you press harder, it becomes more difficult to slide it as the firmer contact generates more friction. But now, researchers in the US and China have shown that if you do the same experiment with an atomic-force-microscope tip on a graphite surface, then you can see the exact opposite effect – friction decreases the harder you push. For large objects such as fingers and tables, the friction between two surfaces results from surface roughness, impurities, oxide layers and numerous other effects. On the nanometre scale, however, individual atomic interactions become relevant. As a result, the laws of nanotribology – the study of nanoscale friction – can be very different from the friction we experience in the macroscopic world. The coefficient of friction measures how friction changes as a function of load. Routine measurements So what was going on? A sticky surface?
Physicists twist water into knots More than a century after the idea was first floated, physicists have finally figured out how to tie water in knots in the laboratory. The gnarly feat, described today in Nature Physics1, paves the way for scientists to experimentally study twists and turns in a range of phenomena — ionized gases like that of the Sun’s outer atmosphere, superconductive materials, liquid crystals and quantum fields that describe elementary particles. Lord Kelvin proposed that atoms were knotted "vortex rings" — which are essentially like tornado bent into closed loops and knotted around themselves, as Daniel Lathrop and Barbara Brawn-Cinani write in an accompanying commentary. In Kelvin's vision, the fluid was the theoretical ‘aether’ then thought to pervade all of space. Each type of atom would be represented by a different knot. Kelvin's interpretation of the periodic table never went anywhere, but his ideas led to the blossoming of the mathematical theory of knots, part of the field of topology.
New experimental findings challenge theory of electromagnetism 29 November 2012 by Will Parker A cornerstone of physics may require a rethink if the results from a series of new ion trap (pictured) experiments at the National Institute of Standards and Technology (NIST) are confirmed. The theory in question is known as quantum electrodynamics (QED). NIST physicist John Gillaspy explained that one way to test QED is to take a fairly heavy atom - titanium or iron, for example - and strip away most of the electrons around its nucleus. Among the many things QED is good for is predicting what will happen when an electron orbiting the nucleus collides with a passing particle. The NIST team found that in ions with a strongly positive charge, the remaining electrons produce photons that are noticeably different in color than QED predicts. Gillaspy says he hopes the findings will stimulate other researchers to repeat the experiments and measure the emitted photons with even greater accuracy. Source: National Institute of Standards and Technology
Live Wires Today’s information age rests on a basic understanding of how electrons move. The remarkable success of computers, cell phones, and other devices, such as solar cells, depends on our ability to mediate the flow of electrons through the semiconductors and microchips that control the function of these machines and give them their intelligence. But the importance of electron flow is by no means limited to these man-made systems; electron transfer is also central to energy storage and conversion in living cells. Organisms depend on the flow of electrons for key energy-generating cellular processes. Continuous electron flow is necessary for the formation of the electrochemical gradients that enable the synthesis of adenosine triphosphate (ATP), life’s energy currency. In eukaryotes, including animals, this power generation is the specialty of mitochondria. So how do they do it? Rock breathers Shuttles and wires Living power cables A multicellular architecture? Mohamed Y. References
One material, two types of magnetism When placed next to a bar magnet, an aluminum ball draws gently towards the magnet. In contrast, a ball made of silver moves out of the magnetic field. The mechanisms underlying these different behaviors are known as paramagnetism and diamagnetism, respectively. Surprisingly, the material called BiTeI—composed of layers of bismuth, tellurium and iodine atoms—can be either diamagnetic or paramagnetic, depending on how it is prepared. The finding, by an international research team led by Naoto Nagaosa and Yoshinori Tokura from the RIKEN Advanced Science Institute in Wako, was unexpected because it requires an unusual mechanism to initially make the material magnetic. Orbital diamagnetism is observed in a very wide variety of materials, including substances as common as water. To generate orbital paramagnetism in BiTeI, the trick is to control the number of electrons moving through the crystal. Explore further: Could 'Jedi Putter' be the force golfers need?