The Physics arXiv Blog
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Why astronomical units need to be redefined
In 1983, the International Bureau of Weights and Measures defined the metre as the distance travelled by light in a vacuum in 1⁄299,792,458 of a second. That makes a metre a fixed unit of length. For astronomers, however, distance is rather more malleable. In astronomy, distance is measured in astronomical units. Astronomers think of an…
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2D image created from a single pixel sensor
Ghost imaging is a curious phenomenon that has had numerous physicists scratching their heads in recent years. It works like this: take two beams of entangled photons and aim the first at an object. The transmitted photons from the object are then collected by a single pixel detector. The second beam is aimed at a…
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How bacterial colonies could drive rotors
E coli bacteria use motors called flagella to generate a force that pushes them along at a rate of up to 10 body lengths per second. That’s a fair rate of knots and in recent years several groups have used this force to turn microrotors. Their approach is to bond the bacteria to a rotor…
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Solving stiction in MEMs devices
Microelectromechanical devices were supposed to change the world, so where are they? A few designs have leaked out, such as the accelerometers in air bags. But most have remained stubbornly, and literally, stuck in the lab. One of the troubling secrets about MEMs is that many designs simply don’t work because their moving parts become…
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Hertz ‘n’ pain
The best of the rest from the physics arXiv this week: Molecular Signatures in the Near Infrared Dayside Spectrum of HD 189733b A New Metric for Robustness with Respect to Virus Spread Combining Chromosomal Arm Status and Significantly Aberrant Genomic Locations Reveals New Cancer Subtypes Ultracold Molecules: Vehicles to Scalable Quantum Information Processing Ten New…
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Graphene transistors clocked at 26GHz
IBM has seen the future of computing and it may not involve silicon. Instead the company has been looking at graphene, the single atom-thick sheets of carbon that has materials scientists entranced by its dazzling array of amazing properties. If graphene ever becomes the material of choice for a new generation of superfast chips, then…
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How to decelerate a molecule
When it comes to shuttling individual atoms about, physicists have made giant strides in cooling, trapping and even collimating them into matter wave beams. These kinds of tricks are already being used for matter-wave interferometry on chips. But if you want to do the same kinds of things with molecules, you’re out of luck. There…
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Modelling the spread of HIV
Modelling the spread of HIV is a difficult business for many reasons: many people are unaware that they are infected, HIV can take a very long time to manifest itself within the body, and researchers are still unsure to what extent different population groups are involved in its transmission. So it’s remarkable that Shan Mei…
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Calculating the probability of immortality
How likely is it that a given object will survive forever? With many groups predicting that human immortality is just around the corner, you could say we all have a vested interest in the answer. A t first glance, the odds are not good. As David Eubanks of Coker College in South Carolina puts it:…
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Secrets ‘n’ lies
The best of the rest from the physics arXiv this week: Grain Size Dependence of Barchan Dune Dynamics On the History of Geometrization of Space-time: From Minkowski to Finsler Geometry Graviton, Ghost and Instanton Condensation on Horizon Scale of the Universe. Dark Energy as a Macroscopic Effect of Quantum Gravity The Upper Atmosphere of HD17156b…