Science

New breath: could Virgo help find evidence for extra dimensions? Signatures of the extra dimensions required by string theory could be seen by future gravitational-wave detectors. That is the conclusion of David Andriot and Gustavo Lucena Gómez at the Max Planck Institute for Gravitational Physics in Germany, who have identified two ways in which gravitational waves could be affected by the consequences of string theory – a theoretical framework that invokes speculative concepts such as extra dimensions to try to fill important gaps in our understanding of physics, including the nature of quantum gravity. Gravitational waves are ripples in space–time that are created when massive objects are accelerated under certain conditions. Andriot and Lucena Gómez calculate that adding N extra dimensions to 4D space–time results in a “breathing-mode” oscillation that would be present in a gravitational wave. The second distinct feature of extra dimensions, say the researchers, is a discrete set of higher-frequency signals accompanying …

Do the twist: ribbon halfbeak fish have a unique method of flight Scientists have uncovered how ribbon halfbeak fish “fly” despite having no hind wing fins. Yoshinobu Inada from Tokai University in Japan and colleagues have mimicked the fish’s flight, hoping to find the optimal design of tandem wing planes. To evade predators, “flying fish” have evolved to propel themselves out of water and soar above the surface. Normally, the fish can achieve this short flight because they have two sets of “wings” – large pelvic fins act as horizontal tail wings similar to those toward the rear of planes, and large pectoral fins are used as the standard large wings. A unique twist The ribbon halfbeak fish, however, lacks the large pelvic fins. To investigate, Inada and colleagues 3D printed a model resembling the fish. They analysed the effect of wing positions on flight performance using a wind tunnel. “Amazingly, they solve the problem …

On balance: the proton could be lighter than previously thought The most precise measurement ever of the mass of the proton suggests that the particle is a tiny bit lighter than the current accepted value. Although the difference is less than one part in 10 billion, it has a statistical significance of 3σ. The measurement was made by Sven Sturm of the Max Planck Institute for Particle Physics and colleagues, who compared the cyclotron frequency of the proton to that of an ionized carbon-12 atom. The particles were held in a Penning trap using magnetic and electric fields. The fields cause a charged particle to follow a looping orbit that is defined by the cyclotron frequency – which is related to the electrical charge and mass of the particle. Comparing the frequencies of the proton and carbon-12 gives the mass of the proton in atomic mass units, which are defined by the mass of the carbon-12 …

1000 days later: after nearly three years, the cement samples are still changing The longest-running synchrotron experiment has reached 1000 days. The experiment has been taking place at the Long Duration Experimental (LDE) facility at the UK synchrotron Diamond Light Source. Led by Claire Corkhill from the University of Sheffield, the experiment investigates the hydration of cement used to store nuclear waste. The only resource of its kind in the world, the LDE facility allows scientists to test complex materials under a range of conditions over long periods of time, and then regularly characterize the material with synchrotron X-ray powder diffraction. The cement experiment was the first to be set up at LDE and is still running 1000 days on, making it the longest-running experiment to take place at a synchrotron. More and more cement Cement (also known as cement paste) is a mixture of silicates and oxides that, after reacting with water, forms a …

Tiny bubbles: cavitation occurring in a liquid crystal The formation and subsequent collapse of bubbles has been seen for the first time in a flowing liquid crystal. This process is called cavitation and occurs when the pressure drop in a flowing fluid is large enough to allow some of the fluid to vaporize and create a bubble. Cavitation is of great interest in hydrodynamics because the collapsing bubbles can dissipate large amounts of energy in small regions and cause significant damage to machinery such as propellers. The discovery was made by Tillmann Stieger and colleagues at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, the Technical University of Berlin and the ETH Zürich. Liquid crystals are fluids that are made of rod-like molecules that tend to align under certain conditions. In its experiments, the team pumped liquid-crystal fluids through tiny channels just 0.1 mm wide. The channels contained obstructions, which increase the speed of …

Freezing depths: physicists want to surround this photomultiplier with optical materials The sensitivity of the IceCube Neutrino Observatory at the South Pole could be boosted by adding optical materials to the icy boreholes that contain its detectors – according to physicists in the US. Encompassing 1 km3 of ice, IceCube comprises 86 cables, each up to 2.5 km long, suspended inside vertical boreholes in the ice. Attached to each cable are dozens of photomultiplier tubes (see figure), which record the Cherenkov radiation given off by the secondary particles created when incoming neutrinos collide with nuclei inside the ice. In 2013, IceCube made the first every detection of cosmic neutrinos from throughout the universe and physicists are now thinking about how the detector could be upgraded. In a preprint on arXiv, Imre Bartos, Zsuzsa Marka and Szabolcs Marka of Columbia University in New York describe how filling sections of the boreholes with materials with desirable optical properties could …

On the move: satellite image of ground deformation near a volcano A new way of monitoring volcanic activity by integrating ongoing satellite measurements into dynamic models has been demonstrated by researchers from France. Based on data assimilation, the method might one day allow for real-time eruption forecasts in volcanic regions. As magma moves beneath the Earth’s surface – such as under a volcano – the ground above flexes. These ground movements can be measured using both GPS and satellite-based radar data, and used to develop models of the depth and shapes underlying magma reservoirs. A limitation of many of these models, however, is that they are kinematic in nature – focusing on motion alone. This makes them unable to yield information on the pressures of the underlying magma system. This is important in determining when a magma chamber will rupture and the volcano’s capacity to feed any resulting eruption. The surface disruption caused by a …

Signed and sealed: US president Trump re-establishes the National Space Council US president Donald Trump has signed an executive order to re-establish the US National Space Council. The council will include key government officials with an interest in space exploration, including the NASA acting administrator Robert Lightfoot and the secretaries of state, commerce and defence. The council will be chaired by US vice president Mike Pence and will also include a “Users’ Advisory Group” that will represent the interests of industries and other organizations not associated with the federal government. The council had existed in 1989–1993 during the presidency of George H W Bush. A previous incarnation called the National Aeronautics and Space Council was in place in 1958–1973. Deep interest Lightfoot says that the council will “ensure that all aspects of the nation’s space power – national security, commerce, international relations, exploration and science – are co-ordinated and aligned to best serve the American people”. He …

Phenomenal physicists: Charles Bennett receives prodigious Isaac Newton Medal The Institute of Physics has announced its award winners for 2017, honouring 21 physicists for outstanding contribution to physics in academia, industry, education and outreach. The highest accolade, the Isaac Newton Medal and Prize, has been awarded to Charles Bennett from Johns Hopkins University in the US. Bennett led the Wilkinson Microwave Anisotropy Probe (WMAP) mission – a satellite experiment measuring temperature fluctuations in the cosmic microwave background. The mission allowed scientists to make many breakthroughs in the field of cosmology, including the first fine-resolution (0.2 degree) full-sky map of the microwave sky, helping to determine the age of the universe to within half a per cent and providing evidence of dark matter and dark energy. “I am sincerely honoured to receive the Isaac Newton Medal and Prize,” says Bennett. “It is humbling to be selected, especially as the previous awardees are all of great distinction.” …

Patient observer: watching the lumbering black holes Two black holes with a combined mass of 15 billion suns have been tracked as they slowly orbit each other at the centre of a galaxy 750 million light-years away. The lumbering pair were watched for 12 years by astronomers led by Greg Taylor at the University of New Mexico in the US – who used a string of radio telescopes stretching from the Caribbean to Alaska. The objects are separated by about 23 light-years, which is the smallest known orbit of two supermassive black holes. Writing in the Astrophysical Journal, the team describes how it tracked the motion of the black holes at a glacial 1 micro-arcsecond per year – which it says is the slowest motion ever tracked in the sky. Based on its observations, the team reckons that the black holes circle each other once every 30,000 years. Never to meet While the black holes are believed to be spiralling towards each …

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