1
16 | NewScientist | 17 December 2011 THE sleeping giant at the centre of the Milky Way is about to wake up. A suicidal gas cloud is heading towards the galaxy’s supermassive black hole. This will shred the cloud, generating enormous flares of radiation that could help explain why the black hole is normally so placid. The doomed cloud was spotted by Stefan Gillessen of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, using images from the Very Large Telescope array in Chile. About three times the mass of Earth, the cloud is moving at nearly 2500 kilometres per second towards our black hole, Sagittarius A*. At present Sagittarius A* is strangely quiet, unlike quasars, the hyperactive black holes that emit huge amounts of radiation, fuelled by inflowing gas. But that Single particle is tiny Stirling engine THE 200-year-old Stirling engine has inspired a power generator made of a single particle. Overshadowed by its steam and internal combustion brethren, the Stirling engine is a quiet, efficient alternative that compresses a fixed amount of gas inside a cylinder. The gas heats up and expands, pushing a piston, before cooling due to the loss of energy, only to be compressed again. In their tiny mimic, Clemens Bechinger and Valentin Blickle at the University of Stuttgart, Germany, replaced the cylinder with a laser that confines the motion of a 3-micrometre-wide lump of melamine in water. A zap of heat from another laser builds up tension in this optical “trap”: like a compressed gas, the particle is aching to break free. Widening the trap by modifying the first laser lets it do so, expending the pent-up energy (Nature Physics, DOI: 10.1038/nphys2163). A spoonful of sugar helps your skin age prematurely A SWEET tooth does more than pack on the pounds. It causes your skin to age prematurely, making you look older than you really are. But how much older? A team led by Diana van Heemst at Leiden University in the Netherlands divided 569 healthy volunteers into three groups according to whether they had low, medium or high concentrations of blood glucose after a meal. They also studied 33 people with diabetes who had even higher blood glucose levels. Sixty independent assessors were then asked to view pictures of the volunteers and rate how old each looked. EMMANUEL PIERROTT/AGENCE VU/CAMERAPRESS IN BRIEF Cloud suicide could transform black hole could change in 2013, when Gillessen’s team has calculated the gas cloud will get dangerously close (Nature, DOI: 10.1038/ nature10652). Much of the cloud will probably swirl down into the black hole and make Sagittarus A* emit vastly more light, says team member Reinhard Genzel. Though not visible to the naked eye, this radiation will give astronomers clues as to why our black hole is normally so different from quasars. The results show that high blood sugar levels made people look older, even when other factors affecting appearance were accounted for, such as actual age, smoking and a history of sunbathing. The largest gap in perceived age was one year seven months, between the lowest glucose group and the diabetics, from an average of 59.6 years old to 61.2 years. But even among those without diabetes, there was a one-year gap between the lowest and highest glucose groups. Overall, there was a five-month hike in perceived age for every 0.18 gram increase in glucose per litre of blood (Age, DOI: 10.1007/s11357-011-9339 -9). “What’s happening in the body is written in the face.” says David Gunn of Unilever Research in Sharnbrook, UK, who co-led the project. A LUNGFISH that uses its fins for walking could help to unravel the steps our distant relations took in order to move from water to land. The African lungfish (Protopterus annectens) has lobe- shaped fins similar to those seen in the ancestors of the first vertebrates to walk on land. Anecdotal evidence suggested that the fish use these to walk along lake beds. Now Heather King of the University of Chicago in Illinois has filmed the lungfish in motion and found that they do indeed walk using their two pelvic fins (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1118669109). This suggests fins were used for walking before they evolved into specialised limbs, says King. Lungfish doesn’t need limbs to walk
