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However, there are two important points that we ought to consider. First, astronomers think that a few faint objects visible to the naked eye are much farther away than a few thousand light years. For instance, M31, the Andromeda Galaxy, the most distant object normally visible to the naked eye, is about two million light years away. Furthermore, since the invention of the telescope four centuries ago, astronomers have discovered many more other galaxies and objects much farther away than a few thousand light years. Most notable are quasars, which according to most estimates, are billions of light years away. If the world is only thousands of light years old, none of these very distant objects ought to be visible. The question is then whether there can be a meta-inductive method which is “predictively optimal” in the sense that following that method succeeds best in predictions among all competing methods, no matter what data is received. Gerhard Schurz has highlighted results from the regret-based learning framework of Cesa-Bianchi that there is a meta-inductive strategy that is predictively optimal among all predictive methods that are accessible to an epistemic agent (Cesa-Bianchi & Lugosi 2006; Schurz 2008, forthcoming). This meta-inductive strategy, which Schurz calls “wMI”, predicts a weighted average of the predictions of the accessible methods, where the weights are “attractivities”, which measure the difference between the method’s own success rate and the success rate of wMI. In the effort to reduce light pollution, researchers have developed a “Unified System of Photometry,” which is a way to measure how much or what kind of street lighting is needed. The Unified System of Photometry allows light fixtures to be designed to reduce energy use while maintaining or improving perceptions of visibility, safety, and security.[101] There was a need to create a new system of light measurement at night because the biological way in which the eye’s rods and cones process light is different in nighttime conditions versus daytime conditions. Using this new system of photometry, results from recent studies have indicated that replacing traditional, yellowish, high-pressure sodium (HPS) lights with “cool” white light sources, such as induction, fluorescent, ceramic metal halide, or LEDs can actually reduce the amount of electric power used for lighting while maintaining or improving visibility in nighttime conditions.[102] The use of full cutoff fixtures help to reduce sky glow by preventing light from escaping above the horizontal. Full cutoff typically reduces the visibility of the lamp and reflector within a luminaire, so the effects of glare are also reduced. Campaigners also commonly argue that full cutoff fixtures are more efficient than other fixtures, since light that would otherwise have escaped into the atmosphere may instead be directed towards the ground. However, full cutoff fixtures may also trap more light in the fixture than other types of luminaires, corresponding to lower luminaire efficiency, suggesting a re-design of some luminaires may be necessary. Street lights district councils are responsible for District councils are responsible for street lights on unadopted highways on district council owned land, for example, car parks, parks, and amenity areas. An unadopted highway is a street which is not maintained by the local highway authority at public expense. If the street light you want to report is one of these please contact your local district council. According to Mario Motta, president of the Massachusetts Medical Society, “… glare from bad lighting is a public-health hazard—especially the older you become. Glare light scattering in the eye causes loss of contrast and leads to unsafe driving conditions, much like the glare on a dirty windshield from low-angle sunlight or the high beams from an oncoming car.”[25] In essence bright and/or badly shielded lights around roads can partially blind drivers or pedestrians and contribute to accidents. To report a faulty light you will need to tell us: Measuring the effect of sky glow on a global scale is a complex procedure. The natural atmosphere is not completely dark, even in the absence of terrestrial sources of light and illumination from the Moon. This is caused by two main sources: airglow and scattered light. In September 2009, the 9th European Dark-Sky Symposium in Armagh, Northern Ireland had a session on the environmental effects of light at night (LAN). It dealt with bats, turtles, the “hidden” harms of LAN, and many other topics.[76] The environmental effects of LAN were mentioned as early as 1897, in a Los Angeles Times article. The following is an excerpt from that article, called “Electricity and English songbirds”: Sea turtle hatchlings emerging from nests on beaches are another casualty of light pollution. It is a common misconception that hatchling sea turtles are attracted to the moon. Rather, they find the ocean by moving away from the dark silhouette of dunes and their vegetation, a behavior with which artificial lights interfere.[67] The breeding activity and reproductive phenology of toads, however, are cued by moonlight.[68] Juvenile seabirds may also be disoriented by lights as they leave their nests and fly out to sea.[69][70][71] Amphibians and reptiles are also affected by light pollution. Introduced light sources during normally dark periods can disrupt levels of melatonin production. Melatonin is a hormone that regulates photoperiodic physiology and behaviour. Some species of frogs and salamanders utilize a light-dependent “compass” to orient their migratory behaviour to breeding sites. Introduced light can also cause developmental irregularities, such as retinal damage, reduced sperm production, and genetic mutation.[53][72][73][58][74][75] We own and look after most of the street lights in Kent. Parish and district councils own and look after some and some are privately owned. One example of a lighting plan assessment can be seen in a report originally commissioned by the Office of the Deputy Prime Minister in the United Kingdom, and now available through the Department for Communities and Local Government.[97] The report details a plan to be implemented throughout the UK, for designing lighting schemes in the countryside, with a particular focus on preserving the environment. Some astronomers do not accept inflationary models and have proposed other possible solutions to the horizon problem. These include: scenarios in which the gravitational constant varies with time,5 the ‘ekpyrotic model’ which involves a cyclic universe,6 scenarios in which light takes ‘shortcuts’ through extra (hypothetical) dimensions,7 ‘null-singularity’ models,8 and models in which the speed of light was much greater in the past.9,10 (Creationists have also pointed out that a changing speed of light may solve light-travel–time difficulties for biblical creation.11) Light pollution is the excessive or misdirected outdoor lighting that is threatening to destroy virtually all casual stargazing. Throughout much of the United States, for instance, millions upon millions of precious watts are wasted because poorly designed streetlamps send a portion of their light into the sky. But it’s not just stargazers who need to be concerned. While some may scoff at preserving the beauty of the night sky, there are other facets of light pollution that have a direct impact on all of us. Here are just a few examples: Astronomy is very sensitive to light pollution. The night sky viewed from a city bears no resemblance to what can be seen from dark skies.[78] Skyglow (the scattering of light in the atmosphere) reduces the contrast between stars and galaxies and the sky itself, making it much harder to see fainter objects. This is one factor that has caused newer telescopes to be built in increasingly remote areas. Some astronomers use narrow-band “nebula filters” which only allow specific wavelengths of light commonly seen in nebulae, or broad-band “light pollution filters” which are designed to reduce (but not eliminate) the effects of light pollution by filtering out spectral lines commonly emitted by sodium- and mercury-vapor lamps, thus enhancing contrast and improving the view of dim objects such as galaxies and nebulae.[79] Unfortunately these light pollution reduction (LPR) filters are not a cure for light pollution. LPR filters reduce the brightness of the object under study and this limits the use of higher magnifications. LPR filters work by blocking light of certain wavelengths, which alters the color of the object, often creating a pronounced green cast. Furthermore, LPR filters only work on certain object types (mainly emission nebulae) and are of little use on galaxies and stars. No filter can match the effectiveness of a dark sky for visual or photographic purposes. Due to their low surface brightness, the visibility of diffuse sky objects such as nebulae and galaxies is affected by light pollution more than are stars. Most such objects are rendered invisible in heavily light polluted skies around major cities. A simple method for estimating the darkness of a location is to look for the Milky Way, which from truly dark skies appears bright enough to cast a shadow.[80] eracto BioBelt xtrasize BeMass el macho xtrasize deseo TestX Core BioBelt Masculin Active