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                                  | Being 
                                    able to bend light backwards would be extremely 
                                    useful for all kinds of optics from telecommunications 
                                    to chipmaking. This kind of bending -- negative 
                                    refraction -- is controversial in physics 
                                    circles and has only been demonstrated using 
                                    carefully designed artificial materials containing 
                                    metal loops. It turns out that a common natural 
                                    crystal has harbored this capability all along. Full 
                                    story
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