E-Mail IMAGE: A scattering-invariant mode of light is generated by sending a laser beam onto a judiciously configured spatial light modulator (see quadratic pixel array on the left). This modulated beam then... view more Credit: Allard Mosk/Matthias Kühmayer Why is sugar not transparent? Because light that penetrates a piece of sugar is scattered, altered and deflected in a highly complicated way. However, as a research team from TU Wien (Vienna) and Utrecht University (Netherlands) has now been able to show, there is a class of very special light waves for which this does not apply: for any specific disordered medium--such as the sugar cube you may just have put in your coffee--tailor-made light beams can be constructed that are practically not changed by this medium, but only attenuated. The light beam penetrates the medium, and a light pattern arrives on the other side that has the same shape as if the medium were not there at all.