The sundial „lux aeterna“ is ment to be a steady counter- pole in today´s data communication traffic, where bits and bytes are clustered to gigas and terras and rushing through space. Energised through the sun, our most natural source of energy and light, the sundial shows the daytime in hours and is intended to communicate the sense of time in a natural way. Fibre optics which are also used in modern data communications, transport the light and the information about time right from the focal point to the clock itself. Even in dark rooms without any windows, a clear picture of time is displayed. Through a spherical glass lense, the sunlight is focussed onto a screen and the focal point is moving with the sun during the day. The design of the frame, carrying the 11 kg spherical lense is based on a topology optimisation. The algorithm is computing the stresslines in the material to get an ideal proportion of stability, weight and mass of material. lux aeterna was nominated for the MDR Designprice 2013. lux aeterna was shown in the exhibition “from the end of the world” by Marke.6 at Neues Museum in Weimar.