Over the past decade tremendous progress has been made in our understanding on galaxy evolution throughout the live time of the universe. Deep sub-millimeter observations are particularly important as they trace dust obscured star-forming galaxies which are often difficult to detect at other wavelength. Unlike observations at other wavelength, the dimming of sub-millimeter light due to the tremendous distances is compensated by increasing intrinsic intensities caused by the redshift and the shape of the spectrum of galaxies at this wavelengh. As such sub-millimeter intensities of distant galaxies remain roughly constant over a large redshift range. In collaboration with researchers all over the word our group has been leading one of the largest sub-millimeter deep field surveys using LABOCA on APEX. The initial detection of dusty starforming high redshift galaxies in this and other survey allows us to study this endigmative objects in great detail at multi-wavelenght. Ongoing studies include follow up observations with the IRAM facilities, ALMA and many other world leading observatories. High spatial resolution imaging and spectroscopic observations at different wavelength allow us to charcterize these mega-starburst and to put them into the context of galaxy evolution over the Hubble time.  Furthermore these distant objects allow us to test fundamental physical paradimes such as potential variations of the fundamental physical constants.
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