The world's most sensitive model-independent experiment to search for particularly light particles, of which dark matter might be composed, starts today at DESY in the form of the 'light shining through a wall' experiment ALPS II. Scientific calculations predict that this ominous form of matter should occur five times as often in the universe as normal, visible matter. Until now, however, no one has been able to identify particles of this substance; the ALPS experiment could now furnish such evidence.