Over billions of years, plants and cyanobacteria changed the Earth’s atmosphere by inhaling carbon dioxide, storing the carbon in solid biomass and exhaling oxygen. Their release of oxygen into the air made animal life possible.  But how, exactly, do plants produce oxygen? Scientists have been puzzling over this for decades. In the past few years, experiments at X-ray lasers such as the Linac Coherent Light Source at SLAC have allowed us to follow the production of oxygen step by step and atom by atom. In this lecture, I will show a molecular movie made here at SLAC of the first half of oxygen production in cyanobacteria.  The movie reveals the amazingly complex, concerted atomic motions that nature has orchestrated to perform this essential reaction. I will discuss what we have learned about the process of oxygen production, and the mysteries that still remain.

The lecture is one hour long, followed by Q&A.