Last weekend, Regensburg hosted a somewhat unusual event: a “duck race.” The organizers threw 6,000 rubber ducks into a shallow canal with virtually still water. The ducks were slowly drifting towards the finish line. How did they make the ducks move in still water? They used high-pressure water streams from hoses to push the water around the ducks towards the finish line. You will be excused for thinking that this is a dumb idea.