The Physics of How Viruses Make New Viruses Abstract: Viruses have enormously rich and varied life cycles. Bacterial viruses have a hallowed position in the development of modern biology and recently have become the subject of intensive physical investigation. Using single-molecule techniques, it has become possible to examine viruses both while they package and eject their DNA. One of the intriguing aspects of these processes is that they bring large forces (greater than 50 pN) into play. My talk will give a general introduction to viruses and their life cycles and will then focus on simple physical arguments about the forces that attend viral DNA packaging and ejection, predictions about the ejection process and single-molecule measurements of ejection itself.