The main use of reflection seismic imaging is petroleum prospecting. Unlike nuclear energy, hydrocarbons are a nonrenewable resource and there is evidence that petroleum production must decline during the lifetimes of the young generation. Does this mean that young people should avoid these studies? I think not. Taking the long-range view, with the population of the earth continuing to increase, it is not easy to imagine people losing interest in the earth's crust. A view of more intermediate range is that as the resource declines in abundance, there will be greater efforts to seek it. A short-range view is that workers are needed today, and there are no coal- or nuclear-powered airplanes. In any case, the skills developed in this book, computer implementations of concepts from physics, will always be of general utility.