One of our favorite stories in the latest issue of Popular Science is an excerpt from Mary Roach's new book Gulp: Adventures on the Alimentary Canal. The story examines the billion-dollar science of convincing dogs and cats to eat their food. We're holding a live chat with the author tomorrow, March 28, at noon EST. Hope you can join us! If not, feel free leave questions in the comments below, and we'll make sure she gets the best ones.