Philadelphia offers a weekend packed with art, science and literature. You don't need to be an expert in physics to enjoy the Science Carnival, part of a 10-day Philadelphia Science Festival. More than 80 exhibitors will offer family-friendly experiments, games, activities and live entertainment. For literary enthusiasts, the Philadelphia Book Festival, featuring a variety of authors, including Robert Polito, Dava Sobel and Jonathan Haidt. Additionally, visitors on Saturday, April 21, can be on the lookout for a series of giant balloons lining the Benjamin Franklin Parkway and creating a Public Art Pathway marking the locations of 12 outdoor sculptures.