From Superman to Ant-Man, comic book heroes can be used to explain some of physics' basic principles -- and make the learning fun. Honest. OK, physics-phobes, here's a test. When the Green Goblin knocks Peter Parker's girlfriend, Gwen Stacy, off a towering bridge in New York City, she dies even though Spider-Man catches her in his web just before she plunges into the river. Did the fall or the webbing kill her? As big questions in physics go, it's not quite up there with string theory and high-temperature superconductivity. But Jim Kakalios, a University of Minnesota physics professor, knows it's...