Does physics professor James Kakalios have an evil alter ego? The cutesy asides threaded into The Physics of Superheroes are surely the work of the nefarious Lily Gilder, and not the readable, creative University of Minnesota professor who apparently penned the rest of this comic-book-themed physics primer. Fortunately, Kakalios prevails: Confused about the concept of center of mass? Learn how Spider-Man could fell Doc Ock simply by chucking an apple at him. Kakalios notes that this approach stymies students’ usual I’ll-never-use-this-stuff-in-the-real-world complaint. After learning, say, that the Flash would have to eat at least 150 million cheeseburgers to run at one percent the speed of light, it’s easy to see why. Kakalios discusses and signs copies of his work at 11:30 a.m. at the Library of Congress, Madison Building, 6th Floor West Dining Room, Independence Ave. between 1st & 2nd Sts. SE. Free. (202) 707-5664. (Joe Dempsey)