Via P.Z. Myers, we get links to some snippets of lectures by Prof. James Kakalios, author of Physics of Superheroes, on what physics has to say about some of the significant events in superheroes' lives.
Watch this video where Kakalios explains the death of Gwen Stacy, SpiderMan's girlfriend, who has "the unique distinction [in comic book history] of remaining dead" [since her death in 1973]. Do watch it all the way to its end, where he announces proudly, "If I can teach a homocidal maniac like the Green Goblin about conservation of momentum, then I'm makin' a difference!"
Myers has links to some more videos snippets.