chunk: While Helen and her boyfriend Tom Stephens (Hugh Marlowe) go out, Klaatu babysits Bobby. The boy takes Klaatu on a tour of the city, including a visit to his father's grave in Arlington National Cemetery; Klaatu learns that most of those buried there were killed in wars. The two visit the Lincoln Memorial, then the heavily guarded spaceship. Klaatu asks Bobby who is the greatest living person; Bobby suggests Professor Barnhardt (Sam Jaffe), who lives in the capital. Bobby takes Klaatu to Barnhardt's home, but the professor is absent. Klaatu adds a mathematical equation to a problem on Barnhardt's blackboard and leaves his contact information with the suspicious housekeeper.