Ep 5. The Hamburger Postulate

Leonard goes to a bar with Howard and Raj, hoping to forget about his problems with Penny. While at the bar, Leonard meets a girl named Leslie who is also a scientist. They have a clash of personalities and end up arguing about science. Meanwhile, Sheldon is obsessed with getting the perfect hamburger and spends the entire episode trying to figure out the perfect formula for the perfect burger. Eventually, everyone ends up back in Leonard and Sheldon's apartment, where Leslie and Sheldon have a heated debate about the existence of God. Overall, the episode explores the personalities and interests of the main characters, highlighting their quirks and differences.