1. "The Expedition Approximation"
Sheldon and Raj test whether they could survive a dark-matter research expedition in a salt mine by simulating the conditions in a steam tunnel. Meanwhile, Leonard and Penny seek advice from Wolowitz and Bernadette after they fight about money, on THE BIG BANG THEORY, Monday, Oct. 20 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Melissa Rauch, Simon Helberg, Kunal Nayyar, Mayim Bialik, Jim Parsons, Johnny Galecki and Kaley Cuoco-Sweeting Photo: Monty Brinton/CBS ©2014 CBS Broadcasting, Inc. All Rights Reserved