[s8e6] The Expedition Approximation -

: Johnny Galecki (Leonard), Jim Parsons (Sheldon), Kaley Cuoco (Penny), Simon Helberg (Howard), Kunal Nayyar (Raj), Mayim Bialik (Amy), and Melissa Rauch (Bernadette).

is the sixth episode of the eighth season of The Big Bang Theory , originally aired on October 20, 2014. The episode features two primary storylines: Sheldon and Raj testing their endurance for an upcoming dark matter research project, and Leonard and Penny dealing with a financial disagreement. Plot Summary

: Sheldon and Raj consider joining a research team in a salt mine to detect dark matter. To see if they can handle the claustrophobic and harsh conditions, they decide to spend time in the university's underground steam tunnels as a simulation. During their stay, Raj shares personal stories, but the "expedition" ends abruptly after just 11 minutes when a family of rats scares Sheldon into fleeing and abandoning Raj.

: Raj's monologue about the Voyager space probe and the reveal of Howard’s incomplete set of Star Trek collectible plates. The Expedition Approximation | The Big Bang Theory Wiki