8 6 2014-10-20 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 deep underground. Leonard and Penny seek advice from Howard and Bernadette after they fight about money. 4997387 20850 https://artworks.thetvdb.com/banners/series/80379/episodes/5ea3100d7730a.jpg false