The Big Bang Theory - 1x9 - The Cooper-Hofstadter Polarization 2008-03-17 Comedy / Romance Jim Parsons - Sheldon Cooper , Johnny Galecki - Leonard Hofstadter , Kaley Cuoco - Penny When they're invited to present at a physics conference, Sheldon's reluctance to share the credit leads to a tiff between him and Leonard, and Penny's intervention only exacerbates the situation. 25 TV-14