Be sure to watch The Big Bang Theory Season 8 Episode online right here via TV Fanatic to find out what happens when Sheldon has difficulty in his research on dark matter. When he finds that he is struggling with the research, he doubts his decision to switch fields of study. But Penny, in her own way, is able to convince Sheldon of a way to get back on track.

With the help of Amy, Sheldon realizes exactly what he needs to help him best focus on his work, and he enlists his friends to help in an experiment that they have a little too much fun with. Watch The Big Bang Theory Season 8 Episode 13 online right here via TV Fanatic to find out what happens.

But how will Sheldon's new experiment affect his relationships with his friends and with Amy?

Meanwhile, Howard pokes fun at Raj with a game called "Emily or Cinnamon" in which everyone guesses if a quote said by Raj was said to his girlfriend or to his cat. As usual, there's great fun to be had with this episode! Watch The Big Bang Theory Season 8 Episode 13 online right now via TV Fanatic.