[s4e10] The Alien Parasite Hypothesis -

Sheldon famously declares 73 the "best number". It is the 21st prime number. Its mirror (37) is the 12th prime. In binary, it's a palindrome: 1001001 .

In The Big Bang Theory Season 4, Episode 10, Sheldon and Amy's relationship faces its first biological "crisis." After Amy experiences a physical reaction to Penny's ex-boyfriend Zack, she and Sheldon attempt to diagnose her symptoms with rigorous scientific logic. The "Diagnosis" Breakdown [S4E10] The Alien Parasite Hypothesis

Sheldon’s preferred theory, as he finds it more plausible than the final option. Sheldon famously declares 73 the "best number"

Howard and Raj fight over who would be the superhero and who would be the sidekick after a lab tech is bitten by a radioactive rat. Production Trivia In binary, it's a palindrome: 1001001

Dismissed by Amy (despite Sheldon's "testy bark of an old biddy" comment).

After rejecting Zack's lack of intellect, Amy adopts the Vulcan practice of Kolinahr to purge her emotions.

Sheldon proposes several possible causes for Amy’s elevated heart rate, sweaty palms, and "localized vascular throbbing": Ruled out via blood work.