: While his friends find partners, Raj continues to struggle with his selective mutism, even attempting to find companionship through a mobile phone's virtual assistant. Cast & Guest Appearances

: Sheldon and Amy formalize their unique bond with a "Relationship Agreement," while Howard and Bernadette prepare for their wedding, culminating in Howard's mission to the International Space Station.

: Amy Farrah Fowler (Mayim Bialik) and Bernadette Rostenkowski (Melissa Rauch) are promoted to main characters, providing a female social circle for Penny that mirrors the guys' group.

The season is notable for bringing together icons of science and science fiction:

: The milestone episode, "The Recombination Hypothesis," sees Leonard and Penny attempt a "beta test" of their relationship after their initial breakup, marking a central narrative shift for the series.

Available on both Blu-ray and DVD , the season set includes several exclusive extras:

pack (2011–2012) captures a pivotal era of the series where it evolves from a quintet of misfits into a more balanced ensemble comedy. This 24-episode collection is defined by major relationship milestones, the expansion of the female cast, and high-profile scientific cameos. Season Overview & Major Arcs

: Stephen Hawking makes his legendary first on-camera appearance, while astronaut Mike Massimino joins as a recurring guest during Howard’s space arc.