This episode premiered just five days after the fourth anniversary of Melissa Rauch's first appearance as Bernadette Rostenkowski, thus the anniversary of her and Howard's first date.
Title Reference: The very different ways that the three couples express romance are examined. Penny trying to be romantic with Leonard, while Resonance is referring to some atomic, particle or molecular resonance as in Sheldon's research.
When Sheldon claims to have discovered a new way to synthesize a super heavy element, the writing on the top of the main whiteboard are electron configurations. This is a short hand way of showing how the electrons are arranged in an element.
The [Uuo] at the start of each line refers to the element Ununoctium, or element 118, also known as Oganesdon. It has a configuration ending in 7s2 5f14, 6d10, 7p6. This is line 5 on the board. The next element would have a configuration of [Uno] 8s1, this element 119 which is on the fourth line. The first line is element 120, then the next two lines are improbable as they skip over multiple election levels. The bottom 3 configurations are for elements 117, 116, and 115, respectively.
A similar set up is seen on the paper Sheldon is writing on when the show opens.
The [Uuo] at the start of each line refers to the element Ununoctium, or element 118, also known as Oganesdon. It has a configuration ending in 7s2 5f14, 6d10, 7p6. This is line 5 on the board. The next element would have a configuration of [Uno] 8s1, this element 119 which is on the fourth line. The first line is element 120, then the next two lines are improbable as they skip over multiple election levels. The bottom 3 configurations are for elements 117, 116, and 115, respectively.
A similar set up is seen on the paper Sheldon is writing on when the show opens.
The dinner rolls on the table at The Cheesecake Factory appear to be the same as those on the table during Penny and Leonard's romantic dinner. Perhaps Penny was able to bring them home from work.