2013-08-13
Explanation
In this comic, a woman is giving a lecture at a blackboard, explaining a formula for what she calls the "mean date-free path." She states that it is calculated by taking the inhabited volume of Earth, dividing by her cross-sectional area, and multiplying by the number of potential mates. This is a humorous application of a real physics concept: the "mean free path" is a term from kinetic theory of gases that describes the average distance a particle travels before colliding with another particle. The formula on the board appears to mimic the actual mean free path equation.
A student challenges her, saying that this explanation for her lack of dates only works if they assume she is an ideal gas molecule. She responds with a deadpan and self-deprecating admission: "I'''m small and nobody'''s attracted to me" -- which are indeed two properties of ideal gas molecules (they are point particles with no intermolecular attractive forces). The student accepts this with "Carry on, then," and she replies "Thank you."
The joke operates on multiple levels. On the surface, it is about a lonely scientist rationalizing her dating life with physics equations. The deeper humor comes from the double meaning of "ideal gas molecule" properties -- having negligible size and no attractive forces between particles maps perfectly onto self-deprecating dating humor. The votey panel continues the physics-as-sadness theme, with the lecturer stating "Now, the sadness distribution is Gaussian," applying yet another statistical physics concept (the Gaussian/normal distribution) to her emotional state.