Title text: Except the people filtering in late are the partiers, so you end up with drunken makeouts in the living room and the next roommate to return home has to sleep in the hall lounge orbital.
This comic is a pun on the Pauli exclusion principle, a principle that states (in part) that no two electrons in the same atom can ever be in the same quantum state simultaneously. The quantum state of two electrons is determined by four numbers, the first three determining its orbital and the fourth its spin, where spin can be one of two values, either +1/2 or -1/2. Thus there can only be two electrons in the same atom that share an orbital (and the two must have opposite spins), and such a pair of electrons is known as an orbital pair.
In this case, the people represent electrons, and rooms appear to represent orbitals, whether they be bedrooms or living rooms. "Romantic pair" is a play on "orbital pair". The "principle" at work here states that when engaging in romantic activity, only two people can be in a room at the same time, and thus any additional people are forced into different rooms. There is additionally a reference to the fact that as electrons are added to an atom, they will attempt to occupy the most stable or low-energy orbital, and so further electrons must occupy less stable/higher energy orbitals. Here, room comfort appears to equate to orbital energy, so the romantic partners all attempt to occupy the most restful or comfortable rooms, the bedrooms, leaving the lone roommate in a less comfortable location.
The title text jokes about drunken party-goers, who ignore the Pauli principle perhaps out of inebriation. They then end up partying and sleeping together with many people in the living room, leaving the roommate stuck in the third desirable location, the hall lounge.
- [Cueball is holding up a pointer in front of a diagram of a dorm apartment. On the diagram, there are two connected pairs of dots in each bedroom, and one dot on the couch.]
- Cueball: Thus, once all the dorm bedrooms are occupied by romantic pairs, additional roommates are forced into less restful "living room couch" orbitals.
- The Pauli Sexclusion Principle