Sheldon's whiteboard

According to him, his board contains some quantum mechanics along with a little string theory, plus a joke, a spoof of the Born-Oppenheimer Approximation. The BO Approximation is a bit of a short-cut used to work out quantum chemical calculations which would otherwise be extremely difficult and time-consuming to solve. Since using the Approximation gives less than perfectly accurate results, Sheldon may be poking fun of it and suggesting that when he works out the energy and wavefunction of a molecule, he actually works it out entirely instead of taking the imprecise short-cut of the BO Approximation.