Feynman diagrams are applied in condensed matter physics. By turning highly complex equations into sets of simple diagrams, the method has established itself as one of the sharpest tools in a theoretical physicist’s toolbox. Giacomo Bighin, a postdoc in the group of Mikhail Lemeshko at the Institute of Science and Technology Austria (IST Austria), has now extended the Feynman diagram technique. Originally devised for subatomic particles, the simplest objects imaginable, the technique can now work with molecules—far more complex objects. The research, which was published in the journal Physical Review Letters, is expected to drastically simplify the description of molecular rotations in solvents. This brings scientists one step closer to their long-term goal of understanding chemical reactions in solvents at the microscopic level, and potentially controlling them.