Spatial harmonics are the laws of theoretical physics that govern the specifications whereby a microcosmic example of universal structure may be attained.
During a game of kal-toh played by Tuvok and Harry Kim, Seven of Nine took a turn for Harry and beat Tuvok in one move, claiming she used elementary spatial harmonics to do so. (VOY: "The Omega Directive")
In 2373, Rislan attempted to convince B'Elanna Torres that a graviton fluctuation caused by the Nyrian translocator was a subspace flow field. She was not fooled after examining the spatial harmonics. (VOY: "Displaced")
Icheb was studying spatial harmonics with Seven of Nine aboard USS Voyager. Seven asked his father, Leucon, if Icheb would be allowed to continue to study them. Leucon said that if he showed an aptitude for science, he would have a lot to learn. (VOY: "Child's Play")