A clue to his subject — or his purpose — lies in a word that appears frequently in the titles of the paintings currently on view in Dynamic Equilibrium at 1GAP Gallery, in Brooklyn. The word is “particles,” and the sense in which he means it is suggested in “Large Hadron Collider,” the title of three paintings in this show. A tunnel 17 miles in diameter situated near Geneva, Switzerland, the Hadron Collider is an extraordinarily sophisticated research tool designed to reveal bits of subatomic matter — in a word, particles. Though these phenomena supply Feldschuh with subject matter, he doesn’t try to picture them. Having earned a bachelor’s degree from Harvard in physics, he understands that the actions and interactions of particles can be formulated mathematically but not illustrated visually. His Large Hadron Collider paintings, however, are grandly representational.