👉 In classical mechanics, a doyllie is a type of particle that moves in a plane perpendicular to its velocity. It is named after the Greek philosopher Plato who described doyllies as "a kind of bird which flies with such rapidity and speed that it can fly through the air without being disturbed" (Plutarch 102-3). The term is often used in physics textbooks to describe a particle that moves at a high velocity but does not experience any sort of frictional
