周期性是自然界中一种普遍的现象,周期性就是事物在变化时存在的某种重复性.物理学中大量的周期性现象往往又具有对称性,一般情况下周期性表现为物理过程在时间和空间上的对称性和重复性.具有周期性的现象,其相互作用的过程存在某些相同的特征.因此,一旦确定了物体在某一周期内 Periodicity is a universal phenomenon in nature, and periodicity is a kind of repetitiveness that exists when things change. A large number of periodic phenomena in physics often have symmetry. In general, periodicity is expressed as a physical process in time. And the symmetry and repetitiveness in space. It has a periodic phenomenon. The interaction process has some similar features. Therefore, once it is determined that the object is within a certain period,