Waving and particle are two properties of wave-particle duality, but they are not equal, for example, in terms of energy, it is necessary to promote wave and suppress particle. In layman's terms, the difference between them lies in concealment, and the so-called "one-leaf obstacle" is the description of particle. And wave will be filled around, cannot be stopped by a leaf. It is this situation that leads to the selection of MSE. Although both waving and particle can involve proper mass when it comes to energy, the latter only involves a little of proper mass even in fission and fusion, rather than the whole proper mass itself. To obtain the energy converted by the entire proper mass itself, only the waving property used in MSE can be utilized. The method of obtaining energy by wave is much more convenient than that by particle, and it has the advantages of being available whenever need, which can be used in the whole universe. It is an inevitable trend for energy to promote waving property and suppress particle property.