  Following the spirit of de Broglie and Einstein, we think the concepts of
matter and radiation can be unified. We know a particle propagates like a wave;
its motion is described by certain wave equations. At this point, it is not
clear what the wave function represents. Besides the statistical meaning
suggested by the Copenhagen interpretation, does the wave function represent
any physical motion? For photon, we know it is an electro-magnetic wave. But
what about particles with rest mass, such as an electron? To investigate the
physical nature of matter wave, we propose that: (1) Like the photon, a
particle is an excitation wave of a real physical field. (2) Different types of
particles are different excitation modes of the same field. Based on this
thinking, we show that the concept of quantum mechanics can be a natural
extension of classical mechanics. By critically analyzing the transition from
classical physics to quantum physics, we found a new physical meaning for the
quantum wave function. This work suggests that various quantum wave equations,
including the Klein-Gordon equation, the Dirac equation and the Schrodinger
equation, could have a common base relating to the Basic Wave Equation of the
matter wave. This work has some interesting implications. It suggests a
possible way to explain the origin of visible matters and dark matters in our
universe.
