Under the frame of thought experiment, the concept of generalized particle which has variable volume or shape is proposed. The origin of the concept of the speed of light is analyzed. The impossibility of faster-than-light is discussed. The view that the universe originated from the split of an initial photon black hole is proposed. The quasars moving at a speed close to the speed of light are the first evidence for supporting the photon splitting model. Photons can be divided into high energy photons and low energy photons. The arrangement and selection of photonic data are discussed. The concept of blackbody can be derived from the black hole. The derivation process of the blackbody radiation formula based on MATLAB is presented. The blackbody radiation formulae for low energy photons (i.e., the Planck''s formulae) can be obtained by adding a ''zero'' in the photonic data sequence; otherwise, the blackbody radiation formula including high energy photons is obtained and the result tends to infinity. For the description of the ultimate fate of the universe, there needs no introduction of any other concepts or terms such as entropy. By using a photon splitting model plus a radiative heat transfer model, the conclusions equivalent to those from the theories of heat silence or dissipative structure can be obtained. The dark matter particle (or simply, the darklet) model based on photon splitting is presented. The darklets are the second evidence for supporting the photon splitting model. A cycle model between the speed of light and the non speed of light is proposed for the evolution of the universe.