<p class="1Body">This article proves that the photons of lower energy are annihilated into dark energy due to the destructive interference of light, and the increase of dark energy makes the universe expand, the Hubble formula could be derived based on it. The energy level of matter reduces, more and more matter becomes the dark matter in the process. The universe stops expanding and starts to contract in the action of gravity when the energy density of radiation field becomes small enough in it.</p>