The light-speed object follows the light-like world line, and the line element DS 2 is always 0. According to the relationship between line element and intrinsic time Dτ, ds 2 =-dτ 2 shows that the intrinsic time dτ of light-speed objects is always 0, that is, the time of light-speed objects will not change, so the time of light-speed objects is stagnant.