The Synchronization of Clock Rate and the Equality of Durations Based on the Poincar\'{e}-Einstein-Landau Conventions

There are two important basic questions in the measurement of time. The first one is how to define the simultaneity of two events occurring at two different places. The second one is how to define the equality of two durations. The first question has been solved by Einstein, Landau and others on the convention that the velocity of light is isotropic and it is a constant in empty space. But no body has answered the second question until today. In this paper, on the same convention about the velocity of light given by Poincar\'{e}, Einstein, Landau and others, we find the solution to the definition of the equality of two durations. Meanwhile, we also find answer to the question about the definition of the synchronization of rate of clocks located at different places. 04.20.Cv, 04.20.-q