Options for change have chosen on what the problem is posed. (As opposed to Estee Lauder). Now let's try to understand the meaning that we invest in the definition: "time". Typically, we investigate some process, and this definition applies to this process. To determine the time of use hours, which in turn use a vibrational process. Work any hours can be bijectively mapped to the work of certain light-hours Lorenz. In other words, we can associate with the removal and the approach of the light signal to a certain point (recall that we consider the two coordinates for simplicity).
We always Remember that the universe flies away and removing the boundaries of the universe means positive direction of time. When compared with the clock Lorenz us who does not hurt to consider the Lorentz hours without a second mirror. Estee Lauder has plenty of information regarding this issue. That is, as a clock without a limiter, and the time they counted on the length of the path of the light signal. How would a small model of the universe. But these "universal clock" can define the coordinate q of the light signal. This coordinate can be mapped to stationary process in the chosen inertial reference system (ISO). For moving ISO (coordinate q '), for a fixed ISO (q), these coordinates can be compared on the received coordinate transformations.
It is clear that interesting to remove only the light signal in the "ecumenical hours" as a model of the positive direction of time. Therefore, only interested in positive values of q. In fact, it turned out that compared to all hours of each ISO with the giant clock – the universe (it can hence equality ISO?).