The cosmological principle 5

Global time. Is there a spatial non-homogeneous of time?

 

   We have already defined the global time of the universe. But we also know about the existence of time dilation - kinematic and possibly also gravitational. It will be discussed elsewhere.

   We are aware that in our eyes the objects, the farther away from us, are the more retarded in their in evolutionary development. [As is well known, an explanation for this is simple and logical. After all, to see what is happening in the object, one has to wait for the light coming from there, for example, after the explosion of a supernova star. However, with regard to the very distant objects (billions of light-years), their motion must also be taken into account.] It follows that the observer himself (on his watch) represents real time (without lag). This is the global time, the time of the universe - a time that has passed since the beginning of the count, from the beginning of being. Here is the definition of global time.

   In this context, it is worth mentioning the existence of kinematic time dilation, related to the expansion of the universe, visible with respect to objects moving at very high speeds (close to the speed of light) - very distant objects. The reason for the existence of this dilatation is that the speed of light does not depend on a system of reference. This dilation does not violate the existence of global time and of course also of the cosmological principle. After all, the size of this dilatation does not depend on the direction of observation. 

   The problem is that there is also (in theory) a local non-homogeneity of time caused by a gravitational field. This is due, as an interpretation, to general relativity. If this type of time dilation exists, the existence of global time is also in doubt. After all, it would violate the internal coordination of the entire universe, for example the course of evolutionary processes - different when looking at different directions.