There is no clock! Clocks are for humans. A present state of NOW is independent of clocks. NOW is not a measurement. It is a present condition of being. The Universe is NOW! You cannot say "some parts of the Universe do not exist NOW". That's a contradiction. The Universe's continuous existence results in a chronology of NOWS since it's beginning, independent of any clock. According to our arbitrary measuring system, the Universe has accumulated 13.7 billion years of NOWS.