What is the proof of existence of &#x27;universal time&#x27; as physical phenomena instead of being a &#x27;derived property&#x27; of some or other physical process?<p>Rotation of Earth around Sun is just a process, there is no time in it apart from the mind of an external observer. Similarly with any so called &quot;atomic clocks&quot; or any other physical process, including so called expansion of the Universe.<p>Time, of course, could be derived as a concept from an observable change (a process) by mind, but this does not imply its physical existence, like it is with what we call physical forces.<p>Space is more subtle, but it is also require an observer and at least two particles related via this or that set of forces.<p>Two random Photons share nothing, and without an observer there is neither space nor time among them.<p>Mathematics does not imply existence of described abstraction.