Is there any inertial frame of reference in the universe?
if I am reading your question correctly, then no, there is no one inertial reference frame in the universe. And ALL reference frames are equally valid. All exist within the constraints of Einsteinian mechanics. Under certain conditions, Newtonian mechanics will break down for EVERY frame of reference This was the shocking (at the time, and really still!) revelation that Einstein used to put a final end to the ‘flat Earth” idea. No only is the earth not flat, not only is it not the center of the universe, but there IS no center of the universe and any point of view or reference frame is just as valid and just as limited as any other.
