One such example is in quantum particle equations where the probability of a particle being in this position or that, a meter from the center of the atom or in Cleveland, does not take into consideration the travel time of the particle from the center of the atom to Cleveland.
So, on the idea of an observer. There is NOT an observer that can experience two events, happening at the same time AT the same time, if the two events are separated by a distance. Light travel time prevents such an experience. Most models include a super observer that sees the two distant events at once.
I disagree with this notion as it is not realistic.
In my old age (84) I have turned to writing poetry, and prose about spiritual events I have experienced. But I am interested in the whole of life. I like science as well as spiritual studies. I have some books published on Kendall. I don't mind discussion as long as it is friendly. At my age life has become less intense and the need to be right has disappeared.
I hope and pray you will get better mate. And that the pain decreases to a tolerable and controllable level so that you can think clearly again. I look forward to your posts. I find heavy rock music to be cathartic when in pain....