I have been reading a bit on Einstein’s special theory of relativity. It seems clear to me from the theory that two observers do not necessarily agree on what events occur simultaneously. However I have difficulty understanding how that relates with the concept of now.
Let’s consider that in my reference frame I am holding my phone typing this question. Suppose that in my reference frame there is someone approaching me from a far distance at a speed close to that of light. Then that person would find my future self to be simultaneous with his/her now (let’s say it’s a future self that is asleep because it’s night time).
I do not know how to interpret this. I am not yet in that state. It seems that I will eventually become that future self but that is not what I am yet. Should I interpret this as simply saying that experiments carried out by that person will reveal my future self to be simultaneous with the person BUT NOT to mean that the future self exists yet (experiments such as obtaining the distance between him/herself and my future self and dividing it by the speed of light)? In other words should I interpret this as saying that the laws of physics only give you what is simultaneous IN your reference frame but not necessarily what is happening in the moment (in the way that it is the case that I am typing on my phone at this moment and not sleeping). And if I bite that bullet it seems I’m forced to consider that the person I say is approaching me might only be doing that in my reference frame and not in his.
The question itself is a bit confusing as well because according to relativity the moment depends on the observer. I guess the question might be a bit more philosophical than scientific but if there is any light you can shed on the problem it would be very appreciated.