Hi, this question may sound similar to the one I asked about a month ago, but I will give my shot to explain what's been bothering me. In almost all interpretations of the special relativity, it is stated that two events that are simultaneous in one reference frame are not in another. And that's okay, it's understandable. The question that's been triggering me is the further implications when implying this to everyday objects. Basically, special relativity say that both persons will agree what happened, they will both have the one and the same event, with its properties in their present reference. What differes is that different observers will have different events in their present frame, but nonetheless as far as the definition of an event goes, they will all have 'that what happened' sooner or later in their present reference frame. The part which gets tricky is applying this to the parts of events or objects. While we may agree on the identity of the event or the state of the object involved, it implies that that event or state is made of something, it has parts, and if the identity of the event or state of thing in question is invariant then it must have parts that are simultaneous (if it's a state) or that occur in a fixed time order (events). The parts of an object at some time may be spacelike separated, so how do we define their simultaneity? If an event/stage of an object has a fixed identity regardless of the frame it happens in, what does this imply for the parts of the events? How is it possible that all observers won't agree on the composition, but they will on the very identity of the thing? It sounds contradictory and I hope some with an understanding could help me.