"In Principle, worldlines allow us to relate events on one another - to do sciecne without using reference frames at all". This was in Wheeler and Taylor's Intro to SR book. My question is, isn't this false? Because worldlines exist in a spacetime diagram. Vertical being time and horizontal is space. One reference frame is always needed, which normally is the one that does not move wrt space. Hence it registers the greatest proper time. All other worldlines are created wrt to this stationary reference frame (i.e. the speed and directions of the particles that translate to worldlines are calculated or measured wrt to the stationary frame). So one reference frame must be needed hence contradicting the statement?