Where’s the Value in Relative Simultaneity?

Eugene Shubert

If no consistent notion of simultaneity exists, why use the idea at all? Where’s the value in relative simultaneity?

Shouldn’t a meaningful theory be based on absolutes? — or at least geometrical invariants, i.e., mathematical quantities that will always give you the same answer no matter what coordinate system you are using.

I believe that the best answer to the pole and barn paradox is “Don’t ask me this question. Forget about it. All physics is local. It doesn’t even make sense to synchronize spatially separated clocks.” Why should anyone think that this riddle requires careful analysis?

The twin paradox is based on the ambiguous phrase, “moving clocks run slow.” Why do physicists even tolerate this self-riddled confusion-producing phrase? Where’s the merit or intelligence in physicists insisting that simultaneity is relative and then using terminology that suggests that absolute synchronization exists?