Dalespam recently brought up an interesting semantic issue. What is the meaning of “relative” versus “absolute”? I did not have time to intervene in that thread but the subject links well with the musings of this Blog.

Obviously “relative” is what is defined “in relation with” or by comparison with another object, but in the context of Special Relativity this may mean three different things:

(a) That a measurement (of time or space) is made from and hence with regard...