I think I get some things in the special theory of relativity (STR) and in the Minkowski representation thereof. I think I get that there is no two-term earlier-than relation: 'X is earlier than Y' is just not well-formed in the theory. It only makes sense to suppose X is earlier than Y in frame of reference F. Now, the Minkowski representation of STR replaces spatial and temporal relations with a more basic spacetime relation. My question: suppose we take two 'events', E1 and E2, in the Minkowski representation, each occupying just one point. (These are not extended events or wordlines, but instantaneous elements.) Is the question what is the spacetime distance between E1 and E2 well formed? Is there a basic spacetime distance relation that is either frame invariant or frame independent in the Minkowski representation?

---Ernani

Yes. The quantity s^2 = x^2 + y^2 + z^2 - c^2*t^2 is invariant (taking x, y, z and t here to be the differences in the coordinates of the 2 events, and c to be the speed of light).

http://en.wikipedia.org/wiki/Space_time#Space-time_intervals

Posted by: Ponder Stibbons | May 13, 2009 at 11:23 PM

Thanks Ernani and Ponder. I was puzzled by the same question.

Posted by: Nick Byrd | November 08, 2009 at 09:26 AM