title_body: Are there constructed languages with a tense system inspired by Theory of Relativity? For readers who aren't familiar with the Theory of Relativity, here is a sketch of how the Special Theory of Relativity structures space and time:
  
  
  There is a point "here and now" where the observer is located
  There is an "absolute past" meaning the region of space and time wherefrom light signals can reach the point "here and now". This region is also termed backward light-cone
  There is an "absolute future" meaning the region of space and time whereto the observer can send light signals. This region is also called foreward light-cone
  There is a "disconnected" region that can neither be reached by light signals nor send light signals to the observer.
  
  
  While present, past, and future are commonly found in natlangs and conlangs of all flavours, the disconnected region is a new feature brought in by the Special Theory of Relativity. Are there conlangs with a tempus system including such a region?
  
  EDIT: In real life, the disconnected region is not determined by the speed of light but by the availability of direct communication channels. Thus a sentence like My husband is in his working office now is about the disconnected region (assume no smart phone stalking to verify the sentence).
upvoted_answer: I think you are looking for the constructed language called Lojban
  According to an earlier reference to its grammar,
  
  Technical note for readers conversant with relativity theory: The Lojban time tenses reflect time as seen by the speaker, who is assumed to be a ``point-like observer'' in the relativistic sense: they do not say anything about physical relationships of relativistic interval, still less about implicit causality. The nature of tense is not only subjective but also observer-based.
  
  Here is a specific reference to its use of a &quot;relativistic tense&quot;
  
  There's been a proposal to have words expressing relativistic tenses that are different &gt; from usual past, current and future used in most historical natural languages.
  How this 4th tense would work? Consider we are 3 light years away from a star that explodes. And in 3 years we see the explosion. So what? How do we use this 4th tense?
  It would be a tag with a modifier ue'ei.
  ue'ei = [MOhI] 4th relativistic tense modifier
  
  There's also an interesting set of charts describing in detail the use of relativity theory in Lojban on the current lojban language site.
  
  Lastly, in the Lojban Reference Grammar site, there is this little intriguing tidbit on Lojban tense usage.
  
  In Lojban, the concept of tense extends to every selbri, not merely the verb-like ones. In addition, tense structures provide information about location in space as well as in time. All tense information is optional in Lojban