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Okay I have Kip Thorne's text in front of me that says the following:

If [tex](\Delta s)^2 > 0 [/tex] the events are calledspacelike

If [tex](\Delta s)^2 = 0 [/tex] the events are calledlightlike

If [tex](\Delta s)^2 < 0 [/tex] the events are calledtimelike

Then I have David W. Hogg's text in front of me that says:

If [tex](\Delta s)^2 > 0 [/tex] the events are calledtimelike

If [tex](\Delta s)^2 = 0 [/tex] the events are calledlightlike

If [tex](\Delta s)^2 < 0 [/tex] the events are calledspacelike

No joke. Which one's right? Understanding of this cursed interval wasjustdawning on me when I saw this. I was coming to the conclusion that [tex]\Delta s [/tex] is the distance light traveled in the frame of reference minus the distance between the events in that frame. I was thinking if this value is positive, light traveled farther than the distance between the events, thus there is a valid space-like interval.

If you don't mind could you also clear up what the sam heck this interval means?! I'm not sure I'm getting it.

TIA

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# Definition of relativity's interval

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