What Distinguishes Timelike from Non-Spacelike Curves in Spacetime?

[emma83]

Hello,

What is the difference between a timelike and a non-spacelike curve ?
Is it only that "non-spacelike" includes timelike and null curves, or is there another difference ?

Thanks a lot for your help.

 

[robphy]

Hello,

What is the difference between a timelike and a non-spacelike curve ?
Is it only that "non-spacelike" includes timelike and null curves, or is there another difference ?

Thanks a lot for your help.

A nonspacelike can include curves whose tangent vector at each point is "either timelike or null" (not just "always timelike" or "always null").