I understand that we could think of a null curve in Minkowski space as being the curve c(s) such that the tangent vector dc(s)/ds = 0 at all s.(adsbygoogle = window.adsbygoogle || []).push({});

So suppose that we have a curve c(s) = (t(s), x(s), y(s), z(s)) and we want to ask ourselves what conditions would make c a straight line. I guess I'm having trouble understanding how c(s) as a straight line relates to tangency, if at all. Certainly one can think of a tangent vector at s as an equivalence class of curves passing through s, but I am not sure that's helpful.

Can anyone clarify this a bit?

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# Null curves vs. straight curves on Minkowski space

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