Orthogonal space-like vectors.

[Felpudio]

Hey, I read that if a four-vector is 'four-orthogonal' to a time-like four vector then it must be space-like. I showed this quite easily.

I also read that a space-like vector can be orthogonal to another space-like vector, but can't seem to prove it. I wondered if someone could help me.

 

[Bill_K]

Take one vector pointing along the x-axis and the other pointing along the y-axis.