In ( t , r , θ , φ ) {\displaystyle (t,r,\theta ,\varphi )} coordinates k a = ( 1 , 0 , 0 , 0 ) {\displaystyle k^{a}=(1,0,0,0)} .
Во ( t , r , θ , φ ) {\displaystyle (t,r,\theta ,\varphi )} , координатите се k a = ( 1 , 0 , 0 , 0 ) {\displaystyle k^{a}=(1,0,0,0)} .