OPTICAL SPACE OF THE KERR SOLUTIONS

In this paper, we discuss the optical geometry of the Kerr solutions, and show the embedding diagram at the equator \theta=\pi/2 for the optical space of the Kerr solution with a/M=1. It is noticed that at the equator \theta=\pi/2, the Gaussian curvature K for the ordinary space is negative, and the \stackrel\simK for the optical space is positive.