Abstract 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 $\stackrel{\sim}{K}$ for the optical space is positive.
Received: 06 November 2000
Revised: 05 May 2001
Accepted manuscript online:
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