It is mathematically interesting and shows how physics behave if you change assumptions about the geometry of space-time.<p>Egan has copious documents on the physics of the Orthogonal universe at his website [ <a href="http:&#x2F;&#x2F;www.gregegan.net&#x2F;ORTHOGONAL&#x2F;ORTHOGONAL.html" rel="nofollow">http:&#x2F;&#x2F;www.gregegan.net&#x2F;ORTHOGONAL&#x2F;ORTHOGONAL.html</a> ]