What metric will make this a model of hyperbolic geometry?

109 Views Asked by At

Consider (a hyperbola after substitution) $\log(x)\log(y)=1$ revolved about the line $f(x)=x.$ Consider a projection from the origin which maps points on the revolution of $\log(x)\log(y)=1$ to the revolution of $g(x)=1-x$ about $f(x),$ bijectively. The projection is given by the revolution of $h_n(x)=x^n,$ $n\in \Bbb R$ about $f(x).$

What metric will make this a model of hyperbolic geometry?

Notes:

a) $\log(x)\log(y)=1$ is a hyperbola with a substitution, and so its revolution is a hyperboloid with a substitution.

b) The revolution of $h_n(x)$ starting from the origin, passes through the hyperboloid and then through the disk, so it projects points from the hyperboloid to the disk.

1

There are 1 best solutions below

0
On BEST ANSWER

There's nothing special about your example. Any smooth 2-manifold $M$ diffeomorphic to the Poincaré disc $\mathbb D^2$ has a Riemannian metric making it isometric to the hyperbolic plane: simply choose a diffeomorphism $f : \mathbb D^2 \to M$; let $\mu$ denote the standard hyperbolic Riemannian metric on $\mathbb D^2$; and then put the metric $f_*(\mu)$ on $M$. Probably you can use the projection in your note (b) to construct $f$, if you first use a diffeomorphism from $\mathbb D^2$ to the disc mentioned in (b).