The G\"odel Universe as a Lie group with left-invariant Lorentz metric and\newline the Iwasawa decomposition

Abstract

We discuss models of the G\"odel Universe as Lie groups with left-invariant Lorentz metric for two simply connected four-dimensional Lie groups, the Iwasawa decomposition for semisimple Lie groups, and left-invariant Lorentz metric on ${\rm SL}(2,\mathbb{R})$, following K.-H.~Neeb. Also we show that the isometry between two non-isomorphic sub-Riemannian Lie group, constructed by A.~Agrachev and D.~Barilari, is induced by some Iwasawa decomposition of ${\rm SL}(2,\mathbb{R})$.