Beyond Reality: From Jordan Algebras to the Leech Lattice in an Exotic Spacetime

This article explores the deep connections between Jordan algebras, octonions, and the Leech lattice. Starting with Pascual Jordan's work in the 1930s on the algebraic properties of Hermitian matrices, it introduces formally real Jordan algebras and their classification, including a special 27-dimensional exceptional Jordan algebra. Building on this, the article explains how projective spaces are constructed from Jordan algebras, focusing on the octonionic projective plane generated by the exceptional Jordan algebra. Finally, it delves into an exotic spacetime constructed from octonionic Hermitian matrices and a unique integral unimodular lattice within it—the Leech lattice. A surprising finding is that this lattice exhibits two distinct orbits under the action of the E6 group, unlike typical understanding.