Ellipsoidal billiards in pseudo-Euclidean spaces and relativistic quadrics

Vladimir Dragovic; Milena Radnovic

doi:10.1016/j.aim.2012.06.004

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arXiv · 1108.4552

Ellipsoidal billiards in pseudo-Euclidean spaces and relativistic quadrics

Vladimir Dragovic·Milena Radnovic

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Abstract

We study geometry of confocal quadrics in pseudo-Euclidean spaces of an arbitrary dimension $d$ and any signature, and related billiard dynamics. The goal is to give a complete description of periodic billiard trajectories within ellipsoids. The novelty of our approach is based on introduction of a new discrete combinatorial-geometric structure associated to a confocal pencil of quadrics, a colouring in $d$ colours, by which we decompose quadrics of $d+1$ geometric types of a pencil into new relativistic quadrics of $d$ relativistic types. Deep insight of related geometry and combinatorics comes from our study of what we call discriminat sets of tropical lines $Σ^+$ and $Σ^-$ and their singularities. All of that enable usto get an analytic criterion describing all periodic billiard trajectories, including the light-like ones as those of a special interest.

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Vladimir Dragovic, Milena Radnovic. 2012-05-11. Ellipsoidal billiards in pseudo-Euclidean spaces and relativistic quadrics. https://doi.org/10.1016/j.aim.2012.06.004

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