Cosmic Polarisation Rotation from CMB Data: a Review for GR110

Abstract

We provide an update on the work of di Serego Alighieri (2015), focusing on recent developments regarding constraints on Cosmic Polarization Rotation (CPR), also known as Cosmic Birefringence (CB), derived from Cosmic Microwave Background (CMB) polarization data.

8 pages, 1 table. To appear in International Journal of Modern Physics D. This paper will also be published in the book "One Hundred and Ten Years of General Relativity: From Genesis and Empirical Foundations to Gravitational Waves, Cosmology, and Quantum Gravity", edited by Wei-Tou Ni (World Scientific, Singapore, 2025)