Magnetar Observations Strengthen Evidence for Quantum Vacuum Birefringence

Observations of magnetar 1E 1547.0−5408 have yielded the strongest evidence to date for quantum vacuum birefringence, a phenomenon where intense magnetic fields alter light's travel through empty space. Reported in Nature, the unusually high and phase-dependent X-ray polarization supports this 1936 quantum-electrodynamic theory. This finding deepens our understanding of fundamental physics and the properties of extreme cosmic environments.