Alladi Ramakrishnan Hall

Is photon really massless?

T R Govindarajan

CMI

This question was posed by Schrodinger decades back. It was not only answered and the bound on the mass was estimated using geomagnetic field by him. We revisit this question from new perspectives about asymptotic symmetries, infrared divergence in QED. We also point out the role of Stueckelberg field in answering this query. We explore implications in unexpected territory as candidate for ultralight dark matter!.