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Physics

Radical photon idea could rewrite standard model of particle physics

Experiments with hydrogen atoms could soon reveal whether particles that were long thought to be forbidden by physics actually do exist

By Karmela Padavic-Callaghan

12 May 2025

Photons could upend the standard model of particle physics

Eduard Muzhevskyi/Alamy

If photons possess more quantum states than expected, it would overhaul our understanding of all particle physics – and now physicists have identified a way to test this radical idea in an experiment.

Certain elementary particles have a property called spin. For particles of light, or photons, spin can be in one of two potential states, which manifests as the light being polarised in one of two directions. But what if photons had more options – what if they could be in any of an infinite number of spin…

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