A photon that challenges Einstein: According to current physics, it should never have reached Earth

Key Points:

• Researchers Giorgio Galanti and Marco Roncadelli propose a new theoretical model to explain how a 300 TeV photon from the gamma-ray burst GRB 221009A traveled over 2 billion light-years to Earth, defying current physics expectations that such a photon should have been absorbed.
• The study combines axion-like particle (ALP) conversion with a possible violation of Lorentz invariance, suggesting that at extremely high energies, spacetime may allow photons to avoid interactions that would normally destroy them, effectively making the universe more transparent to such photons.
• Their model also predicts a delayed arrival time for the highest-energy photon relative to lower-energy photons, matching observations from the Carpet detector and the Chinese LHAASO observatory, providing additional support for the theory.
• If confirmed by future observations, this scenario could provide a natural laboratory for investigating quantum gravity effects at energies far beyond those achievable by Earth-based accelerators, potentially revealing new physics beyond Einstein's relativity.