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Astrophysics study sets new bounds on speed of light across photon energies

Written by  Thursday, 20 November 2025 10:23
Berlin, Germany (SPX) Nov 20, 2025
In 1887, Michelson and Morley conducted a pivotal experiment, searching for evidence that Earth's motion could alter the speed of light. Their null result was instrumental for Einstein, who soon proposed that light speed remains fixed for all observers, foundational for the theory of special relativity. This concept, known as Lorentz invariance, asserts that the laws of physics hold true regardl
by Robert Schreiber
Berlin, Germany (SPX) Nov 20, 2025

In 1887, Michelson and Morley conducted a pivotal experiment, searching for evidence that Earth's motion could alter the speed of light. Their null result was instrumental for Einstein, who soon proposed that light speed remains fixed for all observers, foundational for the theory of special relativity. This concept, known as Lorentz invariance, asserts that the laws of physics hold true regardless of relative motion between observers.

Over time, quantum theory developed alongside Lorentz invariance, with the Standard Model of particle physics standing as its most rigorously tested framework. Nonetheless, Einstein's later work in general relativity introduced a separate model of gravity - tested extensively and proven in strongly curved spacetime - highlighting a persistent incompatibility with quantum field descriptions.

Efforts to reconcile quantum field theory and general relativity have produced quantum gravity models which, in many cases, predict minute violations of Lorentz invariance - manifesting as a potential dependence of light speed on photon energy. Detecting this effect requires observations at the highest photon energies, such as gamma rays originating from distant astrophysical sources.

Researchers Merce Guerrero, Anna Campoy-Ordaz, Robertus Potting, and Markus Gaug analyzed gamma ray bursts from far-off sources, using statistical methods and aggregating astrophysical datasets to probe the Standard Model Extension parameters for Lorentz invariance violation. They investigated whether extremely high-energy photons experience measurable delays upon arrival relative to lower-energy photons - delays that could accumulate across cosmic distances.

Although the team's results again aligned with Einstein's prediction of a universal light speed, their research set new bounds tightening existing constraints by an order of magnitude. This study further restricts possible Lorentz invariance violations, while next-generation instruments such as the Cherenkov Telescope Array Observatory may refine the search for quantum gravity effects in future gamma ray observations.

Research Report:Bounding anisotropic Lorentz invariance violation from measurements of the effective energy scale of quantum gravity

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