Einstein's relativity withstands most precise weak‑gravity test

Scientists from Italy, the United Kingdom and Spain have confirmed Einstein's theory of general relativity with the most accurate weak‑gravity experiment to date. Conducted by the SaToR‑G collaboration and led by researchers at the Istituto Nazionale di Astrofisica (INAF), the study verified the Local Lorentz Invariance (LLI) principle, showing that the PPN parameter α₁ remains zero. The new limit improves the previous bound by more than a factor of four.

The results were published on 27 July 2026 in Physical Review Letters and discussed in Physical Review D. The collaboration includes INAF, the University of Rome Tor Vergata, the Istituto di Scienza e Tecnologie dell'Informazione (ISTI‑CNR), the British Geological Survey and Spain’s Instituto Geográfico Nacional, with funding from the Istituto Nazionale di Fisica Nucleare (INFN). The findings tighten constraints on theories that propose violations of Lorentz invariance, reinforcing the foundations of both relativity and the Standard Model of particle physics.