The whole universe might have performed a giant physics experiment on itself at the Big Bang, and the proof is written in the sky.
March 30, 2026
Original Paper
A Bell Experiment in an Entangled Universe
arXiv · 2603.25879
The Takeaway
Bell experiments are usually performed in high-tech labs to prove the existence of quantum 'spooky action.' This paper suggests that during the universe's rapid expansion, gravity waves became entangled and were 'measured' by the cosmos itself, imprinting that entanglement into the modern distribution of galaxies.
From the abstract
We propose a possible quantum signature of the early Universe that could lead to observational imprints of the quantum nature of the inflationary period. Graviton production from the presence of a classical, coherent state of the inflaton scalar field results in entangled states in the gravitons' polarizations. At horizon crossing, interactions between the gravitons and (lower scale) inflatons, together with the gathering of ``which-path information'' from the cosmological horizon, perform the r