The study published in 'Physical Review Letters' proposes observing the remnants of exploded stars to discover the 'fifth force' of the Universe

General relativity predicts both that gravitational and inertial mass are equivalent, and that the attraction force between two point masses is inversely proportional to the square of their separation distance. The existence of an additional fifth force, that can violate these laws, can thus signal a paradigm shift in physics, and many experiments have been devoted to the quest of such fifth forces. Deviations from gravitation at the mesoscopic level (between the macroscopic and microscopic worlds) is however very challenging to explore. We propose here that the best laboratory in the universe is given by neutron stars. New forces would indeed be mediated by novel particles that can be copiously produced in the scattering between neutrons or protons. Thanks to their extremely large density, the evolution of neutron stars would be dramatically affected by the existence of new forces: neutron stars are like a warm meal that cools down over time, and new particles would cool them down faster. 

“We find the striking conclusion - Edoardo Vitagliano, DFA, explains - that, if a new force acts between particles at a distance smaller than a hair thickness, astronomical observations are actually the best probe to find it”.

Link: https://journals.aps.org/prl/abstract/10.1103/tlqz-713s Titolo: Leading bounds on micro- to picometer fifth forces from neutron star cooling – «Physical Review Letters» – 2025 Autori: Damiano F. G. Fiorillo, Alessandro Lella, Ciaran A. J. O’Hare, Edoardo Vitagliano