In Search of a Fifth Force in the Universe: Neutron Stars Point the Way
20.11.2025
A recent study published in "Physical Review Letters" suggests observing the remnants of exploded stars to search for clues about a possible "fifth force" in the Universe. Currently, the four known fundamental forces - gravitational, electromagnetic, strong nuclear, and weak nuclear - explain interactions in the universe. However, some scientists hypothesize the existence of a fifth force that could revolutionize the laws of physics as we know them.
The research, titled "Leading bounds on micro- to picometer fifth forces from neutron star cooling," was conducted by researchers from the Universities of Padua, Bari, Sydney, and DESY Zeuthen, who propose using neutron stars, the dense remnants of exploded stars, as natural laboratories to search for traces of this fifth force. Due to their density and extreme physical conditions, neutron stars are ideal for studying phenomena that cannot be replicated in a laboratory.
The researchers observed a group of isolated neutron stars, including some of the "Magnificent Seven" and the pulsar PSR J0659, simulating how hypothetical new particles, mediators of a fifth force, could influence their cooling. The results indicate that the existence of a fifth force would significantly alter the cooling rate of these stars, imposing new limits on the properties of such a force, up to a million times more stringent than previous experiments.
"We have come to the surprising conclusion that if a new force acted between particles at a distance less than the thickness of a hair, astronomical observations would be the best tool to discover it," explains Edoardo Vitagliano, professor at the Department of Physics and Astronomy at the University of Padua and lead author of the study.
If confirmed, this discovery would open new perspectives not only for fundamental physics and the possible existence of new dimensions but also for understanding dark matter, one of the greatest mysteries of the universe.
