The universe, often considered a place of eternal cosmic stability, could instead be on a slow but inescapable path toward decay, and one that could arrive far sooner than previously believed.
In a new study published in the Journal of Cosmology and Astroparticle Physics, physicists from Radboud University in the Netherlands present compelling evidence that even the most resilient stellar remnants, such as neutron stars and white dwarfs, are not immune to evaporation by gravitational pair production.
This discovery could redefine our understanding of the distant future of the cosmos and the stability of matter itself.
“So the ultimate end of the universe comes much sooner than expected,” lead author and professor of radio astronomy and astroparticle physics at Radboud University, Dr. Heino Falcke, said in a statement. “But fortunately, it still takes a very long time.”
Shaking the Foundation of Longevity and Cosmic Decay
Until now, the prevailing theory held that only black holes would eventually evaporate over unimaginable periods via Hawking radiation, a phenomenon in which quantum fluctuations near the event horizon create particles that slowly sap the black hole’s mass. By comparison, neutron stars and white dwarfs were considered effectively eternal, their dense matter assumed to be stable over cosmological timescales.
However, the researchers from Radboud University challenge this view. Using advanced covariant perturbation theory, they calculated how gravitational curvature—not the presence of an event horizon—can create virtual particle pairs that fail to annihilate and radiate away, slowly draining the mass of even horizonless objects.
In simple terms, the extreme curvature of space-time around ultra-dense objects is enough to tear apart virtual particle pairs, converting them into real particles that escape into the cosmos.
This effect, analogous to the well-known Schwinger effect in strong electric fields, could spell a slow but inevitable doom for even the most seemingly permanent objects in the universe.
A Ticking Clock for Stellar Remnants
The team’s calculations reveal that the evaporation timescale depends on an object’s density, following a simple but profound relationship: the more dense an object, the faster it decays.
Neutron stars, with densities exceeding 10¹⁴ grams per cubic centimeter, have lifespans on the order of 10⁶⁸ years. This is roughly comparable to small stellar black holes, once thought to outlive neutron stars by vast periods. By comparison, supermassive black holes, like the one at the center of the M87 galaxy, would endure for an astounding 10⁹⁶ years before entirely evaporating.
The team calculates that the final stellar remnants, namely the densest white dwarfs, would take approximately 10⁷⁸ years to evaporate fully—a figure dramatically shorter than the previously postulated upper limit of 10¹¹⁰⁰ years suggested by earlier models.
This adjustment marks a significant refinement in our understanding of cosmic longevity, indicating that even the longest-lasting matter in the universe is destined to vanish eventually.
Yet these numbers offer more than just a grim long-term forecast. They set an upper boundary on how long matter can exist in any form before being reclaimed by the quantum fabric of space-time.
Interestingly, the study proposes that as neutron stars and white dwarfs reach a critical point in their mass loss, they could destabilize catastrophically, ending in an explosive burst of high-energy particles and neutrinos. While this event lies inconceivably far in the future, it offers a tantalizing theoretical window into the final fireworks of a dying universe.
Implications for cosmic decay in our universe
Though direct observation of this process is likely impossible, the implications ripple across fields as diverse as quantum gravity, cosmology, and even speculative multiverse theory.
The study suggests that no stable objects with densities exceeding approximately 3×10^53 grams per cubic centimeter could have survived today. This density threshold effectively rules out the survival of hypothetical Planck-scale relics from a prior universe.
Moreover, the concept could inspire renewed thinking about the cosmic information paradox and the ultimate fate of data encoded in matter. The mechanism also neatly sidesteps the need for proton decay—a hypothetical process never observed in laboratory conditions—to explain how baryonic matter might eventually vanish.
In addition, this work fuels speculation that “fossil” neutron stars from a previous cosmic cycle might exist if they were somehow shielded from this decay process. However, researchers acknowledge that even if such objects did exist, detecting them would be a near-insurmountable challenge.
“If present, fossil neutron stars would now be growing by accretion from the intergalactic medium and the cosmic microwave background rather than shrinking,” researchers wrote. “Unless some instability would make them undergo such a phase transition after all.”
While the evaporation of stellar remnants via gravitational pair production remains theoretical and unconfirmed by observation, the calculations presented offer an intriguing and internally consistent framework for predicting the long-term demise of compact objects.
As with Stephen Hawking’s original work, this study pushes the boundaries of our understanding of how quantum effects interface with gravitational phenomena. It also highlights the power of modern theoretical tools to probe cosmic timescales far beyond the reach of experiments.
While there is little hope of measuring this effect directly, the study authors hope their work will serve as a theoretical lighthouse, helping us navigate the unexplored future of the cosmos.
“By asking these kinds of questions and looking at extreme cases, we want to better understand the theory, and perhaps one day, we will unravel the mystery of Hawking radiation,” Co-author and professor of mathematics at Radboud University, Dr. Walter van Suijlekom, said.
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com