Study claims the universe will end sooner than we thought

Far in the future, long after stars stop shining, the universe will contain nothing but their leftovers: black holes, neutron stars, white dwarfs, and thin gas.

On billion-year timescales and beyond, the question becomes: does any of that matter last forever, or does the universe erase even its toughest objects?

A new theoretical study takes that question seriously. It asks what happens when gravity curves spacetime as in general relativity, and when quantum fields are tracked over very long periods. Tiny effects that look harmless today may quietly decide the fate of everything made of matter.

Predicting the end of the Universe

The study comes from three researchers at Radboud University in Nijmegen in the Netherlands: black hole expert Heino Falcke, quantum physicist Michael Wondrak, and mathematician Walter van Suijlekom.

They argued that black holes, and also dense stars like neutron stars, can lose mass through a Hawking‑like evaporation process, and many people asked how long such a process would take.

To follow their work, it helps to recall the basic idea behind Hawking radiation.

In that prediction, quantum effects near a black hole’s event horizon cause it to emit a faint stream of particles and slowly lose mass, so even a black hole is not permanent.

The paper asks what happens when there is no event horizon at all. A neutron star or a white dwarf can pack a huge amount of mass into a small volume and curve spacetime strongly while still falling short of becoming a black hole.

The authors investigate whether that curvature by itself can create particles and drain energy from such an object.

They treat these compact remnants as endpoints of stellar evolution, focusing on how quantum fields behave around them when other astrophysical complications have faded away.

The calculation targets the ultimate lifetime of such dense bodies when only gravity and quantum physics still matter.

Curved spacetime and quantum particles

The authors use quantum field theory in curved spacetime, a framework that keeps quantum fields but lets spacetime bend as general relativity predicts near dense objects.

In their model, a compact star is a spherical, non‑rotating ball with constant density, surrounded by vacuum. Real neutron stars spin, have complex interiors, and may carry intense magnetic fields, yet this idealized star keeps the key feature of strong curvature in and around a dense body.

Within this setup, they calculate how often the curved spacetime around such an object creates pairs of massless particles out of the vacuum.

Strong curvature can pull virtual particle pairs apart before they annihilate, turning them into real, low‑energy particles such as photons or gravitons that carry energy away.

Pairs created outside the star may send one or both particles off to infinity or bend them back toward the object, while pairs created inside get absorbed and add heat to the star.

From an outside point of view, this leads to two sources of outgoing energy: some particles escape directly into space, and others first fall back in, warm the star slightly, and then reappear as thermal radiation from its surface.

For a star with a surface, both channels operate. “But black holes have no surface,” says co-author and postdoctoral researcher Michael Wondrak, “They reabsorb some of their own radiation which inhibits the process.”

Temperature, compactness and lifetime

A central quantity in their analysis is compactness, which compares the star’s radius with the radius a black hole of the same mass would have.

As an object becomes more compact and its radius gets closer to that black hole value, spacetime around it curves more strongly, and the quantum‑driven power it emits increases. The spectrum of that emission moves toward higher frequencies, as though the object had a higher temperature.

From the total power that leaves the star, they define an effective temperature by treating the object as a glowing sphere and applying the Stefan–Boltzmann law.

They also factor in gravitational redshift to work out what a distant astronomer would measure, and they find that the emission behaves like radiation from a warm object whose temperature is set by this quantum process.

Next they estimate an evaporation time by taking the object’s total mass energy, using E=mc2, and dividing by the energy loss rate.

In this treatment, the lifetime depends mainly on the average density rather than on mass and radius separately. In simplified form, it scales with density raised to about minus three‑halves, so denser objects lose their mass faster through this mechanism.

Neutron stars end up with lifetimes comparable to those of stellar‑mass black holes. White dwarfs evaporate more slowly because they are less dense, and supermassive black holes survive the longest because their average densities are low.

All things must end, even the Universe

Co-author Walter van Suijlekom, a professor of mathematics at Radboud University, notes that the project brings together astrophysics, quantum physics, and mathematics in one study.

“By asking these kinds of questions and looking at extreme cases, we want to better understand the theory, and perhaps one day, we unravel the mystery of Hawking radiation,” van Suijlekom concludes.

In the end, even the most “permanent” parts of the universe are only temporary when you zoom out far enough in time.

Black holes, neutron stars, white dwarfs, planets, and thin gas clouds may look frozen and unchanging on human or even galactic timescales, but quantum fields in curved spacetime keep quietly chipping away at them.

In the end, the Universe becomes a place where gravity and quantum physics slowly turn everything that has mass into faint streams of particles, and where “forever” is just another very long, but still limited, chapter in the story.

The full study was published in the journal arXiv.

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