Black holes have a problem that physicists still cannot explain. According to Stephen Hawking’s famous prediction, black holes are not completely dark. They should slowly emit an extremely faint stream of particles known as Hawking radiation.
Over enough time, this radiation would cause a black hole to shrink and eventually disappear entirely. However, this creates a serious contradiction in physics. If the black hole vanishes, what happens to all the information trapped inside it?
Quantum physics says information cannot be destroyed, yet black hole evaporation seems to suggest otherwise.
For decades, scientists have struggled with this puzzle because Hawking radiation is far too weak to observe directly, and the mathematics connecting gravity with quantum physics is notoriously difficult.
Now, a team of international researchers has found an unexpected new way to study the problem. Instead of tackling black holes head-on, they translated Hawking radiation into the language of particle physics using a mathematical framework called the double copy.
“It allows us to calculate things we’ve never been able to calculate before, just by recycling results in a clever way,” Chris White, one of the researchers and a physicist at Queen Mary University of London, said.
A hidden bridge between gravity and particles
Double copy is an idea that has reshaped parts of theoretical physics over the past decade. At its core, the concept suggests that certain equations describing gravity can be mathematically rewritten using equations from particle physics.
This matters because modern physics is split into two separate frameworks. Einstein’s general relativity explains gravity, black holes, and the motion of massive objects across the universe.
Meanwhile, the Standard Model explains the tiny particles and forces that govern the quantum world.
Both theories work extremely well on their own, but they become difficult to reconcile in extreme environments like black holes. The double copy acts almost like a translation tool between these two worlds.
In simplified terms, physicists can sometimes transform a difficult gravity calculation into a more manageable particle physics calculation.
This technique has already been used to better understand several gravitational phenomena, but Hawking radiation remained one of the missing pieces. Scientists had never found a proper Standard Model counterpart for Hawking radiation before. This gap limited how useful the double copy could become for studying black holes.
Turning Hawking radiation into a particle collision
In their new study, the researchers finally identified a mathematical analog for Hawking radiation. Instead of describing particles escaping from a black hole, the translated version involves a charged particle interacting with a collapsing spherical shell made of charged matter.
“We consider the scattering of a massless scalar particle through a collapsing electromagnetic background,” the researchers wrote while describing the particle-physics setup used to mimic Hawking radiation mathematically.
Surprisingly, the mathematics describing this scattering process matches the equations governing Hawking radiation. Two additional research teams independently reached closely related conclusions in separate studies, strengthening confidence that the connection is genuine rather than accidental.
Together, the papers suggest that important features of black hole physics may already be encoded inside ordinary particle physics equations.
The result is especially significant because Hawking radiation sits at the intersection of two radically different scales. Black holes belong to the realm of enormous cosmic objects governed by gravity, while the emitted particles belong to the microscopic quantum world.
The fact that the double copy can connect both scales suggests the relationship between gravity and particle physics may run deeper than scientists previously realized. The new framework could also provide physicists with a workaround for a major experimental problem.
Since Hawking radiation from real black holes is too faint to detect directly, researchers may instead study its particle-physics counterpart mathematically. That could allow them to investigate aspects of black hole behavior that were previously inaccessible.
The black hole paradox may have a new testing ground
The work does not solve the black hole information paradox, but it gives scientists a fresh way to attack it.
Researchers now hope to push the double copy framework even further by searching for particle-physics equivalents of other black hole features, including the event horizon itself — the boundary beyond which nothing can escape.
If those connections can also be mapped successfully, physicists may be able to study some aspects of black holes using methods originally developed for particle collisions.
This would represent a major shift in how researchers approach quantum gravity, one of the biggest unsolved problems in modern science.
However, for now, the research remains entirely theoretical, and the current mathematical mappings apply only to carefully controlled situations rather than realistic astrophysical black holes.
The study is published in arXiv.