A team of researchers has confirmed Stephen Hawking’s prediction about black holes evaporating via Hawking radiation, although they made a crucial modification. According to their research, the event horizon (the boundary beyond which nothing can escape the gravitational pull of a black hole) is not nearly as important as what was previously thought in the production of Hawking radiation. Instead, gravity and the curvature of space-time play an important role in this process. This insight extends the range of Hawking radiation to all large objects in the universe, which means that over a long enough period, everything in the universe can evaporate.
Research shows that Stephen Hawking was mostly right about black holes evaporating through Hawking radiation. However, the study highlights that an event horizon is not essential for this radiation, and that gravity and the curvature of space-time play important roles. The results indicate that all large objects, not just black holes, can eventually evaporate due to a similar radiation process.
New theoretical research by Michael Wondrak, Walter van Swijelkom and Heino Falk of Radboud University shows that Stephen Hawking was right about black holes, though not entirely. Because of Hawking radiation, black holes will eventually evaporate, but the event horizon is not as critical as it was thought. Gravity and the curvature of space-time also cause this radiation. This means that all large objects in the universe, such as remnants of stars, will eventually evaporate.
Using a clever combination of quantum physics and Einstein’s theory of gravity, Stephen Hawking argued that the spontaneous creation and annihilation of particle pairs must occur near the event horizon (the point beyond which no escape from the gravitational force of[{” attribute=””>black hole). A particle and its anti-particle are created very briefly from the quantum field, after which they immediately annihilate. But sometimes a particle falls into the black hole, and then the other particle can escape: Hawking radiation. According to Hawking, this would eventually result in the evaporation of black holes.
Schematic of the presented gravitational particle production mechanism in a Schwarzschild spacetime. The particle production event rate is highest at small distances, whereas the escape probability [represented by the increasing escape cone (white)] It is the highest at great distances. Credit: Material review letters
spiral
In this new study, researchers at Radboud University revisited this process and investigated whether the existence of an event horizon is critical. They combined techniques from physics, astronomy and mathematics to examine what happens if such pairs of particles are created in the vicinity of black holes. The study showed that new particles can also be created far beyond this horizon. Michael Wondrak: “We prove that in addition to the well-known Hawking radiation, there is also a new form of radiation.”
Everything evaporates
Van Suijlekom: “We show that far from the black hole, the curvature of space-time plays a large role in causing radiation. The particles are already separated there by tidal forces in the gravitational field.” While it was previously thought that no radiation is possible without an event horizon, this study shows that such a horizon is not necessary.
Falk: “This means that objects without event horizons, such as the remnants of dead stars and other large objects in the universe, also have this type of radiation. After a very long time, it will cause everything in the universe to eventually evaporate, just like black holes.” This not only changes our understanding of Hawking radiation, but also our view of the universe and its future.”
The study was published June 2 in DOI: 10.1103/PhysRevLett.130.221502
Michael Wondrak is excellence fellow at Radboud University and an expert in quantum field theory. Walter van Suijlekom is a Professor of Mathematics at Radboud University and works on the mathematical formulation of physics problems. Heino Falcke is an award-winning Professor of Radio Astronomy and Astroparticle Physics at Radboud University and known for his work on predicting and making the first picture of a black hole.