New study finds new form of radiation emitted by black holes

Recent theoretical research conducted by Michael Wondrak, Walter van Suijlekom, and Heino Falcke from Radboud University has provided further support for Stephen Hawking’s ideas about black holes, although with some important nuances. The research indicates that black holes will eventually evaporate due to a phenomenon known as Hawking radiation, but the significance of the event horizon is not as absolute as previously believed. Instead, gravity and the curvature of spacetime play a role in the generation of this radiation as well. As a consequence, all large celestial objects in the universe, including stellar remnants, will eventually undergo evaporation.

Stephen Hawking’s groundbreaking work combined quantum physics with Einstein’s theory of gravity to propose that the spontaneous creation and annihilation of particle pairs must occur near the event horizon—the point beyond which gravitational force prevents escape from a black hole. When a particle and its antiparticle are briefly created from the quantum field, they rapidly annihilate each other. However, occasionally, one of the particles falls into the black hole, while the other escapes—this is known as Hawking radiation. According to Hawking’s theory, this process leads to the gradual evaporation of black holes.

The recent study conducted by Radboud University researchers revisits this process and examines whether the presence of an event horizon is truly indispensable. Employing a combination of techniques from physics, astronomy, and mathematics, the researchers explore what happens when particle pairs are created in the vicinity of black holes. Surprisingly, the study demonstrates that new particles can also be generated far beyond the traditional understanding of the event horizon. As Michael Wondrak explains, “We show that, in addition to the well-established Hawking radiation, there exists a novel form of radiation.”

Everything evaporates

Walter van Suijlekom emphasizes that their research demonstrates the significant role played by the curvature of spacetime in generating radiation, extending far beyond the confines of a black hole. The gravitational field’s tidal forces already separate the particles in those regions. This finding challenges the previous notion that radiation could only occur within the event horizon, indicating that the horizon is not a prerequisite for radiation generation.

Heino Falcke adds that this revelation implies that objects lacking an event horizon, such as remnants of deceased stars and other substantial entities in the universe, also possess this form of radiation. Over an extensive period, this radiation would eventually cause everything in the universe to evaporate, mirroring the fate of black holes. This realization not only transforms our understanding of Hawking radiation but also alters our perspective on the universe and its future.

The research has been accepted for publication in Physical Review Letters, and a version of the paper is currently accessible on the arXiv preprint server.

Source: Radboud University Nijmegen

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