Hawking radiation doesn’t just evaporate black holes

Stephen Hawking showed nearly fifty years ago that a black hole can evaporate very slowly by emitting radiation. The Nijmegen researchers have now shown that such radiation is not limited to black holes.

Theoretical physicist Stephen Hawking has shown that black holes are not the very stable things we thought they were. It can emit radiation through a quantum effect, causing it to slowly evaporate. Hawking radiation would be unique to black holes because it only occurs on the event horizon. This is the limit beyond which nothing, not even light, can escape from a black hole.

Three scientists from Radboud University Nijmegen have now shown that the event horizon is not necessary at all. to Their theoretical research is published in Physical Review LettersThey showed that such radiation is produced by anything that warps space-time due to gravity. This could mean that not just black holes, but all things in the universe are evaporating very slowly.

Hawking radiation

Hawking radiation is caused by small fluctuations in quantum fields that exist everywhere in the universe. These fluctuations create “virtual” particle pairs. Under normal circumstances, they quickly combine with each other, disappearing into the quantum sea from which they were born. If this happened on the black hole’s event horizon, half of a pair of particles could disappear into the black hole. Then the other particle escapes as Hawking radiation.

The energy carried by Hawking radiation is extracted from the black hole. This loses a very small amount of energy, which results in a loss of mass, according to Einstein’s well-known equation: E = mc². For example, a black hole evaporates very slowly by emitting radiation.

observation horizon

Radboud’s research is a collaboration between astrophysicists Michael Wendrickmy mathematician Walter Van Suilicum and astronomer Hino Falcon. Together, they calculated what would happen if the quantum fluctuations did not appear at the event horizon, but only slightly away from the black hole. They studied the formation of massless particles, such as particles of light, in a region where the black hole’s gravity is still so strong that space-time is bent.

“If a hypothetical pair of particles is created there, both particles explore a slightly different environment, and therefore experience a slightly different force due to the curvature that is present,” Wondrak says. As a result, it is dismantled and can no longer be reunited. Then it becomes “real”, and is released as radiation.

With this mechanism, one of them does not have to disappear behind the black hole’s event horizon, which is already the case with Hawking radiation. Both particles can escape if they are far enough from the black hole. Wondrak: ‘This happens when you’re 1.5 times more than Schwarzschild planethe distance from the center to the event horizon of a black hole.

Earth radiation

Researchers are not yet sure if this mechanism is something that could coexist with Hawking radiation or if Hawking radiation is a part of it. In the latter case, Hawking radiation would be a consequence of this mechanism near the event horizon.

“The idea that curvature and particle formation — or radiation — go together is not new,” says Van Suijlekom. We’ve basically been working on this and looking at what it means to generate radiation in a wider region around a black hole than just the event horizon. More research is needed to understand the exact nature of this radiation.

The existence of this radiation or Hawking radiation cannot currently be proven. If it is present, it is so weak that it is impossible to detect it with current technologies.

Everything evaporates

The fact that the origin of this radiation does not depend on the event horizon, but only on the curvature of space-time, means that the effect is not limited to black holes.

“In principle, any object with mass can produce this radiation,” Wondrak says. Only the effect is much smaller for planets, for example, than for massive stars, such as neutron stars or black holes. But this means that if you wait long enough, all things in the universe will eventually evaporate.

You need a lot of patience for that. A black hole of the same mass as the Sun would have 10⁶⁷ It takes years for it to vaporize by emitting Hawking radiation.