The most famous theory of Stephen Hawking about black holes has just received an update. The new theory states that everything in the universe is destined to slowly evaporate. In 1974, Hawking proposed that black holes would evaporate by losing what is now known as Hawking radiation. It is a slow and relentless draining of energy in the form of particles of light that form around the immensely powerful gravitational fields of black holes.
The new update to the theory suggests that Hawking radiation is not only created by stealing energy from black holes, but from all objects with sufficient mass. If the theory is true, it means that everything in the universe will eventually disappear, releasing energy in the form of light.
“This means that objects without an event horizon, like the remnants of dead stars and other large objects in the universe, emit this type of radiation” said the lead author (ref.) Heino Falcke, a professor of astrophysics at Radboud University. “And after a very long period, this would lead to the evaporation of everything in the universe, just like black holes. This not only changes our understanding of Hawking radiation but also our view of the universe and its future”.
The researchers published their findings on June 2 in the journal Physical Review Letters (ref.). According to the quantum field theory, there is no such thing as empty space. Space teems with tiny vibrations that, with sufficient energy, randomly explode into virtual particles, producing packets of extremely low-energy light, or photons.
In 1974, Hawking predicted that the gravitational force at the event horizon of black holes would cause photons to come into existence in this way. Gravity, according to Einstein‘s general theory of relativity, distorts spacetime, so that quantum fields deform as they approach the immense gravitational attraction of a black hole’s singularity.
Does this phenomenon only occur with black holes?
Due to the uncertainty of quantum mechanics, Hawking claimed that these energy mismatches make photons appear in the warped space around black holes. If the particles then escape the black hole, over a very long timescale, they would eventually lose all their energy and disappear.
If a gravitational field is all that is needed to produce quantum fluctuations and photons, what prevents any object with mass from creating Hawking radiation? Does Hawking radiation need an event horizon, or can it be produced anywhere in space, meaning that the entire universe is destined to evaporate? To answer these questions, the study’s authors analyzed Hawking radiation through a process called the Schwinger effect. Matter can theoretically be generated by the powerful distortions caused by an electromagnetic field.
In this way, theoretical physicists produced a mathematical model that reproduced Hawking radiation in spaces experiencing a range of gravitational field intensities. According to their theory, an event horizon is not necessary for energy to slowly escape from a massive object in the form of light. The object’s gravitational field can accomplish this on its own.
Speculation awaiting confirmation
“Beyond a black hole and the curvature of spacetime, all other objects play a significant role in radiation creation” said Walter van Suijlekom. “The particles are already separated, beyond the black hole, from the tidal forces of the gravitational field”.
What the researchers’ theory actually means is still unclear. Perhaps the matter that makes up aging stars and planets will undergo an energy transition into a completely new state of ultra-low energy. This could be sufficient to collapse matter into black holes, which would continue to slowly produce light until they disappear without a trace.
Unfortunately or fortunately, all of this is just speculation awaiting confirmation. To understand if the universe is destined to evaporate, physicists will have to detect Hawking radiation produced around gravitationally dense objects such as black holes, planets, stars, or neutron stars. If everything is destined to disappear in a flash of cold light, they will have many places to look.