Quantum Vacuum Behaviour near Black Holes Explored by Tokyo University Researchers

Posted on June 22, 2023 • 3 minutes • 564 words

Tokyo University researchers have uncovered new information about the behaviour of the quantum vacuum near black holes. According to the study published in Physical Review D, the quantum vacuum separates a virtual particle-antiparticle pair from the point event horizon of a black hole. The event horizon marks the ‘point of no return’ in which any matter or energy that enters it is unable to escape.

The research was led by Professor Akira Ishibashi from the university’s Department of Physics and Astronomy. ‘Our study contributes to a deeper understanding of the nature of black holes and how they interact with their surrounding quantum environment,’ he said.

The study used a combination of quantum field theory and a semiclassical model to show how the vacuum behaves close to the event horizon. The semiclassical model allowed the researchers to examine the quantum behaviour near the black hole while taking general relativity into account. The research team’s findings support the theory that black holes emit Hawking radiation, a form of thermal radiation predicted by physicist Stephen Hawking in 1974. Hawking radiation results from virtual particle-antiparticle pairs near the event horizon, where one particle falls into the black hole while the other escapes as radiation. This causes the black hole to gradually lose mass over time and ultimately evaporate.

‘The vacuum fluctuations give rise to a negative energy near the event horizon, which causes a quantum radiation effect. Our study confirms that Hawking radiation is a natural consequence of the gravitational bending of spacetime,’ explained co-author Professor Yasusada Nambu, also from the university’s Department of Physics and Astronomy.

The research team’s methodology involved studying the effect of the quantum environment on the black hole’s mass. They found that the presence of vacuum fluctuations near the black hole’s event horizon causes it to lose mass at a constant rate, consistent with Hawking radiation. This rate of mass loss depends on the ratio of the black hole’s Schwarzschild radius to the Compton wavelength of the particle involved.

The study also found that the black hole’s temperature is proportional to its surface gravity, which is a measure of the strength of gravity at its surface. This confirms the validity of the Hawking radiation concept, which predicts that the temperature of the radiation emitted by a black hole is inversely proportional to its mass.

The research has important implications for our understanding of the fundamental laws of physics. The study supports the theory of quantum gravity, which aims to unify general relativity and quantum mechanics into a single, coherent theory. It also adds to our knowledge of the behaviour of the quantum vacuum and its interactions with massive objects. The research may also have implications for the development of new technologies, such as quantum computers.

‘This research opens up new directions in our understanding of the quantum nature of the universe,’ said Professor Ishibashi. ‘Our findings may have broader implications beyond the field of black hole physics, which could lead to new technologies and applications in the future.’

The study adds to the growing body of research into the behaviour of black holes and their implications for our understanding of the universe. The findings may also have implications for ongoing efforts to explore the nature of dark matter and dark energy, which make up the vast majority of the universe’s mass and energy but remain elusive to direct detection.

References: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.107.044022 https://en.wikipedia.org/wiki/Black_hole https://en.wikipedia.org/wiki/Hawking_radiation