For the first time in science, physicists at the University of Sussex discovered that black holes exert pressure on the environment. In 1974, Stephen Hawking made an important discovery: black holes emit thermal radiation. Until then, black holes were thought to be inert, the last stage of a dying heavy star.
Scientists from the University of Sussex have shown that in fact these are even more complex thermodynamic systems, not only with temperature, but also with pressure. The discovery was made by Professor Xavier Calmet and Folkert Kuipers in the Department of Physics and Astronomy at the University of Sussex, and is published today in Physical Review D.
Calmett and Kuipers were perplexed by the additional figure presented in the equations that they used quantum gravitational corrections to the black hole’s entropy.
While discussing this curious outcome at Christmas 2020, the realization came that what they were seeing was acting like pressure. After further calculations, they confirmed their exciting discovery that quantum gravity can lead to pressure in black holes.
Xavier Calmet, professor of physics at the University of Sussex, said: “Our discovery that Schwarzschild black holes have pressure as well as temperature is even more exciting given that it was a complete surprise. I am delighted that the research we are undertaking at the University of Sussex on quantum gravity research has contributed to a broader understanding of the nature of black holes in the scientific community.
Hawking’s remarkable intuition that black holes are not black, but have a spectrum very similar to that of a black body, makes black holes an ideal laboratory for exploring the interactions between quantum mechanics, gravity and thermodynamics.