The gravitational field of a black hole may provide information about its inside.
According to the equations of general relativity, anything falls into a black hole remains in a black hole. However, recent study reveals that the material within a black hole may leave a quantum imprint on the gravitational field around it.
If correct, this discovery might answer Stephen Hawking’s black hole information conundrum, a long-standing physics puzzle. Hawking estimated in the 1970s that black holes may not be completely one-way streets, and that they might generate heat radiation known as Hawking radiation. This Hawking radiation, on the other hand, is just thermal radiation, or heat, and contains no information about the black hole’s origin or the stuff that had vanished within it. To put it another way, detecting the radiation won’t tell you anything about its past.
The paradox emerges because quantum physics dictates that information cannot be destroyed; knowing an object’s end state provides clues to its original state, enabling you to “rewind the movie,” according to Xavier Calmet, a physicist at the University of Sussex in England who led the new study. These rules can’t be correct if a black hole consumes information irreversibly. Because of this inconsistency, black holes are an excellent spot to see how quantum physics and Albert Einstein’s theory of general relativity interact.
Calmet told Live Science, “What we’re proving is that the two ideas are far more compatible than anyone had envisioned, that there is no contradiction.”
Black holes with hairs on them.
The no-hair theory, a concept popularized by physicist John Wheeler, states that black holes have few traits that identify them from one another. Beyond mass, charge, and spin, black holes are thought to lack distinctive characteristics, such as a distinct hairdo, cut, or color.
Calmet and his colleagues discovered that black holes may contain hair, although very little hair, in their new research, which was published March 17 in the journal Physical Review Letters. Quantum gravity is a branch of physics that aims to comprehend gravitational forces using quantum mechanics. The study team analyzed two theoretical stars that collapse into black holes of the same size, charge, and spin, but with different chemical compositions, using simulations produced over the last decade.
According to the no-hair theory, it’s difficult to discern whether the stars that formed these two black holes were originally distinct.
However, the team’s simulations revealed that the gravitational field surrounding the black hole differed. Gravons, a hypothetical basic particle that mediates gravitational forces in quantum gravity, were used to retain information on the black hole’s makeup.
Calmet added, “We discovered that quantum gravity allows us to determine the difference in the gravitational field.” “What fell into the black hole has a memory in the gravitational field.”
Is it possible to solve a paradox?
Efforts are being made to find information seeping from black holes. The Laser Interferometer Gravitational-Wave Observatory (LIGO) detects gravitational waves, which are space-time disturbances caused by enormous objects such as black holes. The European Space Agency is planning to send three spacecraft in 2037 to detect gravitational waves from space, dubbed the Laser Interferometer Space Antenna project (LISA).
However, the graviton impacts described in the new calculations are minor, and Calmet believes they would be impossible to detect with today’s equipment. Simulators that can handle the subtlety may become available in the future. (Hawking radiation has also never been seen directly in a genuine black hole, but it has been seen in simulations.)
Calmet said the discoveries have sparked curiosity in the physics community, but he doesn’t anticipate the conclusions to be adopted immediately. “Most people assumed you’d have to tweak physics in some manner to make it work,” he says of the black hole information dilemma.
Calmet and his colleagues now intend to utilize their discoveries to delve further into the potential of quantum gravity, which remains an area rife with rival ideas and no clear winner.
“This might help us get closer to a quantum gravity theory,” Calmet added.