Confirmation for Hawking: Artificial black hole quantitatively confirms the temperature and thermal nature of Hawking radiation

A team of researchers from the Faculty of Physics at the Technion has developed an artificial black hole in which sound plays the role of light. By developing a method to measure the spectrum of Hawking radiation, they found that artificial black holes do indeed emit radiation similar to a normal hot object, as Hawking's predictions stated

During his career as a theoretical physicist and cosmologist, the late Stephen Hawking believed that black holes - a phenomenon in space that has an enormous mass and is invisible and has gravity so strong that nothing, not even light, can escape its deep, dark grip - emit radiation. This Hawking radiation should have a thermal spectrum, similar to the radiation emitted by any hot object. The temperature of Hawking radiation should rise in line with the temperature predicted by the late astrophysicist Jacob Beckenstein.

Now, a team of researchers from the Faculty of Physics at the Technion has developed an artificial black hole in which sound plays the role of light. By developing a method to measure the spectrum of Hawking radiation, they found that artificial black holes do indeed emit radiation similar to a normal hot object, as predicted by Hawking. An article explaining their groundbreaking research Published in the May 30, 2019 issue of the journal Nature.

Almost four decades ago, a theory was proposed according to which it would be possible to build artificial black holes and use them to measure the physics of Hawking radiation, a type of thermal radiation, whose existence was predicted by Hawking in the 20s and is now named after him. However, it was the task of creating an artificial black hole and finding ways to measure the spectrum of Hawking radiation and its temperature that led to the latest breakthrough. "Our artificial black hole confirms the thermal nature of Hawking radiation," explained the head of the research team, Prof. Jeff Steinhauer. "In addition, we found that the temperature is determined by the artificial gravity on the surface of the artificial black hole, also in accordance with Hawking's predictions."

The success of their research provides further insight into the nature of black holes, one of the least understood mysteries of the universe. The idea of ​​an object in space having such strong gravitational fields that light cannot escape was proposed back in the 18th century. The first modern theory about the existence of black holes was developed in 1916, but was not fully developed and was considered purely mathematical in nature until the mid-60s, when theories emerged following the understanding of the mechanism of the collapse of massive stars. Although they could not be seen, it was soon agreed that black holes exist in most galaxies.

After a decade of studying the phenomenon and the problem, the team of researchers has steadily improved its experimental tools over the past three years. The goal was not only to create artificial black holes, but also to develop measurement methods to test Hawking's predictions. To reach their conclusions, they repeated the Hawking radiation experiment 7,400 times, where for each "run" a density profile was obtained, from which the researchers calculated average values.

"Theoretical work, combined with our long-term research on the subject, enabled the observation of spontaneous Hawking radiation in an artificial black hole," reports Steinhauer. "The improvements in our experimental system allowed us to measure the thermals of Hawking's spectrum and compare the temperature with Hawking's prediction, according to gravity on the surface."

According to the researchers, this temperature (as predicted) creates an interesting connection between Hawking's theories and the theories of the astrophysicist Jacob Beckenstein. In 1972, Beckenstein also presented a theory about the thermodynamics of black holes. "Surprisingly, although their calculations were based on very different ideas, Hawking and Bekenstein reached the same conclusion that the temperature is determined by gravity on the surface of the black hole," said Steinhauer. "We confirmed their predictions."

While the Technion physicists' discovery sheds light on the nature of artificial black holes by measuring the emitted radiation spectrum (very similar to the spectrum emitted by a normal hot object), the low radiation levels not only confirm Hawking's theory, but may also lead to further research.

According to Steinhauer and his team, their findings provide clues not only about the nature of real black holes, but also about the "information paradox". According to Hawking, its radiation and thermal spectrum contain very little information. This idea is the basis of the information paradox that raises questions such as: What happens to information that falls into a real black hole? Has he disappeared from the universe? If not, where does he go?

The researchers found that the spectrum of Hawking radiation is indeed thermal. Therefore, the information paradox remains unsolved and future researchers will have to look elsewhere for answers to crack the information paradox puzzle.

for the scientific article

More of the topic in Hayadan:

• Scientists at the Technion have created a black hole that captures sound waves
• Even atoms, and not only electrons, are able to pass through a barrier
• "Hawking's discussion of black holes drew attention to the need to unify the basic teachings in science"
• Hawking did not claim that black holes do not exist, but that black holes do not have an event horizon