Stephen Hawking was right. The late a theoretical physicist and cosmologist predicted the existence of black holes. A black hole defined as a dark mass, invisible, with such strong gravity that nothing, even light, couldn’t escape its grip and thus it did not emit radiation.
Hawking’s radiation requires a thermal spectrum, similar to the radiation from any hot object. The temperature of the Hawking radiation should agree with the temperature predicted by astrophysicist Jacob Bekenstein.
Now, a team of researchers at the Technion, Israel Institute of Technology, have modeled an artificial black hole and, by devising a way to measure the spectrum of Hawking radiation, they have found that black holes do emit radiation like an ordinary warm object, as Hawking claimed.
What led to the breakthrough was the ability of the Israeli team to create an artificial black hole and measure the temperature of Hawking’s radiation spectrum
“Our artificially-constructed black hole provides confirmation of the thermality of Hawking radiation,” explained lead researcher Professor Jeff Steinhauer. “In addition, we found that the temperature is determined by the artificial gravity at the surface of the artificial black hole, also consistent with Hawking’s predictions.”
The success of their work is yet another profound insight into the nature of black holes, among the most mysterious and least understood secrets of the universe.
The idea that there is an object in the space with gravitational fields so strong that it does not allow light to escape began in the 18th century.
The first modern theory of black holes developed in 1916, but was considered only mathematical theory.
In the late 1960s, theories became reality when theories were sparked by knowledge about the collapse of massive stars. Although they could not be seen, a consensus was soon reached that black holes existed in most galaxies.
Having studied this phenomenon for a decade, the research team made constant improvements to their experimental tools over the last three years. To reach their conclusions, the Hawking radiation experiment was repeated 7,400 times, providing a density profile for each “run” from which the researchers computed averages.
“The improvements in our experimental apparatus allowed us to measure the thermality of the Hawking spectrum and compare its temperature with Hawking’s prediction, given by the surface gravity,” reported Steinhauer.
According to the researchers, that temperature, as predicted, provides an interesting link between the theories of Hawking and those of astrophysicist Jacob Bekenstein. In 1972, Bekenstein also presented a theory on black hole thermodynamics.
“Remarkably, although their calculations were based on very different ideas, both Hawking and Bekenstein came up with the same conclusion that the temperature was determined by the gravity at the surface of the black hole,” said Steinhauer. “We confirmed their predictions.”
The discovery made by the Technion physicists makes clearer the nature of black holes by measuring the spectrum emitted, very similar to the spectrum that would be emitted by an ordinary warm object. The low levels of radiation not only confirm Hawking’s theory, but could also lead to further research.
According to Steinhauer and his team, their findings provide not only hints about the nature of real black holes, but also about the “information paradox.” According to Hawking, the radiation and its thermal spectrum contain very little information. This idea is the basis of the information paradox, which poses questions such as: What is the fate of information that falls into a real black hole? Does it disappear from the universe? And, if not, where does it go?
The researchers found that the spectrum of the Hawking radiation is indeed thermal. So, the information paradox remains unresolved, with future researchers needing to look elsewhere to investigate the information paradox enigma.
The research appeared in Nature.