A kind of echo in the received signals of gravitational waves can serve as confirmation that the event horizon of a black hole is a more complex formation than was previously thought. And recently, researchers at the University of Waterloo were the first to detect the signals of such a gravitational echo, the source of which, presumably, is the quantum “fluff” surrounding some of the newly formed black holes.

We remind our readers that gravitational waves are pulsations of the distortions of the space-time continuum that are caused by large-scale cosmic cataclysms, most often collisions of high-energy and dense, but compact objects in space, such as black holes and neutron stars.

“According to Albert Einstein’s General Theory of Relativity, nothing can escape from a black hole as soon as it passes a certain point of no return, known by the term event horizon”, says Niayesh Afshordi, professor of physics and astronomy, “So scientists thought until Stephen Hawking, using the theory of quantum mechanics, showed that, under certain conditions, quantum particles can slowly seep through the event horizon in the opposite direction, which is called Hawking radiation”.

“Moreover, scientists were not able to determine experimentally whether any matter leaves the black hole horizon before the first detection of gravitational waves”, explains Professor Afshordi, “and if the quantum” fluff “responsible for Hawking radiation really exists around black holes, it can become a kind of mirror reflecting gravitational waves, which would create gravitational signals of lower amplitude”.

Scientists from the University of Waterloo, working with colleagues from the Max Planck Institute of Gravitational Physics in Germany, recorded the first repetitive signals of the gravitational echo, which indicate that the nature of black holes and the nature of their event horizon are radically different from what Albert’s General Theory of Relativity indicates Einstein’s. Note that gravitational echo signals were detected in data collected by LIGO / Virgo detectors, which recorded waves from the collision of two neutron stars for the very first time.

The signals of the gravitational echo in form and other parameters completely correspond to the signals obtained by calculating the most complicated mathematical models of black breaths, which, using quantum mechanics, describe Hawking radiation and other related phenomena.

“Our results are still preliminary due to the very small chance that everything we managed to see was due to random interference in gravitational wave detectors. But this chance will decrease, and the reliability of the results will increase when we we’ll find other similar cases”, says Professor Afshordi. “And now that we know exactly what we need to look for, we will no doubt find more examples that will become a kind of “probes” for the quantum structure of space-time ennogo continuum”.

In conclusion, it should be noted that this work, entitled “Echoes from the Abyss: A highly spinning black hole remnant for the binary neutron star merger GW170817”, won first place in the Buchalter Cosmology Prize competition, in which only innovative theoretical and experimental work in the field of cosmology.