Similar to sonic echoes, such signatures would be much weaker and ever-so-slightly delayed, compared with the original gravitational waves from the merger.Įxactly what such echoes would look like depends on the exact physics being modeled. If so, echolike signatures of this could be present in the information collected by LIGO, Virgo and other detectors. Physicists think that some combination of quantum physics and general relativity is needed to fully describe black holes, in which case it is possible that a portion of the infalling gravitational waves could be reflected-either because of quantum effects near the horizon or because the dense, compact object created by the merger lacks a horizon and has some internal structure. So the inward-going gravitational waves should just disappear.īut that might not be what happened. “In the standard black hole picture, the event horizon of a black hole absorbs all the radiation,” says Paolo Pani, a theoretical physicist at Sapienza University of Rome. If black holes are described entirely by Einstein’s general theory of relativity, then they have an event horizon-a one-way boundary that anything can fall into but from which nothing can escape. What happened next depends on your view of black hole physics. The gravitational waves from this event, named GW190521, not only rippled out to eventually interact with LIGO’s and Virgo’s detectors on Earth they also washed over the remnant black hole produced by the initial collision. “This is the most massive event observed to date,” says Jahed Abedi of the University of Stavanger in Norway, who co-authored a preprint paper in which he and his colleagues claim to have measured the Hawking radiation of this merger.

The difference of nine solar masses was radiated away, almost all of it in the form of gravitational waves. The merger left behind a black hole of 142 solar masses. and Virgo in Italy observed gravitational waves-ripples in the fabric of space-time-from the merger of two black holes that had a total mass of 151 suns. In May 2019 the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the U.S. The claim, however, is extremely controversial, because other searches for such echoes of gravitational waves have come up empty-handed. And they are now claiming to have seen signs of it in the aftermath of the most massive collision of black holes ever observed. But if this “Hawking radiation” could somehow be stimulated and amplified, it might be detectable, according to some astrophysicists. Hawking’s prediction shook physics to its core because it implied that black holes cannot last forever and that they instead, over eons, evaporate into nothingness-except, however, for one small problem: there is simply no way to see such faint radiation. In 1974 Stephen Hawking theorized that black holes are not black but slowly emit thermal radiation.

Stephen hawking black hole theory