The international LVK network of scientists, which includes three researchers from the National Centre for Nuclear Research (NCBJ), has confirmed Stephen Hawking’s theory that the total surface area of black holes never decreases, NCBJ reported on Friday. This comes ten years after the first detection of gravitational waves.
“It is a great satisfaction for me that after years of work we can confirm one of Stephen Hawking’s most important predictions. Gravitational waves opened a new window to the Universe, and now they also allow us to verify the fundamental laws of black hole physics. I am glad that together with the team from the National Centre for Nuclear Research and the Polgraw–Virgo group we could contribute to this breakthrough discovery,” said Prof. Andrzej Królak of the Department of Astrophysics at NCBJ, quoted in the communiqué.
Prof. Królak, together with Dr. Orest Dorosh and Dr. Sreekanth Harikumar from NCBJ’s Department of Astrophysics, are members of the Polgraw–Virgo group, which made this discovery in collaboration with the LVK team.
Ten years earlier, on 14 September 2015, a very faint signal reached Earth after travelling through space for 1.3 billion years. “It was not a light signal, but a subtle vibration of spacetime itself—gravitational waves, first predicted by Albert Einstein a hundred years earlier. On that day, the twin Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors recorded the first direct evidence of the existence of gravitational waves—an achievement announced to the world in February 2016,” the communiqué recalled.
Since then, the LIGO detectors in Hanford (Washington, USA) and Livingston (Louisiana, USA), together with the Virgo detector in Italy and KAGRA in Japan, have formed an international network known as LVK (LIGO–Virgo–KAGRA).
According to NCBJ, within this collaboration an average of one black hole collision is now recorded every three days. To date, the network has observed more than 300 black hole mergers, many already confirmed and others awaiting analysis. During its fourth series of observations, LVK identified about 230 candidate collisions—more than twice the total from the first three series combined.
The communiqué highlighted that the enormous progress in detector sensitivity is illustrated by the most recent discovery, GW250114 (recorded on 14 January 2025). “As with the first detection, GW150914, this event involved two black holes of about 30–40 solar masses colliding at a distance of 1.3 billion light-years from Earth. However, thanks to a decade of technological improvements reducing instrumental noise, the new signal is much clearer and allows for more precise measurements,” NCBJ noted.
In their latest article, published on 10 September this year, the LVK team reported that this event provided the strongest observational evidence to date for Stephen Hawking’s black hole area theorem.
First formulated in 1971, the theorem states that the total surface area of black holes cannot decrease. During a merger, black holes lose energy in the form of gravitational waves and can simultaneously increase their spin, or internal angular momentum, which could in principle reduce their surface area. However, the theorem predicts that despite these factors, the final black hole will always have a larger surface area than the combined surface areas of the black holes before the collision.
“GW250114 confirms this prediction with unprecedented precision. Prof. Królak has generalised the theorem to also include cosmological cases,” the communiqué noted.
Source: naukawpolsce.pl
