[NTD News, Beijing time, December 21, 2025]On December 18, scientists announced that they had directly observed evidence that a rotating black hole distorts the space-time of the universe for the first time. Imagine that when you stir a bowl of sugar water, the rotating spoon will cause the surrounding water to rotate with it. Now, this scene has been enlarged to the scale of the universe. A huge black hole is spinning. It not only swallows everything, but also “drags” the surrounding space and time, making the entire structure of the universe twist like stirred sugar water.
This discovery was published in the latest journal Science Advances and was completed by a research team led by the National Astronomical Observatory of the Chinese Academy of Sciences and supported by Cardiff University. It not only confirmed Einstein’s prediction more than 100 years ago, but also revealed more secrets of black holes for us.
Black holes are among the most extreme objects in the universe. It is formed by the collapse of a star. When a massive star runs out of fuel, its core collapses into an extremely dense point – the singularity. The gravitational pull of a black hole is so strong that not even light can escape.
According to the general theory of relativity proposed by Albert Einstein in 1915, gravity is not a “force” but the curvature of space-time. Spacetime is like a giant rubber membrane, and heavy objects (such as planets or black holes) can dent it, affecting the motion of nearby objects.
Rotating black holes are even more special: they not only bend space-time, but also “drag” it, just like a high-speed spinning top pulling on the surrounding air. This is the so-called “frame drag” effect. Simply put, when a black hole rotates, it “churns” space-time like a blender, causing the orbits of nearby matter to wobble. This effect is minimal in daily life, but near a black hole, it can create dramatic cosmic events.
The focus of the research team is a tidal disruption event (TDE) called AT2020afhd. What is TDE? Imagine a star that is unfortunately close to a supermassive black hole. The black hole’s gravity pulls on the star’s ends like a tidal force, tearing it into pieces. The debris will form an “accretion disk” that orbits the black hole – a hot, spinning ring of material, like Saturn’s rings but more violent. From this disk, the black hole will eject high-energy material streams approaching the speed of light, called “jets.” In the AT2020afhd event, scientists found that the accretion disk and jets were oscillating in a 20-day cycle. This is not random shaking, but direct evidence that the black hole’s rotation drags space-time.
Why is this the first time? In the past, scientists have seen stable signals in other TDEs, but AT2020afhd’s signal had short-term changes that could not be explained by energy release. This convinced the team that this was “frame drag” at work. By analyzing X-ray, radio and spectroscopic data, they mapped out how black holes act like magnets and produce “gravitational magnetic fields” that affect nearby matter.
Shockingly, Einstein proposed that black holes would produce a “frame drag” effect more than 100 years ago, but only now do we have the technology to capture it and directly confirm a key prediction of general relativity. It helps us understand how fast a black hole spins, the accretion process (how matter falls into a black hole), and the formation of jets. Jets are one of the most powerful energy sources in the universe and can influence the evolution of entire galaxies. Knowing how black holes drag space and time allows us to better simulate these processes and even predict more TDE events.
(Comprehensive reporting by reporter Li Siwen/Editor in charge: Lin Qing)
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