Predicted by Einstein 100 Years Ago, This Cosmic Phenomenon Has Finally Been Observed
jelizondo writes:
Futura reports the first observation of a phenomenon predicted by Einstein over a 100 years ago:
The event, catalogued as AT2020afhd, is what astronomers call a tidal disruption event. As the star approached the supermassive black hole, gravitational forces stretched and tore it apart. Its debris spiraled inward, forming a rapidly spinning disk of superheated gas. From that disk, jets of matter launched outward at nearly the speed of light.
As researchers tracked the event in X-ray and radio, they noticed something unexpected. The disk and the jet were wobbling in unison, completing a full cycle every 19.6 days. That synchronized motion pointed to a single cause: the black hole itself was dragging spacetime around with it as it spun, pulling the entire disk-and-jet system into a slow, rhythmic precession.
The phenomenon has a name: Lense-Thirring precession, or frame dragging. Einstein laid the theoretical groundwork in 1913. Physicists Josef Lense and Hans Thirring put it into mathematical form in 1918. Until now, no one had observed it so directly around a black hole.
The study, published December 10, 2025 in Science Advances, was led by Yanan Wang and colleagues at the National Astronomical Observatories of the Chinese Academy of Sciences, with support from a multinational team including Cardiff University. To detect the precession, researchers combined data from NASA's Neil Gehrels Swift Observatory and the Karl G. Jansky Very Large Array, cross-referencing X-ray and radio observations over several months.
Dr. Cosimo Inserra, Reader in the School of Physics and Astronomy at Cardiff University and one of the paper's co-authors, described the detection plainly. A spinning black hole drags spacetime along with it the way a spinning top stirs water in a whirlpool. When incoming gas orbits at a tilt, the inner disk wobbles. Any jet anchored to that disk wobbles with it.
[...] Prior tidal disruption events showed steady radio signals. AT2020afhd did not. Its short term radio variability couldn't be attributed to the energy output of the black hole or its surrounding components, which, Inserra noted, further confirms the dragging effect and offers a new observational tool for studying similar events in the future.
Black holes have been studied through their effects on light, gas, and nearby stars for decades. AT2020afhd doesn't just add another data point to that record, it makes the mechanics of spacetime distortion directly measurable for the first time.
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