Black holes have this weird 'fuzz' that lets them remember everything that’s ever fallen in, long after the object is gone.
arXiv · March 16, 2026 · 2603.12670
Why it matters
Physicists have found that quantum charges on a black hole's horizon, known as 'soft hair,' cause its visual image to rotate and move over time. If a smaller object passes nearby, it can leave a 'smoking gun' shift in the black hole's shadow that future detectors could use to prove these exotic structures exist.
From the abstract
Soft hairs of black holes are the Noether charges associated to the generalized Bondi-Metzner-Sachs symmetries. In this work, the images of soft-haired Kerr black holes were studied. For an eternal black hole, the image is rotated, dilated and drifting compared to that of the bald counterpart in the celestial plane. The rotation and the dilation are independent of the time, while the drifting is at a constant speed and in a fixed direction. These effects all depend on angular directions. The sof