Black holes might have 'hair' that lets them feel and remember how the entire universe is expanding.
March 25, 2026
Original Paper
Stable black hole solutions with cosmological hair
arXiv · 2603.22398
The Takeaway
Usually, black holes are thought to be defined only by their mass and spin, ignoring the rest of the universe. This discovery suggests they are actually physically linked to dark energy, meaning we could study the fate of the cosmos by looking at individual black holes.
From the abstract
Dynamical dark energy theories generically introduce a time-dependent field that causes the accelerated expansion of the Universe on large scales. When embedding black hole solutions in such a cosmological space-time, this time dependence naturally gives rise to cosmological hair, i.e. the local black hole physics is no longer controlled by just the mass and spin of the black hole, but also impacted by the dark energy field. However, known such solutions are unstable. Focusing on the cubic Galil