Black holes resemble funnels in a stretched sheet. But if we allow a fifth dimension, the sheet gains hidden springs. Any mass, even uncharged, indents it not to infinity, but to a clear limit. Thus, spacetime curvature gets nonlinear corrections — a new kind of black holes with an innate minimum mass.
And the main surprise: reaching that limit, the hole doesn't cool to absolute zero. Its entropy, a measure of hidden disorder, doesn't vanish, as standard theory would demand. It turns out the universe is strewn with invisible warm cores that hold the memory of hidden dimensions.
as written by the authors arXiv:2603.07125
We study the general black hole solutions of dimensionally reduced five-dimensional Einstein-Gauss-Bonnet gravity. The reduced theory contains gravity, electromagnetism and a scalar field, with nonlinear corrections to the action and nontrivial couplings. The solutions can be classified through mass and electric and magnetic charge. They present peculiar features with respect to the solutions of the standard Kaluza-Klein theory without Gauss-Bonnet corrections, like the existence of an extremal mass even in the neutral case. Also the thermodynamics is affected, for example, extremal black holes display nonvanishing temperature and entropy.
Usually, an uncharged black hole should evaporate completely. But with an extra dimension, it leaves behind a warm, indestructible clot of spacetime.
It brings to mind 'Interstellar': Gargantua warped time thanks to hidden dimensions. This work makes the science fiction a bit more real.