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.