We investigated general black hole solutions in Einstein-Gauss-Bonnet theory, compactified from five to four dimensions. The effective theory includes gravity, electromagnetism, and a scalar field with nonlinear corrections to the action and nontrivial interactions. Solutions are classified by mass, electric and magnetic charges. We found features not present in the standard Kaluza-Klein theory without Gauss-Bonnet terms: the existence of an extreme mass even in the neutral case. Thermodynamics is also altered — extreme black holes have nonzero temperature and entropy.
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.
🎯 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.