General Relativity2026-07-072 minarXiv:2607.06704expressBlack Hole Refrigerator: How Charge Controls HeatGas passing through a narrow valve can heat up or cool down: this is the Joule–Thomson effect, which powers refrigerators and air liquefiers. It turns out black holes can do the same.Shyamalee Bora·Dhruba Jyoti Gogoi·Pralay Kumar KarmakarFirst law of black hole mechanicsUnruh effectJacob BekensteinStephen HawkingWilliam Unruhgravitational potentialblack hole👍👎☆SimplePopularAdvanced