The obscure regions of space called BH have, at least theoretically, a counterpart mathematical description, which would imply an opposite behavior; a region of space where nothing — not even light — could ever enter. For this reason, they are referred to as white holes (WH). Just as BH, WH started as a hypothetical mathematical situation with no equivalence in the physical realm, and just as BH, maybe WH do exist after all.
White holes, which are theoretically the exact opposites of black holes, could constitute a major portion of the mysterious dark matter that's thought to make up most of the matter in the universe, a new study finds. And some of these bizarre white holes may even predate the Big Bang, the researchers said.
Previous research has suggested that black holes and white holes are connected, with matter and energy falling into a black hole potentially emerging from a white hole either somewhere else in the cosmos or in another universe entirely. In 2014, Carlo Rovelli, a theoretical physicist at Aix-Marseille University in France, and his colleagues suggested that black holes and white holes might be connected in another way: When black holes die, they could become white holes.