A black hole differs from a white one not only in color, but also in the quality of the opposite. If a black hole is an entrance without an exit, then a white hole is an exit without an entrance. Thus, they can form one «space tunnel».
A white hole is a hypothetical physical object of the universe, into which nothing can get. From white holes, matter only comes out — unlike real-life black holes, which pull everything into themselves, including light. According to some scientists, if there are black holes in the universe, then there must be their antipodes — white holes into which nothing can enter.
Most theories about white holes explain their properties through the concept of a black hole, because black holes really exist and are actively studied. White holes have been discovered so far only in theory: this is a mathematical concept that has no real confirmation.
The argument for the existence of white holes is Albert Einstein’s general theory of relativity (GRT). It has equations relating to wormholes or «wormholes» — tunnels in space-time. The general theory of relativity allows for the existence of such tunnels. In 1916, German scientist Karl Schwarzschild was the first in the world to use GRT to solve a specific astrophysical problem. One of the consequences of Schwarzschild’s decision is a wormhole named after him, which consists of a black hole, a white hole and two separate universes connected through them. His mathematical equations that predicted the existence of black holes also predict white holes.
*A white hole is a hypothetical physical object in the universe, their existence has not been proven.
