We went to a planetarium last night last night and watched "Black Holes" narrated by Liam Neeson. If I recall correctly, he said that scientists believe that they have identified a number of Black Holes, and that they think there are White Holes at the bottom of Black Holes and instead of drawing matter/light in, the White Holes spew matter out. I didn't get to ask this question after the session was over: Have scientists been able to find an example of a possible White Hole?
It's only a fictional object that agrees with einstein's formulas. But there is no evidence that that objects exists or had existed.
White hole is possible under General Relativity but violates the second law of thermodynamics. It is thus impossible.