What are White Holes??

 White Holes are not things that actually exist. They are the hypothetical region of spacetime which cannot be entered from the outside. They are totally opposite to black holes.. energy matter and light can escape from it.

White Holes repel positive mass.. this is why black holes and white Holes can never collide as black holes are positive masses.

Physicist believe that white holes might explain the big bang theory since this is another situation where a tremendous amount of matter and energy spontaneously appeared.

If white holes exist, which they probably don't, they would behave like reverse black holes. Instead of pulling material inward, a white holes would blast material out into space like some kind of white chocolate fountain.