The relationship between Black and White Holes.
Since they were first postulated by Oppenheimer and Volkoff  Black Holes have been a popular area of science. This is in part to their mysterious nature and also to them providing science fiction writers with a handy Deus Ex in stories. In turn this has led to Black Holes being part of everyday vocabulary and knowledge despite the fact that we know very little of them. This mysterious nature was partially reinforced by our inability to detect Black Holes and so prove their existence for much of the 20th Century in fact it was only into the 1970s that laws explaining how they could exist and be tracked were proven . It has also been shown that we can now detect Black Holes due to their radio frequency output .
There has also been links shown between Black Holes and White Holes. The evidence supporting the relationship between the two has been shown experimentally in laboratories and the red and blue shift associated with light at their respective horizons . The linking of White and Black holes in a similar way to which two ends of an Einstein-Rosen bridge link  is an interesting thought when we consider the nature of Black Holes. Often we think of them as being similar to either an egg timer or a funnel. This is our 2D way of resolving something in 4D which our minds can’t comprehend. If ever you have seen a Black Hole on a film or television program you may have seen that they appear to be disks which then funnel inwards linking another part of space-time. However space time is not a 2D flat land and so the disk idea of a Black Hole does not fit.
A better analogy for our minds to understand is to imagine space-time as being something denser that we are familiar with. If you can picture a giant swimming pool and imagine that the swimming pool has objects suspended into it – similar to how space has planets and stars. Now if we imagine something akin to a black marble suspended in the water, then that would be more similar to a Black Hole than a disk like object. The reason being that whichever angle we approach the Black Hole would be the same as the other directions of approach. If we are in our swimming pool universe then we could swim around the black marble and it would be identical from all angles. This would be more in keeping with the high gravity present than a disk shaped Black Hole.
Why is this analogy important? We have evidence proving that Black and White Holes are able to exist in space-time   although as yet no way to identify White Holes then it is important to consider their relationship to one another. The reason for this is that there is an idea that they are joined together so that the Black Hole will lead to the White Hole. If we consider the Black Hole to be the marble in a swimming pool however, then there can be nowhere for it to lead to, at least not in our perception of space and time. This is because you can move around the Black Hole and not disturb any passage way it might be creating. As it is in an environment which is at least 3D then there has to be another solution which does not involve a drastic alteration of what is the fabric of reality. A possible solution lies in the idea that our Universe is within a Black Hole, and as such would be a White Hole . In this idea imagine that a Black Hole is within another Universe (U0). The Black Hole is absorbing matter from U0 and expanding. Inside U0 the matter is able to be compressed and drawn together due to gravity and form stars, nebulae and galaxies. As a result we could begin to think of another Universe (U1) as having begun to exist within the confines of the original U0 Black Hole. As the Black Hole begins to engulf more matter it stands to reason that it would begin to expand, giving rise to our evidence of an expanding universe. Also there is no reason for the U1 to have begun with a Big Bang, which would still fit our models of the creation of everything and also answer the question of where the initial matter came from. In this way we have the inverse of a Black Hole present, a White Hole and our idea of the cosmic marble works. It is just that the marble is gradually expanding.
This concept works if we accept that due to scale it is possible for the Universe either U1 or U0 to be much larger than we can ever imagine. In the same way that electrons are much smaller than human minds are able to comprehend just by observing the macro structure of the Universe. It does not however concern the formation of Einstein-Rosen Bridges but just that Black Holes lead to White Holes. Only that instead of the White Hole being another point in the same space time the White Hole is within the Black Hole and present as a separate Universe, in this example U1.
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