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If TIME slows down as you approach a Black Hole, has there been sufficient time in our Universe (13.8 Billion Years since the Big Bang occurred) for ANY matter inside the Event Horizon of ANY Black Hole to reach the "center" - or form a singularity ? In the given age of our Universe (13.8 Billion Years) would not all Black Holes be huge (rotating) spherical SHELLS where the in-falling Matter accumulates and gets compressed just inside of the Event Horizon and , in it's very slow time frame, has not had sufficient time to traverse the space toward the supposed central SINGULARITY ? This might obviate the actual existence of "Singularities". That is, there may not been sufficient elapsed TIME (in 13.8 Billion of our years) for any singularity to have actually formed in OUR 'normal time' universe. It might be that our Universe is too young to have had enough time (inside the Black Holes) for a true 'singularity' to have formed....it may be an ongoing process and takes maybe Trillions of years to accomplish.