# Was our Universe born inside a Black Hole [duplicate]

Is there any possibility that our Universe was just born inside a Black Hole? If so, then mathematically prove that it happened and if it didn't happen, then please mathematically disprove it.

• This needs more details to be answerable. Perhaps you are refering to the observation that a black hole with a mass the size of the observable universe would have a radius about the same as the observable universe. Oct 10 '20 at 9:17
• – user24157
Oct 10 '20 at 10:37
• No................ Oct 10 '20 at 13:48
• Mine was, but it's a secret.
– uhoh
Oct 11 '20 at 1:18
• The math proof is hard and over my skills. But, what I know: the space-like slices of the Universe are flat, while of the Block Hole are curved. The Universe is not static in time, the black hole is. So, on the level of the formulas, these looks really very different, but... a physicist once explained to me that a bijection between them is still possible. So, really we do not know. They look very different on the first spot, but possibly these are not so different. Oct 15 '20 at 15:44

Near a big black hole the geometry is very directional. The radial coordinate behaves very differently from the other two spatial directions: a spherical object even when falling freely is squeezed from the sides and pulled apart radially. When you are inside the event horizon this remains true, although the radial coordinate in some sense becomes like time: it is not possible to move towards larger $$r$$. The spaghettification still applies.