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In "The Physics of Star Trek" by Lawrence M. Krauss, he mentions that our universe, by all calculations, should actually be a black hole. I read it a while ago, but I think he mentioned that the mass in our (observable) universe is higher than the size of it, to the point where the observable universe is smaller than the Schwarzschild radius. If that is correct, then our universe should collapse into a singularity. Maybe I don't remember it correctly, or the problem is that we do not "see" the actual size of the universe, but only a small part (however, due to the homogenicity of it all, the density would be the same).

My question is if Krauss is correct in what he says (assuming I remember correctly), and if there is a reference to the original paper?

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marked as duplicate by DavePhD, John Rennie, Brandon Enright, Qmechanic May 8 '14 at 15:04

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No. The large scale geometry of the universe is described by the Friedmann-Lemaitre-Robertson-Walker metric.

The geometry of the spacetime of a black hole (in its simplest form) is described by the Schwartzschild metric.

These are totally different solutions of the Einstein Field Equations. For example, in the Schwarzschild metric, the timelike part of the spacetime is curved, in the FLRW metric they are planar.

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  • $\begingroup$ For others: There are some issues with this absolute statement, see the other question for for more information. $\endgroup$ – John Jan 18 at 14:16

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