24-26 September 2020
Europe/Warsaw timezone

Universe in a black hole with spin and torsion

25 Sep 2020, 17:15
20m
selected talk Cosmology

Speaker

Nikodem Popławski (University of New Haven)

Description

The conservation law for the total (orbital and spin) angular momentum of a Dirac particle in the presence of gravity requires that spacetime is not only curved, but also has a nonzero torsion. The coupling between the spin and torsion in the Einstein-Cartan theory of gravity generates gravitational repulsion at extremely high densities. We consider gravitational collapse of a spin-fluid sphere into a black hole. We show that a singularity is replaced with a nonsingular bounce if there is no shear. We also show that torsion and quantum particle production during contraction avoid a singularity even if shear is present. Particle production during expansion can generate a finite period of inflation and produce enormous amounts of matter. The resulting closed universe on the other side of the event horizon may have several bounces. Such a universe is oscillatory, with each cycle larger in size then the previous cycle, until it reaches the cosmological size and expands indefinitely. Our universe might have therefore originated from a black hole.

Primary author

Nikodem Popławski (University of New Haven)

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