An emergent Universe scenario is a cosmological model that features the Universe being in a low-entropy "dormant" state before the

Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from t ...

or the beginning of the

cosmic inflation In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from seconds after the conjectured Big Bang singulari ...

. Several such scenarios have been proposed in the literature.

"Cosmic egg" scenarios

A popular version proposed by George Ellis and others involves the Universe shaped like a 3-dimensional sphere (or another

compact manifold In mathematics, a closed manifold is a manifold without boundary that is compact. In comparison, an open manifold is a manifold without boundary that has only ''non-compact'' components. Examples The only connected one-dimensional example i ...

) until a rolling scalar field begins inflating it. These models are notable as potentially avoiding both a Big Bang singularity and a

quantum gravity Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics; it deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the v ...

era.

Criticism

This proposal has been criticised by Vilenkin and Mithani and on different grounds by Aguirre and Kehayias as inconsistent if quantum-mechanical effects are taken into account.

References

{{Reflist Physical cosmology