Emergent Universe Explained

An emergent Universe scenario is a cosmological model that features the Universe being in a low-entropy "dormant" state before the Big Bang or the beginning of the cosmic inflation. 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) until a rolling scalar field begins inflating it. These models are notable as potentially avoiding both a Big Bang singularity and a quantum gravity era.^[1]

Criticism

This proposal has been criticised by Vilenkin and Mithani^[2] and on different grounds by Aguirre and Kehayias^[3] as inconsistent if quantum-mechanical effects are taken into account.

Notes and References

1. The Emergent Universe: inflationary cosmology with no singularity. George. Ellis. Roy. Maartens. January 7, 2004. Classical and Quantum Gravity. 21. 1. 223–232. 10.1088/0264-9381/21/1/015. gr-qc/0211082. 2004CQGra..21..223E . 250819315 .
2. Collapse of simple harmonic universe. Audrey T.. Mithani. Alexander. Vilenkin. January 10, 2012. Journal of Cosmology and Astroparticle Physics. 2012. 1. 28. 10.1088/1475-7516/2012/01/028. 1110.4096. 2012JCAP...01..028M . 250740037 .
3. Quantum Instability of the Emergent Universe. Anthony. Aguirre. John. Kehayias. November 7, 2013. Physical Review D. 88. 10. 103504. 10.1103/PhysRevD.88.103504. 1306.3232. 2013PhRvD..88j3504A . 118348623 .