Cosmic eggs to relax the cosmological constant. Issue 8 (31st August 2021)

• Record Type: Journal Article
• Authors: Hertog, Thomas; Tielemans, Rob; Van Riet, Thomas
• Is Part Of: Journal of cosmology and astroparticle physics. Volume 2021:Issue 8(2021)
• Publication Date: 2021-08-31
• Subjects: cosmological applications of theories with extra dimensions -- initial conditions and eternal universe -- quantum cosmology -- string theory and cosmology; Cosmology -- Periodicals; Astrophysics -- Periodicals; 523.0105
• DOI: 10.1088/1475-7516/2021/08/064
• Languages: English
• ISSNs: 1475-7516

Abstract

Abstract: In theories with extra dimensions, the cosmological hierarchy problem can be thought of as the unnaturally large radius of the observable universe in Kaluza-Klein units. We sketch a dynamical mechanism that relaxes this. In the early universe scenario we propose, three large spatial dimensions arise through tunneling from a `cosmic egg', an effectively one-dimensional configuration with all spatial dimensions compact and of comparable, small size. If the string landscape is dominated by low-dimensional compactifications, cosmic eggs would be natural initial conditions for cosmology. A quantum cosmological treatment of a toy model egg predicts that, in a variant of the Hartle-Hawking state, cosmic eggs break to form higher dimensional universes with a small, but positive cosmological constant or quintessence energy. Hence cosmic egg cosmology yields a scenario in which the seemingly unnaturally small observed value of the vacuum energy can arise from natural initial conditions.