Cosmic eggs to relax the cosmological constant

Understand

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.