Soviet physicists L. Gurevich and V. Mostepanenko considered the possibility that there may exist an ensemble of universes in this unimaginably vaster spacetime manifesting all possible dimensionalities and physical laws. It may also be possible that the creation of new universes is a process occurring even now. Since their expansion occurs in a region of spacetime completely disconnected from our own, they are forever beyond observation. The artificial manufacture of such universes may be possible under laboratory conditions, unfortunately, the same calculations seem to indicate that these conditions may not be easily achievable. A similar idea of bubbling baby universes was later formulated by K. Ghoroku and Sidney Coleman in 1994.
Universes can interact with each other at the quantum level via wormholes.
A great many universes could be created from nothing, each disconnected at the scale we live in, but in contact at the Planck-level via a process called 'quantum wormhole interference'. These universes are considered to be defined by fields in superspace, and can be coherently coupled to each other via universal wave functions. As a result of quantum interference, and the spawning of baby universes by our own spacetime, the cosmological constant has a vanishing magnitude in all universes similar to our own as Sidney Coleman pointed out. Stringy Cosmology M. Gasperini and G. Veneziano applied string theory to understanding the physics of the Big Bang near the Planck Era and found that Singularity might actually be avoidable at the quantum level. The curvature grows to a maximum, then starts decreasing as we pass through the Planck Time into the present expansion era.